1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Dynamic function tracing support. |
4 | * |
5 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> |
6 | * |
7 | * Thanks goes to Ingo Molnar, for suggesting the idea. |
8 | * Mathieu Desnoyers, for suggesting postponing the modifications. |
9 | * Arjan van de Ven, for keeping me straight, and explaining to me |
10 | * the dangers of modifying code on the run. |
11 | */ |
12 | |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | |
15 | #include <linux/spinlock.h> |
16 | #include <linux/hardirq.h> |
17 | #include <linux/uaccess.h> |
18 | #include <linux/ftrace.h> |
19 | #include <linux/percpu.h> |
20 | #include <linux/sched.h> |
21 | #include <linux/slab.h> |
22 | #include <linux/init.h> |
23 | #include <linux/list.h> |
24 | #include <linux/module.h> |
25 | #include <linux/memory.h> |
26 | #include <linux/vmalloc.h> |
27 | #include <linux/set_memory.h> |
28 | |
29 | #include <trace/syscall.h> |
30 | |
31 | #include <asm/kprobes.h> |
32 | #include <asm/ftrace.h> |
33 | #include <asm/nops.h> |
34 | #include <asm/text-patching.h> |
35 | |
36 | #ifdef CONFIG_DYNAMIC_FTRACE |
37 | |
38 | static int ftrace_poke_late = 0; |
39 | |
40 | void ftrace_arch_code_modify_prepare(void) |
41 | __acquires(&text_mutex) |
42 | { |
43 | /* |
44 | * Need to grab text_mutex to prevent a race from module loading |
45 | * and live kernel patching from changing the text permissions while |
46 | * ftrace has it set to "read/write". |
47 | */ |
48 | mutex_lock(&text_mutex); |
49 | ftrace_poke_late = 1; |
50 | } |
51 | |
52 | void ftrace_arch_code_modify_post_process(void) |
53 | __releases(&text_mutex) |
54 | { |
55 | /* |
56 | * ftrace_make_{call,nop}() may be called during |
57 | * module load, and we need to finish the text_poke_queue() |
58 | * that they do, here. |
59 | */ |
60 | text_poke_finish(); |
61 | ftrace_poke_late = 0; |
62 | mutex_unlock(lock: &text_mutex); |
63 | } |
64 | |
65 | static const char *ftrace_nop_replace(void) |
66 | { |
67 | return x86_nops[5]; |
68 | } |
69 | |
70 | static const char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
71 | { |
72 | /* |
73 | * No need to translate into a callthunk. The trampoline does |
74 | * the depth accounting itself. |
75 | */ |
76 | return text_gen_insn(CALL_INSN_OPCODE, addr: (void *)ip, dest: (void *)addr); |
77 | } |
78 | |
79 | static int ftrace_verify_code(unsigned long ip, const char *old_code) |
80 | { |
81 | char cur_code[MCOUNT_INSN_SIZE]; |
82 | |
83 | /* |
84 | * Note: |
85 | * We are paranoid about modifying text, as if a bug was to happen, it |
86 | * could cause us to read or write to someplace that could cause harm. |
87 | * Carefully read and modify the code with probe_kernel_*(), and make |
88 | * sure what we read is what we expected it to be before modifying it. |
89 | */ |
90 | /* read the text we want to modify */ |
91 | if (copy_from_kernel_nofault(dst: cur_code, src: (void *)ip, MCOUNT_INSN_SIZE)) { |
92 | WARN_ON(1); |
93 | return -EFAULT; |
94 | } |
95 | |
96 | /* Make sure it is what we expect it to be */ |
97 | if (memcmp(p: cur_code, q: old_code, MCOUNT_INSN_SIZE) != 0) { |
98 | ftrace_expected = old_code; |
99 | WARN_ON(1); |
100 | return -EINVAL; |
101 | } |
102 | |
103 | return 0; |
104 | } |
105 | |
106 | /* |
107 | * Marked __ref because it calls text_poke_early() which is .init.text. That is |
108 | * ok because that call will happen early, during boot, when .init sections are |
109 | * still present. |
110 | */ |
111 | static int __ref |
112 | ftrace_modify_code_direct(unsigned long ip, const char *old_code, |
113 | const char *new_code) |
114 | { |
115 | int ret = ftrace_verify_code(ip, old_code); |
116 | if (ret) |
117 | return ret; |
118 | |
119 | /* replace the text with the new text */ |
120 | if (ftrace_poke_late) |
121 | text_poke_queue(addr: (void *)ip, opcode: new_code, MCOUNT_INSN_SIZE, NULL); |
122 | else |
123 | text_poke_early(addr: (void *)ip, opcode: new_code, MCOUNT_INSN_SIZE); |
124 | return 0; |
125 | } |
126 | |
127 | int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) |
128 | { |
129 | unsigned long ip = rec->ip; |
130 | const char *new, *old; |
131 | |
132 | old = ftrace_call_replace(ip, addr); |
133 | new = ftrace_nop_replace(); |
134 | |
135 | /* |
136 | * On boot up, and when modules are loaded, the MCOUNT_ADDR |
137 | * is converted to a nop, and will never become MCOUNT_ADDR |
138 | * again. This code is either running before SMP (on boot up) |
139 | * or before the code will ever be executed (module load). |
140 | * We do not want to use the breakpoint version in this case, |
141 | * just modify the code directly. |
142 | */ |
143 | if (addr == MCOUNT_ADDR) |
144 | return ftrace_modify_code_direct(ip, old_code: old, new_code: new); |
145 | |
146 | /* |
147 | * x86 overrides ftrace_replace_code -- this function will never be used |
148 | * in this case. |
149 | */ |
150 | WARN_ONCE(1, "invalid use of ftrace_make_nop" ); |
151 | return -EINVAL; |
152 | } |
153 | |
154 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
155 | { |
156 | unsigned long ip = rec->ip; |
157 | const char *new, *old; |
158 | |
159 | old = ftrace_nop_replace(); |
160 | new = ftrace_call_replace(ip, addr); |
161 | |
162 | /* Should only be called when module is loaded */ |
163 | return ftrace_modify_code_direct(ip: rec->ip, old_code: old, new_code: new); |
164 | } |
165 | |
166 | /* |
167 | * Should never be called: |
168 | * As it is only called by __ftrace_replace_code() which is called by |
169 | * ftrace_replace_code() that x86 overrides, and by ftrace_update_code() |
170 | * which is called to turn mcount into nops or nops into function calls |
171 | * but not to convert a function from not using regs to one that uses |
172 | * regs, which ftrace_modify_call() is for. |
173 | */ |
174 | int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, |
175 | unsigned long addr) |
176 | { |
177 | WARN_ON(1); |
178 | return -EINVAL; |
179 | } |
180 | |
181 | int ftrace_update_ftrace_func(ftrace_func_t func) |
182 | { |
183 | unsigned long ip; |
184 | const char *new; |
185 | |
186 | ip = (unsigned long)(&ftrace_call); |
187 | new = ftrace_call_replace(ip, addr: (unsigned long)func); |
188 | text_poke_bp(addr: (void *)ip, opcode: new, MCOUNT_INSN_SIZE, NULL); |
189 | |
190 | ip = (unsigned long)(&ftrace_regs_call); |
191 | new = ftrace_call_replace(ip, addr: (unsigned long)func); |
192 | text_poke_bp(addr: (void *)ip, opcode: new, MCOUNT_INSN_SIZE, NULL); |
193 | |
194 | return 0; |
195 | } |
196 | |
197 | void ftrace_replace_code(int enable) |
198 | { |
199 | struct ftrace_rec_iter *iter; |
200 | struct dyn_ftrace *rec; |
201 | const char *new, *old; |
202 | int ret; |
203 | |
204 | for_ftrace_rec_iter(iter) { |
205 | rec = ftrace_rec_iter_record(iter); |
206 | |
207 | switch (ftrace_test_record(rec, enable)) { |
208 | case FTRACE_UPDATE_IGNORE: |
209 | default: |
210 | continue; |
211 | |
212 | case FTRACE_UPDATE_MAKE_CALL: |
213 | old = ftrace_nop_replace(); |
214 | break; |
215 | |
216 | case FTRACE_UPDATE_MODIFY_CALL: |
217 | case FTRACE_UPDATE_MAKE_NOP: |
218 | old = ftrace_call_replace(ip: rec->ip, addr: ftrace_get_addr_curr(rec)); |
219 | break; |
220 | } |
221 | |
222 | ret = ftrace_verify_code(ip: rec->ip, old_code: old); |
223 | if (ret) { |
224 | ftrace_expected = old; |
225 | ftrace_bug(err: ret, rec); |
226 | ftrace_expected = NULL; |
227 | return; |
228 | } |
229 | } |
230 | |
231 | for_ftrace_rec_iter(iter) { |
232 | rec = ftrace_rec_iter_record(iter); |
233 | |
234 | switch (ftrace_test_record(rec, enable)) { |
235 | case FTRACE_UPDATE_IGNORE: |
236 | default: |
237 | continue; |
238 | |
239 | case FTRACE_UPDATE_MAKE_CALL: |
240 | case FTRACE_UPDATE_MODIFY_CALL: |
241 | new = ftrace_call_replace(ip: rec->ip, addr: ftrace_get_addr_new(rec)); |
242 | break; |
243 | |
244 | case FTRACE_UPDATE_MAKE_NOP: |
245 | new = ftrace_nop_replace(); |
246 | break; |
247 | } |
248 | |
249 | text_poke_queue(addr: (void *)rec->ip, opcode: new, MCOUNT_INSN_SIZE, NULL); |
250 | ftrace_update_record(rec, enable); |
251 | } |
252 | text_poke_finish(); |
253 | } |
254 | |
255 | void arch_ftrace_update_code(int command) |
256 | { |
257 | ftrace_modify_all_code(command); |
258 | } |
259 | |
260 | /* Currently only x86_64 supports dynamic trampolines */ |
261 | #ifdef CONFIG_X86_64 |
262 | |
263 | #ifdef CONFIG_MODULES |
264 | #include <linux/moduleloader.h> |
265 | /* Module allocation simplifies allocating memory for code */ |
266 | static inline void *alloc_tramp(unsigned long size) |
267 | { |
268 | return module_alloc(size); |
269 | } |
270 | static inline void tramp_free(void *tramp) |
271 | { |
272 | module_memfree(module_region: tramp); |
273 | } |
274 | #else |
275 | /* Trampolines can only be created if modules are supported */ |
276 | static inline void *alloc_tramp(unsigned long size) |
277 | { |
278 | return NULL; |
279 | } |
280 | static inline void tramp_free(void *tramp) { } |
281 | #endif |
282 | |
283 | /* Defined as markers to the end of the ftrace default trampolines */ |
284 | extern void ftrace_regs_caller_end(void); |
285 | extern void ftrace_caller_end(void); |
286 | extern void ftrace_caller_op_ptr(void); |
287 | extern void ftrace_regs_caller_op_ptr(void); |
288 | extern void ftrace_regs_caller_jmp(void); |
289 | |
290 | /* movq function_trace_op(%rip), %rdx */ |
291 | /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */ |
292 | #define OP_REF_SIZE 7 |
293 | |
294 | /* |
295 | * The ftrace_ops is passed to the function callback. Since the |
296 | * trampoline only services a single ftrace_ops, we can pass in |
297 | * that ops directly. |
298 | * |
299 | * The ftrace_op_code_union is used to create a pointer to the |
300 | * ftrace_ops that will be passed to the callback function. |
301 | */ |
302 | union ftrace_op_code_union { |
303 | char code[OP_REF_SIZE]; |
304 | struct { |
305 | char op[3]; |
306 | int offset; |
307 | } __attribute__((packed)); |
308 | }; |
309 | |
310 | #define RET_SIZE \ |
311 | (IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_MITIGATION_SLS)) |
312 | |
313 | static unsigned long |
314 | create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) |
315 | { |
316 | unsigned long start_offset; |
317 | unsigned long end_offset; |
318 | unsigned long op_offset; |
319 | unsigned long call_offset; |
320 | unsigned long jmp_offset; |
321 | unsigned long offset; |
322 | unsigned long npages; |
323 | unsigned long size; |
324 | unsigned long *ptr; |
325 | void *trampoline; |
326 | void *ip, *dest; |
327 | /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */ |
328 | unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 }; |
329 | unsigned const char retq[] = { RET_INSN_OPCODE, INT3_INSN_OPCODE }; |
330 | union ftrace_op_code_union op_ptr; |
331 | int ret; |
332 | |
333 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { |
334 | start_offset = (unsigned long)ftrace_regs_caller; |
335 | end_offset = (unsigned long)ftrace_regs_caller_end; |
336 | op_offset = (unsigned long)ftrace_regs_caller_op_ptr; |
337 | call_offset = (unsigned long)ftrace_regs_call; |
338 | jmp_offset = (unsigned long)ftrace_regs_caller_jmp; |
339 | } else { |
340 | start_offset = (unsigned long)ftrace_caller; |
341 | end_offset = (unsigned long)ftrace_caller_end; |
342 | op_offset = (unsigned long)ftrace_caller_op_ptr; |
343 | call_offset = (unsigned long)ftrace_call; |
344 | jmp_offset = 0; |
345 | } |
346 | |
347 | size = end_offset - start_offset; |
348 | |
349 | /* |
350 | * Allocate enough size to store the ftrace_caller code, |
351 | * the iret , as well as the address of the ftrace_ops this |
352 | * trampoline is used for. |
353 | */ |
354 | trampoline = alloc_tramp(size: size + RET_SIZE + sizeof(void *)); |
355 | if (!trampoline) |
356 | return 0; |
357 | |
358 | *tramp_size = size + RET_SIZE + sizeof(void *); |
359 | npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE); |
360 | |
361 | /* Copy ftrace_caller onto the trampoline memory */ |
362 | ret = copy_from_kernel_nofault(dst: trampoline, src: (void *)start_offset, size); |
363 | if (WARN_ON(ret < 0)) |
364 | goto fail; |
365 | |
366 | ip = trampoline + size; |
367 | if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) |
368 | __text_gen_insn(buf: ip, JMP32_INSN_OPCODE, addr: ip, dest: x86_return_thunk, JMP32_INSN_SIZE); |
369 | else |
370 | memcpy(ip, retq, sizeof(retq)); |
371 | |
372 | /* No need to test direct calls on created trampolines */ |
373 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { |
374 | /* NOP the jnz 1f; but make sure it's a 2 byte jnz */ |
375 | ip = trampoline + (jmp_offset - start_offset); |
376 | if (WARN_ON(*(char *)ip != 0x75)) |
377 | goto fail; |
378 | ret = copy_from_kernel_nofault(dst: ip, src: x86_nops[2], size: 2); |
379 | if (ret < 0) |
380 | goto fail; |
381 | } |
382 | |
383 | /* |
384 | * The address of the ftrace_ops that is used for this trampoline |
385 | * is stored at the end of the trampoline. This will be used to |
386 | * load the third parameter for the callback. Basically, that |
387 | * location at the end of the trampoline takes the place of |
388 | * the global function_trace_op variable. |
389 | */ |
390 | |
391 | ptr = (unsigned long *)(trampoline + size + RET_SIZE); |
392 | *ptr = (unsigned long)ops; |
393 | |
394 | op_offset -= start_offset; |
395 | memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE); |
396 | |
397 | /* Are we pointing to the reference? */ |
398 | if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) |
399 | goto fail; |
400 | |
401 | /* Load the contents of ptr into the callback parameter */ |
402 | offset = (unsigned long)ptr; |
403 | offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE; |
404 | |
405 | op_ptr.offset = offset; |
406 | |
407 | /* put in the new offset to the ftrace_ops */ |
408 | memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE); |
409 | |
410 | /* put in the call to the function */ |
411 | mutex_lock(&text_mutex); |
412 | call_offset -= start_offset; |
413 | /* |
414 | * No need to translate into a callthunk. The trampoline does |
415 | * the depth accounting before the call already. |
416 | */ |
417 | dest = ftrace_ops_get_func(ops); |
418 | memcpy(trampoline + call_offset, |
419 | text_gen_insn(CALL_INSN_OPCODE, trampoline + call_offset, dest), |
420 | CALL_INSN_SIZE); |
421 | mutex_unlock(lock: &text_mutex); |
422 | |
423 | /* ALLOC_TRAMP flags lets us know we created it */ |
424 | ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP; |
425 | |
426 | set_memory_rox(addr: (unsigned long)trampoline, numpages: npages); |
427 | return (unsigned long)trampoline; |
428 | fail: |
429 | tramp_free(tramp: trampoline); |
430 | return 0; |
431 | } |
432 | |
433 | void set_ftrace_ops_ro(void) |
434 | { |
435 | struct ftrace_ops *ops; |
436 | unsigned long start_offset; |
437 | unsigned long end_offset; |
438 | unsigned long npages; |
439 | unsigned long size; |
440 | |
441 | do_for_each_ftrace_op(ops, ftrace_ops_list) { |
442 | if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) |
443 | continue; |
444 | |
445 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { |
446 | start_offset = (unsigned long)ftrace_regs_caller; |
447 | end_offset = (unsigned long)ftrace_regs_caller_end; |
448 | } else { |
449 | start_offset = (unsigned long)ftrace_caller; |
450 | end_offset = (unsigned long)ftrace_caller_end; |
451 | } |
452 | size = end_offset - start_offset; |
453 | size = size + RET_SIZE + sizeof(void *); |
454 | npages = DIV_ROUND_UP(size, PAGE_SIZE); |
455 | set_memory_ro(addr: (unsigned long)ops->trampoline, numpages: npages); |
456 | } while_for_each_ftrace_op(ops); |
457 | } |
458 | |
459 | static unsigned long calc_trampoline_call_offset(bool save_regs) |
460 | { |
461 | unsigned long start_offset; |
462 | unsigned long call_offset; |
463 | |
464 | if (save_regs) { |
465 | start_offset = (unsigned long)ftrace_regs_caller; |
466 | call_offset = (unsigned long)ftrace_regs_call; |
467 | } else { |
468 | start_offset = (unsigned long)ftrace_caller; |
469 | call_offset = (unsigned long)ftrace_call; |
470 | } |
471 | |
472 | return call_offset - start_offset; |
473 | } |
474 | |
475 | void arch_ftrace_update_trampoline(struct ftrace_ops *ops) |
476 | { |
477 | ftrace_func_t func; |
478 | unsigned long offset; |
479 | unsigned long ip; |
480 | unsigned int size; |
481 | const char *new; |
482 | |
483 | if (!ops->trampoline) { |
484 | ops->trampoline = create_trampoline(ops, tramp_size: &size); |
485 | if (!ops->trampoline) |
486 | return; |
487 | ops->trampoline_size = size; |
488 | return; |
489 | } |
490 | |
491 | /* |
492 | * The ftrace_ops caller may set up its own trampoline. |
493 | * In such a case, this code must not modify it. |
494 | */ |
495 | if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) |
496 | return; |
497 | |
498 | offset = calc_trampoline_call_offset(save_regs: ops->flags & FTRACE_OPS_FL_SAVE_REGS); |
499 | ip = ops->trampoline + offset; |
500 | func = ftrace_ops_get_func(ops); |
501 | |
502 | mutex_lock(&text_mutex); |
503 | /* Do a safe modify in case the trampoline is executing */ |
504 | new = ftrace_call_replace(ip, addr: (unsigned long)func); |
505 | text_poke_bp(addr: (void *)ip, opcode: new, MCOUNT_INSN_SIZE, NULL); |
506 | mutex_unlock(lock: &text_mutex); |
507 | } |
508 | |
509 | /* Return the address of the function the trampoline calls */ |
510 | static void *addr_from_call(void *ptr) |
511 | { |
512 | union text_poke_insn call; |
513 | int ret; |
514 | |
515 | ret = copy_from_kernel_nofault(dst: &call, src: ptr, CALL_INSN_SIZE); |
516 | if (WARN_ON_ONCE(ret < 0)) |
517 | return NULL; |
518 | |
519 | /* Make sure this is a call */ |
520 | if (WARN_ON_ONCE(call.opcode != CALL_INSN_OPCODE)) { |
521 | pr_warn("Expected E8, got %x\n" , call.opcode); |
522 | return NULL; |
523 | } |
524 | |
525 | return ptr + CALL_INSN_SIZE + call.disp; |
526 | } |
527 | |
528 | /* |
529 | * If the ops->trampoline was not allocated, then it probably |
530 | * has a static trampoline func, or is the ftrace caller itself. |
531 | */ |
532 | static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) |
533 | { |
534 | unsigned long offset; |
535 | bool save_regs = rec->flags & FTRACE_FL_REGS_EN; |
536 | void *ptr; |
537 | |
538 | if (ops && ops->trampoline) { |
539 | #if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) && \ |
540 | defined(CONFIG_FUNCTION_GRAPH_TRACER) |
541 | /* |
542 | * We only know about function graph tracer setting as static |
543 | * trampoline. |
544 | */ |
545 | if (ops->trampoline == FTRACE_GRAPH_ADDR) |
546 | return (void *)prepare_ftrace_return; |
547 | #endif |
548 | return NULL; |
549 | } |
550 | |
551 | offset = calc_trampoline_call_offset(save_regs); |
552 | |
553 | if (save_regs) |
554 | ptr = (void *)FTRACE_REGS_ADDR + offset; |
555 | else |
556 | ptr = (void *)FTRACE_ADDR + offset; |
557 | |
558 | return addr_from_call(ptr); |
559 | } |
560 | |
561 | void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) |
562 | { |
563 | unsigned long offset; |
564 | |
565 | /* If we didn't allocate this trampoline, consider it static */ |
566 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) |
567 | return static_tramp_func(ops, rec); |
568 | |
569 | offset = calc_trampoline_call_offset(save_regs: ops->flags & FTRACE_OPS_FL_SAVE_REGS); |
570 | return addr_from_call(ptr: (void *)ops->trampoline + offset); |
571 | } |
572 | |
573 | void arch_ftrace_trampoline_free(struct ftrace_ops *ops) |
574 | { |
575 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) |
576 | return; |
577 | |
578 | tramp_free(tramp: (void *)ops->trampoline); |
579 | ops->trampoline = 0; |
580 | } |
581 | |
582 | #endif /* CONFIG_X86_64 */ |
583 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
584 | |
585 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
586 | |
587 | #if defined(CONFIG_DYNAMIC_FTRACE) && !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) |
588 | extern void ftrace_graph_call(void); |
589 | static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) |
590 | { |
591 | return text_gen_insn(JMP32_INSN_OPCODE, (void *)ip, (void *)addr); |
592 | } |
593 | |
594 | static int ftrace_mod_jmp(unsigned long ip, void *func) |
595 | { |
596 | const char *new; |
597 | |
598 | new = ftrace_jmp_replace(ip, (unsigned long)func); |
599 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); |
600 | return 0; |
601 | } |
602 | |
603 | int ftrace_enable_ftrace_graph_caller(void) |
604 | { |
605 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
606 | |
607 | return ftrace_mod_jmp(ip, &ftrace_graph_caller); |
608 | } |
609 | |
610 | int ftrace_disable_ftrace_graph_caller(void) |
611 | { |
612 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
613 | |
614 | return ftrace_mod_jmp(ip, &ftrace_stub); |
615 | } |
616 | #endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ |
617 | |
618 | /* |
619 | * Hook the return address and push it in the stack of return addrs |
620 | * in current thread info. |
621 | */ |
622 | void prepare_ftrace_return(unsigned long ip, unsigned long *parent, |
623 | unsigned long frame_pointer) |
624 | { |
625 | unsigned long return_hooker = (unsigned long)&return_to_handler; |
626 | int bit; |
627 | |
628 | /* |
629 | * When resuming from suspend-to-ram, this function can be indirectly |
630 | * called from early CPU startup code while the CPU is in real mode, |
631 | * which would fail miserably. Make sure the stack pointer is a |
632 | * virtual address. |
633 | * |
634 | * This check isn't as accurate as virt_addr_valid(), but it should be |
635 | * good enough for this purpose, and it's fast. |
636 | */ |
637 | if (unlikely((long)__builtin_frame_address(0) >= 0)) |
638 | return; |
639 | |
640 | if (unlikely(ftrace_graph_is_dead())) |
641 | return; |
642 | |
643 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
644 | return; |
645 | |
646 | bit = ftrace_test_recursion_trylock(ip, parent_ip: *parent); |
647 | if (bit < 0) |
648 | return; |
649 | |
650 | if (!function_graph_enter(ret: *parent, func: ip, frame_pointer, retp: parent)) |
651 | *parent = return_hooker; |
652 | |
653 | ftrace_test_recursion_unlock(bit); |
654 | } |
655 | |
656 | #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS |
657 | void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, |
658 | struct ftrace_ops *op, struct ftrace_regs *fregs) |
659 | { |
660 | struct pt_regs *regs = &fregs->regs; |
661 | unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); |
662 | |
663 | prepare_ftrace_return(ip, parent: (unsigned long *)stack, frame_pointer: 0); |
664 | } |
665 | #endif |
666 | |
667 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
668 | |