Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
3d083395 | 2 | /* |
9d2099ab | 3 | * Dynamic function tracing support. |
3d083395 SR |
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 | ||
3bb258bf JP |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | ||
3d083395 SR |
15 | #include <linux/spinlock.h> |
16 | #include <linux/hardirq.h> | |
6f93fc07 | 17 | #include <linux/uaccess.h> |
3d083395 SR |
18 | #include <linux/ftrace.h> |
19 | #include <linux/percpu.h> | |
19b3e967 | 20 | #include <linux/sched.h> |
f3bea491 | 21 | #include <linux/slab.h> |
3d083395 SR |
22 | #include <linux/init.h> |
23 | #include <linux/list.h> | |
84e1c6bb | 24 | #include <linux/module.h> |
d5b844a2 | 25 | #include <linux/memory.h> |
ac0b14dc | 26 | #include <linux/vmalloc.h> |
3d083395 | 27 | |
47788c58 FW |
28 | #include <trace/syscall.h> |
29 | ||
d1163651 | 30 | #include <asm/set_memory.h> |
59a094c9 | 31 | #include <asm/kprobes.h> |
395a59d0 | 32 | #include <asm/ftrace.h> |
732f3ca7 | 33 | #include <asm/nops.h> |
9e298e86 | 34 | #include <asm/text-patching.h> |
3d083395 | 35 | |
caf4b323 | 36 | #ifdef CONFIG_DYNAMIC_FTRACE |
3d083395 | 37 | |
768ae440 PZ |
38 | static int ftrace_poke_late = 0; |
39 | ||
16239630 | 40 | int ftrace_arch_code_modify_prepare(void) |
074376ac | 41 | __acquires(&text_mutex) |
16239630 | 42 | { |
39611265 SRV |
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 | */ | |
d5b844a2 | 48 | mutex_lock(&text_mutex); |
768ae440 | 49 | ftrace_poke_late = 1; |
16239630 SR |
50 | return 0; |
51 | } | |
52 | ||
53 | int ftrace_arch_code_modify_post_process(void) | |
074376ac | 54 | __releases(&text_mutex) |
16239630 | 55 | { |
768ae440 PZ |
56 | /* |
57 | * ftrace_make_{call,nop}() may be called during | |
58 | * module load, and we need to finish the text_poke_queue() | |
59 | * that they do, here. | |
60 | */ | |
61 | text_poke_finish(); | |
62 | ftrace_poke_late = 0; | |
d5b844a2 | 63 | mutex_unlock(&text_mutex); |
16239630 SR |
64 | return 0; |
65 | } | |
66 | ||
768ae440 | 67 | static const char *ftrace_nop_replace(void) |
17666f02 | 68 | { |
a89dfde3 | 69 | return x86_nops[5]; |
17666f02 SR |
70 | } |
71 | ||
768ae440 | 72 | static const char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
caf4b323 | 73 | { |
67c1d4a2 | 74 | return text_gen_insn(CALL_INSN_OPCODE, (void *)ip, (void *)addr); |
caf4b323 FW |
75 | } |
76 | ||
768ae440 | 77 | static int ftrace_verify_code(unsigned long ip, const char *old_code) |
3d083395 | 78 | { |
768ae440 | 79 | char cur_code[MCOUNT_INSN_SIZE]; |
b05086c7 | 80 | |
3d083395 | 81 | /* |
c5d641f9 LB |
82 | * Note: |
83 | * We are paranoid about modifying text, as if a bug was to happen, it | |
84 | * could cause us to read or write to someplace that could cause harm. | |
85 | * Carefully read and modify the code with probe_kernel_*(), and make | |
86 | * sure what we read is what we expected it to be before modifying it. | |
3d083395 | 87 | */ |
76aefee5 | 88 | /* read the text we want to modify */ |
fe557319 | 89 | if (copy_from_kernel_nofault(cur_code, (void *)ip, MCOUNT_INSN_SIZE)) { |
768ae440 | 90 | WARN_ON(1); |
593eb8a2 | 91 | return -EFAULT; |
768ae440 | 92 | } |
6f93fc07 | 93 | |
76aefee5 | 94 | /* Make sure it is what we expect it to be */ |
768ae440 PZ |
95 | if (memcmp(cur_code, old_code, MCOUNT_INSN_SIZE) != 0) { |
96 | WARN_ON(1); | |
593eb8a2 | 97 | return -EINVAL; |
768ae440 | 98 | } |
3d083395 | 99 | |
768ae440 PZ |
100 | return 0; |
101 | } | |
6f93fc07 | 102 | |
38ebd8d1 BP |
103 | /* |
104 | * Marked __ref because it calls text_poke_early() which is .init.text. That is | |
105 | * ok because that call will happen early, during boot, when .init sections are | |
106 | * still present. | |
107 | */ | |
108 | static int __ref | |
768ae440 PZ |
109 | ftrace_modify_code_direct(unsigned long ip, const char *old_code, |
110 | const char *new_code) | |
111 | { | |
112 | int ret = ftrace_verify_code(ip, old_code); | |
113 | if (ret) | |
114 | return ret; | |
3d083395 | 115 | |
768ae440 PZ |
116 | /* replace the text with the new text */ |
117 | if (ftrace_poke_late) | |
118 | text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL); | |
119 | else | |
120 | text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); | |
6f93fc07 | 121 | return 0; |
3d083395 SR |
122 | } |
123 | ||
768ae440 | 124 | int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) |
31e88909 | 125 | { |
31e88909 | 126 | unsigned long ip = rec->ip; |
768ae440 | 127 | const char *new, *old; |
31e88909 SR |
128 | |
129 | old = ftrace_call_replace(ip, addr); | |
130 | new = ftrace_nop_replace(); | |
131 | ||
8a4d0a68 SR |
132 | /* |
133 | * On boot up, and when modules are loaded, the MCOUNT_ADDR | |
134 | * is converted to a nop, and will never become MCOUNT_ADDR | |
135 | * again. This code is either running before SMP (on boot up) | |
136 | * or before the code will ever be executed (module load). | |
137 | * We do not want to use the breakpoint version in this case, | |
138 | * just modify the code directly. | |
139 | */ | |
140 | if (addr == MCOUNT_ADDR) | |
768ae440 | 141 | return ftrace_modify_code_direct(ip, old, new); |
b05086c7 | 142 | |
768ae440 PZ |
143 | /* |
144 | * x86 overrides ftrace_replace_code -- this function will never be used | |
145 | * in this case. | |
146 | */ | |
8a4d0a68 SR |
147 | WARN_ONCE(1, "invalid use of ftrace_make_nop"); |
148 | return -EINVAL; | |
31e88909 SR |
149 | } |
150 | ||
151 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
152 | { | |
31e88909 | 153 | unsigned long ip = rec->ip; |
768ae440 | 154 | const char *new, *old; |
31e88909 SR |
155 | |
156 | old = ftrace_nop_replace(); | |
157 | new = ftrace_call_replace(ip, addr); | |
158 | ||
8a4d0a68 SR |
159 | /* Should only be called when module is loaded */ |
160 | return ftrace_modify_code_direct(rec->ip, old, new); | |
d61f82d0 SR |
161 | } |
162 | ||
08f6fba5 SR |
163 | /* |
164 | * Should never be called: | |
165 | * As it is only called by __ftrace_replace_code() which is called by | |
166 | * ftrace_replace_code() that x86 overrides, and by ftrace_update_code() | |
167 | * which is called to turn mcount into nops or nops into function calls | |
168 | * but not to convert a function from not using regs to one that uses | |
169 | * regs, which ftrace_modify_call() is for. | |
170 | */ | |
171 | int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, | |
172 | unsigned long addr) | |
173 | { | |
174 | WARN_ON(1); | |
175 | return -EINVAL; | |
176 | } | |
08f6fba5 | 177 | |
87fbb2ac | 178 | int ftrace_update_ftrace_func(ftrace_func_t func) |
08d636b6 | 179 | { |
ab4ead02 | 180 | unsigned long ip; |
768ae440 | 181 | const char *new; |
ab4ead02 | 182 | |
768ae440 PZ |
183 | ip = (unsigned long)(&ftrace_call); |
184 | new = ftrace_call_replace(ip, (unsigned long)func); | |
185 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); | |
08d636b6 | 186 | |
768ae440 PZ |
187 | ip = (unsigned long)(&ftrace_regs_call); |
188 | new = ftrace_call_replace(ip, (unsigned long)func); | |
189 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); | |
08d636b6 SR |
190 | |
191 | return 0; | |
192 | } | |
193 | ||
e4f5d544 | 194 | void ftrace_replace_code(int enable) |
08d636b6 SR |
195 | { |
196 | struct ftrace_rec_iter *iter; | |
197 | struct dyn_ftrace *rec; | |
768ae440 | 198 | const char *new, *old; |
08d636b6 SR |
199 | int ret; |
200 | ||
201 | for_ftrace_rec_iter(iter) { | |
202 | rec = ftrace_rec_iter_record(iter); | |
203 | ||
768ae440 PZ |
204 | switch (ftrace_test_record(rec, enable)) { |
205 | case FTRACE_UPDATE_IGNORE: | |
206 | default: | |
207 | continue; | |
08d636b6 | 208 | |
768ae440 PZ |
209 | case FTRACE_UPDATE_MAKE_CALL: |
210 | old = ftrace_nop_replace(); | |
211 | break; | |
08d636b6 | 212 | |
768ae440 PZ |
213 | case FTRACE_UPDATE_MODIFY_CALL: |
214 | case FTRACE_UPDATE_MAKE_NOP: | |
215 | old = ftrace_call_replace(rec->ip, ftrace_get_addr_curr(rec)); | |
216 | break; | |
217 | } | |
08d636b6 | 218 | |
768ae440 PZ |
219 | ret = ftrace_verify_code(rec->ip, old); |
220 | if (ret) { | |
221 | ftrace_bug(ret, rec); | |
222 | return; | |
223 | } | |
08d636b6 SR |
224 | } |
225 | ||
08d636b6 SR |
226 | for_ftrace_rec_iter(iter) { |
227 | rec = ftrace_rec_iter_record(iter); | |
228 | ||
768ae440 PZ |
229 | switch (ftrace_test_record(rec, enable)) { |
230 | case FTRACE_UPDATE_IGNORE: | |
231 | default: | |
232 | continue; | |
08d636b6 | 233 | |
768ae440 PZ |
234 | case FTRACE_UPDATE_MAKE_CALL: |
235 | case FTRACE_UPDATE_MODIFY_CALL: | |
236 | new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec)); | |
237 | break; | |
08d636b6 | 238 | |
768ae440 PZ |
239 | case FTRACE_UPDATE_MAKE_NOP: |
240 | new = ftrace_nop_replace(); | |
241 | break; | |
242 | } | |
08d636b6 | 243 | |
768ae440 PZ |
244 | text_poke_queue((void *)rec->ip, new, MCOUNT_INSN_SIZE, NULL); |
245 | ftrace_update_record(rec, enable); | |
08d636b6 | 246 | } |
768ae440 | 247 | text_poke_finish(); |
8a4d0a68 SR |
248 | } |
249 | ||
08d636b6 SR |
250 | void arch_ftrace_update_code(int command) |
251 | { | |
e4f5d544 | 252 | ftrace_modify_all_code(command); |
08d636b6 SR |
253 | } |
254 | ||
f3bea491 SRRH |
255 | /* Currently only x86_64 supports dynamic trampolines */ |
256 | #ifdef CONFIG_X86_64 | |
257 | ||
258 | #ifdef CONFIG_MODULES | |
259 | #include <linux/moduleloader.h> | |
260 | /* Module allocation simplifies allocating memory for code */ | |
261 | static inline void *alloc_tramp(unsigned long size) | |
262 | { | |
263 | return module_alloc(size); | |
264 | } | |
7fdfe1e4 | 265 | static inline void tramp_free(void *tramp) |
f3bea491 | 266 | { |
be1f221c | 267 | module_memfree(tramp); |
f3bea491 SRRH |
268 | } |
269 | #else | |
270 | /* Trampolines can only be created if modules are supported */ | |
271 | static inline void *alloc_tramp(unsigned long size) | |
272 | { | |
273 | return NULL; | |
274 | } | |
7fdfe1e4 | 275 | static inline void tramp_free(void *tramp) { } |
f3bea491 SRRH |
276 | #endif |
277 | ||
278 | /* Defined as markers to the end of the ftrace default trampolines */ | |
f3bea491 | 279 | extern void ftrace_regs_caller_end(void); |
0298739b PZ |
280 | extern void ftrace_regs_caller_ret(void); |
281 | extern void ftrace_caller_end(void); | |
f3bea491 SRRH |
282 | extern void ftrace_caller_op_ptr(void); |
283 | extern void ftrace_regs_caller_op_ptr(void); | |
fe58acef | 284 | extern void ftrace_regs_caller_jmp(void); |
f3bea491 SRRH |
285 | |
286 | /* movq function_trace_op(%rip), %rdx */ | |
287 | /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */ | |
288 | #define OP_REF_SIZE 7 | |
289 | ||
290 | /* | |
291 | * The ftrace_ops is passed to the function callback. Since the | |
292 | * trampoline only services a single ftrace_ops, we can pass in | |
293 | * that ops directly. | |
294 | * | |
295 | * The ftrace_op_code_union is used to create a pointer to the | |
296 | * ftrace_ops that will be passed to the callback function. | |
297 | */ | |
298 | union ftrace_op_code_union { | |
299 | char code[OP_REF_SIZE]; | |
300 | struct { | |
301 | char op[3]; | |
302 | int offset; | |
303 | } __attribute__((packed)); | |
304 | }; | |
305 | ||
e463a09a | 306 | #define RET_SIZE 1 + IS_ENABLED(CONFIG_SLS) |
d2a68c4e | 307 | |
aec0be2d SRRH |
308 | static unsigned long |
309 | create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) | |
f3bea491 | 310 | { |
f3bea491 SRRH |
311 | unsigned long start_offset; |
312 | unsigned long end_offset; | |
313 | unsigned long op_offset; | |
768ae440 | 314 | unsigned long call_offset; |
fe58acef | 315 | unsigned long jmp_offset; |
f3bea491 | 316 | unsigned long offset; |
3c0dab44 | 317 | unsigned long npages; |
f3bea491 | 318 | unsigned long size; |
f3bea491 SRRH |
319 | unsigned long *ptr; |
320 | void *trampoline; | |
d2a68c4e | 321 | void *ip; |
f3bea491 SRRH |
322 | /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */ |
323 | unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 }; | |
e52fc2cf | 324 | unsigned const char retq[] = { RET_INSN_OPCODE, INT3_INSN_OPCODE }; |
f3bea491 SRRH |
325 | union ftrace_op_code_union op_ptr; |
326 | int ret; | |
327 | ||
328 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { | |
329 | start_offset = (unsigned long)ftrace_regs_caller; | |
330 | end_offset = (unsigned long)ftrace_regs_caller_end; | |
331 | op_offset = (unsigned long)ftrace_regs_caller_op_ptr; | |
768ae440 | 332 | call_offset = (unsigned long)ftrace_regs_call; |
fe58acef | 333 | jmp_offset = (unsigned long)ftrace_regs_caller_jmp; |
f3bea491 SRRH |
334 | } else { |
335 | start_offset = (unsigned long)ftrace_caller; | |
0298739b | 336 | end_offset = (unsigned long)ftrace_caller_end; |
f3bea491 | 337 | op_offset = (unsigned long)ftrace_caller_op_ptr; |
768ae440 | 338 | call_offset = (unsigned long)ftrace_call; |
fe58acef | 339 | jmp_offset = 0; |
f3bea491 SRRH |
340 | } |
341 | ||
342 | size = end_offset - start_offset; | |
343 | ||
344 | /* | |
345 | * Allocate enough size to store the ftrace_caller code, | |
d2a68c4e SRV |
346 | * the iret , as well as the address of the ftrace_ops this |
347 | * trampoline is used for. | |
f3bea491 | 348 | */ |
d2a68c4e | 349 | trampoline = alloc_tramp(size + RET_SIZE + sizeof(void *)); |
f3bea491 SRRH |
350 | if (!trampoline) |
351 | return 0; | |
352 | ||
d2a68c4e | 353 | *tramp_size = size + RET_SIZE + sizeof(void *); |
3c0dab44 | 354 | npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE); |
aec0be2d | 355 | |
f3bea491 | 356 | /* Copy ftrace_caller onto the trampoline memory */ |
fe557319 | 357 | ret = copy_from_kernel_nofault(trampoline, (void *)start_offset, size); |
d2a68c4e SRV |
358 | if (WARN_ON(ret < 0)) |
359 | goto fail; | |
f3bea491 | 360 | |
d2a68c4e | 361 | ip = trampoline + size; |
e52fc2cf | 362 | memcpy(ip, retq, RET_SIZE); |
f3bea491 | 363 | |
fe58acef SRV |
364 | /* No need to test direct calls on created trampolines */ |
365 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { | |
366 | /* NOP the jnz 1f; but make sure it's a 2 byte jnz */ | |
367 | ip = trampoline + (jmp_offset - start_offset); | |
368 | if (WARN_ON(*(char *)ip != 0x75)) | |
369 | goto fail; | |
a89dfde3 | 370 | ret = copy_from_kernel_nofault(ip, x86_nops[2], 2); |
fe58acef SRV |
371 | if (ret < 0) |
372 | goto fail; | |
373 | } | |
374 | ||
f3bea491 SRRH |
375 | /* |
376 | * The address of the ftrace_ops that is used for this trampoline | |
377 | * is stored at the end of the trampoline. This will be used to | |
378 | * load the third parameter for the callback. Basically, that | |
379 | * location at the end of the trampoline takes the place of | |
380 | * the global function_trace_op variable. | |
381 | */ | |
382 | ||
d2a68c4e | 383 | ptr = (unsigned long *)(trampoline + size + RET_SIZE); |
f3bea491 SRRH |
384 | *ptr = (unsigned long)ops; |
385 | ||
386 | op_offset -= start_offset; | |
387 | memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE); | |
388 | ||
389 | /* Are we pointing to the reference? */ | |
d2a68c4e SRV |
390 | if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) |
391 | goto fail; | |
f3bea491 SRRH |
392 | |
393 | /* Load the contents of ptr into the callback parameter */ | |
394 | offset = (unsigned long)ptr; | |
395 | offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE; | |
396 | ||
397 | op_ptr.offset = offset; | |
398 | ||
399 | /* put in the new offset to the ftrace_ops */ | |
400 | memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE); | |
401 | ||
768ae440 PZ |
402 | /* put in the call to the function */ |
403 | mutex_lock(&text_mutex); | |
404 | call_offset -= start_offset; | |
405 | memcpy(trampoline + call_offset, | |
406 | text_gen_insn(CALL_INSN_OPCODE, | |
407 | trampoline + call_offset, | |
408 | ftrace_ops_get_func(ops)), CALL_INSN_SIZE); | |
409 | mutex_unlock(&text_mutex); | |
410 | ||
f3bea491 SRRH |
411 | /* ALLOC_TRAMP flags lets us know we created it */ |
412 | ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP; | |
413 | ||
7fdfe1e4 RE |
414 | set_vm_flush_reset_perms(trampoline); |
415 | ||
59566b0b SRV |
416 | if (likely(system_state != SYSTEM_BOOTING)) |
417 | set_memory_ro((unsigned long)trampoline, npages); | |
3c0dab44 | 418 | set_memory_x((unsigned long)trampoline, npages); |
f3bea491 | 419 | return (unsigned long)trampoline; |
d2a68c4e | 420 | fail: |
7fdfe1e4 | 421 | tramp_free(trampoline); |
d2a68c4e | 422 | return 0; |
f3bea491 SRRH |
423 | } |
424 | ||
59566b0b SRV |
425 | void set_ftrace_ops_ro(void) |
426 | { | |
427 | struct ftrace_ops *ops; | |
428 | unsigned long start_offset; | |
429 | unsigned long end_offset; | |
430 | unsigned long npages; | |
431 | unsigned long size; | |
432 | ||
433 | do_for_each_ftrace_op(ops, ftrace_ops_list) { | |
434 | if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
435 | continue; | |
436 | ||
437 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { | |
438 | start_offset = (unsigned long)ftrace_regs_caller; | |
439 | end_offset = (unsigned long)ftrace_regs_caller_end; | |
440 | } else { | |
441 | start_offset = (unsigned long)ftrace_caller; | |
7c0577f4 | 442 | end_offset = (unsigned long)ftrace_caller_end; |
59566b0b SRV |
443 | } |
444 | size = end_offset - start_offset; | |
445 | size = size + RET_SIZE + sizeof(void *); | |
446 | npages = DIV_ROUND_UP(size, PAGE_SIZE); | |
447 | set_memory_ro((unsigned long)ops->trampoline, npages); | |
448 | } while_for_each_ftrace_op(ops); | |
449 | } | |
450 | ||
15d5b02c SRRH |
451 | static unsigned long calc_trampoline_call_offset(bool save_regs) |
452 | { | |
453 | unsigned long start_offset; | |
454 | unsigned long call_offset; | |
455 | ||
456 | if (save_regs) { | |
457 | start_offset = (unsigned long)ftrace_regs_caller; | |
458 | call_offset = (unsigned long)ftrace_regs_call; | |
459 | } else { | |
460 | start_offset = (unsigned long)ftrace_caller; | |
461 | call_offset = (unsigned long)ftrace_call; | |
462 | } | |
463 | ||
464 | return call_offset - start_offset; | |
465 | } | |
466 | ||
f3bea491 SRRH |
467 | void arch_ftrace_update_trampoline(struct ftrace_ops *ops) |
468 | { | |
469 | ftrace_func_t func; | |
f3bea491 SRRH |
470 | unsigned long offset; |
471 | unsigned long ip; | |
aec0be2d | 472 | unsigned int size; |
768ae440 | 473 | const char *new; |
f3bea491 | 474 | |
768ae440 | 475 | if (!ops->trampoline) { |
aec0be2d | 476 | ops->trampoline = create_trampoline(ops, &size); |
f3bea491 SRRH |
477 | if (!ops->trampoline) |
478 | return; | |
aec0be2d | 479 | ops->trampoline_size = size; |
768ae440 | 480 | return; |
f3bea491 SRRH |
481 | } |
482 | ||
768ae440 PZ |
483 | /* |
484 | * The ftrace_ops caller may set up its own trampoline. | |
485 | * In such a case, this code must not modify it. | |
486 | */ | |
487 | if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
488 | return; | |
489 | ||
15d5b02c | 490 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); |
f3bea491 | 491 | ip = ops->trampoline + offset; |
f3bea491 SRRH |
492 | func = ftrace_ops_get_func(ops); |
493 | ||
768ae440 | 494 | mutex_lock(&text_mutex); |
f3bea491 SRRH |
495 | /* Do a safe modify in case the trampoline is executing */ |
496 | new = ftrace_call_replace(ip, (unsigned long)func); | |
768ae440 PZ |
497 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); |
498 | mutex_unlock(&text_mutex); | |
f3bea491 | 499 | } |
15d5b02c SRRH |
500 | |
501 | /* Return the address of the function the trampoline calls */ | |
502 | static void *addr_from_call(void *ptr) | |
503 | { | |
67c1d4a2 | 504 | union text_poke_insn call; |
15d5b02c SRRH |
505 | int ret; |
506 | ||
fe557319 | 507 | ret = copy_from_kernel_nofault(&call, ptr, CALL_INSN_SIZE); |
15d5b02c SRRH |
508 | if (WARN_ON_ONCE(ret < 0)) |
509 | return NULL; | |
510 | ||
511 | /* Make sure this is a call */ | |
67c1d4a2 PZ |
512 | if (WARN_ON_ONCE(call.opcode != CALL_INSN_OPCODE)) { |
513 | pr_warn("Expected E8, got %x\n", call.opcode); | |
15d5b02c SRRH |
514 | return NULL; |
515 | } | |
516 | ||
67c1d4a2 | 517 | return ptr + CALL_INSN_SIZE + call.disp; |
15d5b02c SRRH |
518 | } |
519 | ||
0c0593b4 | 520 | void prepare_ftrace_return(unsigned long ip, unsigned long *parent, |
15d5b02c SRRH |
521 | unsigned long frame_pointer); |
522 | ||
523 | /* | |
524 | * If the ops->trampoline was not allocated, then it probably | |
525 | * has a static trampoline func, or is the ftrace caller itself. | |
526 | */ | |
527 | static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) | |
528 | { | |
529 | unsigned long offset; | |
530 | bool save_regs = rec->flags & FTRACE_FL_REGS_EN; | |
531 | void *ptr; | |
532 | ||
533 | if (ops && ops->trampoline) { | |
0c0593b4 SRV |
534 | #if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) && \ |
535 | defined(CONFIG_FUNCTION_GRAPH_TRACER) | |
15d5b02c SRRH |
536 | /* |
537 | * We only know about function graph tracer setting as static | |
538 | * trampoline. | |
539 | */ | |
540 | if (ops->trampoline == FTRACE_GRAPH_ADDR) | |
541 | return (void *)prepare_ftrace_return; | |
542 | #endif | |
543 | return NULL; | |
544 | } | |
545 | ||
546 | offset = calc_trampoline_call_offset(save_regs); | |
547 | ||
548 | if (save_regs) | |
549 | ptr = (void *)FTRACE_REGS_ADDR + offset; | |
550 | else | |
551 | ptr = (void *)FTRACE_ADDR + offset; | |
552 | ||
553 | return addr_from_call(ptr); | |
554 | } | |
555 | ||
556 | void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) | |
557 | { | |
558 | unsigned long offset; | |
559 | ||
560 | /* If we didn't allocate this trampoline, consider it static */ | |
561 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
562 | return static_tramp_func(ops, rec); | |
563 | ||
564 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); | |
565 | return addr_from_call((void *)ops->trampoline + offset); | |
566 | } | |
567 | ||
12cce594 SRRH |
568 | void arch_ftrace_trampoline_free(struct ftrace_ops *ops) |
569 | { | |
570 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
571 | return; | |
572 | ||
7fdfe1e4 | 573 | tramp_free((void *)ops->trampoline); |
12cce594 SRRH |
574 | ops->trampoline = 0; |
575 | } | |
15d5b02c | 576 | |
f3bea491 SRRH |
577 | #endif /* CONFIG_X86_64 */ |
578 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
579 | ||
580 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
581 | ||
e999995c | 582 | #if defined(CONFIG_DYNAMIC_FTRACE) && !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) |
0c0593b4 | 583 | extern void ftrace_graph_call(void); |
768ae440 | 584 | static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) |
745cfeaa | 585 | { |
67c1d4a2 | 586 | return text_gen_insn(JMP32_INSN_OPCODE, (void *)ip, (void *)addr); |
745cfeaa SRV |
587 | } |
588 | ||
87fbb2ac SRRH |
589 | static int ftrace_mod_jmp(unsigned long ip, void *func) |
590 | { | |
768ae440 | 591 | const char *new; |
5a45cfe1 | 592 | |
87fbb2ac | 593 | new = ftrace_jmp_replace(ip, (unsigned long)func); |
768ae440 PZ |
594 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); |
595 | return 0; | |
5a45cfe1 SR |
596 | } |
597 | ||
598 | int ftrace_enable_ftrace_graph_caller(void) | |
599 | { | |
600 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 601 | |
87fbb2ac | 602 | return ftrace_mod_jmp(ip, &ftrace_graph_caller); |
5a45cfe1 SR |
603 | } |
604 | ||
605 | int ftrace_disable_ftrace_graph_caller(void) | |
606 | { | |
607 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 608 | |
87fbb2ac | 609 | return ftrace_mod_jmp(ip, &ftrace_stub); |
5a45cfe1 | 610 | } |
e999995c | 611 | #endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ |
e7d3737e | 612 | |
e7d3737e FW |
613 | /* |
614 | * Hook the return address and push it in the stack of return addrs | |
615 | * in current thread info. | |
616 | */ | |
8646698a | 617 | void prepare_ftrace_return(unsigned long ip, unsigned long *parent, |
71e308a2 | 618 | unsigned long frame_pointer) |
e7d3737e | 619 | { |
768ae440 | 620 | unsigned long return_hooker = (unsigned long)&return_to_handler; |
0c0593b4 | 621 | int bit; |
e7d3737e | 622 | |
34a477e5 JP |
623 | /* |
624 | * When resuming from suspend-to-ram, this function can be indirectly | |
625 | * called from early CPU startup code while the CPU is in real mode, | |
626 | * which would fail miserably. Make sure the stack pointer is a | |
627 | * virtual address. | |
628 | * | |
629 | * This check isn't as accurate as virt_addr_valid(), but it should be | |
630 | * good enough for this purpose, and it's fast. | |
631 | */ | |
632 | if (unlikely((long)__builtin_frame_address(0) >= 0)) | |
633 | return; | |
634 | ||
84b2bc7f SRRH |
635 | if (unlikely(ftrace_graph_is_dead())) |
636 | return; | |
637 | ||
380c4b14 | 638 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
e7d3737e FW |
639 | return; |
640 | ||
0c0593b4 SRV |
641 | bit = ftrace_test_recursion_trylock(ip, *parent); |
642 | if (bit < 0) | |
643 | return; | |
644 | ||
8646698a SRV |
645 | if (!function_graph_enter(*parent, ip, frame_pointer, parent)) |
646 | *parent = return_hooker; | |
0c0593b4 SRV |
647 | |
648 | ftrace_test_recursion_unlock(bit); | |
649 | } | |
650 | ||
651 | #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS | |
652 | void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, | |
653 | struct ftrace_ops *op, struct ftrace_regs *fregs) | |
654 | { | |
655 | struct pt_regs *regs = &fregs->regs; | |
656 | unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); | |
657 | ||
658 | prepare_ftrace_return(ip, (unsigned long *)stack, 0); | |
e7d3737e | 659 | } |
0c0593b4 SRV |
660 | #endif |
661 | ||
fb52607a | 662 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |