btf: expose API to work with raw btf_ext data

This patch changes struct btf_ext to retain original data in sequential
block of memory, which makes it possible to expose
btf_ext__get_raw_data() interface similar to btf__get_raw_data(), allowing
users of libbpf to get access to raw representation of .BTF.ext section.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 4fba0aa989dfe99cfd4d005ec691dbed20d8eb48..f6b724ed1bdd6fab79e3dba112b62e5c24761f37 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -42,9 +42,8 @@ struct btf {
 
 struct btf_ext_info {
        /*
-        * info points to a deep copy of the individual info section
-        * (e.g. func_info and line_info) from the .BTF.ext.
-        * It does not include the __u32 rec_size.
+        * info points to the individual info section (e.g. func_info and
+        * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
         */
        void *info;
        __u32 rec_size;
@@ -52,8 +51,13 @@ struct btf_ext_info {
 };
 
 struct btf_ext {
+       union {
+               struct btf_ext_header *hdr;
+               void *data;
+       };
        struct btf_ext_info func_info;
        struct btf_ext_info line_info;
+       __u32 data_size;
 };
 
 struct btf_ext_info_sec {
@@ -596,7 +600,7 @@ int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
        return 0;
 }
 
-struct btf_ext_sec_copy_param {
+struct btf_ext_sec_setup_param {
        __u32 off;
        __u32 len;
        __u32 min_rec_size;
@@ -604,20 +608,14 @@ struct btf_ext_sec_copy_param {
        const char *desc;
 };
 
-static int btf_ext_copy_info(struct btf_ext *btf_ext,
-                            __u8 *data, __u32 data_size,
-                            struct btf_ext_sec_copy_param *ext_sec)
+static int btf_ext_setup_info(struct btf_ext *btf_ext,
+                             struct btf_ext_sec_setup_param *ext_sec)
 {
-       const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
        const struct btf_ext_info_sec *sinfo;
        struct btf_ext_info *ext_info;
        __u32 info_left, record_size;
        /* The start of the info sec (including the __u32 record_size). */
-       const void *info;
-
-       /* data and data_size do not include btf_ext_header from now on */
-       data = data + hdr->hdr_len;
-       data_size -= hdr->hdr_len;
+       void *info;
 
        if (ext_sec->off & 0x03) {
                pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
@@ -625,16 +623,15 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
                return -EINVAL;
        }
 
-       if (data_size < ext_sec->off ||
-           ext_sec->len > data_size - ext_sec->off) {
+       info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
+       info_left = ext_sec->len;
+
+       if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
                pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
-                    ext_sec->desc, ext_sec->off, ext_sec->len);
+                        ext_sec->desc, ext_sec->off, ext_sec->len);
                return -EINVAL;
        }
 
-       info = data + ext_sec->off;
-       info_left = ext_sec->len;
-
        /* At least a record size */
        if (info_left < sizeof(__u32)) {
                pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
@@ -646,7 +643,7 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
        if (record_size < ext_sec->min_rec_size ||
            record_size & 0x03) {
                pr_debug("%s section in .BTF.ext has invalid record size %u\n",
-                    ext_sec->desc, record_size);
+                        ext_sec->desc, record_size);
                return -EINVAL;
        }
 
@@ -692,42 +689,35 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
        ext_info = ext_sec->ext_info;
        ext_info->len = ext_sec->len - sizeof(__u32);
        ext_info->rec_size = record_size;
-       ext_info->info = malloc(ext_info->len);
-       if (!ext_info->info)
-               return -ENOMEM;
-       memcpy(ext_info->info, info + sizeof(__u32), ext_info->len);
+       ext_info->info = info + sizeof(__u32);
 
        return 0;
 }
 
-static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
-                                 __u8 *data, __u32 data_size)
+static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
 {
-       const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
-       struct btf_ext_sec_copy_param param = {
-               .off = hdr->func_info_off,
-               .len = hdr->func_info_len,
+       struct btf_ext_sec_setup_param param = {
+               .off = btf_ext->hdr->func_info_off,
+               .len = btf_ext->hdr->func_info_len,
                .min_rec_size = sizeof(struct bpf_func_info_min),
                .ext_info = &btf_ext->func_info,
                .desc = "func_info"
        };
 
-       return btf_ext_copy_info(btf_ext, data, data_size, &param);
+       return btf_ext_setup_info(btf_ext, &param);
 }
 
-static int btf_ext_copy_line_info(struct btf_ext *btf_ext,
-                                 __u8 *data, __u32 data_size)
+static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
 {
-       const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
-       struct btf_ext_sec_copy_param param = {
-               .off = hdr->line_info_off,
-               .len = hdr->line_info_len,
+       struct btf_ext_sec_setup_param param = {
+               .off = btf_ext->hdr->line_info_off,
+               .len = btf_ext->hdr->line_info_len,
                .min_rec_size = sizeof(struct bpf_line_info_min),
                .ext_info = &btf_ext->line_info,
                .desc = "line_info",
        };
 
-       return btf_ext_copy_info(btf_ext, data, data_size, &param);
+       return btf_ext_setup_info(btf_ext, &param);
 }
 
 static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
@@ -767,9 +757,7 @@ void btf_ext__free(struct btf_ext *btf_ext)
 {
        if (!btf_ext)
                return;
-
-       free(btf_ext->func_info.info);
-       free(btf_ext->line_info.info);
+       free(btf_ext->data);
        free(btf_ext);
 }
 
@@ -786,13 +774,23 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
        if (!btf_ext)
                return ERR_PTR(-ENOMEM);
 
-       err = btf_ext_copy_func_info(btf_ext, data, size);
-       if (err) {
-               btf_ext__free(btf_ext);
-               return ERR_PTR(err);
+       btf_ext->data_size = size;
+       btf_ext->data = malloc(size);
+       if (!btf_ext->data) {
+               err = -ENOMEM;
+               goto done;
        }
+       memcpy(btf_ext->data, data, size);
+
+       err = btf_ext_setup_func_info(btf_ext);
+       if (err)
+               goto done;
 
-       err = btf_ext_copy_line_info(btf_ext, data, size);
+       err = btf_ext_setup_line_info(btf_ext);
+       if (err)
+               goto done;
+
+done:
        if (err) {
                btf_ext__free(btf_ext);
                return ERR_PTR(err);
@@ -801,6 +799,12 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
        return btf_ext;
 }
 
+const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
+{
+       *size = btf_ext->data_size;
+       return btf_ext->data;
+}
+
 static int btf_ext_reloc_info(const struct btf *btf,
                              const struct btf_ext_info *ext_info,
                              const char *sec_name, __u32 insns_cnt,
@@ -849,7 +853,8 @@ static int btf_ext_reloc_info(const struct btf *btf,
        return -ENOENT;
 }
 
-int btf_ext__reloc_func_info(const struct btf *btf, const struct btf_ext *btf_ext,
+int btf_ext__reloc_func_info(const struct btf *btf,
+                            const struct btf_ext *btf_ext,
                             const char *sec_name, __u32 insns_cnt,
                             void **func_info, __u32 *cnt)
 {
@@ -857,7 +862,8 @@ int btf_ext__reloc_func_info(const struct btf *btf, const struct btf_ext *btf_ex
                                  insns_cnt, func_info, cnt);
 }
 
-int btf_ext__reloc_line_info(const struct btf *btf, const struct btf_ext *btf_ext,
+int btf_ext__reloc_line_info(const struct btf *btf,
+                            const struct btf_ext *btf_ext,
                             const char *sec_name, __u32 insns_cnt,
                             void **line_info, __u32 *cnt)
 {

diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 10fe412461fe899ae0b3a6428bde6dee29ed9254..0306b54d54eb86984b4f3c6218fa17016b2d473a 100644 (file)
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -78,6 +78,8 @@ LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
 
 LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
 LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
+LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext* btf_ext,
+                                            __u32 *size);
 LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,
                                        const struct btf_ext *btf_ext,
                                        const char *sec_name, __u32 insns_cnt,

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 9e10467f8cbb74eedc3ad2b5cbc47ef3705473ee..eb78c7c261d9b3e9cdb11b06c684bbd9ee3aa684 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -141,6 +141,7 @@ LIBBPF_0.0.2 {
                btf__load;
                btf_ext__free;
                btf_ext__func_info_rec_size;
+               btf_ext__get_raw_data;
                btf_ext__line_info_rec_size;
                btf_ext__new;
                btf_ext__reloc_func_info;