Commit | Line | Data |
---|---|---|
3d083395 SR |
1 | /* |
2 | * Code for replacing ftrace calls with jumps. | |
3 | * | |
4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | |
5 | * | |
6 | * Thanks goes to Ingo Molnar, for suggesting the idea. | |
7 | * Mathieu Desnoyers, for suggesting postponing the modifications. | |
8 | * Arjan van de Ven, for keeping me straight, and explaining to me | |
9 | * the dangers of modifying code on the run. | |
10 | */ | |
11 | ||
3bb258bf JP |
12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
13 | ||
3d083395 SR |
14 | #include <linux/spinlock.h> |
15 | #include <linux/hardirq.h> | |
6f93fc07 | 16 | #include <linux/uaccess.h> |
3d083395 SR |
17 | #include <linux/ftrace.h> |
18 | #include <linux/percpu.h> | |
19b3e967 | 19 | #include <linux/sched.h> |
3d083395 SR |
20 | #include <linux/init.h> |
21 | #include <linux/list.h> | |
84e1c6bb | 22 | #include <linux/module.h> |
3d083395 | 23 | |
47788c58 FW |
24 | #include <trace/syscall.h> |
25 | ||
16239630 | 26 | #include <asm/cacheflush.h> |
59a094c9 | 27 | #include <asm/kprobes.h> |
395a59d0 | 28 | #include <asm/ftrace.h> |
732f3ca7 | 29 | #include <asm/nops.h> |
3d083395 | 30 | |
caf4b323 | 31 | #ifdef CONFIG_DYNAMIC_FTRACE |
3d083395 | 32 | |
16239630 SR |
33 | int ftrace_arch_code_modify_prepare(void) |
34 | { | |
35 | set_kernel_text_rw(); | |
84e1c6bb | 36 | set_all_modules_text_rw(); |
16239630 SR |
37 | return 0; |
38 | } | |
39 | ||
40 | int ftrace_arch_code_modify_post_process(void) | |
41 | { | |
84e1c6bb | 42 | set_all_modules_text_ro(); |
16239630 SR |
43 | set_kernel_text_ro(); |
44 | return 0; | |
45 | } | |
46 | ||
3d083395 | 47 | union ftrace_code_union { |
395a59d0 | 48 | char code[MCOUNT_INSN_SIZE]; |
3d083395 SR |
49 | struct { |
50 | char e8; | |
51 | int offset; | |
52 | } __attribute__((packed)); | |
53 | }; | |
54 | ||
15adc048 | 55 | static int ftrace_calc_offset(long ip, long addr) |
3c1720f0 SR |
56 | { |
57 | return (int)(addr - ip); | |
58 | } | |
3d083395 | 59 | |
31e88909 | 60 | static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
3c1720f0 SR |
61 | { |
62 | static union ftrace_code_union calc; | |
3d083395 | 63 | |
3c1720f0 | 64 | calc.e8 = 0xe8; |
395a59d0 | 65 | calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); |
3c1720f0 SR |
66 | |
67 | /* | |
68 | * No locking needed, this must be called via kstop_machine | |
69 | * which in essence is like running on a uniprocessor machine. | |
70 | */ | |
71 | return calc.code; | |
3d083395 SR |
72 | } |
73 | ||
55ca3cc1 SS |
74 | static inline int |
75 | within(unsigned long addr, unsigned long start, unsigned long end) | |
76 | { | |
77 | return addr >= start && addr < end; | |
78 | } | |
79 | ||
87fbb2ac | 80 | static unsigned long text_ip_addr(unsigned long ip) |
17666f02 | 81 | { |
55ca3cc1 SS |
82 | /* |
83 | * On x86_64, kernel text mappings are mapped read-only with | |
84 | * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead | |
85 | * of the kernel text mapping to modify the kernel text. | |
86 | * | |
87 | * For 32bit kernels, these mappings are same and we can use | |
88 | * kernel identity mapping to modify code. | |
89 | */ | |
90 | if (within(ip, (unsigned long)_text, (unsigned long)_etext)) | |
217f155e | 91 | ip = (unsigned long)__va(__pa_symbol(ip)); |
55ca3cc1 | 92 | |
87fbb2ac | 93 | return ip; |
17666f02 SR |
94 | } |
95 | ||
dc326fca | 96 | static const unsigned char *ftrace_nop_replace(void) |
caf4b323 | 97 | { |
dc326fca | 98 | return ideal_nops[NOP_ATOMIC5]; |
caf4b323 FW |
99 | } |
100 | ||
31e88909 | 101 | static int |
8a4d0a68 | 102 | ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code, |
0d098a7d | 103 | unsigned const char *new_code) |
3d083395 | 104 | { |
6f93fc07 | 105 | unsigned char replaced[MCOUNT_INSN_SIZE]; |
3d083395 SR |
106 | |
107 | /* | |
108 | * Note: Due to modules and __init, code can | |
109 | * disappear and change, we need to protect against faulting | |
76aefee5 | 110 | * as well as code changing. We do this by using the |
ab9a0918 | 111 | * probe_kernel_* functions. |
3d083395 SR |
112 | * |
113 | * No real locking needed, this code is run through | |
6f93fc07 | 114 | * kstop_machine, or before SMP starts. |
3d083395 | 115 | */ |
76aefee5 SR |
116 | |
117 | /* read the text we want to modify */ | |
ab9a0918 | 118 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) |
593eb8a2 | 119 | return -EFAULT; |
6f93fc07 | 120 | |
76aefee5 | 121 | /* Make sure it is what we expect it to be */ |
6f93fc07 | 122 | if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) |
593eb8a2 | 123 | return -EINVAL; |
3d083395 | 124 | |
87fbb2ac SRRH |
125 | ip = text_ip_addr(ip); |
126 | ||
76aefee5 | 127 | /* replace the text with the new text */ |
87fbb2ac | 128 | if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE)) |
593eb8a2 | 129 | return -EPERM; |
6f93fc07 SR |
130 | |
131 | sync_core(); | |
3d083395 | 132 | |
6f93fc07 | 133 | return 0; |
3d083395 SR |
134 | } |
135 | ||
31e88909 SR |
136 | int ftrace_make_nop(struct module *mod, |
137 | struct dyn_ftrace *rec, unsigned long addr) | |
138 | { | |
0d098a7d | 139 | unsigned const char *new, *old; |
31e88909 SR |
140 | unsigned long ip = rec->ip; |
141 | ||
142 | old = ftrace_call_replace(ip, addr); | |
143 | new = ftrace_nop_replace(); | |
144 | ||
8a4d0a68 SR |
145 | /* |
146 | * On boot up, and when modules are loaded, the MCOUNT_ADDR | |
147 | * is converted to a nop, and will never become MCOUNT_ADDR | |
148 | * again. This code is either running before SMP (on boot up) | |
149 | * or before the code will ever be executed (module load). | |
150 | * We do not want to use the breakpoint version in this case, | |
151 | * just modify the code directly. | |
152 | */ | |
153 | if (addr == MCOUNT_ADDR) | |
154 | return ftrace_modify_code_direct(rec->ip, old, new); | |
155 | ||
156 | /* Normal cases use add_brk_on_nop */ | |
157 | WARN_ONCE(1, "invalid use of ftrace_make_nop"); | |
158 | return -EINVAL; | |
31e88909 SR |
159 | } |
160 | ||
161 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
162 | { | |
0d098a7d | 163 | unsigned const char *new, *old; |
31e88909 SR |
164 | unsigned long ip = rec->ip; |
165 | ||
166 | old = ftrace_nop_replace(); | |
167 | new = ftrace_call_replace(ip, addr); | |
168 | ||
8a4d0a68 SR |
169 | /* Should only be called when module is loaded */ |
170 | return ftrace_modify_code_direct(rec->ip, old, new); | |
d61f82d0 SR |
171 | } |
172 | ||
a192cd04 SR |
173 | /* |
174 | * The modifying_ftrace_code is used to tell the breakpoint | |
175 | * handler to call ftrace_int3_handler(). If it fails to | |
176 | * call this handler for a breakpoint added by ftrace, then | |
177 | * the kernel may crash. | |
178 | * | |
179 | * As atomic_writes on x86 do not need a barrier, we do not | |
180 | * need to add smp_mb()s for this to work. It is also considered | |
181 | * that we can not read the modifying_ftrace_code before | |
182 | * executing the breakpoint. That would be quite remarkable if | |
183 | * it could do that. Here's the flow that is required: | |
184 | * | |
185 | * CPU-0 CPU-1 | |
186 | * | |
187 | * atomic_inc(mfc); | |
188 | * write int3s | |
189 | * <trap-int3> // implicit (r)mb | |
190 | * if (atomic_read(mfc)) | |
191 | * call ftrace_int3_handler() | |
192 | * | |
193 | * Then when we are finished: | |
194 | * | |
195 | * atomic_dec(mfc); | |
196 | * | |
197 | * If we hit a breakpoint that was not set by ftrace, it does not | |
198 | * matter if ftrace_int3_handler() is called or not. It will | |
199 | * simply be ignored. But it is crucial that a ftrace nop/caller | |
200 | * breakpoint is handled. No other user should ever place a | |
201 | * breakpoint on an ftrace nop/caller location. It must only | |
202 | * be done by this code. | |
203 | */ | |
204 | atomic_t modifying_ftrace_code __read_mostly; | |
08d636b6 | 205 | |
8a4d0a68 SR |
206 | static int |
207 | ftrace_modify_code(unsigned long ip, unsigned const char *old_code, | |
208 | unsigned const char *new_code); | |
209 | ||
08f6fba5 SR |
210 | /* |
211 | * Should never be called: | |
212 | * As it is only called by __ftrace_replace_code() which is called by | |
213 | * ftrace_replace_code() that x86 overrides, and by ftrace_update_code() | |
214 | * which is called to turn mcount into nops or nops into function calls | |
215 | * but not to convert a function from not using regs to one that uses | |
216 | * regs, which ftrace_modify_call() is for. | |
217 | */ | |
218 | int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, | |
219 | unsigned long addr) | |
220 | { | |
221 | WARN_ON(1); | |
222 | return -EINVAL; | |
223 | } | |
08f6fba5 | 224 | |
87fbb2ac SRRH |
225 | static unsigned long ftrace_update_func; |
226 | ||
227 | static int update_ftrace_func(unsigned long ip, void *new) | |
8a4d0a68 | 228 | { |
87fbb2ac | 229 | unsigned char old[MCOUNT_INSN_SIZE]; |
8a4d0a68 SR |
230 | int ret; |
231 | ||
87fbb2ac SRRH |
232 | memcpy(old, (void *)ip, MCOUNT_INSN_SIZE); |
233 | ||
234 | ftrace_update_func = ip; | |
235 | /* Make sure the breakpoints see the ftrace_update_func update */ | |
236 | smp_wmb(); | |
8a4d0a68 SR |
237 | |
238 | /* See comment above by declaration of modifying_ftrace_code */ | |
239 | atomic_inc(&modifying_ftrace_code); | |
240 | ||
241 | ret = ftrace_modify_code(ip, old, new); | |
242 | ||
87fbb2ac SRRH |
243 | atomic_dec(&modifying_ftrace_code); |
244 | ||
245 | return ret; | |
246 | } | |
247 | ||
248 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
249 | { | |
250 | unsigned long ip = (unsigned long)(&ftrace_call); | |
251 | unsigned char *new; | |
252 | int ret; | |
253 | ||
254 | new = ftrace_call_replace(ip, (unsigned long)func); | |
255 | ret = update_ftrace_func(ip, new); | |
256 | ||
08f6fba5 SR |
257 | /* Also update the regs callback function */ |
258 | if (!ret) { | |
259 | ip = (unsigned long)(&ftrace_regs_call); | |
08f6fba5 | 260 | new = ftrace_call_replace(ip, (unsigned long)func); |
87fbb2ac | 261 | ret = update_ftrace_func(ip, new); |
08f6fba5 | 262 | } |
08f6fba5 | 263 | |
8a4d0a68 SR |
264 | return ret; |
265 | } | |
266 | ||
ab4ead02 KH |
267 | static int is_ftrace_caller(unsigned long ip) |
268 | { | |
87fbb2ac | 269 | if (ip == ftrace_update_func) |
ab4ead02 KH |
270 | return 1; |
271 | ||
272 | return 0; | |
273 | } | |
274 | ||
08d636b6 SR |
275 | /* |
276 | * A breakpoint was added to the code address we are about to | |
277 | * modify, and this is the handle that will just skip over it. | |
278 | * We are either changing a nop into a trace call, or a trace | |
279 | * call to a nop. While the change is taking place, we treat | |
280 | * it just like it was a nop. | |
281 | */ | |
282 | int ftrace_int3_handler(struct pt_regs *regs) | |
283 | { | |
ab4ead02 KH |
284 | unsigned long ip; |
285 | ||
08d636b6 SR |
286 | if (WARN_ON_ONCE(!regs)) |
287 | return 0; | |
288 | ||
ab4ead02 KH |
289 | ip = regs->ip - 1; |
290 | if (!ftrace_location(ip) && !is_ftrace_caller(ip)) | |
08d636b6 SR |
291 | return 0; |
292 | ||
293 | regs->ip += MCOUNT_INSN_SIZE - 1; | |
294 | ||
295 | return 1; | |
296 | } | |
297 | ||
298 | static int ftrace_write(unsigned long ip, const char *val, int size) | |
299 | { | |
300 | /* | |
301 | * On x86_64, kernel text mappings are mapped read-only with | |
302 | * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead | |
303 | * of the kernel text mapping to modify the kernel text. | |
304 | * | |
305 | * For 32bit kernels, these mappings are same and we can use | |
306 | * kernel identity mapping to modify code. | |
307 | */ | |
308 | if (within(ip, (unsigned long)_text, (unsigned long)_etext)) | |
217f155e | 309 | ip = (unsigned long)__va(__pa_symbol(ip)); |
08d636b6 | 310 | |
92550405 SRRH |
311 | if (probe_kernel_write((void *)ip, val, size)) |
312 | return -EPERM; | |
313 | ||
314 | return 0; | |
08d636b6 SR |
315 | } |
316 | ||
317 | static int add_break(unsigned long ip, const char *old) | |
318 | { | |
319 | unsigned char replaced[MCOUNT_INSN_SIZE]; | |
320 | unsigned char brk = BREAKPOINT_INSTRUCTION; | |
321 | ||
322 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) | |
323 | return -EFAULT; | |
324 | ||
325 | /* Make sure it is what we expect it to be */ | |
326 | if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0) | |
327 | return -EINVAL; | |
328 | ||
92550405 | 329 | return ftrace_write(ip, &brk, 1); |
08d636b6 SR |
330 | } |
331 | ||
332 | static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr) | |
333 | { | |
334 | unsigned const char *old; | |
335 | unsigned long ip = rec->ip; | |
336 | ||
337 | old = ftrace_call_replace(ip, addr); | |
338 | ||
339 | return add_break(rec->ip, old); | |
340 | } | |
341 | ||
342 | ||
343 | static int add_brk_on_nop(struct dyn_ftrace *rec) | |
344 | { | |
345 | unsigned const char *old; | |
346 | ||
347 | old = ftrace_nop_replace(); | |
348 | ||
349 | return add_break(rec->ip, old); | |
350 | } | |
351 | ||
352 | static int add_breakpoints(struct dyn_ftrace *rec, int enable) | |
353 | { | |
354 | unsigned long ftrace_addr; | |
355 | int ret; | |
356 | ||
7413af1f | 357 | ftrace_addr = ftrace_get_addr_curr(rec); |
08d636b6 | 358 | |
94792ea0 | 359 | ret = ftrace_test_record(rec, enable); |
08d636b6 SR |
360 | |
361 | switch (ret) { | |
362 | case FTRACE_UPDATE_IGNORE: | |
363 | return 0; | |
364 | ||
365 | case FTRACE_UPDATE_MAKE_CALL: | |
366 | /* converting nop to call */ | |
367 | return add_brk_on_nop(rec); | |
368 | ||
08f6fba5 | 369 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
370 | case FTRACE_UPDATE_MAKE_NOP: |
371 | /* converting a call to a nop */ | |
372 | return add_brk_on_call(rec, ftrace_addr); | |
373 | } | |
374 | return 0; | |
375 | } | |
376 | ||
377 | /* | |
378 | * On error, we need to remove breakpoints. This needs to | |
379 | * be done caefully. If the address does not currently have a | |
380 | * breakpoint, we know we are done. Otherwise, we look at the | |
381 | * remaining 4 bytes of the instruction. If it matches a nop | |
382 | * we replace the breakpoint with the nop. Otherwise we replace | |
383 | * it with the call instruction. | |
384 | */ | |
385 | static int remove_breakpoint(struct dyn_ftrace *rec) | |
386 | { | |
387 | unsigned char ins[MCOUNT_INSN_SIZE]; | |
388 | unsigned char brk = BREAKPOINT_INSTRUCTION; | |
389 | const unsigned char *nop; | |
390 | unsigned long ftrace_addr; | |
391 | unsigned long ip = rec->ip; | |
392 | ||
393 | /* If we fail the read, just give up */ | |
394 | if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE)) | |
395 | return -EFAULT; | |
396 | ||
397 | /* If this does not have a breakpoint, we are done */ | |
398 | if (ins[0] != brk) | |
7f11f5ec | 399 | return 0; |
08d636b6 SR |
400 | |
401 | nop = ftrace_nop_replace(); | |
402 | ||
403 | /* | |
404 | * If the last 4 bytes of the instruction do not match | |
405 | * a nop, then we assume that this is a call to ftrace_addr. | |
406 | */ | |
407 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) { | |
408 | /* | |
409 | * For extra paranoidism, we check if the breakpoint is on | |
410 | * a call that would actually jump to the ftrace_addr. | |
411 | * If not, don't touch the breakpoint, we make just create | |
412 | * a disaster. | |
413 | */ | |
7413af1f | 414 | ftrace_addr = ftrace_get_addr_new(rec); |
08f6fba5 SR |
415 | nop = ftrace_call_replace(ip, ftrace_addr); |
416 | ||
417 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0) | |
418 | goto update; | |
419 | ||
420 | /* Check both ftrace_addr and ftrace_old_addr */ | |
7413af1f | 421 | ftrace_addr = ftrace_get_addr_curr(rec); |
08d636b6 SR |
422 | nop = ftrace_call_replace(ip, ftrace_addr); |
423 | ||
424 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) | |
425 | return -EINVAL; | |
426 | } | |
427 | ||
08f6fba5 | 428 | update: |
c932c6b7 | 429 | return ftrace_write(ip, nop, 1); |
08d636b6 SR |
430 | } |
431 | ||
432 | static int add_update_code(unsigned long ip, unsigned const char *new) | |
433 | { | |
434 | /* skip breakpoint */ | |
435 | ip++; | |
436 | new++; | |
92550405 | 437 | return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1); |
08d636b6 SR |
438 | } |
439 | ||
440 | static int add_update_call(struct dyn_ftrace *rec, unsigned long addr) | |
441 | { | |
442 | unsigned long ip = rec->ip; | |
443 | unsigned const char *new; | |
444 | ||
445 | new = ftrace_call_replace(ip, addr); | |
446 | return add_update_code(ip, new); | |
447 | } | |
448 | ||
449 | static int add_update_nop(struct dyn_ftrace *rec) | |
450 | { | |
451 | unsigned long ip = rec->ip; | |
452 | unsigned const char *new; | |
453 | ||
454 | new = ftrace_nop_replace(); | |
455 | return add_update_code(ip, new); | |
456 | } | |
457 | ||
458 | static int add_update(struct dyn_ftrace *rec, int enable) | |
459 | { | |
460 | unsigned long ftrace_addr; | |
461 | int ret; | |
462 | ||
463 | ret = ftrace_test_record(rec, enable); | |
464 | ||
7413af1f | 465 | ftrace_addr = ftrace_get_addr_new(rec); |
08d636b6 SR |
466 | |
467 | switch (ret) { | |
468 | case FTRACE_UPDATE_IGNORE: | |
469 | return 0; | |
470 | ||
08f6fba5 | 471 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
472 | case FTRACE_UPDATE_MAKE_CALL: |
473 | /* converting nop to call */ | |
474 | return add_update_call(rec, ftrace_addr); | |
475 | ||
476 | case FTRACE_UPDATE_MAKE_NOP: | |
477 | /* converting a call to a nop */ | |
478 | return add_update_nop(rec); | |
479 | } | |
480 | ||
481 | return 0; | |
482 | } | |
483 | ||
484 | static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr) | |
485 | { | |
486 | unsigned long ip = rec->ip; | |
487 | unsigned const char *new; | |
488 | ||
489 | new = ftrace_call_replace(ip, addr); | |
490 | ||
92550405 | 491 | return ftrace_write(ip, new, 1); |
08d636b6 SR |
492 | } |
493 | ||
494 | static int finish_update_nop(struct dyn_ftrace *rec) | |
495 | { | |
496 | unsigned long ip = rec->ip; | |
497 | unsigned const char *new; | |
498 | ||
499 | new = ftrace_nop_replace(); | |
500 | ||
92550405 | 501 | return ftrace_write(ip, new, 1); |
08d636b6 SR |
502 | } |
503 | ||
504 | static int finish_update(struct dyn_ftrace *rec, int enable) | |
505 | { | |
506 | unsigned long ftrace_addr; | |
507 | int ret; | |
508 | ||
509 | ret = ftrace_update_record(rec, enable); | |
510 | ||
7413af1f | 511 | ftrace_addr = ftrace_get_addr_new(rec); |
08d636b6 SR |
512 | |
513 | switch (ret) { | |
514 | case FTRACE_UPDATE_IGNORE: | |
515 | return 0; | |
516 | ||
08f6fba5 | 517 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
518 | case FTRACE_UPDATE_MAKE_CALL: |
519 | /* converting nop to call */ | |
520 | return finish_update_call(rec, ftrace_addr); | |
521 | ||
522 | case FTRACE_UPDATE_MAKE_NOP: | |
523 | /* converting a call to a nop */ | |
524 | return finish_update_nop(rec); | |
525 | } | |
526 | ||
527 | return 0; | |
528 | } | |
529 | ||
530 | static void do_sync_core(void *data) | |
531 | { | |
532 | sync_core(); | |
533 | } | |
534 | ||
535 | static void run_sync(void) | |
536 | { | |
537 | int enable_irqs = irqs_disabled(); | |
538 | ||
539 | /* We may be called with interrupts disbled (on bootup). */ | |
540 | if (enable_irqs) | |
541 | local_irq_enable(); | |
542 | on_each_cpu(do_sync_core, NULL, 1); | |
543 | if (enable_irqs) | |
544 | local_irq_disable(); | |
545 | } | |
546 | ||
e4f5d544 | 547 | void ftrace_replace_code(int enable) |
08d636b6 SR |
548 | { |
549 | struct ftrace_rec_iter *iter; | |
550 | struct dyn_ftrace *rec; | |
551 | const char *report = "adding breakpoints"; | |
552 | int count = 0; | |
553 | int ret; | |
554 | ||
555 | for_ftrace_rec_iter(iter) { | |
556 | rec = ftrace_rec_iter_record(iter); | |
557 | ||
558 | ret = add_breakpoints(rec, enable); | |
559 | if (ret) | |
560 | goto remove_breakpoints; | |
561 | count++; | |
562 | } | |
563 | ||
564 | run_sync(); | |
565 | ||
566 | report = "updating code"; | |
567 | ||
568 | for_ftrace_rec_iter(iter) { | |
569 | rec = ftrace_rec_iter_record(iter); | |
570 | ||
571 | ret = add_update(rec, enable); | |
572 | if (ret) | |
573 | goto remove_breakpoints; | |
574 | } | |
575 | ||
576 | run_sync(); | |
577 | ||
578 | report = "removing breakpoints"; | |
579 | ||
580 | for_ftrace_rec_iter(iter) { | |
581 | rec = ftrace_rec_iter_record(iter); | |
582 | ||
583 | ret = finish_update(rec, enable); | |
584 | if (ret) | |
585 | goto remove_breakpoints; | |
586 | } | |
587 | ||
588 | run_sync(); | |
589 | ||
590 | return; | |
591 | ||
592 | remove_breakpoints: | |
74bb8c45 | 593 | pr_warn("Failed on %s (%d):\n", report, count); |
08d636b6 | 594 | ftrace_bug(ret, rec ? rec->ip : 0); |
08d636b6 SR |
595 | for_ftrace_rec_iter(iter) { |
596 | rec = ftrace_rec_iter_record(iter); | |
7f11f5ec PM |
597 | /* |
598 | * Breakpoints are handled only when this function is in | |
599 | * progress. The system could not work with them. | |
600 | */ | |
601 | if (remove_breakpoint(rec)) | |
602 | BUG(); | |
08d636b6 | 603 | } |
c932c6b7 | 604 | run_sync(); |
08d636b6 SR |
605 | } |
606 | ||
8a4d0a68 SR |
607 | static int |
608 | ftrace_modify_code(unsigned long ip, unsigned const char *old_code, | |
609 | unsigned const char *new_code) | |
610 | { | |
611 | int ret; | |
612 | ||
613 | ret = add_break(ip, old_code); | |
614 | if (ret) | |
615 | goto out; | |
616 | ||
617 | run_sync(); | |
618 | ||
619 | ret = add_update_code(ip, new_code); | |
620 | if (ret) | |
621 | goto fail_update; | |
622 | ||
623 | run_sync(); | |
624 | ||
625 | ret = ftrace_write(ip, new_code, 1); | |
7f11f5ec PM |
626 | /* |
627 | * The breakpoint is handled only when this function is in progress. | |
628 | * The system could not work if we could not remove it. | |
629 | */ | |
630 | BUG_ON(ret); | |
8a4d0a68 | 631 | out: |
12729f14 | 632 | run_sync(); |
8a4d0a68 SR |
633 | return ret; |
634 | ||
635 | fail_update: | |
7f11f5ec PM |
636 | /* Also here the system could not work with the breakpoint */ |
637 | if (ftrace_write(ip, old_code, 1)) | |
638 | BUG(); | |
8a4d0a68 SR |
639 | goto out; |
640 | } | |
641 | ||
08d636b6 SR |
642 | void arch_ftrace_update_code(int command) |
643 | { | |
a192cd04 SR |
644 | /* See comment above by declaration of modifying_ftrace_code */ |
645 | atomic_inc(&modifying_ftrace_code); | |
08d636b6 | 646 | |
e4f5d544 | 647 | ftrace_modify_all_code(command); |
08d636b6 | 648 | |
a192cd04 | 649 | atomic_dec(&modifying_ftrace_code); |
08d636b6 SR |
650 | } |
651 | ||
3a36cb11 | 652 | int __init ftrace_dyn_arch_init(void) |
3d083395 | 653 | { |
3d083395 SR |
654 | return 0; |
655 | } | |
caf4b323 | 656 | #endif |
e7d3737e | 657 | |
fb52607a | 658 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
e7d3737e | 659 | |
5a45cfe1 SR |
660 | #ifdef CONFIG_DYNAMIC_FTRACE |
661 | extern void ftrace_graph_call(void); | |
662 | ||
87fbb2ac | 663 | static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) |
5a45cfe1 | 664 | { |
87fbb2ac | 665 | static union ftrace_code_union calc; |
5a45cfe1 | 666 | |
87fbb2ac SRRH |
667 | /* Jmp not a call (ignore the .e8) */ |
668 | calc.e8 = 0xe9; | |
669 | calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); | |
5a45cfe1 | 670 | |
87fbb2ac SRRH |
671 | /* |
672 | * ftrace external locks synchronize the access to the static variable. | |
673 | */ | |
674 | return calc.code; | |
675 | } | |
5a45cfe1 | 676 | |
87fbb2ac SRRH |
677 | static int ftrace_mod_jmp(unsigned long ip, void *func) |
678 | { | |
679 | unsigned char *new; | |
5a45cfe1 | 680 | |
87fbb2ac | 681 | new = ftrace_jmp_replace(ip, (unsigned long)func); |
5a45cfe1 | 682 | |
87fbb2ac | 683 | return update_ftrace_func(ip, new); |
5a45cfe1 SR |
684 | } |
685 | ||
686 | int ftrace_enable_ftrace_graph_caller(void) | |
687 | { | |
688 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 689 | |
87fbb2ac | 690 | return ftrace_mod_jmp(ip, &ftrace_graph_caller); |
5a45cfe1 SR |
691 | } |
692 | ||
693 | int ftrace_disable_ftrace_graph_caller(void) | |
694 | { | |
695 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 696 | |
87fbb2ac | 697 | return ftrace_mod_jmp(ip, &ftrace_stub); |
5a45cfe1 SR |
698 | } |
699 | ||
e7d3737e FW |
700 | #endif /* !CONFIG_DYNAMIC_FTRACE */ |
701 | ||
e7d3737e FW |
702 | /* |
703 | * Hook the return address and push it in the stack of return addrs | |
704 | * in current thread info. | |
705 | */ | |
71e308a2 SR |
706 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, |
707 | unsigned long frame_pointer) | |
e7d3737e FW |
708 | { |
709 | unsigned long old; | |
e7d3737e | 710 | int faulted; |
287b6e68 | 711 | struct ftrace_graph_ent trace; |
e7d3737e FW |
712 | unsigned long return_hooker = (unsigned long) |
713 | &return_to_handler; | |
714 | ||
380c4b14 | 715 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
e7d3737e FW |
716 | return; |
717 | ||
718 | /* | |
719 | * Protect against fault, even if it shouldn't | |
720 | * happen. This tool is too much intrusive to | |
721 | * ignore such a protection. | |
722 | */ | |
723 | asm volatile( | |
96665788 SR |
724 | "1: " _ASM_MOV " (%[parent]), %[old]\n" |
725 | "2: " _ASM_MOV " %[return_hooker], (%[parent])\n" | |
e7d3737e | 726 | " movl $0, %[faulted]\n" |
e3944bfa | 727 | "3:\n" |
e7d3737e FW |
728 | |
729 | ".section .fixup, \"ax\"\n" | |
e3944bfa SR |
730 | "4: movl $1, %[faulted]\n" |
731 | " jmp 3b\n" | |
e7d3737e FW |
732 | ".previous\n" |
733 | ||
e3944bfa SR |
734 | _ASM_EXTABLE(1b, 4b) |
735 | _ASM_EXTABLE(2b, 4b) | |
e7d3737e | 736 | |
aa512a27 | 737 | : [old] "=&r" (old), [faulted] "=r" (faulted) |
96665788 | 738 | : [parent] "r" (parent), [return_hooker] "r" (return_hooker) |
e7d3737e FW |
739 | : "memory" |
740 | ); | |
741 | ||
14a866c5 SR |
742 | if (unlikely(faulted)) { |
743 | ftrace_graph_stop(); | |
744 | WARN_ON(1); | |
e7d3737e FW |
745 | return; |
746 | } | |
747 | ||
287b6e68 | 748 | trace.func = self_addr; |
722b3c74 | 749 | trace.depth = current->curr_ret_stack + 1; |
287b6e68 | 750 | |
e49dc19c SR |
751 | /* Only trace if the calling function expects to */ |
752 | if (!ftrace_graph_entry(&trace)) { | |
e49dc19c | 753 | *parent = old; |
722b3c74 SR |
754 | return; |
755 | } | |
756 | ||
757 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, | |
758 | frame_pointer) == -EBUSY) { | |
759 | *parent = old; | |
760 | return; | |
e49dc19c | 761 | } |
e7d3737e | 762 | } |
fb52607a | 763 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |