1 #include <linux/module.h>
2 #include <linux/sort.h>
3 #include <asm/ptrace.h>
4 #include <asm/stacktrace.h>
5 #include <asm/unwind.h>
6 #include <asm/orc_types.h>
7 #include <asm/orc_lookup.h>
8 #include <asm/sections.h>
10 #define orc_warn(fmt, ...) \
11 printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__)
13 extern int __start_orc_unwind_ip[];
14 extern int __stop_orc_unwind_ip[];
15 extern struct orc_entry __start_orc_unwind[];
16 extern struct orc_entry __stop_orc_unwind[];
18 static DEFINE_MUTEX(sort_mutex);
19 int *cur_orc_ip_table = __start_orc_unwind_ip;
20 struct orc_entry *cur_orc_table = __start_orc_unwind;
22 unsigned int lookup_num_blocks;
25 static inline unsigned long orc_ip(const int *ip)
27 return (unsigned long)ip + *ip;
30 static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
31 unsigned int num_entries, unsigned long ip)
33 int *first = ip_table;
34 int *last = ip_table + num_entries - 1;
35 int *mid = first, *found = first;
41 * Do a binary range search to find the rightmost duplicate of a given
42 * starting address. Some entries are section terminators which are
43 * "weak" entries for ensuring there are no gaps. They should be
44 * ignored when they conflict with a real entry.
46 while (first <= last) {
47 mid = first + ((last - first) / 2);
49 if (orc_ip(mid) <= ip) {
56 return u_table + (found - ip_table);
60 static struct orc_entry *orc_module_find(unsigned long ip)
64 mod = __module_address(ip);
65 if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
67 return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind,
68 mod->arch.num_orcs, ip);
71 static struct orc_entry *orc_module_find(unsigned long ip)
77 static struct orc_entry *orc_find(unsigned long ip)
82 /* For non-init vmlinux addresses, use the fast lookup table: */
83 if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
84 unsigned int idx, start, stop;
86 idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
88 if (unlikely((idx >= lookup_num_blocks-1))) {
89 orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
90 idx, lookup_num_blocks, (void *)ip);
94 start = orc_lookup[idx];
95 stop = orc_lookup[idx + 1] + 1;
97 if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
98 (__start_orc_unwind + stop > __stop_orc_unwind))) {
99 orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
100 idx, lookup_num_blocks, start, stop, (void *)ip);
104 return __orc_find(__start_orc_unwind_ip + start,
105 __start_orc_unwind + start, stop - start, ip);
108 /* vmlinux .init slow lookup: */
109 if (ip >= (unsigned long)_sinittext && ip < (unsigned long)_einittext)
110 return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
111 __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
114 return orc_module_find(ip);
117 static void orc_sort_swap(void *_a, void *_b, int size)
119 struct orc_entry *orc_a, *orc_b;
120 struct orc_entry orc_tmp;
121 int *a = _a, *b = _b, tmp;
124 /* Swap the .orc_unwind_ip entries: */
129 /* Swap the corresponding .orc_unwind entries: */
130 orc_a = cur_orc_table + (a - cur_orc_ip_table);
131 orc_b = cur_orc_table + (b - cur_orc_ip_table);
137 static int orc_sort_cmp(const void *_a, const void *_b)
139 struct orc_entry *orc_a;
140 const int *a = _a, *b = _b;
141 unsigned long a_val = orc_ip(a);
142 unsigned long b_val = orc_ip(b);
150 * The "weak" section terminator entries need to always be on the left
151 * to ensure the lookup code skips them in favor of real entries.
152 * These terminator entries exist to handle any gaps created by
153 * whitelisted .o files which didn't get objtool generation.
155 orc_a = cur_orc_table + (a - cur_orc_ip_table);
156 return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1;
159 #ifdef CONFIG_MODULES
160 void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
161 void *_orc, size_t orc_size)
163 int *orc_ip = _orc_ip;
164 struct orc_entry *orc = _orc;
165 unsigned int num_entries = orc_ip_size / sizeof(int);
167 WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
168 orc_size % sizeof(*orc) != 0 ||
169 num_entries != orc_size / sizeof(*orc));
172 * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
173 * associate an .orc_unwind_ip table entry with its corresponding
174 * .orc_unwind entry so they can both be swapped.
176 mutex_lock(&sort_mutex);
177 cur_orc_ip_table = orc_ip;
179 sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
180 mutex_unlock(&sort_mutex);
182 mod->arch.orc_unwind_ip = orc_ip;
183 mod->arch.orc_unwind = orc;
184 mod->arch.num_orcs = num_entries;
188 void __init unwind_init(void)
190 size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
191 size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
192 size_t num_entries = orc_ip_size / sizeof(int);
193 struct orc_entry *orc;
196 if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
197 orc_size % sizeof(struct orc_entry) != 0 ||
198 num_entries != orc_size / sizeof(struct orc_entry)) {
199 orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n");
203 /* Sort the .orc_unwind and .orc_unwind_ip tables: */
204 sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp,
207 /* Initialize the fast lookup table: */
208 lookup_num_blocks = orc_lookup_end - orc_lookup;
209 for (i = 0; i < lookup_num_blocks-1; i++) {
210 orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
212 LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
214 orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
218 orc_lookup[i] = orc - __start_orc_unwind;
221 /* Initialize the ending block: */
222 orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries,
225 orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
228 orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
233 unsigned long unwind_get_return_address(struct unwind_state *state)
235 if (unwind_done(state))
238 return __kernel_text_address(state->ip) ? state->ip : 0;
240 EXPORT_SYMBOL_GPL(unwind_get_return_address);
242 unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
244 if (unwind_done(state))
248 return &state->regs->ip;
251 return (unsigned long *)state->sp - 1;
256 static bool stack_access_ok(struct unwind_state *state, unsigned long addr,
259 struct stack_info *info = &state->stack_info;
262 * If the address isn't on the current stack, switch to the next one.
264 * We may have to traverse multiple stacks to deal with the possibility
265 * that info->next_sp could point to an empty stack and the address
266 * could be on a subsequent stack.
268 while (!on_stack(info, (void *)addr, len))
269 if (get_stack_info(info->next_sp, state->task, info,
276 static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,
279 if (!stack_access_ok(state, addr, sizeof(long)))
282 *val = READ_ONCE_TASK_STACK(state->task, *(unsigned long *)addr);
286 #define REGS_SIZE (sizeof(struct pt_regs))
287 #define SP_OFFSET (offsetof(struct pt_regs, sp))
288 #define IRET_REGS_SIZE (REGS_SIZE - offsetof(struct pt_regs, ip))
289 #define IRET_SP_OFFSET (SP_OFFSET - offsetof(struct pt_regs, ip))
291 static bool deref_stack_regs(struct unwind_state *state, unsigned long addr,
292 unsigned long *ip, unsigned long *sp, bool full)
294 size_t regs_size = full ? REGS_SIZE : IRET_REGS_SIZE;
295 size_t sp_offset = full ? SP_OFFSET : IRET_SP_OFFSET;
296 struct pt_regs *regs = (struct pt_regs *)(addr + regs_size - REGS_SIZE);
298 if (IS_ENABLED(CONFIG_X86_64)) {
299 if (!stack_access_ok(state, addr, regs_size))
308 if (!stack_access_ok(state, addr, sp_offset))
313 if (user_mode(regs)) {
314 if (!stack_access_ok(state, addr + sp_offset,
315 REGS_SIZE - SP_OFFSET))
320 *sp = (unsigned long)®s->sp;
325 bool unwind_next_frame(struct unwind_state *state)
327 unsigned long ip_p, sp, orig_ip, prev_sp = state->sp;
328 enum stack_type prev_type = state->stack_info.type;
329 struct orc_entry *orc;
330 struct pt_regs *ptregs;
331 bool indirect = false;
333 if (unwind_done(state))
336 /* Don't let modules unload while we're reading their ORC data. */
339 /* Have we reached the end? */
340 if (state->regs && user_mode(state->regs))
344 * Find the orc_entry associated with the text address.
346 * Decrement call return addresses by one so they work for sibling
347 * calls and calls to noreturn functions.
349 orc = orc_find(state->signal ? state->ip : state->ip - 1);
350 if (!orc || orc->sp_reg == ORC_REG_UNDEFINED)
354 /* Find the previous frame's stack: */
355 switch (orc->sp_reg) {
357 sp = state->sp + orc->sp_offset;
361 sp = state->bp + orc->sp_offset;
364 case ORC_REG_SP_INDIRECT:
365 sp = state->sp + orc->sp_offset;
369 case ORC_REG_BP_INDIRECT:
370 sp = state->bp + orc->sp_offset;
375 if (!state->regs || !state->full_regs) {
376 orc_warn("missing regs for base reg R10 at ip %pB\n",
380 sp = state->regs->r10;
384 if (!state->regs || !state->full_regs) {
385 orc_warn("missing regs for base reg R13 at ip %pB\n",
389 sp = state->regs->r13;
393 if (!state->regs || !state->full_regs) {
394 orc_warn("missing regs for base reg DI at ip %pB\n",
398 sp = state->regs->di;
402 if (!state->regs || !state->full_regs) {
403 orc_warn("missing regs for base reg DX at ip %pB\n",
407 sp = state->regs->dx;
411 orc_warn("unknown SP base reg %d for ip %pB\n",
412 orc->sp_reg, (void *)state->ip);
417 if (!deref_stack_reg(state, sp, &sp))
421 /* Find IP, SP and possibly regs: */
424 ip_p = sp - sizeof(long);
426 if (!deref_stack_reg(state, ip_p, &state->ip))
429 state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
430 state->ip, (void *)ip_p);
434 state->signal = false;
438 if (!deref_stack_regs(state, sp, &state->ip, &state->sp, true)) {
439 orc_warn("can't dereference registers at %p for ip %pB\n",
440 (void *)sp, (void *)orig_ip);
444 state->regs = (struct pt_regs *)sp;
445 state->full_regs = true;
446 state->signal = true;
449 case ORC_TYPE_REGS_IRET:
450 if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) {
451 orc_warn("can't dereference iret registers at %p for ip %pB\n",
452 (void *)sp, (void *)orig_ip);
456 ptregs = container_of((void *)sp, struct pt_regs, ip);
457 if ((unsigned long)ptregs >= prev_sp &&
458 on_stack(&state->stack_info, ptregs, REGS_SIZE)) {
459 state->regs = ptregs;
460 state->full_regs = false;
464 state->signal = true;
468 orc_warn("unknown .orc_unwind entry type %d for ip %pB\n",
469 orc->type, (void *)orig_ip);
474 switch (orc->bp_reg) {
475 case ORC_REG_UNDEFINED:
476 if (state->regs && state->full_regs)
477 state->bp = state->regs->bp;
480 case ORC_REG_PREV_SP:
481 if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp))
486 if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp))
491 orc_warn("unknown BP base reg %d for ip %pB\n",
492 orc->bp_reg, (void *)orig_ip);
496 /* Prevent a recursive loop due to bad ORC data: */
497 if (state->stack_info.type == prev_type &&
498 on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) &&
499 state->sp <= prev_sp) {
500 orc_warn("stack going in the wrong direction? ip=%pB\n",
510 state->stack_info.type = STACK_TYPE_UNKNOWN;
513 EXPORT_SYMBOL_GPL(unwind_next_frame);
515 void __unwind_start(struct unwind_state *state, struct task_struct *task,
516 struct pt_regs *regs, unsigned long *first_frame)
518 memset(state, 0, sizeof(*state));
522 * Refuse to unwind the stack of a task while it's executing on another
523 * CPU. This check is racy, but that's ok: the unwinder has other
524 * checks to prevent it from going off the rails.
526 if (task_on_another_cpu(task))
533 state->ip = regs->ip;
534 state->sp = kernel_stack_pointer(regs);
535 state->bp = regs->bp;
537 state->full_regs = true;
538 state->signal = true;
540 } else if (task == current) {
541 asm volatile("lea (%%rip), %0\n\t"
544 : "=r" (state->ip), "=r" (state->sp),
548 struct inactive_task_frame *frame = (void *)task->thread.sp;
550 state->sp = task->thread.sp;
551 state->bp = READ_ONCE_NOCHECK(frame->bp);
552 state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
555 if (get_stack_info((unsigned long *)state->sp, state->task,
556 &state->stack_info, &state->stack_mask))
560 * The caller can provide the address of the first frame directly
561 * (first_frame) or indirectly (regs->sp) to indicate which stack frame
562 * to start unwinding at. Skip ahead until we reach it.
565 /* When starting from regs, skip the regs frame: */
567 unwind_next_frame(state);
571 /* Otherwise, skip ahead to the user-specified starting frame: */
572 while (!unwind_done(state) &&
573 (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
574 state->sp <= (unsigned long)first_frame))
575 unwind_next_frame(state);
580 state->stack_info.type = STACK_TYPE_UNKNOWN;
583 EXPORT_SYMBOL_GPL(__unwind_start);