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> |
f3bea491 | 20 | #include <linux/slab.h> |
3d083395 SR |
21 | #include <linux/init.h> |
22 | #include <linux/list.h> | |
84e1c6bb | 23 | #include <linux/module.h> |
3d083395 | 24 | |
47788c58 FW |
25 | #include <trace/syscall.h> |
26 | ||
16239630 | 27 | #include <asm/cacheflush.h> |
59a094c9 | 28 | #include <asm/kprobes.h> |
395a59d0 | 29 | #include <asm/ftrace.h> |
732f3ca7 | 30 | #include <asm/nops.h> |
3d083395 | 31 | |
caf4b323 | 32 | #ifdef CONFIG_DYNAMIC_FTRACE |
3d083395 | 33 | |
16239630 SR |
34 | int ftrace_arch_code_modify_prepare(void) |
35 | { | |
36 | set_kernel_text_rw(); | |
84e1c6bb | 37 | set_all_modules_text_rw(); |
16239630 SR |
38 | return 0; |
39 | } | |
40 | ||
41 | int ftrace_arch_code_modify_post_process(void) | |
42 | { | |
84e1c6bb | 43 | set_all_modules_text_ro(); |
16239630 SR |
44 | set_kernel_text_ro(); |
45 | return 0; | |
46 | } | |
47 | ||
3d083395 | 48 | union ftrace_code_union { |
395a59d0 | 49 | char code[MCOUNT_INSN_SIZE]; |
3d083395 | 50 | struct { |
15d5b02c | 51 | unsigned char e8; |
3d083395 SR |
52 | int offset; |
53 | } __attribute__((packed)); | |
54 | }; | |
55 | ||
15adc048 | 56 | static int ftrace_calc_offset(long ip, long addr) |
3c1720f0 SR |
57 | { |
58 | return (int)(addr - ip); | |
59 | } | |
3d083395 | 60 | |
31e88909 | 61 | static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
3c1720f0 SR |
62 | { |
63 | static union ftrace_code_union calc; | |
3d083395 | 64 | |
3c1720f0 | 65 | calc.e8 = 0xe8; |
395a59d0 | 66 | calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); |
3c1720f0 SR |
67 | |
68 | /* | |
69 | * No locking needed, this must be called via kstop_machine | |
70 | * which in essence is like running on a uniprocessor machine. | |
71 | */ | |
72 | return calc.code; | |
3d083395 SR |
73 | } |
74 | ||
55ca3cc1 SS |
75 | static inline int |
76 | within(unsigned long addr, unsigned long start, unsigned long end) | |
77 | { | |
78 | return addr >= start && addr < end; | |
79 | } | |
80 | ||
87fbb2ac | 81 | static unsigned long text_ip_addr(unsigned long ip) |
17666f02 | 82 | { |
55ca3cc1 SS |
83 | /* |
84 | * On x86_64, kernel text mappings are mapped read-only with | |
85 | * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead | |
86 | * of the kernel text mapping to modify the kernel text. | |
87 | * | |
88 | * For 32bit kernels, these mappings are same and we can use | |
89 | * kernel identity mapping to modify code. | |
90 | */ | |
91 | if (within(ip, (unsigned long)_text, (unsigned long)_etext)) | |
217f155e | 92 | ip = (unsigned long)__va(__pa_symbol(ip)); |
55ca3cc1 | 93 | |
87fbb2ac | 94 | return ip; |
17666f02 SR |
95 | } |
96 | ||
dc326fca | 97 | static const unsigned char *ftrace_nop_replace(void) |
caf4b323 | 98 | { |
dc326fca | 99 | return ideal_nops[NOP_ATOMIC5]; |
caf4b323 FW |
100 | } |
101 | ||
31e88909 | 102 | static int |
8a4d0a68 | 103 | ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code, |
0d098a7d | 104 | unsigned const char *new_code) |
3d083395 | 105 | { |
6f93fc07 | 106 | unsigned char replaced[MCOUNT_INSN_SIZE]; |
3d083395 SR |
107 | |
108 | /* | |
109 | * Note: Due to modules and __init, code can | |
110 | * disappear and change, we need to protect against faulting | |
76aefee5 | 111 | * as well as code changing. We do this by using the |
ab9a0918 | 112 | * probe_kernel_* functions. |
3d083395 SR |
113 | * |
114 | * No real locking needed, this code is run through | |
6f93fc07 | 115 | * kstop_machine, or before SMP starts. |
3d083395 | 116 | */ |
76aefee5 SR |
117 | |
118 | /* read the text we want to modify */ | |
ab9a0918 | 119 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) |
593eb8a2 | 120 | return -EFAULT; |
6f93fc07 | 121 | |
76aefee5 | 122 | /* Make sure it is what we expect it to be */ |
6f93fc07 | 123 | if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) |
593eb8a2 | 124 | return -EINVAL; |
3d083395 | 125 | |
87fbb2ac SRRH |
126 | ip = text_ip_addr(ip); |
127 | ||
76aefee5 | 128 | /* replace the text with the new text */ |
87fbb2ac | 129 | if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE)) |
593eb8a2 | 130 | return -EPERM; |
6f93fc07 SR |
131 | |
132 | sync_core(); | |
3d083395 | 133 | |
6f93fc07 | 134 | return 0; |
3d083395 SR |
135 | } |
136 | ||
31e88909 SR |
137 | int ftrace_make_nop(struct module *mod, |
138 | struct dyn_ftrace *rec, unsigned long addr) | |
139 | { | |
0d098a7d | 140 | unsigned const char *new, *old; |
31e88909 SR |
141 | unsigned long ip = rec->ip; |
142 | ||
143 | old = ftrace_call_replace(ip, addr); | |
144 | new = ftrace_nop_replace(); | |
145 | ||
8a4d0a68 SR |
146 | /* |
147 | * On boot up, and when modules are loaded, the MCOUNT_ADDR | |
148 | * is converted to a nop, and will never become MCOUNT_ADDR | |
149 | * again. This code is either running before SMP (on boot up) | |
150 | * or before the code will ever be executed (module load). | |
151 | * We do not want to use the breakpoint version in this case, | |
152 | * just modify the code directly. | |
153 | */ | |
154 | if (addr == MCOUNT_ADDR) | |
155 | return ftrace_modify_code_direct(rec->ip, old, new); | |
156 | ||
157 | /* Normal cases use add_brk_on_nop */ | |
158 | WARN_ONCE(1, "invalid use of ftrace_make_nop"); | |
159 | return -EINVAL; | |
31e88909 SR |
160 | } |
161 | ||
162 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
163 | { | |
0d098a7d | 164 | unsigned const char *new, *old; |
31e88909 SR |
165 | unsigned long ip = rec->ip; |
166 | ||
167 | old = ftrace_nop_replace(); | |
168 | new = ftrace_call_replace(ip, addr); | |
169 | ||
8a4d0a68 SR |
170 | /* Should only be called when module is loaded */ |
171 | return ftrace_modify_code_direct(rec->ip, old, new); | |
d61f82d0 SR |
172 | } |
173 | ||
a192cd04 SR |
174 | /* |
175 | * The modifying_ftrace_code is used to tell the breakpoint | |
176 | * handler to call ftrace_int3_handler(). If it fails to | |
177 | * call this handler for a breakpoint added by ftrace, then | |
178 | * the kernel may crash. | |
179 | * | |
180 | * As atomic_writes on x86 do not need a barrier, we do not | |
181 | * need to add smp_mb()s for this to work. It is also considered | |
182 | * that we can not read the modifying_ftrace_code before | |
183 | * executing the breakpoint. That would be quite remarkable if | |
184 | * it could do that. Here's the flow that is required: | |
185 | * | |
186 | * CPU-0 CPU-1 | |
187 | * | |
188 | * atomic_inc(mfc); | |
189 | * write int3s | |
190 | * <trap-int3> // implicit (r)mb | |
191 | * if (atomic_read(mfc)) | |
192 | * call ftrace_int3_handler() | |
193 | * | |
194 | * Then when we are finished: | |
195 | * | |
196 | * atomic_dec(mfc); | |
197 | * | |
198 | * If we hit a breakpoint that was not set by ftrace, it does not | |
199 | * matter if ftrace_int3_handler() is called or not. It will | |
200 | * simply be ignored. But it is crucial that a ftrace nop/caller | |
201 | * breakpoint is handled. No other user should ever place a | |
202 | * breakpoint on an ftrace nop/caller location. It must only | |
203 | * be done by this code. | |
204 | */ | |
205 | atomic_t modifying_ftrace_code __read_mostly; | |
08d636b6 | 206 | |
8a4d0a68 SR |
207 | static int |
208 | ftrace_modify_code(unsigned long ip, unsigned const char *old_code, | |
209 | unsigned const char *new_code); | |
210 | ||
08f6fba5 SR |
211 | /* |
212 | * Should never be called: | |
213 | * As it is only called by __ftrace_replace_code() which is called by | |
214 | * ftrace_replace_code() that x86 overrides, and by ftrace_update_code() | |
215 | * which is called to turn mcount into nops or nops into function calls | |
216 | * but not to convert a function from not using regs to one that uses | |
217 | * regs, which ftrace_modify_call() is for. | |
218 | */ | |
219 | int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, | |
220 | unsigned long addr) | |
221 | { | |
222 | WARN_ON(1); | |
223 | return -EINVAL; | |
224 | } | |
08f6fba5 | 225 | |
87fbb2ac SRRH |
226 | static unsigned long ftrace_update_func; |
227 | ||
228 | static int update_ftrace_func(unsigned long ip, void *new) | |
8a4d0a68 | 229 | { |
87fbb2ac | 230 | unsigned char old[MCOUNT_INSN_SIZE]; |
8a4d0a68 SR |
231 | int ret; |
232 | ||
87fbb2ac SRRH |
233 | memcpy(old, (void *)ip, MCOUNT_INSN_SIZE); |
234 | ||
235 | ftrace_update_func = ip; | |
236 | /* Make sure the breakpoints see the ftrace_update_func update */ | |
237 | smp_wmb(); | |
8a4d0a68 SR |
238 | |
239 | /* See comment above by declaration of modifying_ftrace_code */ | |
240 | atomic_inc(&modifying_ftrace_code); | |
241 | ||
242 | ret = ftrace_modify_code(ip, old, new); | |
243 | ||
87fbb2ac SRRH |
244 | atomic_dec(&modifying_ftrace_code); |
245 | ||
246 | return ret; | |
247 | } | |
248 | ||
249 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
250 | { | |
251 | unsigned long ip = (unsigned long)(&ftrace_call); | |
252 | unsigned char *new; | |
253 | int ret; | |
254 | ||
255 | new = ftrace_call_replace(ip, (unsigned long)func); | |
256 | ret = update_ftrace_func(ip, new); | |
257 | ||
08f6fba5 SR |
258 | /* Also update the regs callback function */ |
259 | if (!ret) { | |
260 | ip = (unsigned long)(&ftrace_regs_call); | |
08f6fba5 | 261 | new = ftrace_call_replace(ip, (unsigned long)func); |
87fbb2ac | 262 | ret = update_ftrace_func(ip, new); |
08f6fba5 | 263 | } |
08f6fba5 | 264 | |
8a4d0a68 SR |
265 | return ret; |
266 | } | |
267 | ||
ab4ead02 KH |
268 | static int is_ftrace_caller(unsigned long ip) |
269 | { | |
87fbb2ac | 270 | if (ip == ftrace_update_func) |
ab4ead02 KH |
271 | return 1; |
272 | ||
273 | return 0; | |
274 | } | |
275 | ||
08d636b6 SR |
276 | /* |
277 | * A breakpoint was added to the code address we are about to | |
278 | * modify, and this is the handle that will just skip over it. | |
279 | * We are either changing a nop into a trace call, or a trace | |
280 | * call to a nop. While the change is taking place, we treat | |
281 | * it just like it was a nop. | |
282 | */ | |
283 | int ftrace_int3_handler(struct pt_regs *regs) | |
284 | { | |
ab4ead02 KH |
285 | unsigned long ip; |
286 | ||
08d636b6 SR |
287 | if (WARN_ON_ONCE(!regs)) |
288 | return 0; | |
289 | ||
ab4ead02 KH |
290 | ip = regs->ip - 1; |
291 | if (!ftrace_location(ip) && !is_ftrace_caller(ip)) | |
08d636b6 SR |
292 | return 0; |
293 | ||
294 | regs->ip += MCOUNT_INSN_SIZE - 1; | |
295 | ||
296 | return 1; | |
297 | } | |
298 | ||
299 | static int ftrace_write(unsigned long ip, const char *val, int size) | |
300 | { | |
964f7b6b | 301 | ip = text_ip_addr(ip); |
08d636b6 | 302 | |
92550405 SRRH |
303 | if (probe_kernel_write((void *)ip, val, size)) |
304 | return -EPERM; | |
305 | ||
306 | return 0; | |
08d636b6 SR |
307 | } |
308 | ||
309 | static int add_break(unsigned long ip, const char *old) | |
310 | { | |
311 | unsigned char replaced[MCOUNT_INSN_SIZE]; | |
312 | unsigned char brk = BREAKPOINT_INSTRUCTION; | |
313 | ||
314 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) | |
315 | return -EFAULT; | |
316 | ||
317 | /* Make sure it is what we expect it to be */ | |
318 | if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0) | |
319 | return -EINVAL; | |
320 | ||
92550405 | 321 | return ftrace_write(ip, &brk, 1); |
08d636b6 SR |
322 | } |
323 | ||
324 | static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr) | |
325 | { | |
326 | unsigned const char *old; | |
327 | unsigned long ip = rec->ip; | |
328 | ||
329 | old = ftrace_call_replace(ip, addr); | |
330 | ||
331 | return add_break(rec->ip, old); | |
332 | } | |
333 | ||
334 | ||
335 | static int add_brk_on_nop(struct dyn_ftrace *rec) | |
336 | { | |
337 | unsigned const char *old; | |
338 | ||
339 | old = ftrace_nop_replace(); | |
340 | ||
341 | return add_break(rec->ip, old); | |
342 | } | |
343 | ||
344 | static int add_breakpoints(struct dyn_ftrace *rec, int enable) | |
345 | { | |
346 | unsigned long ftrace_addr; | |
347 | int ret; | |
348 | ||
7413af1f | 349 | ftrace_addr = ftrace_get_addr_curr(rec); |
08d636b6 | 350 | |
94792ea0 | 351 | ret = ftrace_test_record(rec, enable); |
08d636b6 SR |
352 | |
353 | switch (ret) { | |
354 | case FTRACE_UPDATE_IGNORE: | |
355 | return 0; | |
356 | ||
357 | case FTRACE_UPDATE_MAKE_CALL: | |
358 | /* converting nop to call */ | |
359 | return add_brk_on_nop(rec); | |
360 | ||
08f6fba5 | 361 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
362 | case FTRACE_UPDATE_MAKE_NOP: |
363 | /* converting a call to a nop */ | |
364 | return add_brk_on_call(rec, ftrace_addr); | |
365 | } | |
366 | return 0; | |
367 | } | |
368 | ||
369 | /* | |
370 | * On error, we need to remove breakpoints. This needs to | |
371 | * be done caefully. If the address does not currently have a | |
372 | * breakpoint, we know we are done. Otherwise, we look at the | |
373 | * remaining 4 bytes of the instruction. If it matches a nop | |
374 | * we replace the breakpoint with the nop. Otherwise we replace | |
375 | * it with the call instruction. | |
376 | */ | |
377 | static int remove_breakpoint(struct dyn_ftrace *rec) | |
378 | { | |
379 | unsigned char ins[MCOUNT_INSN_SIZE]; | |
380 | unsigned char brk = BREAKPOINT_INSTRUCTION; | |
381 | const unsigned char *nop; | |
382 | unsigned long ftrace_addr; | |
383 | unsigned long ip = rec->ip; | |
384 | ||
385 | /* If we fail the read, just give up */ | |
386 | if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE)) | |
387 | return -EFAULT; | |
388 | ||
389 | /* If this does not have a breakpoint, we are done */ | |
390 | if (ins[0] != brk) | |
7f11f5ec | 391 | return 0; |
08d636b6 SR |
392 | |
393 | nop = ftrace_nop_replace(); | |
394 | ||
395 | /* | |
396 | * If the last 4 bytes of the instruction do not match | |
397 | * a nop, then we assume that this is a call to ftrace_addr. | |
398 | */ | |
399 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) { | |
400 | /* | |
401 | * For extra paranoidism, we check if the breakpoint is on | |
402 | * a call that would actually jump to the ftrace_addr. | |
403 | * If not, don't touch the breakpoint, we make just create | |
404 | * a disaster. | |
405 | */ | |
7413af1f | 406 | ftrace_addr = ftrace_get_addr_new(rec); |
08f6fba5 SR |
407 | nop = ftrace_call_replace(ip, ftrace_addr); |
408 | ||
409 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0) | |
410 | goto update; | |
411 | ||
412 | /* Check both ftrace_addr and ftrace_old_addr */ | |
7413af1f | 413 | ftrace_addr = ftrace_get_addr_curr(rec); |
08d636b6 SR |
414 | nop = ftrace_call_replace(ip, ftrace_addr); |
415 | ||
416 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) | |
417 | return -EINVAL; | |
418 | } | |
419 | ||
08f6fba5 | 420 | update: |
c932c6b7 | 421 | return ftrace_write(ip, nop, 1); |
08d636b6 SR |
422 | } |
423 | ||
424 | static int add_update_code(unsigned long ip, unsigned const char *new) | |
425 | { | |
426 | /* skip breakpoint */ | |
427 | ip++; | |
428 | new++; | |
92550405 | 429 | return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1); |
08d636b6 SR |
430 | } |
431 | ||
432 | static int add_update_call(struct dyn_ftrace *rec, unsigned long addr) | |
433 | { | |
434 | unsigned long ip = rec->ip; | |
435 | unsigned const char *new; | |
436 | ||
437 | new = ftrace_call_replace(ip, addr); | |
438 | return add_update_code(ip, new); | |
439 | } | |
440 | ||
441 | static int add_update_nop(struct dyn_ftrace *rec) | |
442 | { | |
443 | unsigned long ip = rec->ip; | |
444 | unsigned const char *new; | |
445 | ||
446 | new = ftrace_nop_replace(); | |
447 | return add_update_code(ip, new); | |
448 | } | |
449 | ||
450 | static int add_update(struct dyn_ftrace *rec, int enable) | |
451 | { | |
452 | unsigned long ftrace_addr; | |
453 | int ret; | |
454 | ||
455 | ret = ftrace_test_record(rec, enable); | |
456 | ||
7413af1f | 457 | ftrace_addr = ftrace_get_addr_new(rec); |
08d636b6 SR |
458 | |
459 | switch (ret) { | |
460 | case FTRACE_UPDATE_IGNORE: | |
461 | return 0; | |
462 | ||
08f6fba5 | 463 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
464 | case FTRACE_UPDATE_MAKE_CALL: |
465 | /* converting nop to call */ | |
466 | return add_update_call(rec, ftrace_addr); | |
467 | ||
468 | case FTRACE_UPDATE_MAKE_NOP: | |
469 | /* converting a call to a nop */ | |
470 | return add_update_nop(rec); | |
471 | } | |
472 | ||
473 | return 0; | |
474 | } | |
475 | ||
476 | static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr) | |
477 | { | |
478 | unsigned long ip = rec->ip; | |
479 | unsigned const char *new; | |
480 | ||
481 | new = ftrace_call_replace(ip, addr); | |
482 | ||
92550405 | 483 | return ftrace_write(ip, new, 1); |
08d636b6 SR |
484 | } |
485 | ||
486 | static int finish_update_nop(struct dyn_ftrace *rec) | |
487 | { | |
488 | unsigned long ip = rec->ip; | |
489 | unsigned const char *new; | |
490 | ||
491 | new = ftrace_nop_replace(); | |
492 | ||
92550405 | 493 | return ftrace_write(ip, new, 1); |
08d636b6 SR |
494 | } |
495 | ||
496 | static int finish_update(struct dyn_ftrace *rec, int enable) | |
497 | { | |
498 | unsigned long ftrace_addr; | |
499 | int ret; | |
500 | ||
501 | ret = ftrace_update_record(rec, enable); | |
502 | ||
7413af1f | 503 | ftrace_addr = ftrace_get_addr_new(rec); |
08d636b6 SR |
504 | |
505 | switch (ret) { | |
506 | case FTRACE_UPDATE_IGNORE: | |
507 | return 0; | |
508 | ||
08f6fba5 | 509 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
510 | case FTRACE_UPDATE_MAKE_CALL: |
511 | /* converting nop to call */ | |
512 | return finish_update_call(rec, ftrace_addr); | |
513 | ||
514 | case FTRACE_UPDATE_MAKE_NOP: | |
515 | /* converting a call to a nop */ | |
516 | return finish_update_nop(rec); | |
517 | } | |
518 | ||
519 | return 0; | |
520 | } | |
521 | ||
522 | static void do_sync_core(void *data) | |
523 | { | |
524 | sync_core(); | |
525 | } | |
526 | ||
527 | static void run_sync(void) | |
528 | { | |
529 | int enable_irqs = irqs_disabled(); | |
530 | ||
531 | /* We may be called with interrupts disbled (on bootup). */ | |
532 | if (enable_irqs) | |
533 | local_irq_enable(); | |
534 | on_each_cpu(do_sync_core, NULL, 1); | |
535 | if (enable_irqs) | |
536 | local_irq_disable(); | |
537 | } | |
538 | ||
e4f5d544 | 539 | void ftrace_replace_code(int enable) |
08d636b6 SR |
540 | { |
541 | struct ftrace_rec_iter *iter; | |
542 | struct dyn_ftrace *rec; | |
543 | const char *report = "adding breakpoints"; | |
544 | int count = 0; | |
545 | int ret; | |
546 | ||
547 | for_ftrace_rec_iter(iter) { | |
548 | rec = ftrace_rec_iter_record(iter); | |
549 | ||
550 | ret = add_breakpoints(rec, enable); | |
551 | if (ret) | |
552 | goto remove_breakpoints; | |
553 | count++; | |
554 | } | |
555 | ||
556 | run_sync(); | |
557 | ||
558 | report = "updating code"; | |
559 | ||
560 | for_ftrace_rec_iter(iter) { | |
561 | rec = ftrace_rec_iter_record(iter); | |
562 | ||
563 | ret = add_update(rec, enable); | |
564 | if (ret) | |
565 | goto remove_breakpoints; | |
566 | } | |
567 | ||
568 | run_sync(); | |
569 | ||
570 | report = "removing breakpoints"; | |
571 | ||
572 | for_ftrace_rec_iter(iter) { | |
573 | rec = ftrace_rec_iter_record(iter); | |
574 | ||
575 | ret = finish_update(rec, enable); | |
576 | if (ret) | |
577 | goto remove_breakpoints; | |
578 | } | |
579 | ||
580 | run_sync(); | |
581 | ||
582 | return; | |
583 | ||
584 | remove_breakpoints: | |
74bb8c45 | 585 | pr_warn("Failed on %s (%d):\n", report, count); |
4fd3279b | 586 | ftrace_bug(ret, rec); |
08d636b6 SR |
587 | for_ftrace_rec_iter(iter) { |
588 | rec = ftrace_rec_iter_record(iter); | |
7f11f5ec PM |
589 | /* |
590 | * Breakpoints are handled only when this function is in | |
591 | * progress. The system could not work with them. | |
592 | */ | |
593 | if (remove_breakpoint(rec)) | |
594 | BUG(); | |
08d636b6 | 595 | } |
c932c6b7 | 596 | run_sync(); |
08d636b6 SR |
597 | } |
598 | ||
8a4d0a68 SR |
599 | static int |
600 | ftrace_modify_code(unsigned long ip, unsigned const char *old_code, | |
601 | unsigned const char *new_code) | |
602 | { | |
603 | int ret; | |
604 | ||
605 | ret = add_break(ip, old_code); | |
606 | if (ret) | |
607 | goto out; | |
608 | ||
609 | run_sync(); | |
610 | ||
611 | ret = add_update_code(ip, new_code); | |
612 | if (ret) | |
613 | goto fail_update; | |
614 | ||
615 | run_sync(); | |
616 | ||
617 | ret = ftrace_write(ip, new_code, 1); | |
7f11f5ec PM |
618 | /* |
619 | * The breakpoint is handled only when this function is in progress. | |
620 | * The system could not work if we could not remove it. | |
621 | */ | |
622 | BUG_ON(ret); | |
8a4d0a68 | 623 | out: |
12729f14 | 624 | run_sync(); |
8a4d0a68 SR |
625 | return ret; |
626 | ||
627 | fail_update: | |
7f11f5ec PM |
628 | /* Also here the system could not work with the breakpoint */ |
629 | if (ftrace_write(ip, old_code, 1)) | |
630 | BUG(); | |
8a4d0a68 SR |
631 | goto out; |
632 | } | |
633 | ||
08d636b6 SR |
634 | void arch_ftrace_update_code(int command) |
635 | { | |
a192cd04 SR |
636 | /* See comment above by declaration of modifying_ftrace_code */ |
637 | atomic_inc(&modifying_ftrace_code); | |
08d636b6 | 638 | |
e4f5d544 | 639 | ftrace_modify_all_code(command); |
08d636b6 | 640 | |
a192cd04 | 641 | atomic_dec(&modifying_ftrace_code); |
08d636b6 SR |
642 | } |
643 | ||
3a36cb11 | 644 | int __init ftrace_dyn_arch_init(void) |
3d083395 | 645 | { |
3d083395 SR |
646 | return 0; |
647 | } | |
5a45cfe1 | 648 | |
f3bea491 | 649 | #if defined(CONFIG_X86_64) || defined(CONFIG_FUNCTION_GRAPH_TRACER) |
87fbb2ac | 650 | static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) |
5a45cfe1 | 651 | { |
87fbb2ac | 652 | static union ftrace_code_union calc; |
5a45cfe1 | 653 | |
87fbb2ac SRRH |
654 | /* Jmp not a call (ignore the .e8) */ |
655 | calc.e8 = 0xe9; | |
656 | calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); | |
5a45cfe1 | 657 | |
87fbb2ac SRRH |
658 | /* |
659 | * ftrace external locks synchronize the access to the static variable. | |
660 | */ | |
661 | return calc.code; | |
662 | } | |
f3bea491 SRRH |
663 | #endif |
664 | ||
665 | /* Currently only x86_64 supports dynamic trampolines */ | |
666 | #ifdef CONFIG_X86_64 | |
667 | ||
668 | #ifdef CONFIG_MODULES | |
669 | #include <linux/moduleloader.h> | |
670 | /* Module allocation simplifies allocating memory for code */ | |
671 | static inline void *alloc_tramp(unsigned long size) | |
672 | { | |
673 | return module_alloc(size); | |
674 | } | |
675 | static inline void tramp_free(void *tramp) | |
676 | { | |
677 | module_free(NULL, tramp); | |
678 | } | |
679 | #else | |
680 | /* Trampolines can only be created if modules are supported */ | |
681 | static inline void *alloc_tramp(unsigned long size) | |
682 | { | |
683 | return NULL; | |
684 | } | |
685 | static inline void tramp_free(void *tramp) { } | |
686 | #endif | |
687 | ||
688 | /* Defined as markers to the end of the ftrace default trampolines */ | |
689 | extern void ftrace_caller_end(void); | |
690 | extern void ftrace_regs_caller_end(void); | |
691 | extern void ftrace_return(void); | |
692 | extern void ftrace_caller_op_ptr(void); | |
693 | extern void ftrace_regs_caller_op_ptr(void); | |
694 | ||
695 | /* movq function_trace_op(%rip), %rdx */ | |
696 | /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */ | |
697 | #define OP_REF_SIZE 7 | |
698 | ||
699 | /* | |
700 | * The ftrace_ops is passed to the function callback. Since the | |
701 | * trampoline only services a single ftrace_ops, we can pass in | |
702 | * that ops directly. | |
703 | * | |
704 | * The ftrace_op_code_union is used to create a pointer to the | |
705 | * ftrace_ops that will be passed to the callback function. | |
706 | */ | |
707 | union ftrace_op_code_union { | |
708 | char code[OP_REF_SIZE]; | |
709 | struct { | |
710 | char op[3]; | |
711 | int offset; | |
712 | } __attribute__((packed)); | |
713 | }; | |
714 | ||
aec0be2d SRRH |
715 | static unsigned long |
716 | create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) | |
f3bea491 SRRH |
717 | { |
718 | unsigned const char *jmp; | |
719 | unsigned long start_offset; | |
720 | unsigned long end_offset; | |
721 | unsigned long op_offset; | |
722 | unsigned long offset; | |
723 | unsigned long size; | |
724 | unsigned long ip; | |
725 | unsigned long *ptr; | |
726 | void *trampoline; | |
727 | /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */ | |
728 | unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 }; | |
729 | union ftrace_op_code_union op_ptr; | |
730 | int ret; | |
731 | ||
732 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { | |
733 | start_offset = (unsigned long)ftrace_regs_caller; | |
734 | end_offset = (unsigned long)ftrace_regs_caller_end; | |
735 | op_offset = (unsigned long)ftrace_regs_caller_op_ptr; | |
736 | } else { | |
737 | start_offset = (unsigned long)ftrace_caller; | |
738 | end_offset = (unsigned long)ftrace_caller_end; | |
739 | op_offset = (unsigned long)ftrace_caller_op_ptr; | |
740 | } | |
741 | ||
742 | size = end_offset - start_offset; | |
743 | ||
744 | /* | |
745 | * Allocate enough size to store the ftrace_caller code, | |
746 | * the jmp to ftrace_return, as well as the address of | |
747 | * the ftrace_ops this trampoline is used for. | |
748 | */ | |
749 | trampoline = alloc_tramp(size + MCOUNT_INSN_SIZE + sizeof(void *)); | |
750 | if (!trampoline) | |
751 | return 0; | |
752 | ||
aec0be2d SRRH |
753 | *tramp_size = size + MCOUNT_INSN_SIZE + sizeof(void *); |
754 | ||
f3bea491 SRRH |
755 | /* Copy ftrace_caller onto the trampoline memory */ |
756 | ret = probe_kernel_read(trampoline, (void *)start_offset, size); | |
757 | if (WARN_ON(ret < 0)) { | |
758 | tramp_free(trampoline); | |
759 | return 0; | |
760 | } | |
761 | ||
762 | ip = (unsigned long)trampoline + size; | |
763 | ||
764 | /* The trampoline ends with a jmp to ftrace_return */ | |
765 | jmp = ftrace_jmp_replace(ip, (unsigned long)ftrace_return); | |
766 | memcpy(trampoline + size, jmp, MCOUNT_INSN_SIZE); | |
767 | ||
768 | /* | |
769 | * The address of the ftrace_ops that is used for this trampoline | |
770 | * is stored at the end of the trampoline. This will be used to | |
771 | * load the third parameter for the callback. Basically, that | |
772 | * location at the end of the trampoline takes the place of | |
773 | * the global function_trace_op variable. | |
774 | */ | |
775 | ||
776 | ptr = (unsigned long *)(trampoline + size + MCOUNT_INSN_SIZE); | |
777 | *ptr = (unsigned long)ops; | |
778 | ||
779 | op_offset -= start_offset; | |
780 | memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE); | |
781 | ||
782 | /* Are we pointing to the reference? */ | |
783 | if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) { | |
784 | tramp_free(trampoline); | |
785 | return 0; | |
786 | } | |
787 | ||
788 | /* Load the contents of ptr into the callback parameter */ | |
789 | offset = (unsigned long)ptr; | |
790 | offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE; | |
791 | ||
792 | op_ptr.offset = offset; | |
793 | ||
794 | /* put in the new offset to the ftrace_ops */ | |
795 | memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE); | |
796 | ||
797 | /* ALLOC_TRAMP flags lets us know we created it */ | |
798 | ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP; | |
799 | ||
800 | return (unsigned long)trampoline; | |
801 | } | |
802 | ||
15d5b02c SRRH |
803 | static unsigned long calc_trampoline_call_offset(bool save_regs) |
804 | { | |
805 | unsigned long start_offset; | |
806 | unsigned long call_offset; | |
807 | ||
808 | if (save_regs) { | |
809 | start_offset = (unsigned long)ftrace_regs_caller; | |
810 | call_offset = (unsigned long)ftrace_regs_call; | |
811 | } else { | |
812 | start_offset = (unsigned long)ftrace_caller; | |
813 | call_offset = (unsigned long)ftrace_call; | |
814 | } | |
815 | ||
816 | return call_offset - start_offset; | |
817 | } | |
818 | ||
f3bea491 SRRH |
819 | void arch_ftrace_update_trampoline(struct ftrace_ops *ops) |
820 | { | |
821 | ftrace_func_t func; | |
822 | unsigned char *new; | |
f3bea491 SRRH |
823 | unsigned long offset; |
824 | unsigned long ip; | |
aec0be2d | 825 | unsigned int size; |
f3bea491 SRRH |
826 | int ret; |
827 | ||
828 | if (ops->trampoline) { | |
829 | /* | |
830 | * The ftrace_ops caller may set up its own trampoline. | |
831 | * In such a case, this code must not modify it. | |
832 | */ | |
833 | if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
834 | return; | |
835 | } else { | |
aec0be2d | 836 | ops->trampoline = create_trampoline(ops, &size); |
f3bea491 SRRH |
837 | if (!ops->trampoline) |
838 | return; | |
aec0be2d | 839 | ops->trampoline_size = size; |
f3bea491 SRRH |
840 | } |
841 | ||
15d5b02c | 842 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); |
f3bea491 SRRH |
843 | ip = ops->trampoline + offset; |
844 | ||
845 | func = ftrace_ops_get_func(ops); | |
846 | ||
847 | /* Do a safe modify in case the trampoline is executing */ | |
848 | new = ftrace_call_replace(ip, (unsigned long)func); | |
849 | ret = update_ftrace_func(ip, new); | |
850 | ||
851 | /* The update should never fail */ | |
852 | WARN_ON(ret); | |
853 | } | |
15d5b02c SRRH |
854 | |
855 | /* Return the address of the function the trampoline calls */ | |
856 | static void *addr_from_call(void *ptr) | |
857 | { | |
858 | union ftrace_code_union calc; | |
859 | int ret; | |
860 | ||
861 | ret = probe_kernel_read(&calc, ptr, MCOUNT_INSN_SIZE); | |
862 | if (WARN_ON_ONCE(ret < 0)) | |
863 | return NULL; | |
864 | ||
865 | /* Make sure this is a call */ | |
866 | if (WARN_ON_ONCE(calc.e8 != 0xe8)) { | |
867 | pr_warn("Expected e8, got %x\n", calc.e8); | |
868 | return NULL; | |
869 | } | |
870 | ||
871 | return ptr + MCOUNT_INSN_SIZE + calc.offset; | |
872 | } | |
873 | ||
6a06bdbf | 874 | void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, |
15d5b02c SRRH |
875 | unsigned long frame_pointer); |
876 | ||
877 | /* | |
878 | * If the ops->trampoline was not allocated, then it probably | |
879 | * has a static trampoline func, or is the ftrace caller itself. | |
880 | */ | |
881 | static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) | |
882 | { | |
883 | unsigned long offset; | |
884 | bool save_regs = rec->flags & FTRACE_FL_REGS_EN; | |
885 | void *ptr; | |
886 | ||
887 | if (ops && ops->trampoline) { | |
888 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
889 | /* | |
890 | * We only know about function graph tracer setting as static | |
891 | * trampoline. | |
892 | */ | |
893 | if (ops->trampoline == FTRACE_GRAPH_ADDR) | |
894 | return (void *)prepare_ftrace_return; | |
895 | #endif | |
896 | return NULL; | |
897 | } | |
898 | ||
899 | offset = calc_trampoline_call_offset(save_regs); | |
900 | ||
901 | if (save_regs) | |
902 | ptr = (void *)FTRACE_REGS_ADDR + offset; | |
903 | else | |
904 | ptr = (void *)FTRACE_ADDR + offset; | |
905 | ||
906 | return addr_from_call(ptr); | |
907 | } | |
908 | ||
909 | void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) | |
910 | { | |
911 | unsigned long offset; | |
912 | ||
913 | /* If we didn't allocate this trampoline, consider it static */ | |
914 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
915 | return static_tramp_func(ops, rec); | |
916 | ||
917 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); | |
918 | return addr_from_call((void *)ops->trampoline + offset); | |
919 | } | |
920 | ||
12cce594 SRRH |
921 | void arch_ftrace_trampoline_free(struct ftrace_ops *ops) |
922 | { | |
923 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
924 | return; | |
925 | ||
926 | tramp_free((void *)ops->trampoline); | |
927 | ops->trampoline = 0; | |
928 | } | |
15d5b02c | 929 | |
f3bea491 SRRH |
930 | #endif /* CONFIG_X86_64 */ |
931 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
932 | ||
933 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
934 | ||
935 | #ifdef CONFIG_DYNAMIC_FTRACE | |
936 | extern void ftrace_graph_call(void); | |
5a45cfe1 | 937 | |
87fbb2ac SRRH |
938 | static int ftrace_mod_jmp(unsigned long ip, void *func) |
939 | { | |
940 | unsigned char *new; | |
5a45cfe1 | 941 | |
87fbb2ac | 942 | new = ftrace_jmp_replace(ip, (unsigned long)func); |
5a45cfe1 | 943 | |
87fbb2ac | 944 | return update_ftrace_func(ip, new); |
5a45cfe1 SR |
945 | } |
946 | ||
947 | int ftrace_enable_ftrace_graph_caller(void) | |
948 | { | |
949 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 950 | |
87fbb2ac | 951 | return ftrace_mod_jmp(ip, &ftrace_graph_caller); |
5a45cfe1 SR |
952 | } |
953 | ||
954 | int ftrace_disable_ftrace_graph_caller(void) | |
955 | { | |
956 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 957 | |
87fbb2ac | 958 | return ftrace_mod_jmp(ip, &ftrace_stub); |
5a45cfe1 SR |
959 | } |
960 | ||
e7d3737e FW |
961 | #endif /* !CONFIG_DYNAMIC_FTRACE */ |
962 | ||
e7d3737e FW |
963 | /* |
964 | * Hook the return address and push it in the stack of return addrs | |
965 | * in current thread info. | |
966 | */ | |
6a06bdbf | 967 | void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, |
71e308a2 | 968 | unsigned long frame_pointer) |
e7d3737e FW |
969 | { |
970 | unsigned long old; | |
e7d3737e | 971 | int faulted; |
287b6e68 | 972 | struct ftrace_graph_ent trace; |
e7d3737e FW |
973 | unsigned long return_hooker = (unsigned long) |
974 | &return_to_handler; | |
975 | ||
84b2bc7f SRRH |
976 | if (unlikely(ftrace_graph_is_dead())) |
977 | return; | |
978 | ||
380c4b14 | 979 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
e7d3737e FW |
980 | return; |
981 | ||
982 | /* | |
983 | * Protect against fault, even if it shouldn't | |
984 | * happen. This tool is too much intrusive to | |
985 | * ignore such a protection. | |
986 | */ | |
987 | asm volatile( | |
96665788 SR |
988 | "1: " _ASM_MOV " (%[parent]), %[old]\n" |
989 | "2: " _ASM_MOV " %[return_hooker], (%[parent])\n" | |
e7d3737e | 990 | " movl $0, %[faulted]\n" |
e3944bfa | 991 | "3:\n" |
e7d3737e FW |
992 | |
993 | ".section .fixup, \"ax\"\n" | |
e3944bfa SR |
994 | "4: movl $1, %[faulted]\n" |
995 | " jmp 3b\n" | |
e7d3737e FW |
996 | ".previous\n" |
997 | ||
e3944bfa SR |
998 | _ASM_EXTABLE(1b, 4b) |
999 | _ASM_EXTABLE(2b, 4b) | |
e7d3737e | 1000 | |
aa512a27 | 1001 | : [old] "=&r" (old), [faulted] "=r" (faulted) |
96665788 | 1002 | : [parent] "r" (parent), [return_hooker] "r" (return_hooker) |
e7d3737e FW |
1003 | : "memory" |
1004 | ); | |
1005 | ||
14a866c5 SR |
1006 | if (unlikely(faulted)) { |
1007 | ftrace_graph_stop(); | |
1008 | WARN_ON(1); | |
e7d3737e FW |
1009 | return; |
1010 | } | |
1011 | ||
287b6e68 | 1012 | trace.func = self_addr; |
722b3c74 | 1013 | trace.depth = current->curr_ret_stack + 1; |
287b6e68 | 1014 | |
e49dc19c SR |
1015 | /* Only trace if the calling function expects to */ |
1016 | if (!ftrace_graph_entry(&trace)) { | |
e49dc19c | 1017 | *parent = old; |
722b3c74 SR |
1018 | return; |
1019 | } | |
1020 | ||
1021 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, | |
1022 | frame_pointer) == -EBUSY) { | |
1023 | *parent = old; | |
1024 | return; | |
e49dc19c | 1025 | } |
e7d3737e | 1026 | } |
fb52607a | 1027 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |