Merge tag 'staging-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh...

[linux.git] / kernel / bpf / btf.c

/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2018 Facebook */

#include <uapi/linux/btf.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/sort.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
#include <net/sock.h>

/* BTF (BPF Type Format) is the meta data format which describes
 * the data types of BPF program/map.  Hence, it basically focus
 * on the C programming language which the modern BPF is primary
 * using.
 *
 * ELF Section:
 * ~~~~~~~~~~~
 * The BTF data is stored under the ".BTF" ELF section
 *
 * struct btf_type:
 * ~~~~~~~~~~~~~~~
 * Each 'struct btf_type' object describes a C data type.
 * Depending on the type it is describing, a 'struct btf_type'
 * object may be followed by more data.  F.e.
 * To describe an array, 'struct btf_type' is followed by
 * 'struct btf_array'.
 *
 * 'struct btf_type' and any extra data following it are
 * 4 bytes aligned.
 *
 * Type section:
 * ~~~~~~~~~~~~~
 * The BTF type section contains a list of 'struct btf_type' objects.
 * Each one describes a C type.  Recall from the above section
 * that a 'struct btf_type' object could be immediately followed by extra
 * data in order to desribe some particular C types.
 *
 * type_id:
 * ~~~~~~~
 * Each btf_type object is identified by a type_id.  The type_id
 * is implicitly implied by the location of the btf_type object in
 * the BTF type section.  The first one has type_id 1.  The second
 * one has type_id 2...etc.  Hence, an earlier btf_type has
 * a smaller type_id.
 *
 * A btf_type object may refer to another btf_type object by using
 * type_id (i.e. the "type" in the "struct btf_type").
 *
 * NOTE that we cannot assume any reference-order.
 * A btf_type object can refer to an earlier btf_type object
 * but it can also refer to a later btf_type object.
 *
 * For example, to describe "const void *".  A btf_type
 * object describing "const" may refer to another btf_type
 * object describing "void *".  This type-reference is done
 * by specifying type_id:
 *
 * [1] CONST (anon) type_id=2
 * [2] PTR (anon) type_id=0
 *
 * The above is the btf_verifier debug log:
 *   - Each line started with "[?]" is a btf_type object
 *   - [?] is the type_id of the btf_type object.
 *   - CONST/PTR is the BTF_KIND_XXX
 *   - "(anon)" is the name of the type.  It just
 *     happens that CONST and PTR has no name.
 *   - type_id=XXX is the 'u32 type' in btf_type
 *
 * NOTE: "void" has type_id 0
 *
 * String section:
 * ~~~~~~~~~~~~~~
 * The BTF string section contains the names used by the type section.
 * Each string is referred by an "offset" from the beginning of the
 * string section.
 *
 * Each string is '\0' terminated.
 *
 * The first character in the string section must be '\0'
 * which is used to mean 'anonymous'. Some btf_type may not
 * have a name.
 */

/* BTF verification:
 *
 * To verify BTF data, two passes are needed.
 *
 * Pass #1
 * ~~~~~~~
 * The first pass is to collect all btf_type objects to
 * an array: "btf->types".
 *
 * Depending on the C type that a btf_type is describing,
 * a btf_type may be followed by extra data.  We don't know
 * how many btf_type is there, and more importantly we don't
 * know where each btf_type is located in the type section.
 *
 * Without knowing the location of each type_id, most verifications
 * cannot be done.  e.g. an earlier btf_type may refer to a later
 * btf_type (recall the "const void *" above), so we cannot
 * check this type-reference in the first pass.
 *
 * In the first pass, it still does some verifications (e.g.
 * checking the name is a valid offset to the string section).
 *
 * Pass #2
 * ~~~~~~~
 * The main focus is to resolve a btf_type that is referring
 * to another type.
 *
 * We have to ensure the referring type:
 * 1) does exist in the BTF (i.e. in btf->types[])
 * 2) does not cause a loop:
 *      struct A {
 *              struct B b;
 *      };
 *
 *      struct B {
 *              struct A a;
 *      };
 *
 * btf_type_needs_resolve() decides if a btf_type needs
 * to be resolved.
 *
 * The needs_resolve type implements the "resolve()" ops which
 * essentially does a DFS and detects backedge.
 *
 * During resolve (or DFS), different C types have different
 * "RESOLVED" conditions.
 *
 * When resolving a BTF_KIND_STRUCT, we need to resolve all its
 * members because a member is always referring to another
 * type.  A struct's member can be treated as "RESOLVED" if
 * it is referring to a BTF_KIND_PTR.  Otherwise, the
 * following valid C struct would be rejected:
 *
 *      struct A {
 *              int m;
 *              struct A *a;
 *      };
 *
 * When resolving a BTF_KIND_PTR, it needs to keep resolving if
 * it is referring to another BTF_KIND_PTR.  Otherwise, we cannot
 * detect a pointer loop, e.g.:
 * BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
 *                        ^                                         |
 *                        +-----------------------------------------+
 *
 */

#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
#define BITS_ROUNDUP_BYTES(bits) \
        (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))

#define BTF_INFO_MASK 0x8f00ffff
#define BTF_INT_MASK 0x0fffffff
#define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
#define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)

/* 16MB for 64k structs and each has 16 members and
 * a few MB spaces for the string section.
 * The hard limit is S32_MAX.
 */
#define BTF_MAX_SIZE (16 * 1024 * 1024)

#define for_each_member(i, struct_type, member)                 \
        for (i = 0, member = btf_type_member(struct_type);      \
             i < btf_type_vlen(struct_type);                    \
             i++, member++)

#define for_each_member_from(i, from, struct_type, member)              \
        for (i = from, member = btf_type_member(struct_type) + from;    \
             i < btf_type_vlen(struct_type);                            \
             i++, member++)

#define for_each_vsi(i, struct_type, member)                    \
        for (i = 0, member = btf_type_var_secinfo(struct_type); \
             i < btf_type_vlen(struct_type);                    \
             i++, member++)

#define for_each_vsi_from(i, from, struct_type, member)                         \
        for (i = from, member = btf_type_var_secinfo(struct_type) + from;       \
             i < btf_type_vlen(struct_type);                                    \
             i++, member++)

DEFINE_IDR(btf_idr);
DEFINE_SPINLOCK(btf_idr_lock);

struct btf {
        void *data;
        struct btf_type **types;
        u32 *resolved_ids;
        u32 *resolved_sizes;
        const char *strings;
        void *nohdr_data;
        struct btf_header hdr;
        u32 nr_types;
        u32 types_size;
        u32 data_size;
        refcount_t refcnt;
        u32 id;
        struct rcu_head rcu;
};

enum verifier_phase {
        CHECK_META,
        CHECK_TYPE,
};

struct resolve_vertex {
        const struct btf_type *t;
        u32 type_id;
        u16 next_member;
};

enum visit_state {
        NOT_VISITED,
        VISITED,
        RESOLVED,
};

enum resolve_mode {
        RESOLVE_TBD,    /* To Be Determined */
        RESOLVE_PTR,    /* Resolving for Pointer */
        RESOLVE_STRUCT_OR_ARRAY,        /* Resolving for struct/union
                                         * or array
                                         */
};

#define MAX_RESOLVE_DEPTH 32

struct btf_sec_info {
        u32 off;
        u32 len;
};

struct btf_verifier_env {
        struct btf *btf;
        u8 *visit_states;
        struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
        struct bpf_verifier_log log;
        u32 log_type_id;
        u32 top_stack;
        enum verifier_phase phase;
        enum resolve_mode resolve_mode;
};

static const char * const btf_kind_str[NR_BTF_KINDS] = {
        [BTF_KIND_UNKN]         = "UNKNOWN",
        [BTF_KIND_INT]          = "INT",
        [BTF_KIND_PTR]          = "PTR",
        [BTF_KIND_ARRAY]        = "ARRAY",
        [BTF_KIND_STRUCT]       = "STRUCT",
        [BTF_KIND_UNION]        = "UNION",
        [BTF_KIND_ENUM]         = "ENUM",
        [BTF_KIND_FWD]          = "FWD",
        [BTF_KIND_TYPEDEF]      = "TYPEDEF",
        [BTF_KIND_VOLATILE]     = "VOLATILE",
        [BTF_KIND_CONST]        = "CONST",
        [BTF_KIND_RESTRICT]     = "RESTRICT",
        [BTF_KIND_FUNC]         = "FUNC",
        [BTF_KIND_FUNC_PROTO]   = "FUNC_PROTO",
        [BTF_KIND_VAR]          = "VAR",
        [BTF_KIND_DATASEC]      = "DATASEC",
};

struct btf_kind_operations {
        s32 (*check_meta)(struct btf_verifier_env *env,
                          const struct btf_type *t,
                          u32 meta_left);
        int (*resolve)(struct btf_verifier_env *env,
                       const struct resolve_vertex *v);
        int (*check_member)(struct btf_verifier_env *env,
                            const struct btf_type *struct_type,
                            const struct btf_member *member,
                            const struct btf_type *member_type);
        int (*check_kflag_member)(struct btf_verifier_env *env,
                                  const struct btf_type *struct_type,
                                  const struct btf_member *member,
                                  const struct btf_type *member_type);
        void (*log_details)(struct btf_verifier_env *env,
                            const struct btf_type *t);
        void (*seq_show)(const struct btf *btf, const struct btf_type *t,
                         u32 type_id, void *data, u8 bits_offsets,
                         struct seq_file *m);
};

static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
static struct btf_type btf_void;

static int btf_resolve(struct btf_verifier_env *env,
                       const struct btf_type *t, u32 type_id);

static bool btf_type_is_modifier(const struct btf_type *t)
{
        /* Some of them is not strictly a C modifier
         * but they are grouped into the same bucket
         * for BTF concern:
         *   A type (t) that refers to another
         *   type through t->type AND its size cannot
         *   be determined without following the t->type.
         *
         * ptr does not fall into this bucket
         * because its size is always sizeof(void *).
         */
        switch (BTF_INFO_KIND(t->info)) {
        case BTF_KIND_TYPEDEF:
        case BTF_KIND_VOLATILE:
        case BTF_KIND_CONST:
        case BTF_KIND_RESTRICT:
                return true;
        }

        return false;
}

bool btf_type_is_void(const struct btf_type *t)
{
        return t == &btf_void;
}

static bool btf_type_is_fwd(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}

static bool btf_type_nosize(const struct btf_type *t)
{
        return btf_type_is_void(t) || btf_type_is_fwd(t) ||
               btf_type_is_func(t) || btf_type_is_func_proto(t);
}

static bool btf_type_nosize_or_null(const struct btf_type *t)
{
        return !t || btf_type_nosize(t);
}

/* union is only a special case of struct:
 * all its offsetof(member) == 0
 */
static bool btf_type_is_struct(const struct btf_type *t)
{
        u8 kind = BTF_INFO_KIND(t->info);

        return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
}

static bool __btf_type_is_struct(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
}

static bool btf_type_is_array(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
}

static bool btf_type_is_var(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
}

static bool btf_type_is_datasec(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
}

/* Types that act only as a source, not sink or intermediate
 * type when resolving.
 */
static bool btf_type_is_resolve_source_only(const struct btf_type *t)
{
        return btf_type_is_var(t) ||
               btf_type_is_datasec(t);
}

/* What types need to be resolved?
 *
 * btf_type_is_modifier() is an obvious one.
 *
 * btf_type_is_struct() because its member refers to
 * another type (through member->type).
 *
 * btf_type_is_var() because the variable refers to
 * another type. btf_type_is_datasec() holds multiple
 * btf_type_is_var() types that need resolving.
 *
 * btf_type_is_array() because its element (array->type)
 * refers to another type.  Array can be thought of a
 * special case of struct while array just has the same
 * member-type repeated by array->nelems of times.
 */
static bool btf_type_needs_resolve(const struct btf_type *t)
{
        return btf_type_is_modifier(t) ||
               btf_type_is_ptr(t) ||
               btf_type_is_struct(t) ||
               btf_type_is_array(t) ||
               btf_type_is_var(t) ||
               btf_type_is_datasec(t);
}

/* t->size can be used */
static bool btf_type_has_size(const struct btf_type *t)
{
        switch (BTF_INFO_KIND(t->info)) {
        case BTF_KIND_INT:
        case BTF_KIND_STRUCT:
        case BTF_KIND_UNION:
        case BTF_KIND_ENUM:
        case BTF_KIND_DATASEC:
                return true;
        }

        return false;
}

static const char *btf_int_encoding_str(u8 encoding)
{
        if (encoding == 0)
                return "(none)";
        else if (encoding == BTF_INT_SIGNED)
                return "SIGNED";
        else if (encoding == BTF_INT_CHAR)
                return "CHAR";
        else if (encoding == BTF_INT_BOOL)
                return "BOOL";
        else
                return "UNKN";
}

static u16 btf_type_vlen(const struct btf_type *t)
{
        return BTF_INFO_VLEN(t->info);
}

static bool btf_type_kflag(const struct btf_type *t)
{
        return BTF_INFO_KFLAG(t->info);
}

static u32 btf_member_bit_offset(const struct btf_type *struct_type,
                             const struct btf_member *member)
{
        return btf_type_kflag(struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
                                           : member->offset;
}

static u32 btf_member_bitfield_size(const struct btf_type *struct_type,
                                    const struct btf_member *member)
{
        return btf_type_kflag(struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
                                           : 0;
}

static u32 btf_type_int(const struct btf_type *t)
{
        return *(u32 *)(t + 1);
}

static const struct btf_array *btf_type_array(const struct btf_type *t)
{
        return (const struct btf_array *)(t + 1);
}

static const struct btf_member *btf_type_member(const struct btf_type *t)
{
        return (const struct btf_member *)(t + 1);
}

static const struct btf_enum *btf_type_enum(const struct btf_type *t)
{
        return (const struct btf_enum *)(t + 1);
}

static const struct btf_var *btf_type_var(const struct btf_type *t)
{
        return (const struct btf_var *)(t + 1);
}

static const struct btf_var_secinfo *btf_type_var_secinfo(const struct btf_type *t)
{
        return (const struct btf_var_secinfo *)(t + 1);
}

static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
{
        return kind_ops[BTF_INFO_KIND(t->info)];
}

static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
{
        return BTF_STR_OFFSET_VALID(offset) &&
                offset < btf->hdr.str_len;
}

static bool __btf_name_char_ok(char c, bool first, bool dot_ok)
{
        if ((first ? !isalpha(c) :
                     !isalnum(c)) &&
            c != '_' &&
            ((c == '.' && !dot_ok) ||
              c != '.'))
                return false;
        return true;
}

static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok)
{
        /* offset must be valid */
        const char *src = &btf->strings[offset];
        const char *src_limit;

        if (!__btf_name_char_ok(*src, true, dot_ok))
                return false;

        /* set a limit on identifier length */
        src_limit = src + KSYM_NAME_LEN;
        src++;
        while (*src && src < src_limit) {
                if (!__btf_name_char_ok(*src, false, dot_ok))
                        return false;
                src++;
        }

        return !*src;
}

/* Only C-style identifier is permitted. This can be relaxed if
 * necessary.
 */
static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
{
        return __btf_name_valid(btf, offset, false);
}

static bool btf_name_valid_section(const struct btf *btf, u32 offset)
{
        return __btf_name_valid(btf, offset, true);
}

static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
{
        if (!offset)
                return "(anon)";
        else if (offset < btf->hdr.str_len)
                return &btf->strings[offset];
        else
                return "(invalid-name-offset)";
}

const char *btf_name_by_offset(const struct btf *btf, u32 offset)
{
        if (offset < btf->hdr.str_len)
                return &btf->strings[offset];

        return NULL;
}

const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
{
        if (type_id > btf->nr_types)
                return NULL;

        return btf->types[type_id];
}

/*
 * Regular int is not a bit field and it must be either
 * u8/u16/u32/u64 or __int128.
 */
static bool btf_type_int_is_regular(const struct btf_type *t)
{
        u8 nr_bits, nr_bytes;
        u32 int_data;

        int_data = btf_type_int(t);
        nr_bits = BTF_INT_BITS(int_data);
        nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
        if (BITS_PER_BYTE_MASKED(nr_bits) ||
            BTF_INT_OFFSET(int_data) ||
            (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
             nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
             nr_bytes != (2 * sizeof(u64)))) {
                return false;
        }

        return true;
}

/*
 * Check that given struct member is a regular int with expected
 * offset and size.
 */
bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
                           const struct btf_member *m,
                           u32 expected_offset, u32 expected_size)
{
        const struct btf_type *t;
        u32 id, int_data;
        u8 nr_bits;

        id = m->type;
        t = btf_type_id_size(btf, &id, NULL);
        if (!t || !btf_type_is_int(t))
                return false;

        int_data = btf_type_int(t);
        nr_bits = BTF_INT_BITS(int_data);
        if (btf_type_kflag(s)) {
                u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
                u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);

                /* if kflag set, int should be a regular int and
                 * bit offset should be at byte boundary.
                 */
                return !bitfield_size &&
                       BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
                       BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
        }

        if (BTF_INT_OFFSET(int_data) ||
            BITS_PER_BYTE_MASKED(m->offset) ||
            BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
            BITS_PER_BYTE_MASKED(nr_bits) ||
            BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
                return false;

        return true;
}

__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
                                              const char *fmt, ...)
{
        va_list args;

        va_start(args, fmt);
        bpf_verifier_vlog(log, fmt, args);
        va_end(args);
}

__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
                                            const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;

        va_start(args, fmt);
        bpf_verifier_vlog(log, fmt, args);
        va_end(args);
}

__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
                                                   const struct btf_type *t,
                                                   bool log_details,
                                                   const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        u8 kind = BTF_INFO_KIND(t->info);
        struct btf *btf = env->btf;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;

        /* btf verifier prints all types it is processing via
         * btf_verifier_log_type(..., fmt = NULL).
         * Skip those prints for in-kernel BTF verification.
         */
        if (log->level == BPF_LOG_KERNEL && !fmt)
                return;

        __btf_verifier_log(log, "[%u] %s %s%s",
                           env->log_type_id,
                           btf_kind_str[kind],
                           __btf_name_by_offset(btf, t->name_off),
                           log_details ? " " : "");

        if (log_details)
                btf_type_ops(t)->log_details(env, t);

        if (fmt && *fmt) {
                __btf_verifier_log(log, " ");
                va_start(args, fmt);
                bpf_verifier_vlog(log, fmt, args);
                va_end(args);
        }

        __btf_verifier_log(log, "\n");
}

#define btf_verifier_log_type(env, t, ...) \
        __btf_verifier_log_type((env), (t), true, __VA_ARGS__)
#define btf_verifier_log_basic(env, t, ...) \
        __btf_verifier_log_type((env), (t), false, __VA_ARGS__)

__printf(4, 5)
static void btf_verifier_log_member(struct btf_verifier_env *env,
                                    const struct btf_type *struct_type,
                                    const struct btf_member *member,
                                    const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        struct btf *btf = env->btf;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;

        if (log->level == BPF_LOG_KERNEL && !fmt)
                return;
        /* The CHECK_META phase already did a btf dump.
         *
         * If member is logged again, it must hit an error in
         * parsing this member.  It is useful to print out which
         * struct this member belongs to.
         */
        if (env->phase != CHECK_META)
                btf_verifier_log_type(env, struct_type, NULL);

        if (btf_type_kflag(struct_type))
                __btf_verifier_log(log,
                                   "\t%s type_id=%u bitfield_size=%u bits_offset=%u",
                                   __btf_name_by_offset(btf, member->name_off),
                                   member->type,
                                   BTF_MEMBER_BITFIELD_SIZE(member->offset),
                                   BTF_MEMBER_BIT_OFFSET(member->offset));
        else
                __btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
                                   __btf_name_by_offset(btf, member->name_off),
                                   member->type, member->offset);

        if (fmt && *fmt) {
                __btf_verifier_log(log, " ");
                va_start(args, fmt);
                bpf_verifier_vlog(log, fmt, args);
                va_end(args);
        }

        __btf_verifier_log(log, "\n");
}

__printf(4, 5)
static void btf_verifier_log_vsi(struct btf_verifier_env *env,
                                 const struct btf_type *datasec_type,
                                 const struct btf_var_secinfo *vsi,
                                 const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;
        if (log->level == BPF_LOG_KERNEL && !fmt)
                return;
        if (env->phase != CHECK_META)
                btf_verifier_log_type(env, datasec_type, NULL);

        __btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
                           vsi->type, vsi->offset, vsi->size);
        if (fmt && *fmt) {
                __btf_verifier_log(log, " ");
                va_start(args, fmt);
                bpf_verifier_vlog(log, fmt, args);
                va_end(args);
        }

        __btf_verifier_log(log, "\n");
}

static void btf_verifier_log_hdr(struct btf_verifier_env *env,
                                 u32 btf_data_size)
{
        struct bpf_verifier_log *log = &env->log;
        const struct btf *btf = env->btf;
        const struct btf_header *hdr;

        if (!bpf_verifier_log_needed(log))
                return;

        if (log->level == BPF_LOG_KERNEL)
                return;
        hdr = &btf->hdr;
        __btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
        __btf_verifier_log(log, "version: %u\n", hdr->version);
        __btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
        __btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
        __btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
        __btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
        __btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
        __btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
        __btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
}

static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
{
        struct btf *btf = env->btf;

        /* < 2 because +1 for btf_void which is always in btf->types[0].
         * btf_void is not accounted in btf->nr_types because btf_void
         * does not come from the BTF file.
         */
        if (btf->types_size - btf->nr_types < 2) {
                /* Expand 'types' array */

                struct btf_type **new_types;
                u32 expand_by, new_size;

                if (btf->types_size == BTF_MAX_TYPE) {
                        btf_verifier_log(env, "Exceeded max num of types");
                        return -E2BIG;
                }

                expand_by = max_t(u32, btf->types_size >> 2, 16);
                new_size = min_t(u32, BTF_MAX_TYPE,
                                 btf->types_size + expand_by);

                new_types = kvcalloc(new_size, sizeof(*new_types),
                                     GFP_KERNEL | __GFP_NOWARN);
                if (!new_types)
                        return -ENOMEM;

                if (btf->nr_types == 0)
                        new_types[0] = &btf_void;
                else
                        memcpy(new_types, btf->types,
                               sizeof(*btf->types) * (btf->nr_types + 1));

                kvfree(btf->types);
                btf->types = new_types;
                btf->types_size = new_size;
        }

        btf->types[++(btf->nr_types)] = t;

        return 0;
}

static int btf_alloc_id(struct btf *btf)
{
        int id;

        idr_preload(GFP_KERNEL);
        spin_lock_bh(&btf_idr_lock);
        id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
        if (id > 0)
                btf->id = id;
        spin_unlock_bh(&btf_idr_lock);
        idr_preload_end();

        if (WARN_ON_ONCE(!id))
                return -ENOSPC;

        return id > 0 ? 0 : id;
}

static void btf_free_id(struct btf *btf)
{
        unsigned long flags;

        /*
         * In map-in-map, calling map_delete_elem() on outer
         * map will call bpf_map_put on the inner map.
         * It will then eventually call btf_free_id()
         * on the inner map.  Some of the map_delete_elem()
         * implementation may have irq disabled, so
         * we need to use the _irqsave() version instead
         * of the _bh() version.
         */
        spin_lock_irqsave(&btf_idr_lock, flags);
        idr_remove(&btf_idr, btf->id);
        spin_unlock_irqrestore(&btf_idr_lock, flags);
}

static void btf_free(struct btf *btf)
{
        kvfree(btf->types);
        kvfree(btf->resolved_sizes);
        kvfree(btf->resolved_ids);
        kvfree(btf->data);
        kfree(btf);
}

static void btf_free_rcu(struct rcu_head *rcu)
{
        struct btf *btf = container_of(rcu, struct btf, rcu);

        btf_free(btf);
}

void btf_put(struct btf *btf)
{
        if (btf && refcount_dec_and_test(&btf->refcnt)) {
                btf_free_id(btf);
                call_rcu(&btf->rcu, btf_free_rcu);
        }
}

static int env_resolve_init(struct btf_verifier_env *env)
{
        struct btf *btf = env->btf;
        u32 nr_types = btf->nr_types;
        u32 *resolved_sizes = NULL;
        u32 *resolved_ids = NULL;
        u8 *visit_states = NULL;

        /* +1 for btf_void */
        resolved_sizes = kvcalloc(nr_types + 1, sizeof(*resolved_sizes),
                                  GFP_KERNEL | __GFP_NOWARN);
        if (!resolved_sizes)
                goto nomem;

        resolved_ids = kvcalloc(nr_types + 1, sizeof(*resolved_ids),
                                GFP_KERNEL | __GFP_NOWARN);
        if (!resolved_ids)
                goto nomem;

        visit_states = kvcalloc(nr_types + 1, sizeof(*visit_states),
                                GFP_KERNEL | __GFP_NOWARN);
        if (!visit_states)
                goto nomem;

        btf->resolved_sizes = resolved_sizes;
        btf->resolved_ids = resolved_ids;
        env->visit_states = visit_states;

        return 0;

nomem:
        kvfree(resolved_sizes);
        kvfree(resolved_ids);
        kvfree(visit_states);
        return -ENOMEM;
}

static void btf_verifier_env_free(struct btf_verifier_env *env)
{
        kvfree(env->visit_states);
        kfree(env);
}

static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
                                     const struct btf_type *next_type)
{
        switch (env->resolve_mode) {
        case RESOLVE_TBD:
                /* int, enum or void is a sink */
                return !btf_type_needs_resolve(next_type);
        case RESOLVE_PTR:
                /* int, enum, void, struct, array, func or func_proto is a sink
                 * for ptr
                 */
                return !btf_type_is_modifier(next_type) &&
                        !btf_type_is_ptr(next_type);
        case RESOLVE_STRUCT_OR_ARRAY:
                /* int, enum, void, ptr, func or func_proto is a sink
                 * for struct and array
                 */
                return !btf_type_is_modifier(next_type) &&
                        !btf_type_is_array(next_type) &&
                        !btf_type_is_struct(next_type);
        default:
                BUG();
        }
}

static bool env_type_is_resolved(const struct btf_verifier_env *env,
                                 u32 type_id)
{
        return env->visit_states[type_id] == RESOLVED;
}

static int env_stack_push(struct btf_verifier_env *env,
                          const struct btf_type *t, u32 type_id)
{
        struct resolve_vertex *v;

        if (env->top_stack == MAX_RESOLVE_DEPTH)
                return -E2BIG;

        if (env->visit_states[type_id] != NOT_VISITED)
                return -EEXIST;

        env->visit_states[type_id] = VISITED;

        v = &env->stack[env->top_stack++];
        v->t = t;
        v->type_id = type_id;
        v->next_member = 0;

        if (env->resolve_mode == RESOLVE_TBD) {
                if (btf_type_is_ptr(t))
                        env->resolve_mode = RESOLVE_PTR;
                else if (btf_type_is_struct(t) || btf_type_is_array(t))
                        env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
        }

        return 0;
}

static void env_stack_set_next_member(struct btf_verifier_env *env,
                                      u16 next_member)
{
        env->stack[env->top_stack - 1].next_member = next_member;
}

static void env_stack_pop_resolved(struct btf_verifier_env *env,
                                   u32 resolved_type_id,
                                   u32 resolved_size)
{
        u32 type_id = env->stack[--(env->top_stack)].type_id;
        struct btf *btf = env->btf;

        btf->resolved_sizes[type_id] = resolved_size;
        btf->resolved_ids[type_id] = resolved_type_id;
        env->visit_states[type_id] = RESOLVED;
}

static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
{
        return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
}

/* Resolve the size of a passed-in "type"
 *
 * type: is an array (e.g. u32 array[x][y])
 * return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
 * *type_size: (x * y * sizeof(u32)).  Hence, *type_size always
 *             corresponds to the return type.
 * *elem_type: u32
 * *total_nelems: (x * y).  Hence, individual elem size is
 *                (*type_size / *total_nelems)
 *
 * type: is not an array (e.g. const struct X)
 * return type: type "struct X"
 * *type_size: sizeof(struct X)
 * *elem_type: same as return type ("struct X")
 * *total_nelems: 1
 */
static const struct btf_type *
btf_resolve_size(const struct btf *btf, const struct btf_type *type,
                 u32 *type_size, const struct btf_type **elem_type,
                 u32 *total_nelems)
{
        const struct btf_type *array_type = NULL;
        const struct btf_array *array;
        u32 i, size, nelems = 1;

        for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
                switch (BTF_INFO_KIND(type->info)) {
                /* type->size can be used */
                case BTF_KIND_INT:
                case BTF_KIND_STRUCT:
                case BTF_KIND_UNION:
                case BTF_KIND_ENUM:
                        size = type->size;
                        goto resolved;

                case BTF_KIND_PTR:
                        size = sizeof(void *);
                        goto resolved;

                /* Modifiers */
                case BTF_KIND_TYPEDEF:
                case BTF_KIND_VOLATILE:
                case BTF_KIND_CONST:
                case BTF_KIND_RESTRICT:
                        type = btf_type_by_id(btf, type->type);
                        break;

                case BTF_KIND_ARRAY:
                        if (!array_type)
                                array_type = type;
                        array = btf_type_array(type);
                        if (nelems && array->nelems > U32_MAX / nelems)
                                return ERR_PTR(-EINVAL);
                        nelems *= array->nelems;
                        type = btf_type_by_id(btf, array->type);
                        break;

                /* type without size */
                default:
                        return ERR_PTR(-EINVAL);
                }
        }

        return ERR_PTR(-EINVAL);

resolved:
        if (nelems && size > U32_MAX / nelems)
                return ERR_PTR(-EINVAL);

        *type_size = nelems * size;
        *total_nelems = nelems;
        *elem_type = type;

        return array_type ? : type;
}

/* The input param "type_id" must point to a needs_resolve type */
static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
                                                  u32 *type_id)
{
        *type_id = btf->resolved_ids[*type_id];
        return btf_type_by_id(btf, *type_id);
}

const struct btf_type *btf_type_id_size(const struct btf *btf,
                                        u32 *type_id, u32 *ret_size)
{
        const struct btf_type *size_type;
        u32 size_type_id = *type_id;
        u32 size = 0;

        size_type = btf_type_by_id(btf, size_type_id);
        if (btf_type_nosize_or_null(size_type))
                return NULL;

        if (btf_type_has_size(size_type)) {
                size = size_type->size;
        } else if (btf_type_is_array(size_type)) {
                size = btf->resolved_sizes[size_type_id];
        } else if (btf_type_is_ptr(size_type)) {
                size = sizeof(void *);
        } else {
                if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
                                 !btf_type_is_var(size_type)))
                        return NULL;

                size_type_id = btf->resolved_ids[size_type_id];
                size_type = btf_type_by_id(btf, size_type_id);
                if (btf_type_nosize_or_null(size_type))
                        return NULL;
                else if (btf_type_has_size(size_type))
                        size = size_type->size;
                else if (btf_type_is_array(size_type))
                        size = btf->resolved_sizes[size_type_id];
                else if (btf_type_is_ptr(size_type))
                        size = sizeof(void *);
                else
                        return NULL;
        }

        *type_id = size_type_id;
        if (ret_size)
                *ret_size = size;

        return size_type;
}

static int btf_df_check_member(struct btf_verifier_env *env,
                               const struct btf_type *struct_type,
                               const struct btf_member *member,
                               const struct btf_type *member_type)
{
        btf_verifier_log_basic(env, struct_type,
                               "Unsupported check_member");
        return -EINVAL;
}

static int btf_df_check_kflag_member(struct btf_verifier_env *env,
                                     const struct btf_type *struct_type,
                                     const struct btf_member *member,
                                     const struct btf_type *member_type)
{
        btf_verifier_log_basic(env, struct_type,
                               "Unsupported check_kflag_member");
        return -EINVAL;
}

/* Used for ptr, array and struct/union type members.
 * int, enum and modifier types have their specific callback functions.
 */
static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
                                          const struct btf_type *struct_type,
                                          const struct btf_member *member,
                                          const struct btf_type *member_type)
{
        if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member bitfield_size");
                return -EINVAL;
        }

        /* bitfield size is 0, so member->offset represents bit offset only.
         * It is safe to call non kflag check_member variants.
         */
        return btf_type_ops(member_type)->check_member(env, struct_type,
                                                       member,
                                                       member_type);
}

static int btf_df_resolve(struct btf_verifier_env *env,
                          const struct resolve_vertex *v)
{
        btf_verifier_log_basic(env, v->t, "Unsupported resolve");
        return -EINVAL;
}

static void btf_df_seq_show(const struct btf *btf, const struct btf_type *t,
                            u32 type_id, void *data, u8 bits_offsets,
                            struct seq_file *m)
{
        seq_printf(m, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
}

static int btf_int_check_member(struct btf_verifier_env *env,
                                const struct btf_type *struct_type,
                                const struct btf_member *member,
                                const struct btf_type *member_type)
{
        u32 int_data = btf_type_int(member_type);
        u32 struct_bits_off = member->offset;
        u32 struct_size = struct_type->size;
        u32 nr_copy_bits;
        u32 bytes_offset;

        if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "bits_offset exceeds U32_MAX");
                return -EINVAL;
        }

        struct_bits_off += BTF_INT_OFFSET(int_data);
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        nr_copy_bits = BTF_INT_BITS(int_data) +
                BITS_PER_BYTE_MASKED(struct_bits_off);

        if (nr_copy_bits > BITS_PER_U128) {
                btf_verifier_log_member(env, struct_type, member,
                                        "nr_copy_bits exceeds 128");
                return -EINVAL;
        }

        if (struct_size < bytes_offset ||
            struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static int btf_int_check_kflag_member(struct btf_verifier_env *env,
                                      const struct btf_type *struct_type,
                                      const struct btf_member *member,
                                      const struct btf_type *member_type)
{
        u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
        u32 int_data = btf_type_int(member_type);
        u32 struct_size = struct_type->size;
        u32 nr_copy_bits;

        /* a regular int type is required for the kflag int member */
        if (!btf_type_int_is_regular(member_type)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member base type");
                return -EINVAL;
        }

        /* check sanity of bitfield size */
        nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
        struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
        nr_int_data_bits = BTF_INT_BITS(int_data);
        if (!nr_bits) {
                /* Not a bitfield member, member offset must be at byte
                 * boundary.
                 */
                if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                        btf_verifier_log_member(env, struct_type, member,
                                                "Invalid member offset");
                        return -EINVAL;
                }

                nr_bits = nr_int_data_bits;
        } else if (nr_bits > nr_int_data_bits) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member bitfield_size");
                return -EINVAL;
        }

        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
        if (nr_copy_bits > BITS_PER_U128) {
                btf_verifier_log_member(env, struct_type, member,
                                        "nr_copy_bits exceeds 128");
                return -EINVAL;
        }

        if (struct_size < bytes_offset ||
            struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_int_check_meta(struct btf_verifier_env *env,
                              const struct btf_type *t,
                              u32 meta_left)
{
        u32 int_data, nr_bits, meta_needed = sizeof(int_data);
        u16 encoding;

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        int_data = btf_type_int(t);
        if (int_data & ~BTF_INT_MASK) {
                btf_verifier_log_basic(env, t, "Invalid int_data:%x",
                                       int_data);
                return -EINVAL;
        }

        nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);

        if (nr_bits > BITS_PER_U128) {
                btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
                                      BITS_PER_U128);
                return -EINVAL;
        }

        if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
                btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
                return -EINVAL;
        }

        /*
         * Only one of the encoding bits is allowed and it
         * should be sufficient for the pretty print purpose (i.e. decoding).
         * Multiple bits can be allowed later if it is found
         * to be insufficient.
         */
        encoding = BTF_INT_ENCODING(int_data);
        if (encoding &&
            encoding != BTF_INT_SIGNED &&
            encoding != BTF_INT_CHAR &&
            encoding != BTF_INT_BOOL) {
                btf_verifier_log_type(env, t, "Unsupported encoding");
                return -ENOTSUPP;
        }

        btf_verifier_log_type(env, t, NULL);

        return meta_needed;
}

static void btf_int_log(struct btf_verifier_env *env,
                        const struct btf_type *t)
{
        int int_data = btf_type_int(t);

        btf_verifier_log(env,
                         "size=%u bits_offset=%u nr_bits=%u encoding=%s",
                         t->size, BTF_INT_OFFSET(int_data),
                         BTF_INT_BITS(int_data),
                         btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
}

static void btf_int128_print(struct seq_file *m, void *data)
{
        /* data points to a __int128 number.
         * Suppose
         *     int128_num = *(__int128 *)data;
         * The below formulas shows what upper_num and lower_num represents:
         *     upper_num = int128_num >> 64;
         *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
         */
        u64 upper_num, lower_num;

#ifdef __BIG_ENDIAN_BITFIELD
        upper_num = *(u64 *)data;
        lower_num = *(u64 *)(data + 8);
#else
        upper_num = *(u64 *)(data + 8);
        lower_num = *(u64 *)data;
#endif
        if (upper_num == 0)
                seq_printf(m, "0x%llx", lower_num);
        else
                seq_printf(m, "0x%llx%016llx", upper_num, lower_num);
}

static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
                             u16 right_shift_bits)
{
        u64 upper_num, lower_num;

#ifdef __BIG_ENDIAN_BITFIELD
        upper_num = print_num[0];
        lower_num = print_num[1];
#else
        upper_num = print_num[1];
        lower_num = print_num[0];
#endif

        /* shake out un-needed bits by shift/or operations */
        if (left_shift_bits >= 64) {
                upper_num = lower_num << (left_shift_bits - 64);
                lower_num = 0;
        } else {
                upper_num = (upper_num << left_shift_bits) |
                            (lower_num >> (64 - left_shift_bits));
                lower_num = lower_num << left_shift_bits;
        }

        if (right_shift_bits >= 64) {
                lower_num = upper_num >> (right_shift_bits - 64);
                upper_num = 0;
        } else {
                lower_num = (lower_num >> right_shift_bits) |
                            (upper_num << (64 - right_shift_bits));
                upper_num = upper_num >> right_shift_bits;
        }

#ifdef __BIG_ENDIAN_BITFIELD
        print_num[0] = upper_num;
        print_num[1] = lower_num;
#else
        print_num[0] = lower_num;
        print_num[1] = upper_num;
#endif
}

static void btf_bitfield_seq_show(void *data, u8 bits_offset,
                                  u8 nr_bits, struct seq_file *m)
{
        u16 left_shift_bits, right_shift_bits;
        u8 nr_copy_bytes;
        u8 nr_copy_bits;
        u64 print_num[2] = {};

        nr_copy_bits = nr_bits + bits_offset;
        nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);

        memcpy(print_num, data, nr_copy_bytes);

#ifdef __BIG_ENDIAN_BITFIELD
        left_shift_bits = bits_offset;
#else
        left_shift_bits = BITS_PER_U128 - nr_copy_bits;
#endif
        right_shift_bits = BITS_PER_U128 - nr_bits;

        btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
        btf_int128_print(m, print_num);
}


static void btf_int_bits_seq_show(const struct btf *btf,
                                  const struct btf_type *t,
                                  void *data, u8 bits_offset,
                                  struct seq_file *m)
{
        u32 int_data = btf_type_int(t);
        u8 nr_bits = BTF_INT_BITS(int_data);
        u8 total_bits_offset;

        /*
         * bits_offset is at most 7.
         * BTF_INT_OFFSET() cannot exceed 128 bits.
         */
        total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
        data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
        bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
        btf_bitfield_seq_show(data, bits_offset, nr_bits, m);
}

static void btf_int_seq_show(const struct btf *btf, const struct btf_type *t,
                             u32 type_id, void *data, u8 bits_offset,
                             struct seq_file *m)
{
        u32 int_data = btf_type_int(t);
        u8 encoding = BTF_INT_ENCODING(int_data);
        bool sign = encoding & BTF_INT_SIGNED;
        u8 nr_bits = BTF_INT_BITS(int_data);

        if (bits_offset || BTF_INT_OFFSET(int_data) ||
            BITS_PER_BYTE_MASKED(nr_bits)) {
                btf_int_bits_seq_show(btf, t, data, bits_offset, m);
                return;
        }

        switch (nr_bits) {
        case 128:
                btf_int128_print(m, data);
                break;
        case 64:
                if (sign)
                        seq_printf(m, "%lld", *(s64 *)data);
                else
                        seq_printf(m, "%llu", *(u64 *)data);
                break;
        case 32:
                if (sign)
                        seq_printf(m, "%d", *(s32 *)data);
                else
                        seq_printf(m, "%u", *(u32 *)data);
                break;
        case 16:
                if (sign)
                        seq_printf(m, "%d", *(s16 *)data);
                else
                        seq_printf(m, "%u", *(u16 *)data);
                break;
        case 8:
                if (sign)
                        seq_printf(m, "%d", *(s8 *)data);
                else
                        seq_printf(m, "%u", *(u8 *)data);
                break;
        default:
                btf_int_bits_seq_show(btf, t, data, bits_offset, m);
        }
}

static const struct btf_kind_operations int_ops = {
        .check_meta = btf_int_check_meta,
        .resolve = btf_df_resolve,
        .check_member = btf_int_check_member,
        .check_kflag_member = btf_int_check_kflag_member,
        .log_details = btf_int_log,
        .seq_show = btf_int_seq_show,
};

static int btf_modifier_check_member(struct btf_verifier_env *env,
                                     const struct btf_type *struct_type,
                                     const struct btf_member *member,
                                     const struct btf_type *member_type)
{
        const struct btf_type *resolved_type;
        u32 resolved_type_id = member->type;
        struct btf_member resolved_member;
        struct btf *btf = env->btf;

        resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
        if (!resolved_type) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member");
                return -EINVAL;
        }

        resolved_member = *member;
        resolved_member.type = resolved_type_id;

        return btf_type_ops(resolved_type)->check_member(env, struct_type,
                                                         &resolved_member,
                                                         resolved_type);
}

static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
                                           const struct btf_type *struct_type,
                                           const struct btf_member *member,
                                           const struct btf_type *member_type)
{
        const struct btf_type *resolved_type;
        u32 resolved_type_id = member->type;
        struct btf_member resolved_member;
        struct btf *btf = env->btf;

        resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
        if (!resolved_type) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member");
                return -EINVAL;
        }

        resolved_member = *member;
        resolved_member.type = resolved_type_id;

        return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
                                                               &resolved_member,
                                                               resolved_type);
}

static int btf_ptr_check_member(struct btf_verifier_env *env,
                                const struct btf_type *struct_type,
                                const struct btf_member *member,
                                const struct btf_type *member_type)
{
        u32 struct_size, struct_bits_off, bytes_offset;

        struct_size = struct_type->size;
        struct_bits_off = member->offset;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        if (struct_size - bytes_offset < sizeof(void *)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static int btf_ref_type_check_meta(struct btf_verifier_env *env,
                                   const struct btf_type *t,
                                   u32 meta_left)
{
        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (!BTF_TYPE_ID_VALID(t->type)) {
                btf_verifier_log_type(env, t, "Invalid type_id");
                return -EINVAL;
        }

        /* typedef type must have a valid name, and other ref types,
         * volatile, const, restrict, should have a null name.
         */
        if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
                if (!t->name_off ||
                    !btf_name_valid_identifier(env->btf, t->name_off)) {
                        btf_verifier_log_type(env, t, "Invalid name");
                        return -EINVAL;
                }
        } else {
                if (t->name_off) {
                        btf_verifier_log_type(env, t, "Invalid name");
                        return -EINVAL;
                }
        }

        btf_verifier_log_type(env, t, NULL);

        return 0;
}

static int btf_modifier_resolve(struct btf_verifier_env *env,
                                const struct resolve_vertex *v)
{
        const struct btf_type *t = v->t;
        const struct btf_type *next_type;
        u32 next_type_id = t->type;
        struct btf *btf = env->btf;

        next_type = btf_type_by_id(btf, next_type_id);
        if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, next_type) &&
            !env_type_is_resolved(env, next_type_id))
                return env_stack_push(env, next_type, next_type_id);

        /* Figure out the resolved next_type_id with size.
         * They will be stored in the current modifier's
         * resolved_ids and resolved_sizes such that it can
         * save us a few type-following when we use it later (e.g. in
         * pretty print).
         */
        if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                if (env_type_is_resolved(env, next_type_id))
                        next_type = btf_type_id_resolve(btf, &next_type_id);

                /* "typedef void new_void", "const void"...etc */
                if (!btf_type_is_void(next_type) &&
                    !btf_type_is_fwd(next_type) &&
                    !btf_type_is_func_proto(next_type)) {
                        btf_verifier_log_type(env, v->t, "Invalid type_id");
                        return -EINVAL;
                }
        }

        env_stack_pop_resolved(env, next_type_id, 0);

        return 0;
}

static int btf_var_resolve(struct btf_verifier_env *env,
                           const struct resolve_vertex *v)
{
        const struct btf_type *next_type;
        const struct btf_type *t = v->t;
        u32 next_type_id = t->type;
        struct btf *btf = env->btf;

        next_type = btf_type_by_id(btf, next_type_id);
        if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, next_type) &&
            !env_type_is_resolved(env, next_type_id))
                return env_stack_push(env, next_type, next_type_id);

        if (btf_type_is_modifier(next_type)) {
                const struct btf_type *resolved_type;
                u32 resolved_type_id;

                resolved_type_id = next_type_id;
                resolved_type = btf_type_id_resolve(btf, &resolved_type_id);

                if (btf_type_is_ptr(resolved_type) &&
                    !env_type_is_resolve_sink(env, resolved_type) &&
                    !env_type_is_resolved(env, resolved_type_id))
                        return env_stack_push(env, resolved_type,
                                              resolved_type_id);
        }

        /* We must resolve to something concrete at this point, no
         * forward types or similar that would resolve to size of
         * zero is allowed.
         */
        if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        env_stack_pop_resolved(env, next_type_id, 0);

        return 0;
}

static int btf_ptr_resolve(struct btf_verifier_env *env,
                           const struct resolve_vertex *v)
{
        const struct btf_type *next_type;
        const struct btf_type *t = v->t;
        u32 next_type_id = t->type;
        struct btf *btf = env->btf;

        next_type = btf_type_by_id(btf, next_type_id);
        if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, next_type) &&
            !env_type_is_resolved(env, next_type_id))
                return env_stack_push(env, next_type, next_type_id);

        /* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
         * the modifier may have stopped resolving when it was resolved
         * to a ptr (last-resolved-ptr).
         *
         * We now need to continue from the last-resolved-ptr to
         * ensure the last-resolved-ptr will not referring back to
         * the currenct ptr (t).
         */
        if (btf_type_is_modifier(next_type)) {
                const struct btf_type *resolved_type;
                u32 resolved_type_id;

                resolved_type_id = next_type_id;
                resolved_type = btf_type_id_resolve(btf, &resolved_type_id);

                if (btf_type_is_ptr(resolved_type) &&
                    !env_type_is_resolve_sink(env, resolved_type) &&
                    !env_type_is_resolved(env, resolved_type_id))
                        return env_stack_push(env, resolved_type,
                                              resolved_type_id);
        }

        if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                if (env_type_is_resolved(env, next_type_id))
                        next_type = btf_type_id_resolve(btf, &next_type_id);

                if (!btf_type_is_void(next_type) &&
                    !btf_type_is_fwd(next_type) &&
                    !btf_type_is_func_proto(next_type)) {
                        btf_verifier_log_type(env, v->t, "Invalid type_id");
                        return -EINVAL;
                }
        }

        env_stack_pop_resolved(env, next_type_id, 0);

        return 0;
}

static void btf_modifier_seq_show(const struct btf *btf,
                                  const struct btf_type *t,
                                  u32 type_id, void *data,
                                  u8 bits_offset, struct seq_file *m)
{
        t = btf_type_id_resolve(btf, &type_id);

        btf_type_ops(t)->seq_show(btf, t, type_id, data, bits_offset, m);
}

static void btf_var_seq_show(const struct btf *btf, const struct btf_type *t,
                             u32 type_id, void *data, u8 bits_offset,
                             struct seq_file *m)
{
        t = btf_type_id_resolve(btf, &type_id);

        btf_type_ops(t)->seq_show(btf, t, type_id, data, bits_offset, m);
}

static void btf_ptr_seq_show(const struct btf *btf, const struct btf_type *t,
                             u32 type_id, void *data, u8 bits_offset,
                             struct seq_file *m)
{
        /* It is a hashed value */
        seq_printf(m, "%p", *(void **)data);
}

static void btf_ref_type_log(struct btf_verifier_env *env,
                             const struct btf_type *t)
{
        btf_verifier_log(env, "type_id=%u", t->type);
}

static struct btf_kind_operations modifier_ops = {
        .check_meta = btf_ref_type_check_meta,
        .resolve = btf_modifier_resolve,
        .check_member = btf_modifier_check_member,
        .check_kflag_member = btf_modifier_check_kflag_member,
        .log_details = btf_ref_type_log,
        .seq_show = btf_modifier_seq_show,
};

static struct btf_kind_operations ptr_ops = {
        .check_meta = btf_ref_type_check_meta,
        .resolve = btf_ptr_resolve,
        .check_member = btf_ptr_check_member,
        .check_kflag_member = btf_generic_check_kflag_member,
        .log_details = btf_ref_type_log,
        .seq_show = btf_ptr_seq_show,
};

static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
                              const struct btf_type *t,
                              u32 meta_left)
{
        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (t->type) {
                btf_verifier_log_type(env, t, "type != 0");
                return -EINVAL;
        }

        /* fwd type must have a valid name */
        if (!t->name_off ||
            !btf_name_valid_identifier(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return 0;
}

static void btf_fwd_type_log(struct btf_verifier_env *env,
                             const struct btf_type *t)
{
        btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
}

static struct btf_kind_operations fwd_ops = {
        .check_meta = btf_fwd_check_meta,
        .resolve = btf_df_resolve,
        .check_member = btf_df_check_member,
        .check_kflag_member = btf_df_check_kflag_member,
        .log_details = btf_fwd_type_log,
        .seq_show = btf_df_seq_show,
};

static int btf_array_check_member(struct btf_verifier_env *env,
                                  const struct btf_type *struct_type,
                                  const struct btf_member *member,
                                  const struct btf_type *member_type)
{
        u32 struct_bits_off = member->offset;
        u32 struct_size, bytes_offset;
        u32 array_type_id, array_size;
        struct btf *btf = env->btf;

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        array_type_id = member->type;
        btf_type_id_size(btf, &array_type_id, &array_size);
        struct_size = struct_type->size;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        if (struct_size - bytes_offset < array_size) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_array_check_meta(struct btf_verifier_env *env,
                                const struct btf_type *t,
                                u32 meta_left)
{
        const struct btf_array *array = btf_type_array(t);
        u32 meta_needed = sizeof(*array);

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        /* array type should not have a name */
        if (t->name_off) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (t->size) {
                btf_verifier_log_type(env, t, "size != 0");
                return -EINVAL;
        }

        /* Array elem type and index type cannot be in type void,
         * so !array->type and !array->index_type are not allowed.
         */
        if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
                btf_verifier_log_type(env, t, "Invalid elem");
                return -EINVAL;
        }

        if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
                btf_verifier_log_type(env, t, "Invalid index");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return meta_needed;
}

static int btf_array_resolve(struct btf_verifier_env *env,
                             const struct resolve_vertex *v)
{
        const struct btf_array *array = btf_type_array(v->t);
        const struct btf_type *elem_type, *index_type;
        u32 elem_type_id, index_type_id;
        struct btf *btf = env->btf;
        u32 elem_size;

        /* Check array->index_type */
        index_type_id = array->index_type;
        index_type = btf_type_by_id(btf, index_type_id);
        if (btf_type_nosize_or_null(index_type) ||
            btf_type_is_resolve_source_only(index_type)) {
                btf_verifier_log_type(env, v->t, "Invalid index");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, index_type) &&
            !env_type_is_resolved(env, index_type_id))
                return env_stack_push(env, index_type, index_type_id);

        index_type = btf_type_id_size(btf, &index_type_id, NULL);
        if (!index_type || !btf_type_is_int(index_type) ||
            !btf_type_int_is_regular(index_type)) {
                btf_verifier_log_type(env, v->t, "Invalid index");
                return -EINVAL;
        }

        /* Check array->type */
        elem_type_id = array->type;
        elem_type = btf_type_by_id(btf, elem_type_id);
        if (btf_type_nosize_or_null(elem_type) ||
            btf_type_is_resolve_source_only(elem_type)) {
                btf_verifier_log_type(env, v->t,
                                      "Invalid elem");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, elem_type) &&
            !env_type_is_resolved(env, elem_type_id))
                return env_stack_push(env, elem_type, elem_type_id);

        elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
        if (!elem_type) {
                btf_verifier_log_type(env, v->t, "Invalid elem");
                return -EINVAL;
        }

        if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
                btf_verifier_log_type(env, v->t, "Invalid array of int");
                return -EINVAL;
        }

        if (array->nelems && elem_size > U32_MAX / array->nelems) {
                btf_verifier_log_type(env, v->t,
                                      "Array size overflows U32_MAX");
                return -EINVAL;
        }

        env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);

        return 0;
}

static void btf_array_log(struct btf_verifier_env *env,
                          const struct btf_type *t)
{
        const struct btf_array *array = btf_type_array(t);

        btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
                         array->type, array->index_type, array->nelems);
}

static void btf_array_seq_show(const struct btf *btf, const struct btf_type *t,
                               u32 type_id, void *data, u8 bits_offset,
                               struct seq_file *m)
{
        const struct btf_array *array = btf_type_array(t);
        const struct btf_kind_operations *elem_ops;
        const struct btf_type *elem_type;
        u32 i, elem_size, elem_type_id;

        elem_type_id = array->type;
        elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
        elem_ops = btf_type_ops(elem_type);
        seq_puts(m, "[");
        for (i = 0; i < array->nelems; i++) {
                if (i)
                        seq_puts(m, ",");

                elem_ops->seq_show(btf, elem_type, elem_type_id, data,
                                   bits_offset, m);
                data += elem_size;
        }
        seq_puts(m, "]");
}

static struct btf_kind_operations array_ops = {
        .check_meta = btf_array_check_meta,
        .resolve = btf_array_resolve,
        .check_member = btf_array_check_member,
        .check_kflag_member = btf_generic_check_kflag_member,
        .log_details = btf_array_log,
        .seq_show = btf_array_seq_show,
};

static int btf_struct_check_member(struct btf_verifier_env *env,
                                   const struct btf_type *struct_type,
                                   const struct btf_member *member,
                                   const struct btf_type *member_type)
{
        u32 struct_bits_off = member->offset;
        u32 struct_size, bytes_offset;

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        struct_size = struct_type->size;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        if (struct_size - bytes_offset < member_type->size) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_struct_check_meta(struct btf_verifier_env *env,
                                 const struct btf_type *t,
                                 u32 meta_left)
{
        bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
        const struct btf_member *member;
        u32 meta_needed, last_offset;
        struct btf *btf = env->btf;
        u32 struct_size = t->size;
        u32 offset;
        u16 i;

        meta_needed = btf_type_vlen(t) * sizeof(*member);
        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        /* struct type either no name or a valid one */
        if (t->name_off &&
            !btf_name_valid_identifier(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        last_offset = 0;
        for_each_member(i, t, member) {
                if (!btf_name_offset_valid(btf, member->name_off)) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid member name_offset:%u",
                                                member->name_off);
                        return -EINVAL;
                }

                /* struct member either no name or a valid one */
                if (member->name_off &&
                    !btf_name_valid_identifier(btf, member->name_off)) {
                        btf_verifier_log_member(env, t, member, "Invalid name");
                        return -EINVAL;
                }
                /* A member cannot be in type void */
                if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid type_id");
                        return -EINVAL;
                }

                offset = btf_member_bit_offset(t, member);
                if (is_union && offset) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid member bits_offset");
                        return -EINVAL;
                }

                /*
                 * ">" instead of ">=" because the last member could be
                 * "char a[0];"
                 */
                if (last_offset > offset) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid member bits_offset");
                        return -EINVAL;
                }

                if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
                        btf_verifier_log_member(env, t, member,
                                                "Member bits_offset exceeds its struct size");
                        return -EINVAL;
                }

                btf_verifier_log_member(env, t, member, NULL);
                last_offset = offset;
        }

        return meta_needed;
}

static int btf_struct_resolve(struct btf_verifier_env *env,
                              const struct resolve_vertex *v)
{
        const struct btf_member *member;
        int err;
        u16 i;

        /* Before continue resolving the next_member,
         * ensure the last member is indeed resolved to a
         * type with size info.
         */
        if (v->next_member) {
                const struct btf_type *last_member_type;
                const struct btf_member *last_member;
                u16 last_member_type_id;

                last_member = btf_type_member(v->t) + v->next_member - 1;
                last_member_type_id = last_member->type;
                if (WARN_ON_ONCE(!env_type_is_resolved(env,
                                                       last_member_type_id)))
                        return -EINVAL;

                last_member_type = btf_type_by_id(env->btf,
                                                  last_member_type_id);
                if (btf_type_kflag(v->t))
                        err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
                                                                last_member,
                                                                last_member_type);
                else
                        err = btf_type_ops(last_member_type)->check_member(env, v->t,
                                                                last_member,
                                                                last_member_type);
                if (err)
                        return err;
        }

        for_each_member_from(i, v->next_member, v->t, member) {
                u32 member_type_id = member->type;
                const struct btf_type *member_type = btf_type_by_id(env->btf,
                                                                member_type_id);

                if (btf_type_nosize_or_null(member_type) ||
                    btf_type_is_resolve_source_only(member_type)) {
                        btf_verifier_log_member(env, v->t, member,
                                                "Invalid member");
                        return -EINVAL;
                }

                if (!env_type_is_resolve_sink(env, member_type) &&
                    !env_type_is_resolved(env, member_type_id)) {
                        env_stack_set_next_member(env, i + 1);
                        return env_stack_push(env, member_type, member_type_id);
                }

                if (btf_type_kflag(v->t))
                        err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
                                                                            member,
                                                                            member_type);
                else
                        err = btf_type_ops(member_type)->check_member(env, v->t,
                                                                      member,
                                                                      member_type);
                if (err)
                        return err;
        }

        env_stack_pop_resolved(env, 0, 0);

        return 0;
}

static void btf_struct_log(struct btf_verifier_env *env,
                           const struct btf_type *t)
{
        btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

/* find 'struct bpf_spin_lock' in map value.
 * return >= 0 offset if found
 * and < 0 in case of error
 */
int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
{
        const struct btf_member *member;
        u32 i, off = -ENOENT;

        if (!__btf_type_is_struct(t))
                return -EINVAL;

        for_each_member(i, t, member) {
                const struct btf_type *member_type = btf_type_by_id(btf,
                                                                    member->type);
                if (!__btf_type_is_struct(member_type))
                        continue;
                if (member_type->size != sizeof(struct bpf_spin_lock))
                        continue;
                if (strcmp(__btf_name_by_offset(btf, member_type->name_off),
                           "bpf_spin_lock"))
                        continue;
                if (off != -ENOENT)
                        /* only one 'struct bpf_spin_lock' is allowed */
                        return -E2BIG;
                off = btf_member_bit_offset(t, member);
                if (off % 8)
                        /* valid C code cannot generate such BTF */
                        return -EINVAL;
                off /= 8;
                if (off % __alignof__(struct bpf_spin_lock))
                        /* valid struct bpf_spin_lock will be 4 byte aligned */
                        return -EINVAL;
        }
        return off;
}

static void btf_struct_seq_show(const struct btf *btf, const struct btf_type *t,
                                u32 type_id, void *data, u8 bits_offset,
                                struct seq_file *m)
{
        const char *seq = BTF_INFO_KIND(t->info) == BTF_KIND_UNION ? "|" : ",";
        const struct btf_member *member;
        u32 i;

        seq_puts(m, "{");
        for_each_member(i, t, member) {
                const struct btf_type *member_type = btf_type_by_id(btf,
                                                                member->type);
                const struct btf_kind_operations *ops;
                u32 member_offset, bitfield_size;
                u32 bytes_offset;
                u8 bits8_offset;

                if (i)
                        seq_puts(m, seq);

                member_offset = btf_member_bit_offset(t, member);
                bitfield_size = btf_member_bitfield_size(t, member);
                bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
                bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
                if (bitfield_size) {
                        btf_bitfield_seq_show(data + bytes_offset, bits8_offset,
                                              bitfield_size, m);
                } else {
                        ops = btf_type_ops(member_type);
                        ops->seq_show(btf, member_type, member->type,
                                      data + bytes_offset, bits8_offset, m);
                }
        }
        seq_puts(m, "}");
}

static struct btf_kind_operations struct_ops = {
        .check_meta = btf_struct_check_meta,
        .resolve = btf_struct_resolve,
        .check_member = btf_struct_check_member,
        .check_kflag_member = btf_generic_check_kflag_member,
        .log_details = btf_struct_log,
        .seq_show = btf_struct_seq_show,
};

static int btf_enum_check_member(struct btf_verifier_env *env,
                                 const struct btf_type *struct_type,
                                 const struct btf_member *member,
                                 const struct btf_type *member_type)
{
        u32 struct_bits_off = member->offset;
        u32 struct_size, bytes_offset;

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        struct_size = struct_type->size;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        if (struct_size - bytes_offset < sizeof(int)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static int btf_enum_check_kflag_member(struct btf_verifier_env *env,
                                       const struct btf_type *struct_type,
                                       const struct btf_member *member,
                                       const struct btf_type *member_type)
{
        u32 struct_bits_off, nr_bits, bytes_end, struct_size;
        u32 int_bitsize = sizeof(int) * BITS_PER_BYTE;

        struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
        nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
        if (!nr_bits) {
                if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                        btf_verifier_log_member(env, struct_type, member,
                                                "Member is not byte aligned");
                        return -EINVAL;
                }

                nr_bits = int_bitsize;
        } else if (nr_bits > int_bitsize) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member bitfield_size");
                return -EINVAL;
        }

        struct_size = struct_type->size;
        bytes_end = BITS_ROUNDUP_BYTES(struct_bits_off + nr_bits);
        if (struct_size < bytes_end) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_enum_check_meta(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 meta_left)
{
        const struct btf_enum *enums = btf_type_enum(t);
        struct btf *btf = env->btf;
        u16 i, nr_enums;
        u32 meta_needed;

        nr_enums = btf_type_vlen(t);
        meta_needed = nr_enums * sizeof(*enums);

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (t->size > 8 || !is_power_of_2(t->size)) {
                btf_verifier_log_type(env, t, "Unexpected size");
                return -EINVAL;
        }

        /* enum type either no name or a valid one */
        if (t->name_off &&
            !btf_name_valid_identifier(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        for (i = 0; i < nr_enums; i++) {
                if (!btf_name_offset_valid(btf, enums[i].name_off)) {
                        btf_verifier_log(env, "\tInvalid name_offset:%u",
                                         enums[i].name_off);
                        return -EINVAL;
                }

                /* enum member must have a valid name */
                if (!enums[i].name_off ||
                    !btf_name_valid_identifier(btf, enums[i].name_off)) {
                        btf_verifier_log_type(env, t, "Invalid name");
                        return -EINVAL;
                }

                if (env->log.level == BPF_LOG_KERNEL)
                        continue;
                btf_verifier_log(env, "\t%s val=%d\n",
                                 __btf_name_by_offset(btf, enums[i].name_off),
                                 enums[i].val);
        }

        return meta_needed;
}

static void btf_enum_log(struct btf_verifier_env *env,
                         const struct btf_type *t)
{
        btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

static void btf_enum_seq_show(const struct btf *btf, const struct btf_type *t,
                              u32 type_id, void *data, u8 bits_offset,
                              struct seq_file *m)
{
        const struct btf_enum *enums = btf_type_enum(t);
        u32 i, nr_enums = btf_type_vlen(t);
        int v = *(int *)data;

        for (i = 0; i < nr_enums; i++) {
                if (v == enums[i].val) {
                        seq_printf(m, "%s",
                                   __btf_name_by_offset(btf,
                                                        enums[i].name_off));
                        return;
                }
        }

        seq_printf(m, "%d", v);
}

static struct btf_kind_operations enum_ops = {
        .check_meta = btf_enum_check_meta,
        .resolve = btf_df_resolve,
        .check_member = btf_enum_check_member,
        .check_kflag_member = btf_enum_check_kflag_member,
        .log_details = btf_enum_log,
        .seq_show = btf_enum_seq_show,
};

static s32 btf_func_proto_check_meta(struct btf_verifier_env *env,
                                     const struct btf_type *t,
                                     u32 meta_left)
{
        u32 meta_needed = btf_type_vlen(t) * sizeof(struct btf_param);

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        if (t->name_off) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return meta_needed;
}

static void btf_func_proto_log(struct btf_verifier_env *env,
                               const struct btf_type *t)
{
        const struct btf_param *args = (const struct btf_param *)(t + 1);
        u16 nr_args = btf_type_vlen(t), i;

        btf_verifier_log(env, "return=%u args=(", t->type);
        if (!nr_args) {
                btf_verifier_log(env, "void");
                goto done;
        }

        if (nr_args == 1 && !args[0].type) {
                /* Only one vararg */
                btf_verifier_log(env, "vararg");
                goto done;
        }

        btf_verifier_log(env, "%u %s", args[0].type,
                         __btf_name_by_offset(env->btf,
                                              args[0].name_off));
        for (i = 1; i < nr_args - 1; i++)
                btf_verifier_log(env, ", %u %s", args[i].type,
                                 __btf_name_by_offset(env->btf,
                                                      args[i].name_off));

        if (nr_args > 1) {
                const struct btf_param *last_arg = &args[nr_args - 1];

                if (last_arg->type)
                        btf_verifier_log(env, ", %u %s", last_arg->type,
                                         __btf_name_by_offset(env->btf,
                                                              last_arg->name_off));
                else
                        btf_verifier_log(env, ", vararg");
        }

done:
        btf_verifier_log(env, ")");
}

static struct btf_kind_operations func_proto_ops = {
        .check_meta = btf_func_proto_check_meta,
        .resolve = btf_df_resolve,
        /*
         * BTF_KIND_FUNC_PROTO cannot be directly referred by
         * a struct's member.
         *
         * It should be a funciton pointer instead.
         * (i.e. struct's member -> BTF_KIND_PTR -> BTF_KIND_FUNC_PROTO)
         *
         * Hence, there is no btf_func_check_member().
         */
        .check_member = btf_df_check_member,
        .check_kflag_member = btf_df_check_kflag_member,
        .log_details = btf_func_proto_log,
        .seq_show = btf_df_seq_show,
};

static s32 btf_func_check_meta(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 meta_left)
{
        if (!t->name_off ||
            !btf_name_valid_identifier(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return 0;
}

static struct btf_kind_operations func_ops = {
        .check_meta = btf_func_check_meta,
        .resolve = btf_df_resolve,
        .check_member = btf_df_check_member,
        .check_kflag_member = btf_df_check_kflag_member,
        .log_details = btf_ref_type_log,
        .seq_show = btf_df_seq_show,
};

static s32 btf_var_check_meta(struct btf_verifier_env *env,
                              const struct btf_type *t,
                              u32 meta_left)
{
        const struct btf_var *var;
        u32 meta_needed = sizeof(*var);

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (!t->name_off ||
            !__btf_name_valid(env->btf, t->name_off, true)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        /* A var cannot be in type void */
        if (!t->type || !BTF_TYPE_ID_VALID(t->type)) {
                btf_verifier_log_type(env, t, "Invalid type_id");
                return -EINVAL;
        }

        var = btf_type_var(t);
        if (var->linkage != BTF_VAR_STATIC &&
            var->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
                btf_verifier_log_type(env, t, "Linkage not supported");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return meta_needed;
}

static void btf_var_log(struct btf_verifier_env *env, const struct btf_type *t)
{
        const struct btf_var *var = btf_type_var(t);

        btf_verifier_log(env, "type_id=%u linkage=%u", t->type, var->linkage);
}

static const struct btf_kind_operations var_ops = {
        .check_meta             = btf_var_check_meta,
        .resolve                = btf_var_resolve,
        .check_member           = btf_df_check_member,
        .check_kflag_member     = btf_df_check_kflag_member,
        .log_details            = btf_var_log,
        .seq_show               = btf_var_seq_show,
};

static s32 btf_datasec_check_meta(struct btf_verifier_env *env,
                                  const struct btf_type *t,
                                  u32 meta_left)
{
        const struct btf_var_secinfo *vsi;
        u64 last_vsi_end_off = 0, sum = 0;
        u32 i, meta_needed;

        meta_needed = btf_type_vlen(t) * sizeof(*vsi);
        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        if (!btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen == 0");
                return -EINVAL;
        }

        if (!t->size) {
                btf_verifier_log_type(env, t, "size == 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (!t->name_off ||
            !btf_name_valid_section(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        for_each_vsi(i, t, vsi) {
                /* A var cannot be in type void */
                if (!vsi->type || !BTF_TYPE_ID_VALID(vsi->type)) {
                        btf_verifier_log_vsi(env, t, vsi,
                                             "Invalid type_id");
                        return -EINVAL;
                }

                if (vsi->offset < last_vsi_end_off || vsi->offset >= t->size) {
                        btf_verifier_log_vsi(env, t, vsi,
                                             "Invalid offset");
                        return -EINVAL;
                }

                if (!vsi->size || vsi->size > t->size) {
                        btf_verifier_log_vsi(env, t, vsi,
                                             "Invalid size");
                        return -EINVAL;
                }

                last_vsi_end_off = vsi->offset + vsi->size;
                if (last_vsi_end_off > t->size) {
                        btf_verifier_log_vsi(env, t, vsi,
                                             "Invalid offset+size");
                        return -EINVAL;
                }

                btf_verifier_log_vsi(env, t, vsi, NULL);
                sum += vsi->size;
        }

        if (t->size < sum) {
                btf_verifier_log_type(env, t, "Invalid btf_info size");
                return -EINVAL;
        }

        return meta_needed;
}

static int btf_datasec_resolve(struct btf_verifier_env *env,
                               const struct resolve_vertex *v)
{
        const struct btf_var_secinfo *vsi;
        struct btf *btf = env->btf;
        u16 i;

        for_each_vsi_from(i, v->next_member, v->t, vsi) {
                u32 var_type_id = vsi->type, type_id, type_size = 0;
                const struct btf_type *var_type = btf_type_by_id(env->btf,
                                                                 var_type_id);
                if (!var_type || !btf_type_is_var(var_type)) {
                        btf_verifier_log_vsi(env, v->t, vsi,
                                             "Not a VAR kind member");
                        return -EINVAL;
                }

                if (!env_type_is_resolve_sink(env, var_type) &&
                    !env_type_is_resolved(env, var_type_id)) {
                        env_stack_set_next_member(env, i + 1);
                        return env_stack_push(env, var_type, var_type_id);
                }

                type_id = var_type->type;
                if (!btf_type_id_size(btf, &type_id, &type_size)) {
                        btf_verifier_log_vsi(env, v->t, vsi, "Invalid type");
                        return -EINVAL;
                }

                if (vsi->size < type_size) {
                        btf_verifier_log_vsi(env, v->t, vsi, "Invalid size");
                        return -EINVAL;
                }
        }

        env_stack_pop_resolved(env, 0, 0);
        return 0;
}

static void btf_datasec_log(struct btf_verifier_env *env,
                            const struct btf_type *t)
{
        btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

static void btf_datasec_seq_show(const struct btf *btf,
                                 const struct btf_type *t, u32 type_id,
                                 void *data, u8 bits_offset,
                                 struct seq_file *m)
{
        const struct btf_var_secinfo *vsi;
        const struct btf_type *var;
        u32 i;

        seq_printf(m, "section (\"%s\") = {", __btf_name_by_offset(btf, t->name_off));
        for_each_vsi(i, t, vsi) {
                var = btf_type_by_id(btf, vsi->type);
                if (i)
                        seq_puts(m, ",");
                btf_type_ops(var)->seq_show(btf, var, vsi->type,
                                            data + vsi->offset, bits_offset, m);
        }
        seq_puts(m, "}");
}

static const struct btf_kind_operations datasec_ops = {
        .check_meta             = btf_datasec_check_meta,
        .resolve                = btf_datasec_resolve,
        .check_member           = btf_df_check_member,
        .check_kflag_member     = btf_df_check_kflag_member,
        .log_details            = btf_datasec_log,
        .seq_show               = btf_datasec_seq_show,
};

static int btf_func_proto_check(struct btf_verifier_env *env,
                                const struct btf_type *t)
{
        const struct btf_type *ret_type;
        const struct btf_param *args;
        const struct btf *btf;
        u16 nr_args, i;
        int err;

        btf = env->btf;
        args = (const struct btf_param *)(t + 1);
        nr_args = btf_type_vlen(t);

        /* Check func return type which could be "void" (t->type == 0) */
        if (t->type) {
                u32 ret_type_id = t->type;

                ret_type = btf_type_by_id(btf, ret_type_id);
                if (!ret_type) {
                        btf_verifier_log_type(env, t, "Invalid return type");
                        return -EINVAL;
                }

                if (btf_type_needs_resolve(ret_type) &&
                    !env_type_is_resolved(env, ret_type_id)) {
                        err = btf_resolve(env, ret_type, ret_type_id);
                        if (err)
                                return err;
                }

                /* Ensure the return type is a type that has a size */
                if (!btf_type_id_size(btf, &ret_type_id, NULL)) {
                        btf_verifier_log_type(env, t, "Invalid return type");
                        return -EINVAL;
                }
        }

        if (!nr_args)
                return 0;

        /* Last func arg type_id could be 0 if it is a vararg */
        if (!args[nr_args - 1].type) {
                if (args[nr_args - 1].name_off) {
                        btf_verifier_log_type(env, t, "Invalid arg#%u",
                                              nr_args);
                        return -EINVAL;
                }
                nr_args--;
        }

        err = 0;
        for (i = 0; i < nr_args; i++) {
                const struct btf_type *arg_type;
                u32 arg_type_id;

                arg_type_id = args[i].type;
                arg_type = btf_type_by_id(btf, arg_type_id);
                if (!arg_type) {
                        btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                        err = -EINVAL;
                        break;
                }

                if (args[i].name_off &&
                    (!btf_name_offset_valid(btf, args[i].name_off) ||
                     !btf_name_valid_identifier(btf, args[i].name_off))) {
                        btf_verifier_log_type(env, t,
                                              "Invalid arg#%u", i + 1);
                        err = -EINVAL;
                        break;
                }

                if (btf_type_needs_resolve(arg_type) &&
                    !env_type_is_resolved(env, arg_type_id)) {
                        err = btf_resolve(env, arg_type, arg_type_id);
                        if (err)
                                break;
                }

                if (!btf_type_id_size(btf, &arg_type_id, NULL)) {
                        btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                        err = -EINVAL;
                        break;
                }
        }

        return err;
}

static int btf_func_check(struct btf_verifier_env *env,
                          const struct btf_type *t)
{
        const struct btf_type *proto_type;
        const struct btf_param *args;
        const struct btf *btf;
        u16 nr_args, i;

        btf = env->btf;
        proto_type = btf_type_by_id(btf, t->type);

        if (!proto_type || !btf_type_is_func_proto(proto_type)) {
                btf_verifier_log_type(env, t, "Invalid type_id");
                return -EINVAL;
        }

        args = (const struct btf_param *)(proto_type + 1);
        nr_args = btf_type_vlen(proto_type);
        for (i = 0; i < nr_args; i++) {
                if (!args[i].name_off && args[i].type) {
                        btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                        return -EINVAL;
                }
        }

        return 0;
}

static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
        [BTF_KIND_INT] = &int_ops,
        [BTF_KIND_PTR] = &ptr_ops,
        [BTF_KIND_ARRAY] = &array_ops,
        [BTF_KIND_STRUCT] = &struct_ops,
        [BTF_KIND_UNION] = &struct_ops,
        [BTF_KIND_ENUM] = &enum_ops,
        [BTF_KIND_FWD] = &fwd_ops,
        [BTF_KIND_TYPEDEF] = &modifier_ops,
        [BTF_KIND_VOLATILE] = &modifier_ops,
        [BTF_KIND_CONST] = &modifier_ops,
        [BTF_KIND_RESTRICT] = &modifier_ops,
        [BTF_KIND_FUNC] = &func_ops,
        [BTF_KIND_FUNC_PROTO] = &func_proto_ops,
        [BTF_KIND_VAR] = &var_ops,
        [BTF_KIND_DATASEC] = &datasec_ops,
};

static s32 btf_check_meta(struct btf_verifier_env *env,
                          const struct btf_type *t,
                          u32 meta_left)
{
        u32 saved_meta_left = meta_left;
        s32 var_meta_size;

        if (meta_left < sizeof(*t)) {
                btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
                                 env->log_type_id, meta_left, sizeof(*t));
                return -EINVAL;
        }
        meta_left -= sizeof(*t);

        if (t->info & ~BTF_INFO_MASK) {
                btf_verifier_log(env, "[%u] Invalid btf_info:%x",
                                 env->log_type_id, t->info);
                return -EINVAL;
        }

        if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
            BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
                btf_verifier_log(env, "[%u] Invalid kind:%u",
                                 env->log_type_id, BTF_INFO_KIND(t->info));
                return -EINVAL;
        }

        if (!btf_name_offset_valid(env->btf, t->name_off)) {
                btf_verifier_log(env, "[%u] Invalid name_offset:%u",
                                 env->log_type_id, t->name_off);
                return -EINVAL;
        }

        var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
        if (var_meta_size < 0)
                return var_meta_size;

        meta_left -= var_meta_size;

        return saved_meta_left - meta_left;
}

static int btf_check_all_metas(struct btf_verifier_env *env)
{
        struct btf *btf = env->btf;
        struct btf_header *hdr;
        void *cur, *end;

        hdr = &btf->hdr;
        cur = btf->nohdr_data + hdr->type_off;
        end = cur + hdr->type_len;

        env->log_type_id = 1;
        while (cur < end) {
                struct btf_type *t = cur;
                s32 meta_size;

                meta_size = btf_check_meta(env, t, end - cur);
                if (meta_size < 0)
                        return meta_size;

                btf_add_type(env, t);
                cur += meta_size;
                env->log_type_id++;
        }

        return 0;
}

static bool btf_resolve_valid(struct btf_verifier_env *env,
                              const struct btf_type *t,
                              u32 type_id)
{
        struct btf *btf = env->btf;

        if (!env_type_is_resolved(env, type_id))
                return false;

        if (btf_type_is_struct(t) || btf_type_is_datasec(t))
                return !btf->resolved_ids[type_id] &&
                       !btf->resolved_sizes[type_id];

        if (btf_type_is_modifier(t) || btf_type_is_ptr(t) ||
            btf_type_is_var(t)) {
                t = btf_type_id_resolve(btf, &type_id);
                return t &&
                       !btf_type_is_modifier(t) &&
                       !btf_type_is_var(t) &&
                       !btf_type_is_datasec(t);
        }

        if (btf_type_is_array(t)) {
                const struct btf_array *array = btf_type_array(t);
                const struct btf_type *elem_type;
                u32 elem_type_id = array->type;
                u32 elem_size;

                elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
                return elem_type && !btf_type_is_modifier(elem_type) &&
                        (array->nelems * elem_size ==
                         btf->resolved_sizes[type_id]);
        }

        return false;
}

static int btf_resolve(struct btf_verifier_env *env,
                       const struct btf_type *t, u32 type_id)
{
        u32 save_log_type_id = env->log_type_id;
        const struct resolve_vertex *v;
        int err = 0;

        env->resolve_mode = RESOLVE_TBD;
        env_stack_push(env, t, type_id);
        while (!err && (v = env_stack_peak(env))) {
                env->log_type_id = v->type_id;
                err = btf_type_ops(v->t)->resolve(env, v);
        }

        env->log_type_id = type_id;
        if (err == -E2BIG) {
                btf_verifier_log_type(env, t,
                                      "Exceeded max resolving depth:%u",
                                      MAX_RESOLVE_DEPTH);
        } else if (err == -EEXIST) {
                btf_verifier_log_type(env, t, "Loop detected");
        }

        /* Final sanity check */
        if (!err && !btf_resolve_valid(env, t, type_id)) {
                btf_verifier_log_type(env, t, "Invalid resolve state");
                err = -EINVAL;
        }

        env->log_type_id = save_log_type_id;
        return err;
}

static int btf_check_all_types(struct btf_verifier_env *env)
{
        struct btf *btf = env->btf;
        u32 type_id;
        int err;

        err = env_resolve_init(env);
        if (err)
                return err;

        env->phase++;
        for (type_id = 1; type_id <= btf->nr_types; type_id++) {
                const struct btf_type *t = btf_type_by_id(btf, type_id);

                env->log_type_id = type_id;
                if (btf_type_needs_resolve(t) &&
                    !env_type_is_resolved(env, type_id)) {
                        err = btf_resolve(env, t, type_id);
                        if (err)
                                return err;
                }

                if (btf_type_is_func_proto(t)) {
                        err = btf_func_proto_check(env, t);
                        if (err)
                                return err;
                }

                if (btf_type_is_func(t)) {
                        err = btf_func_check(env, t);
                        if (err)
                                return err;
                }
        }

        return 0;
}

static int btf_parse_type_sec(struct btf_verifier_env *env)
{
        const struct btf_header *hdr = &env->btf->hdr;
        int err;

        /* Type section must align to 4 bytes */
        if (hdr->type_off & (sizeof(u32) - 1)) {
                btf_verifier_log(env, "Unaligned type_off");
                return -EINVAL;
        }

        if (!hdr->type_len) {
                btf_verifier_log(env, "No type found");
                return -EINVAL;
        }

        err = btf_check_all_metas(env);
        if (err)
                return err;

        return btf_check_all_types(env);
}

static int btf_parse_str_sec(struct btf_verifier_env *env)
{
        const struct btf_header *hdr;
        struct btf *btf = env->btf;
        const char *start, *end;

        hdr = &btf->hdr;
        start = btf->nohdr_data + hdr->str_off;
        end = start + hdr->str_len;

        if (end != btf->data + btf->data_size) {
                btf_verifier_log(env, "String section is not at the end");
                return -EINVAL;
        }

        if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
            start[0] || end[-1]) {
                btf_verifier_log(env, "Invalid string section");
                return -EINVAL;
        }

        btf->strings = start;

        return 0;
}

static const size_t btf_sec_info_offset[] = {
        offsetof(struct btf_header, type_off),
        offsetof(struct btf_header, str_off),
};

static int btf_sec_info_cmp(const void *a, const void *b)
{
        const struct btf_sec_info *x = a;
        const struct btf_sec_info *y = b;

        return (int)(x->off - y->off) ? : (int)(x->len - y->len);
}

static int btf_check_sec_info(struct btf_verifier_env *env,
                              u32 btf_data_size)
{
        struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
        u32 total, expected_total, i;
        const struct btf_header *hdr;
        const struct btf *btf;

        btf = env->btf;
        hdr = &btf->hdr;

        /* Populate the secs from hdr */
        for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
                secs[i] = *(struct btf_sec_info *)((void *)hdr +
                                                   btf_sec_info_offset[i]);

        sort(secs, ARRAY_SIZE(btf_sec_info_offset),
             sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);

        /* Check for gaps and overlap among sections */
        total = 0;
        expected_total = btf_data_size - hdr->hdr_len;
        for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
                if (expected_total < secs[i].off) {
                        btf_verifier_log(env, "Invalid section offset");
                        return -EINVAL;
                }
                if (total < secs[i].off) {
                        /* gap */
                        btf_verifier_log(env, "Unsupported section found");
                        return -EINVAL;
                }
                if (total > secs[i].off) {
                        btf_verifier_log(env, "Section overlap found");
                        return -EINVAL;
                }
                if (expected_total - total < secs[i].len) {
                        btf_verifier_log(env,
                                         "Total section length too long");
                        return -EINVAL;
                }
                total += secs[i].len;
        }

        /* There is data other than hdr and known sections */
        if (expected_total != total) {
                btf_verifier_log(env, "Unsupported section found");
                return -EINVAL;
        }

        return 0;
}

static int btf_parse_hdr(struct btf_verifier_env *env)
{
        u32 hdr_len, hdr_copy, btf_data_size;
        const struct btf_header *hdr;
        struct btf *btf;
        int err;

        btf = env->btf;
        btf_data_size = btf->data_size;

        if (btf_data_size <
            offsetof(struct btf_header, hdr_len) + sizeof(hdr->hdr_len)) {
                btf_verifier_log(env, "hdr_len not found");
                return -EINVAL;
        }

        hdr = btf->data;
        hdr_len = hdr->hdr_len;
        if (btf_data_size < hdr_len) {
                btf_verifier_log(env, "btf_header not found");
                return -EINVAL;
        }

        /* Ensure the unsupported header fields are zero */
        if (hdr_len > sizeof(btf->hdr)) {
                u8 *expected_zero = btf->data + sizeof(btf->hdr);
                u8 *end = btf->data + hdr_len;

                for (; expected_zero < end; expected_zero++) {
                        if (*expected_zero) {
                                btf_verifier_log(env, "Unsupported btf_header");
                                return -E2BIG;
                        }
                }
        }

        hdr_copy = min_t(u32, hdr_len, sizeof(btf->hdr));
        memcpy(&btf->hdr, btf->data, hdr_copy);

        hdr = &btf->hdr;

        btf_verifier_log_hdr(env, btf_data_size);

        if (hdr->magic != BTF_MAGIC) {
                btf_verifier_log(env, "Invalid magic");
                return -EINVAL;
        }

        if (hdr->version != BTF_VERSION) {
                btf_verifier_log(env, "Unsupported version");
                return -ENOTSUPP;
        }

        if (hdr->flags) {
                btf_verifier_log(env, "Unsupported flags");
                return -ENOTSUPP;
        }

        if (btf_data_size == hdr->hdr_len) {
                btf_verifier_log(env, "No data");
                return -EINVAL;
        }

        err = btf_check_sec_info(env, btf_data_size);
        if (err)
                return err;

        return 0;
}

static struct btf *btf_parse(void __user *btf_data, u32 btf_data_size,
                             u32 log_level, char __user *log_ubuf, u32 log_size)
{
        struct btf_verifier_env *env = NULL;
        struct bpf_verifier_log *log;
        struct btf *btf = NULL;
        u8 *data;
        int err;

        if (btf_data_size > BTF_MAX_SIZE)
                return ERR_PTR(-E2BIG);

        env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
        if (!env)
                return ERR_PTR(-ENOMEM);

        log = &env->log;
        if (log_level || log_ubuf || log_size) {
                /* user requested verbose verifier output
                 * and supplied buffer to store the verification trace
                 */
                log->level = log_level;
                log->ubuf = log_ubuf;
                log->len_total = log_size;

                /* log attributes have to be sane */
                if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
                    !log->level || !log->ubuf) {
                        err = -EINVAL;
                        goto errout;
                }
        }

        btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
        if (!btf) {
                err = -ENOMEM;
                goto errout;
        }
        env->btf = btf;

        data = kvmalloc(btf_data_size, GFP_KERNEL | __GFP_NOWARN);
        if (!data) {
                err = -ENOMEM;
                goto errout;
        }

        btf->data = data;
        btf->data_size = btf_data_size;

        if (copy_from_user(data, btf_data, btf_data_size)) {
                err = -EFAULT;
                goto errout;
        }

        err = btf_parse_hdr(env);
        if (err)
                goto errout;

        btf->nohdr_data = btf->data + btf->hdr.hdr_len;

        err = btf_parse_str_sec(env);
        if (err)
                goto errout;

        err = btf_parse_type_sec(env);
        if (err)
                goto errout;

        if (log->level && bpf_verifier_log_full(log)) {
                err = -ENOSPC;
                goto errout;
        }

        btf_verifier_env_free(env);
        refcount_set(&btf->refcnt, 1);
        return btf;

errout:
        btf_verifier_env_free(env);
        if (btf)
                btf_free(btf);
        return ERR_PTR(err);
}

extern char __weak _binary__btf_vmlinux_bin_start[];
extern char __weak _binary__btf_vmlinux_bin_end[];
extern struct btf *btf_vmlinux;

#define BPF_MAP_TYPE(_id, _ops)
static union {
        struct bpf_ctx_convert {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        prog_ctx_type _id##_prog; \
        kern_ctx_type _id##_kern;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
        } *__t;
        /* 't' is written once under lock. Read many times. */
        const struct btf_type *t;
} bpf_ctx_convert;
enum {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        __ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
        __ctx_convert_unused, /* to avoid empty enum in extreme .config */
};
static u8 bpf_ctx_convert_map[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        [_id] = __ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
};
#undef BPF_MAP_TYPE

static const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
                      const struct btf_type *t, enum bpf_prog_type prog_type)
{
        const struct btf_type *conv_struct;
        const struct btf_type *ctx_struct;
        const struct btf_member *ctx_type;
        const char *tname, *ctx_tname;

        conv_struct = bpf_ctx_convert.t;
        if (!conv_struct) {
                bpf_log(log, "btf_vmlinux is malformed\n");
                return NULL;
        }
        t = btf_type_by_id(btf, t->type);
        while (btf_type_is_modifier(t))
                t = btf_type_by_id(btf, t->type);
        if (!btf_type_is_struct(t)) {
                /* Only pointer to struct is supported for now.
                 * That means that BPF_PROG_TYPE_TRACEPOINT with BTF
                 * is not supported yet.
                 * BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
                 */
                bpf_log(log, "BPF program ctx type is not a struct\n");
                return NULL;
        }
        tname = btf_name_by_offset(btf, t->name_off);
        if (!tname) {
                bpf_log(log, "BPF program ctx struct doesn't have a name\n");
                return NULL;
        }
        /* prog_type is valid bpf program type. No need for bounds check. */
        ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
        /* ctx_struct is a pointer to prog_ctx_type in vmlinux.
         * Like 'struct __sk_buff'
         */
        ctx_struct = btf_type_by_id(btf_vmlinux, ctx_type->type);
        if (!ctx_struct)
                /* should not happen */
                return NULL;
        ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off);
        if (!ctx_tname) {
                /* should not happen */
                bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
                return NULL;
        }
        /* only compare that prog's ctx type name is the same as
         * kernel expects. No need to compare field by field.
         * It's ok for bpf prog to do:
         * struct __sk_buff {};
         * int socket_filter_bpf_prog(struct __sk_buff *skb)
         * { // no fields of skb are ever used }
         */
        if (strcmp(ctx_tname, tname))
                return NULL;
        return ctx_type;
}

static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
                                     struct btf *btf,
                                     const struct btf_type *t,
                                     enum bpf_prog_type prog_type)
{
        const struct btf_member *prog_ctx_type, *kern_ctx_type;

        prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type);
        if (!prog_ctx_type)
                return -ENOENT;
        kern_ctx_type = prog_ctx_type + 1;
        return kern_ctx_type->type;
}

struct btf *btf_parse_vmlinux(void)
{
        struct btf_verifier_env *env = NULL;
        struct bpf_verifier_log *log;
        struct btf *btf = NULL;
        int err, i;

        env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
        if (!env)
                return ERR_PTR(-ENOMEM);

        log = &env->log;
        log->level = BPF_LOG_KERNEL;

        btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
        if (!btf) {
                err = -ENOMEM;
                goto errout;
        }
        env->btf = btf;

        btf->data = _binary__btf_vmlinux_bin_start;
        btf->data_size = _binary__btf_vmlinux_bin_end -
                _binary__btf_vmlinux_bin_start;

        err = btf_parse_hdr(env);
        if (err)
                goto errout;

        btf->nohdr_data = btf->data + btf->hdr.hdr_len;

        err = btf_parse_str_sec(env);
        if (err)
                goto errout;

        err = btf_check_all_metas(env);
        if (err)
                goto errout;

        /* find struct bpf_ctx_convert for type checking later */
        for (i = 1; i <= btf->nr_types; i++) {
                const struct btf_type *t;
                const char *tname;

                t = btf_type_by_id(btf, i);
                if (!__btf_type_is_struct(t))
                        continue;
                tname = __btf_name_by_offset(btf, t->name_off);
                if (!strcmp(tname, "bpf_ctx_convert")) {
                        /* btf_parse_vmlinux() runs under bpf_verifier_lock */
                        bpf_ctx_convert.t = t;
                        break;
                }
        }
        if (i > btf->nr_types) {
                err = -ENOENT;
                goto errout;
        }

        btf_verifier_env_free(env);
        refcount_set(&btf->refcnt, 1);
        return btf;

errout:
        btf_verifier_env_free(env);
        if (btf) {
                kvfree(btf->types);
                kfree(btf);
        }
        return ERR_PTR(err);
}

struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog)
{
        struct bpf_prog *tgt_prog = prog->aux->linked_prog;

        if (tgt_prog) {
                return tgt_prog->aux->btf;
        } else {
                return btf_vmlinux;
        }
}

bool btf_ctx_access(int off, int size, enum bpf_access_type type,
                    const struct bpf_prog *prog,
                    struct bpf_insn_access_aux *info)
{
        const struct btf_type *t = prog->aux->attach_func_proto;
        struct bpf_prog *tgt_prog = prog->aux->linked_prog;
        struct btf *btf = bpf_prog_get_target_btf(prog);
        const char *tname = prog->aux->attach_func_name;
        struct bpf_verifier_log *log = info->log;
        const struct btf_param *args;
        u32 nr_args, arg;
        int ret;

        if (off % 8) {
                bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
                        tname, off);
                return false;
        }
        arg = off / 8;
        args = (const struct btf_param *)(t + 1);
        /* if (t == NULL) Fall back to default BPF prog with 5 u64 arguments */
        nr_args = t ? btf_type_vlen(t) : 5;
        if (prog->aux->attach_btf_trace) {
                /* skip first 'void *__data' argument in btf_trace_##name typedef */
                args++;
                nr_args--;
        }

        if (prog->expected_attach_type == BPF_TRACE_FEXIT &&
            arg == nr_args) {
                if (!t)
                        /* Default prog with 5 args. 6th arg is retval. */
                        return true;
                /* function return type */
                t = btf_type_by_id(btf, t->type);
        } else if (arg >= nr_args) {
                bpf_log(log, "func '%s' doesn't have %d-th argument\n",
                        tname, arg + 1);
                return false;
        } else {
                if (!t)
                        /* Default prog with 5 args */
                        return true;
                t = btf_type_by_id(btf, args[arg].type);
        }
        /* skip modifiers */
        while (btf_type_is_modifier(t))
                t = btf_type_by_id(btf, t->type);
        if (btf_type_is_int(t))
                /* accessing a scalar */
                return true;
        if (!btf_type_is_ptr(t)) {
                bpf_log(log,
                        "func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
                        tname, arg,
                        __btf_name_by_offset(btf, t->name_off),
                        btf_kind_str[BTF_INFO_KIND(t->info)]);
                return false;
        }
        if (t->type == 0)
                /* This is a pointer to void.
                 * It is the same as scalar from the verifier safety pov.
                 * No further pointer walking is allowed.
                 */
                return true;

        /* this is a pointer to another type */
        info->reg_type = PTR_TO_BTF_ID;
        info->btf_id = t->type;

        if (tgt_prog) {
                ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type);
                if (ret > 0) {
                        info->btf_id = ret;
                        return true;
                } else {
                        return false;
                }
        }
        t = btf_type_by_id(btf, t->type);
        /* skip modifiers */
        while (btf_type_is_modifier(t))
                t = btf_type_by_id(btf, t->type);
        if (!btf_type_is_struct(t)) {
                bpf_log(log,
                        "func '%s' arg%d type %s is not a struct\n",
                        tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]);
                return false;
        }
        bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
                tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)],
                __btf_name_by_offset(btf, t->name_off));
        return true;
}

int btf_struct_access(struct bpf_verifier_log *log,
                      const struct btf_type *t, int off, int size,
                      enum bpf_access_type atype,
                      u32 *next_btf_id)
{
        u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
        const struct btf_type *mtype, *elem_type = NULL;
        const struct btf_member *member;
        const char *tname, *mname;

again:
        tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
        if (!btf_type_is_struct(t)) {
                bpf_log(log, "Type '%s' is not a struct", tname);
                return -EINVAL;
        }

        for_each_member(i, t, member) {
                if (btf_member_bitfield_size(t, member))
                        /* bitfields are not supported yet */
                        continue;

                /* offset of the field in bytes */
                moff = btf_member_bit_offset(t, member) / 8;
                if (off + size <= moff)
                        /* won't find anything, field is already too far */
                        break;
                /* In case of "off" is pointing to holes of a struct */
                if (off < moff)
                        continue;

                /* type of the field */
                mtype = btf_type_by_id(btf_vmlinux, member->type);
                mname = __btf_name_by_offset(btf_vmlinux, member->name_off);

                mtype = btf_resolve_size(btf_vmlinux, mtype, &msize,
                                         &elem_type, &total_nelems);
                if (IS_ERR(mtype)) {
                        bpf_log(log, "field %s doesn't have size\n", mname);
                        return -EFAULT;
                }

                mtrue_end = moff + msize;
                if (off >= mtrue_end)
                        /* no overlap with member, keep iterating */
                        continue;

                if (btf_type_is_array(mtype)) {
                        u32 elem_idx;

                        /* btf_resolve_size() above helps to
                         * linearize a multi-dimensional array.
                         *
                         * The logic here is treating an array
                         * in a struct as the following way:
                         *
                         * struct outer {
                         *      struct inner array[2][2];
                         * };
                         *
                         * looks like:
                         *
                         * struct outer {
                         *      struct inner array_elem0;
                         *      struct inner array_elem1;
                         *      struct inner array_elem2;
                         *      struct inner array_elem3;
                         * };
                         *
                         * When accessing outer->array[1][0], it moves
                         * moff to "array_elem2", set mtype to
                         * "struct inner", and msize also becomes
                         * sizeof(struct inner).  Then most of the
                         * remaining logic will fall through without
                         * caring the current member is an array or
                         * not.
                         *
                         * Unlike mtype/msize/moff, mtrue_end does not
                         * change.  The naming difference ("_true") tells
                         * that it is not always corresponding to
                         * the current mtype/msize/moff.
                         * It is the true end of the current
                         * member (i.e. array in this case).  That
                         * will allow an int array to be accessed like
                         * a scratch space,
                         * i.e. allow access beyond the size of
                         *      the array's element as long as it is
                         *      within the mtrue_end boundary.
                         */

                        /* skip empty array */
                        if (moff == mtrue_end)
                                continue;

                        msize /= total_nelems;
                        elem_idx = (off - moff) / msize;
                        moff += elem_idx * msize;
                        mtype = elem_type;
                }

                /* the 'off' we're looking for is either equal to start
                 * of this field or inside of this struct
                 */
                if (btf_type_is_struct(mtype)) {
                        /* our field must be inside that union or struct */
                        t = mtype;

                        /* adjust offset we're looking for */
                        off -= moff;
                        goto again;
                }

                if (btf_type_is_ptr(mtype)) {
                        const struct btf_type *stype;

                        if (msize != size || off != moff) {
                                bpf_log(log,
                                        "cannot access ptr member %s with moff %u in struct %s with off %u size %u\n",
                                        mname, moff, tname, off, size);
                                return -EACCES;
                        }

                        stype = btf_type_by_id(btf_vmlinux, mtype->type);
                        /* skip modifiers */
                        while (btf_type_is_modifier(stype))
                                stype = btf_type_by_id(btf_vmlinux, stype->type);
                        if (btf_type_is_struct(stype)) {
                                *next_btf_id = mtype->type;
                                return PTR_TO_BTF_ID;
                        }
                }

                /* Allow more flexible access within an int as long as
                 * it is within mtrue_end.
                 * Since mtrue_end could be the end of an array,
                 * that also allows using an array of int as a scratch
                 * space. e.g. skb->cb[].
                 */
                if (off + size > mtrue_end) {
                        bpf_log(log,
                                "access beyond the end of member %s (mend:%u) in struct %s with off %u size %u\n",
                                mname, mtrue_end, tname, off, size);
                        return -EACCES;
                }

                return SCALAR_VALUE;
        }
        bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
        return -EINVAL;
}

static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn,
                                   int arg)
{
        char fnname[KSYM_SYMBOL_LEN + 4] = "btf_";
        const struct btf_param *args;
        const struct btf_type *t;
        const char *tname, *sym;
        u32 btf_id, i;

        if (IS_ERR(btf_vmlinux)) {
                bpf_log(log, "btf_vmlinux is malformed\n");
                return -EINVAL;
        }

        sym = kallsyms_lookup((long)fn, NULL, NULL, NULL, fnname + 4);
        if (!sym) {
                bpf_log(log, "kernel doesn't have kallsyms\n");
                return -EFAULT;
        }

        for (i = 1; i <= btf_vmlinux->nr_types; i++) {
                t = btf_type_by_id(btf_vmlinux, i);
                if (BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF)
                        continue;
                tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
                if (!strcmp(tname, fnname))
                        break;
        }
        if (i > btf_vmlinux->nr_types) {
                bpf_log(log, "helper %s type is not found\n", fnname);
                return -ENOENT;
        }

        t = btf_type_by_id(btf_vmlinux, t->type);
        if (!btf_type_is_ptr(t))
                return -EFAULT;
        t = btf_type_by_id(btf_vmlinux, t->type);
        if (!btf_type_is_func_proto(t))
                return -EFAULT;

        args = (const struct btf_param *)(t + 1);
        if (arg >= btf_type_vlen(t)) {
                bpf_log(log, "bpf helper %s doesn't have %d-th argument\n",
                        fnname, arg);
                return -EINVAL;
        }

        t = btf_type_by_id(btf_vmlinux, args[arg].type);
        if (!btf_type_is_ptr(t) || !t->type) {
                /* anything but the pointer to struct is a helper config bug */
                bpf_log(log, "ARG_PTR_TO_BTF is misconfigured\n");
                return -EFAULT;
        }
        btf_id = t->type;
        t = btf_type_by_id(btf_vmlinux, t->type);
        /* skip modifiers */
        while (btf_type_is_modifier(t)) {
                btf_id = t->type;
                t = btf_type_by_id(btf_vmlinux, t->type);
        }
        if (!btf_type_is_struct(t)) {
                bpf_log(log, "ARG_PTR_TO_BTF is not a struct\n");
                return -EFAULT;
        }
        bpf_log(log, "helper %s arg%d has btf_id %d struct %s\n", fnname + 4,
                arg, btf_id, __btf_name_by_offset(btf_vmlinux, t->name_off));
        return btf_id;
}

int btf_resolve_helper_id(struct bpf_verifier_log *log,
                          const struct bpf_func_proto *fn, int arg)
{
        int *btf_id = &fn->btf_id[arg];
        int ret;

        if (fn->arg_type[arg] != ARG_PTR_TO_BTF_ID)
                return -EINVAL;

        ret = READ_ONCE(*btf_id);
        if (ret)
                return ret;
        /* ok to race the search. The result is the same */
        ret = __btf_resolve_helper_id(log, fn->func, arg);
        if (!ret) {
                /* Function argument cannot be type 'void' */
                bpf_log(log, "BTF resolution bug\n");
                return -EFAULT;
        }
        WRITE_ONCE(*btf_id, ret);
        return ret;
}

static int __get_type_size(struct btf *btf, u32 btf_id,
                           const struct btf_type **bad_type)
{
        const struct btf_type *t;

        if (!btf_id)
                /* void */
                return 0;
        t = btf_type_by_id(btf, btf_id);
        while (t && btf_type_is_modifier(t))
                t = btf_type_by_id(btf, t->type);
        if (!t) {
                *bad_type = btf->types[0];
                return -EINVAL;
        }
        if (btf_type_is_ptr(t))
                /* kernel size of pointer. Not BPF's size of pointer*/
                return sizeof(void *);
        if (btf_type_is_int(t) || btf_type_is_enum(t))
                return t->size;
        *bad_type = t;
        return -EINVAL;
}

int btf_distill_func_proto(struct bpf_verifier_log *log,
                           struct btf *btf,
                           const struct btf_type *func,
                           const char *tname,
                           struct btf_func_model *m)
{
        const struct btf_param *args;
        const struct btf_type *t;
        u32 i, nargs;
        int ret;

        if (!func) {
                /* BTF function prototype doesn't match the verifier types.
                 * Fall back to 5 u64 args.
                 */
                for (i = 0; i < 5; i++)
                        m->arg_size[i] = 8;
                m->ret_size = 8;
                m->nr_args = 5;
                return 0;
        }
        args = (const struct btf_param *)(func + 1);
        nargs = btf_type_vlen(func);
        if (nargs >= MAX_BPF_FUNC_ARGS) {
                bpf_log(log,
                        "The function %s has %d arguments. Too many.\n",
                        tname, nargs);
                return -EINVAL;
        }
        ret = __get_type_size(btf, func->type, &t);
        if (ret < 0) {
                bpf_log(log,
                        "The function %s return type %s is unsupported.\n",
                        tname, btf_kind_str[BTF_INFO_KIND(t->info)]);
                return -EINVAL;
        }
        m->ret_size = ret;

        for (i = 0; i < nargs; i++) {
                ret = __get_type_size(btf, args[i].type, &t);
                if (ret < 0) {
                        bpf_log(log,
                                "The function %s arg%d type %s is unsupported.\n",
                                tname, i, btf_kind_str[BTF_INFO_KIND(t->info)]);
                        return -EINVAL;
                }
                m->arg_size[i] = ret;
        }
        m->nr_args = nargs;
        return 0;
}

int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
{
        struct bpf_verifier_state *st = env->cur_state;
        struct bpf_func_state *func = st->frame[st->curframe];
        struct bpf_reg_state *reg = func->regs;
        struct bpf_verifier_log *log = &env->log;
        struct bpf_prog *prog = env->prog;
        struct btf *btf = prog->aux->btf;
        const struct btf_param *args;
        const struct btf_type *t;
        u32 i, nargs, btf_id;
        const char *tname;

        if (!prog->aux->func_info)
                return 0;

        btf_id = prog->aux->func_info[subprog].type_id;
        if (!btf_id)
                return 0;

        if (prog->aux->func_info_aux[subprog].unreliable)
                return 0;

        t = btf_type_by_id(btf, btf_id);
        if (!t || !btf_type_is_func(t)) {
                bpf_log(log, "BTF of subprog %d doesn't point to KIND_FUNC\n",
                        subprog);
                return -EINVAL;
        }
        tname = btf_name_by_offset(btf, t->name_off);

        t = btf_type_by_id(btf, t->type);
        if (!t || !btf_type_is_func_proto(t)) {
                bpf_log(log, "Invalid type of func %s\n", tname);
                return -EINVAL;
        }
        args = (const struct btf_param *)(t + 1);
        nargs = btf_type_vlen(t);
        if (nargs > 5) {
                bpf_log(log, "Function %s has %d > 5 args\n", tname, nargs);
                goto out;
        }
        /* check that BTF function arguments match actual types that the
         * verifier sees.
         */
        for (i = 0; i < nargs; i++) {
                t = btf_type_by_id(btf, args[i].type);
                while (btf_type_is_modifier(t))
                        t = btf_type_by_id(btf, t->type);
                if (btf_type_is_int(t) || btf_type_is_enum(t)) {
                        if (reg[i + 1].type == SCALAR_VALUE)
                                continue;
                        bpf_log(log, "R%d is not a scalar\n", i + 1);
                        goto out;
                }
                if (btf_type_is_ptr(t)) {
                        if (reg[i + 1].type == SCALAR_VALUE) {
                                bpf_log(log, "R%d is not a pointer\n", i + 1);
                                goto out;
                        }
                        /* If program is passing PTR_TO_CTX into subprogram
                         * check that BTF type matches.
                         */
                        if (reg[i + 1].type == PTR_TO_CTX &&
                            !btf_get_prog_ctx_type(log, btf, t, prog->type))
                                goto out;
                        /* All other pointers are ok */
                        continue;
                }
                bpf_log(log, "Unrecognized argument type %s\n",
                        btf_kind_str[BTF_INFO_KIND(t->info)]);
                goto out;
        }
        return 0;
out:
        /* LLVM optimizations can remove arguments from static functions. */
        bpf_log(log,
                "Type info disagrees with actual arguments due to compiler optimizations\n");
        prog->aux->func_info_aux[subprog].unreliable = true;
        return 0;
}

void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
                       struct seq_file *m)
{
        const struct btf_type *t = btf_type_by_id(btf, type_id);

        btf_type_ops(t)->seq_show(btf, t, type_id, obj, 0, m);
}

#ifdef CONFIG_PROC_FS
static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
{
        const struct btf *btf = filp->private_data;

        seq_printf(m, "btf_id:\t%u\n", btf->id);
}
#endif

static int btf_release(struct inode *inode, struct file *filp)
{
        btf_put(filp->private_data);
        return 0;
}

const struct file_operations btf_fops = {
#ifdef CONFIG_PROC_FS
        .show_fdinfo    = bpf_btf_show_fdinfo,
#endif
        .release        = btf_release,
};

static int __btf_new_fd(struct btf *btf)
{
        return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
}

int btf_new_fd(const union bpf_attr *attr)
{
        struct btf *btf;
        int ret;

        btf = btf_parse(u64_to_user_ptr(attr->btf),
                        attr->btf_size, attr->btf_log_level,
                        u64_to_user_ptr(attr->btf_log_buf),
                        attr->btf_log_size);
        if (IS_ERR(btf))
                return PTR_ERR(btf);

        ret = btf_alloc_id(btf);
        if (ret) {
                btf_free(btf);
                return ret;
        }

        /*
         * The BTF ID is published to the userspace.
         * All BTF free must go through call_rcu() from
         * now on (i.e. free by calling btf_put()).
         */

        ret = __btf_new_fd(btf);
        if (ret < 0)
                btf_put(btf);

        return ret;
}

struct btf *btf_get_by_fd(int fd)
{
        struct btf *btf;
        struct fd f;

        f = fdget(fd);

        if (!f.file)
                return ERR_PTR(-EBADF);

        if (f.file->f_op != &btf_fops) {
                fdput(f);
                return ERR_PTR(-EINVAL);
        }

        btf = f.file->private_data;
        refcount_inc(&btf->refcnt);
        fdput(f);

        return btf;
}

int btf_get_info_by_fd(const struct btf *btf,
                       const union bpf_attr *attr,
                       union bpf_attr __user *uattr)
{
        struct bpf_btf_info __user *uinfo;
        struct bpf_btf_info info = {};
        u32 info_copy, btf_copy;
        void __user *ubtf;
        u32 uinfo_len;

        uinfo = u64_to_user_ptr(attr->info.info);
        uinfo_len = attr->info.info_len;

        info_copy = min_t(u32, uinfo_len, sizeof(info));
        if (copy_from_user(&info, uinfo, info_copy))
                return -EFAULT;

        info.id = btf->id;
        ubtf = u64_to_user_ptr(info.btf);
        btf_copy = min_t(u32, btf->data_size, info.btf_size);
        if (copy_to_user(ubtf, btf->data, btf_copy))
                return -EFAULT;
        info.btf_size = btf->data_size;

        if (copy_to_user(uinfo, &info, info_copy) ||
            put_user(info_copy, &uattr->info.info_len))
                return -EFAULT;

        return 0;
}

int btf_get_fd_by_id(u32 id)
{
        struct btf *btf;
        int fd;

        rcu_read_lock();
        btf = idr_find(&btf_idr, id);
        if (!btf || !refcount_inc_not_zero(&btf->refcnt))
                btf = ERR_PTR(-ENOENT);
        rcu_read_unlock();

        if (IS_ERR(btf))
                return PTR_ERR(btf);

        fd = __btf_new_fd(btf);
        if (fd < 0)
                btf_put(btf);

        return fd;
}

u32 btf_id(const struct btf *btf)
{
        return btf->id;
}