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> |
d48567c9 | 27 | #include <linux/set_memory.h> |
3d083395 | 28 | |
47788c58 FW |
29 | #include <trace/syscall.h> |
30 | ||
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 | ||
3a2bfec0 | 40 | void 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 | } |
51 | ||
3a2bfec0 | 52 | void ftrace_arch_code_modify_post_process(void) |
074376ac | 53 | __releases(&text_mutex) |
16239630 | 54 | { |
768ae440 PZ |
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; | |
d5b844a2 | 62 | mutex_unlock(&text_mutex); |
16239630 SR |
63 | } |
64 | ||
768ae440 | 65 | static const char *ftrace_nop_replace(void) |
17666f02 | 66 | { |
a89dfde3 | 67 | return x86_nops[5]; |
17666f02 SR |
68 | } |
69 | ||
768ae440 | 70 | static const char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
caf4b323 | 71 | { |
ee3e2469 PZ |
72 | /* |
73 | * No need to translate into a callthunk. The trampoline does | |
74 | * the depth accounting itself. | |
75 | */ | |
67c1d4a2 | 76 | return text_gen_insn(CALL_INSN_OPCODE, (void *)ip, (void *)addr); |
caf4b323 FW |
77 | } |
78 | ||
768ae440 | 79 | static int ftrace_verify_code(unsigned long ip, const char *old_code) |
3d083395 | 80 | { |
768ae440 | 81 | char cur_code[MCOUNT_INSN_SIZE]; |
b05086c7 | 82 | |
3d083395 | 83 | /* |
c5d641f9 LB |
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. | |
3d083395 | 89 | */ |
76aefee5 | 90 | /* read the text we want to modify */ |
fe557319 | 91 | if (copy_from_kernel_nofault(cur_code, (void *)ip, MCOUNT_INSN_SIZE)) { |
768ae440 | 92 | WARN_ON(1); |
593eb8a2 | 93 | return -EFAULT; |
768ae440 | 94 | } |
6f93fc07 | 95 | |
76aefee5 | 96 | /* Make sure it is what we expect it to be */ |
768ae440 | 97 | if (memcmp(cur_code, old_code, MCOUNT_INSN_SIZE) != 0) { |
ac6c1b2c | 98 | ftrace_expected = old_code; |
768ae440 | 99 | WARN_ON(1); |
593eb8a2 | 100 | return -EINVAL; |
768ae440 | 101 | } |
3d083395 | 102 | |
768ae440 PZ |
103 | return 0; |
104 | } | |
6f93fc07 | 105 | |
38ebd8d1 BP |
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 | |
768ae440 PZ |
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; | |
3d083395 | 118 | |
768ae440 PZ |
119 | /* replace the text with the new text */ |
120 | if (ftrace_poke_late) | |
121 | text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL); | |
122 | else | |
123 | text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); | |
6f93fc07 | 124 | return 0; |
3d083395 SR |
125 | } |
126 | ||
768ae440 | 127 | int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) |
31e88909 | 128 | { |
31e88909 | 129 | unsigned long ip = rec->ip; |
768ae440 | 130 | const char *new, *old; |
31e88909 SR |
131 | |
132 | old = ftrace_call_replace(ip, addr); | |
133 | new = ftrace_nop_replace(); | |
134 | ||
8a4d0a68 SR |
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) | |
768ae440 | 144 | return ftrace_modify_code_direct(ip, old, new); |
b05086c7 | 145 | |
768ae440 PZ |
146 | /* |
147 | * x86 overrides ftrace_replace_code -- this function will never be used | |
148 | * in this case. | |
149 | */ | |
8a4d0a68 SR |
150 | WARN_ONCE(1, "invalid use of ftrace_make_nop"); |
151 | return -EINVAL; | |
31e88909 SR |
152 | } |
153 | ||
154 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
155 | { | |
31e88909 | 156 | unsigned long ip = rec->ip; |
768ae440 | 157 | const char *new, *old; |
31e88909 SR |
158 | |
159 | old = ftrace_nop_replace(); | |
160 | new = ftrace_call_replace(ip, addr); | |
161 | ||
8a4d0a68 SR |
162 | /* Should only be called when module is loaded */ |
163 | return ftrace_modify_code_direct(rec->ip, old, new); | |
d61f82d0 SR |
164 | } |
165 | ||
08f6fba5 SR |
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 | } | |
08f6fba5 | 180 | |
87fbb2ac | 181 | int ftrace_update_ftrace_func(ftrace_func_t func) |
08d636b6 | 182 | { |
ab4ead02 | 183 | unsigned long ip; |
768ae440 | 184 | const char *new; |
ab4ead02 | 185 | |
768ae440 PZ |
186 | ip = (unsigned long)(&ftrace_call); |
187 | new = ftrace_call_replace(ip, (unsigned long)func); | |
188 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); | |
08d636b6 | 189 | |
768ae440 PZ |
190 | ip = (unsigned long)(&ftrace_regs_call); |
191 | new = ftrace_call_replace(ip, (unsigned long)func); | |
192 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); | |
08d636b6 SR |
193 | |
194 | return 0; | |
195 | } | |
196 | ||
e4f5d544 | 197 | void ftrace_replace_code(int enable) |
08d636b6 SR |
198 | { |
199 | struct ftrace_rec_iter *iter; | |
200 | struct dyn_ftrace *rec; | |
768ae440 | 201 | const char *new, *old; |
08d636b6 SR |
202 | int ret; |
203 | ||
204 | for_ftrace_rec_iter(iter) { | |
205 | rec = ftrace_rec_iter_record(iter); | |
206 | ||
768ae440 PZ |
207 | switch (ftrace_test_record(rec, enable)) { |
208 | case FTRACE_UPDATE_IGNORE: | |
209 | default: | |
210 | continue; | |
08d636b6 | 211 | |
768ae440 PZ |
212 | case FTRACE_UPDATE_MAKE_CALL: |
213 | old = ftrace_nop_replace(); | |
214 | break; | |
08d636b6 | 215 | |
768ae440 PZ |
216 | case FTRACE_UPDATE_MODIFY_CALL: |
217 | case FTRACE_UPDATE_MAKE_NOP: | |
218 | old = ftrace_call_replace(rec->ip, ftrace_get_addr_curr(rec)); | |
219 | break; | |
220 | } | |
08d636b6 | 221 | |
768ae440 PZ |
222 | ret = ftrace_verify_code(rec->ip, old); |
223 | if (ret) { | |
fd3dc562 | 224 | ftrace_expected = old; |
768ae440 | 225 | ftrace_bug(ret, rec); |
fd3dc562 | 226 | ftrace_expected = NULL; |
768ae440 PZ |
227 | return; |
228 | } | |
08d636b6 SR |
229 | } |
230 | ||
08d636b6 SR |
231 | for_ftrace_rec_iter(iter) { |
232 | rec = ftrace_rec_iter_record(iter); | |
233 | ||
768ae440 PZ |
234 | switch (ftrace_test_record(rec, enable)) { |
235 | case FTRACE_UPDATE_IGNORE: | |
236 | default: | |
237 | continue; | |
08d636b6 | 238 | |
768ae440 PZ |
239 | case FTRACE_UPDATE_MAKE_CALL: |
240 | case FTRACE_UPDATE_MODIFY_CALL: | |
241 | new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec)); | |
242 | break; | |
08d636b6 | 243 | |
768ae440 PZ |
244 | case FTRACE_UPDATE_MAKE_NOP: |
245 | new = ftrace_nop_replace(); | |
246 | break; | |
247 | } | |
08d636b6 | 248 | |
768ae440 PZ |
249 | text_poke_queue((void *)rec->ip, new, MCOUNT_INSN_SIZE, NULL); |
250 | ftrace_update_record(rec, enable); | |
08d636b6 | 251 | } |
768ae440 | 252 | text_poke_finish(); |
8a4d0a68 SR |
253 | } |
254 | ||
08d636b6 SR |
255 | void arch_ftrace_update_code(int command) |
256 | { | |
e4f5d544 | 257 | ftrace_modify_all_code(command); |
08d636b6 SR |
258 | } |
259 | ||
f3bea491 SRRH |
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 | } | |
7fdfe1e4 | 270 | static inline void tramp_free(void *tramp) |
f3bea491 | 271 | { |
be1f221c | 272 | module_memfree(tramp); |
f3bea491 SRRH |
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 | } | |
7fdfe1e4 | 280 | static inline void tramp_free(void *tramp) { } |
f3bea491 SRRH |
281 | #endif |
282 | ||
283 | /* Defined as markers to the end of the ftrace default trampolines */ | |
f3bea491 | 284 | extern void ftrace_regs_caller_end(void); |
0298739b PZ |
285 | extern void ftrace_regs_caller_ret(void); |
286 | extern void ftrace_caller_end(void); | |
f3bea491 SRRH |
287 | extern void ftrace_caller_op_ptr(void); |
288 | extern void ftrace_regs_caller_op_ptr(void); | |
fe58acef | 289 | extern void ftrace_regs_caller_jmp(void); |
f3bea491 SRRH |
290 | |
291 | /* movq function_trace_op(%rip), %rdx */ | |
292 | /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */ | |
293 | #define OP_REF_SIZE 7 | |
294 | ||
295 | /* | |
296 | * The ftrace_ops is passed to the function callback. Since the | |
297 | * trampoline only services a single ftrace_ops, we can pass in | |
298 | * that ops directly. | |
299 | * | |
300 | * The ftrace_op_code_union is used to create a pointer to the | |
301 | * ftrace_ops that will be passed to the callback function. | |
302 | */ | |
303 | union ftrace_op_code_union { | |
304 | char code[OP_REF_SIZE]; | |
305 | struct { | |
306 | char op[3]; | |
307 | int offset; | |
308 | } __attribute__((packed)); | |
309 | }; | |
310 | ||
1f001e9d | 311 | #define RET_SIZE (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS)) |
d2a68c4e | 312 | |
aec0be2d SRRH |
313 | static unsigned long |
314 | create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) | |
f3bea491 | 315 | { |
f3bea491 SRRH |
316 | unsigned long start_offset; |
317 | unsigned long end_offset; | |
318 | unsigned long op_offset; | |
768ae440 | 319 | unsigned long call_offset; |
fe58acef | 320 | unsigned long jmp_offset; |
f3bea491 | 321 | unsigned long offset; |
3c0dab44 | 322 | unsigned long npages; |
f3bea491 | 323 | unsigned long size; |
f3bea491 SRRH |
324 | unsigned long *ptr; |
325 | void *trampoline; | |
ee3e2469 | 326 | void *ip, *dest; |
f3bea491 SRRH |
327 | /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */ |
328 | unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 }; | |
e52fc2cf | 329 | unsigned const char retq[] = { RET_INSN_OPCODE, INT3_INSN_OPCODE }; |
f3bea491 SRRH |
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; | |
768ae440 | 337 | call_offset = (unsigned long)ftrace_regs_call; |
fe58acef | 338 | jmp_offset = (unsigned long)ftrace_regs_caller_jmp; |
f3bea491 SRRH |
339 | } else { |
340 | start_offset = (unsigned long)ftrace_caller; | |
0298739b | 341 | end_offset = (unsigned long)ftrace_caller_end; |
f3bea491 | 342 | op_offset = (unsigned long)ftrace_caller_op_ptr; |
768ae440 | 343 | call_offset = (unsigned long)ftrace_call; |
fe58acef | 344 | jmp_offset = 0; |
f3bea491 SRRH |
345 | } |
346 | ||
347 | size = end_offset - start_offset; | |
348 | ||
349 | /* | |
350 | * Allocate enough size to store the ftrace_caller code, | |
d2a68c4e SRV |
351 | * the iret , as well as the address of the ftrace_ops this |
352 | * trampoline is used for. | |
f3bea491 | 353 | */ |
d2a68c4e | 354 | trampoline = alloc_tramp(size + RET_SIZE + sizeof(void *)); |
f3bea491 SRRH |
355 | if (!trampoline) |
356 | return 0; | |
357 | ||
d2a68c4e | 358 | *tramp_size = size + RET_SIZE + sizeof(void *); |
3c0dab44 | 359 | npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE); |
aec0be2d | 360 | |
f3bea491 | 361 | /* Copy ftrace_caller onto the trampoline memory */ |
fe557319 | 362 | ret = copy_from_kernel_nofault(trampoline, (void *)start_offset, size); |
d2a68c4e SRV |
363 | if (WARN_ON(ret < 0)) |
364 | goto fail; | |
f3bea491 | 365 | |
d2a68c4e | 366 | ip = trampoline + size; |
1f001e9d | 367 | if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) |
770ae1b7 | 368 | __text_gen_insn(ip, JMP32_INSN_OPCODE, ip, x86_return_thunk, JMP32_INSN_SIZE); |
1f001e9d PZ |
369 | else |
370 | memcpy(ip, retq, sizeof(retq)); | |
f3bea491 | 371 | |
fe58acef SRV |
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; | |
a89dfde3 | 378 | ret = copy_from_kernel_nofault(ip, x86_nops[2], 2); |
fe58acef SRV |
379 | if (ret < 0) |
380 | goto fail; | |
381 | } | |
382 | ||
f3bea491 SRRH |
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 | ||
d2a68c4e | 391 | ptr = (unsigned long *)(trampoline + size + RET_SIZE); |
f3bea491 SRRH |
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? */ | |
d2a68c4e SRV |
398 | if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) |
399 | goto fail; | |
f3bea491 SRRH |
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 | ||
768ae440 PZ |
410 | /* put in the call to the function */ |
411 | mutex_lock(&text_mutex); | |
412 | call_offset -= start_offset; | |
ee3e2469 PZ |
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); | |
768ae440 | 418 | memcpy(trampoline + call_offset, |
ee3e2469 PZ |
419 | text_gen_insn(CALL_INSN_OPCODE, trampoline + call_offset, dest), |
420 | CALL_INSN_SIZE); | |
768ae440 PZ |
421 | mutex_unlock(&text_mutex); |
422 | ||
f3bea491 SRRH |
423 | /* ALLOC_TRAMP flags lets us know we created it */ |
424 | ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP; | |
425 | ||
d48567c9 | 426 | set_memory_rox((unsigned long)trampoline, npages); |
f3bea491 | 427 | return (unsigned long)trampoline; |
d2a68c4e | 428 | fail: |
7fdfe1e4 | 429 | tramp_free(trampoline); |
d2a68c4e | 430 | return 0; |
f3bea491 SRRH |
431 | } |
432 | ||
59566b0b SRV |
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; | |
7c0577f4 | 450 | end_offset = (unsigned long)ftrace_caller_end; |
59566b0b SRV |
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((unsigned long)ops->trampoline, npages); | |
456 | } while_for_each_ftrace_op(ops); | |
457 | } | |
458 | ||
15d5b02c SRRH |
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 | ||
f3bea491 SRRH |
475 | void arch_ftrace_update_trampoline(struct ftrace_ops *ops) |
476 | { | |
477 | ftrace_func_t func; | |
f3bea491 SRRH |
478 | unsigned long offset; |
479 | unsigned long ip; | |
aec0be2d | 480 | unsigned int size; |
768ae440 | 481 | const char *new; |
f3bea491 | 482 | |
768ae440 | 483 | if (!ops->trampoline) { |
aec0be2d | 484 | ops->trampoline = create_trampoline(ops, &size); |
f3bea491 SRRH |
485 | if (!ops->trampoline) |
486 | return; | |
aec0be2d | 487 | ops->trampoline_size = size; |
768ae440 | 488 | return; |
f3bea491 SRRH |
489 | } |
490 | ||
768ae440 PZ |
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 | ||
15d5b02c | 498 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); |
f3bea491 | 499 | ip = ops->trampoline + offset; |
f3bea491 SRRH |
500 | func = ftrace_ops_get_func(ops); |
501 | ||
768ae440 | 502 | mutex_lock(&text_mutex); |
f3bea491 SRRH |
503 | /* Do a safe modify in case the trampoline is executing */ |
504 | new = ftrace_call_replace(ip, (unsigned long)func); | |
768ae440 PZ |
505 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); |
506 | mutex_unlock(&text_mutex); | |
f3bea491 | 507 | } |
15d5b02c SRRH |
508 | |
509 | /* Return the address of the function the trampoline calls */ | |
510 | static void *addr_from_call(void *ptr) | |
511 | { | |
67c1d4a2 | 512 | union text_poke_insn call; |
15d5b02c SRRH |
513 | int ret; |
514 | ||
fe557319 | 515 | ret = copy_from_kernel_nofault(&call, ptr, CALL_INSN_SIZE); |
15d5b02c SRRH |
516 | if (WARN_ON_ONCE(ret < 0)) |
517 | return NULL; | |
518 | ||
519 | /* Make sure this is a call */ | |
67c1d4a2 PZ |
520 | if (WARN_ON_ONCE(call.opcode != CALL_INSN_OPCODE)) { |
521 | pr_warn("Expected E8, got %x\n", call.opcode); | |
15d5b02c SRRH |
522 | return NULL; |
523 | } | |
524 | ||
67c1d4a2 | 525 | return ptr + CALL_INSN_SIZE + call.disp; |
15d5b02c SRRH |
526 | } |
527 | ||
15d5b02c SRRH |
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) { | |
0c0593b4 SRV |
539 | #if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) && \ |
540 | defined(CONFIG_FUNCTION_GRAPH_TRACER) | |
15d5b02c SRRH |
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(ops->flags & FTRACE_OPS_FL_SAVE_REGS); | |
570 | return addr_from_call((void *)ops->trampoline + offset); | |
571 | } | |
572 | ||
12cce594 SRRH |
573 | void arch_ftrace_trampoline_free(struct ftrace_ops *ops) |
574 | { | |
575 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
576 | return; | |
577 | ||
7fdfe1e4 | 578 | tramp_free((void *)ops->trampoline); |
12cce594 SRRH |
579 | ops->trampoline = 0; |
580 | } | |
15d5b02c | 581 | |
f3bea491 SRRH |
582 | #endif /* CONFIG_X86_64 */ |
583 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
584 | ||
585 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
586 | ||
e999995c | 587 | #if defined(CONFIG_DYNAMIC_FTRACE) && !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) |
0c0593b4 | 588 | extern void ftrace_graph_call(void); |
768ae440 | 589 | static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) |
745cfeaa | 590 | { |
67c1d4a2 | 591 | return text_gen_insn(JMP32_INSN_OPCODE, (void *)ip, (void *)addr); |
745cfeaa SRV |
592 | } |
593 | ||
87fbb2ac SRRH |
594 | static int ftrace_mod_jmp(unsigned long ip, void *func) |
595 | { | |
768ae440 | 596 | const char *new; |
5a45cfe1 | 597 | |
87fbb2ac | 598 | new = ftrace_jmp_replace(ip, (unsigned long)func); |
768ae440 PZ |
599 | text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL); |
600 | return 0; | |
5a45cfe1 SR |
601 | } |
602 | ||
603 | int ftrace_enable_ftrace_graph_caller(void) | |
604 | { | |
605 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 606 | |
87fbb2ac | 607 | return ftrace_mod_jmp(ip, &ftrace_graph_caller); |
5a45cfe1 SR |
608 | } |
609 | ||
610 | int ftrace_disable_ftrace_graph_caller(void) | |
611 | { | |
612 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 613 | |
87fbb2ac | 614 | return ftrace_mod_jmp(ip, &ftrace_stub); |
5a45cfe1 | 615 | } |
e999995c | 616 | #endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ |
e7d3737e | 617 | |
e7d3737e FW |
618 | /* |
619 | * Hook the return address and push it in the stack of return addrs | |
620 | * in current thread info. | |
621 | */ | |
8646698a | 622 | void prepare_ftrace_return(unsigned long ip, unsigned long *parent, |
71e308a2 | 623 | unsigned long frame_pointer) |
e7d3737e | 624 | { |
768ae440 | 625 | unsigned long return_hooker = (unsigned long)&return_to_handler; |
0c0593b4 | 626 | int bit; |
e7d3737e | 627 | |
34a477e5 JP |
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 | ||
84b2bc7f SRRH |
640 | if (unlikely(ftrace_graph_is_dead())) |
641 | return; | |
642 | ||
380c4b14 | 643 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
e7d3737e FW |
644 | return; |
645 | ||
0c0593b4 SRV |
646 | bit = ftrace_test_recursion_trylock(ip, *parent); |
647 | if (bit < 0) | |
648 | return; | |
649 | ||
8646698a SRV |
650 | if (!function_graph_enter(*parent, ip, frame_pointer, parent)) |
651 | *parent = return_hooker; | |
0c0593b4 SRV |
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, (unsigned long *)stack, 0); | |
e7d3737e | 664 | } |
0c0593b4 SRV |
665 | #endif |
666 | ||
fb52607a | 667 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |