Commit | Line | Data |
---|---|---|
3d083395 | 1 | /* |
9d2099ab | 2 | * Dynamic function tracing support. |
3d083395 SR |
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 | |
3f135e57 JP |
32 | #if defined(CONFIG_FUNCTION_GRAPH_TRACER) && \ |
33 | !defined(CC_USING_FENTRY) && \ | |
34 | !defined(CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE) | |
35 | # error The following combination is not supported: ((compiler missing -mfentry) || (CONFIG_X86_32 and !CONFIG_DYNAMIC_FTRACE)) && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE | |
36 | #endif | |
37 | ||
caf4b323 | 38 | #ifdef CONFIG_DYNAMIC_FTRACE |
3d083395 | 39 | |
16239630 SR |
40 | int ftrace_arch_code_modify_prepare(void) |
41 | { | |
42 | set_kernel_text_rw(); | |
84e1c6bb | 43 | set_all_modules_text_rw(); |
16239630 SR |
44 | return 0; |
45 | } | |
46 | ||
47 | int ftrace_arch_code_modify_post_process(void) | |
48 | { | |
84e1c6bb | 49 | set_all_modules_text_ro(); |
16239630 SR |
50 | set_kernel_text_ro(); |
51 | return 0; | |
52 | } | |
53 | ||
3d083395 | 54 | union ftrace_code_union { |
395a59d0 | 55 | char code[MCOUNT_INSN_SIZE]; |
3d083395 | 56 | struct { |
15d5b02c | 57 | unsigned char e8; |
3d083395 SR |
58 | int offset; |
59 | } __attribute__((packed)); | |
60 | }; | |
61 | ||
15adc048 | 62 | static int ftrace_calc_offset(long ip, long addr) |
3c1720f0 SR |
63 | { |
64 | return (int)(addr - ip); | |
65 | } | |
3d083395 | 66 | |
31e88909 | 67 | static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
3c1720f0 SR |
68 | { |
69 | static union ftrace_code_union calc; | |
3d083395 | 70 | |
3c1720f0 | 71 | calc.e8 = 0xe8; |
395a59d0 | 72 | calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); |
3c1720f0 SR |
73 | |
74 | /* | |
75 | * No locking needed, this must be called via kstop_machine | |
76 | * which in essence is like running on a uniprocessor machine. | |
77 | */ | |
78 | return calc.code; | |
3d083395 SR |
79 | } |
80 | ||
55ca3cc1 SS |
81 | static inline int |
82 | within(unsigned long addr, unsigned long start, unsigned long end) | |
83 | { | |
84 | return addr >= start && addr < end; | |
85 | } | |
86 | ||
87fbb2ac | 87 | static unsigned long text_ip_addr(unsigned long ip) |
17666f02 | 88 | { |
55ca3cc1 | 89 | /* |
9ccaf77c KC |
90 | * On x86_64, kernel text mappings are mapped read-only, so we use |
91 | * the kernel identity mapping instead of the kernel text mapping | |
92 | * to modify the kernel text. | |
55ca3cc1 SS |
93 | * |
94 | * For 32bit kernels, these mappings are same and we can use | |
95 | * kernel identity mapping to modify code. | |
96 | */ | |
97 | if (within(ip, (unsigned long)_text, (unsigned long)_etext)) | |
217f155e | 98 | ip = (unsigned long)__va(__pa_symbol(ip)); |
55ca3cc1 | 99 | |
87fbb2ac | 100 | return ip; |
17666f02 SR |
101 | } |
102 | ||
dc326fca | 103 | static const unsigned char *ftrace_nop_replace(void) |
caf4b323 | 104 | { |
dc326fca | 105 | return ideal_nops[NOP_ATOMIC5]; |
caf4b323 FW |
106 | } |
107 | ||
31e88909 | 108 | static int |
8a4d0a68 | 109 | ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code, |
0d098a7d | 110 | unsigned const char *new_code) |
3d083395 | 111 | { |
6f93fc07 | 112 | unsigned char replaced[MCOUNT_INSN_SIZE]; |
3d083395 | 113 | |
b05086c7 SRRH |
114 | ftrace_expected = old_code; |
115 | ||
3d083395 | 116 | /* |
c5d641f9 LB |
117 | * Note: |
118 | * We are paranoid about modifying text, as if a bug was to happen, it | |
119 | * could cause us to read or write to someplace that could cause harm. | |
120 | * Carefully read and modify the code with probe_kernel_*(), and make | |
121 | * sure what we read is what we expected it to be before modifying it. | |
3d083395 | 122 | */ |
76aefee5 SR |
123 | |
124 | /* read the text we want to modify */ | |
ab9a0918 | 125 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) |
593eb8a2 | 126 | return -EFAULT; |
6f93fc07 | 127 | |
76aefee5 | 128 | /* Make sure it is what we expect it to be */ |
6f93fc07 | 129 | if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) |
593eb8a2 | 130 | return -EINVAL; |
3d083395 | 131 | |
87fbb2ac SRRH |
132 | ip = text_ip_addr(ip); |
133 | ||
76aefee5 | 134 | /* replace the text with the new text */ |
87fbb2ac | 135 | if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE)) |
593eb8a2 | 136 | return -EPERM; |
6f93fc07 SR |
137 | |
138 | sync_core(); | |
3d083395 | 139 | |
6f93fc07 | 140 | return 0; |
3d083395 SR |
141 | } |
142 | ||
31e88909 SR |
143 | int ftrace_make_nop(struct module *mod, |
144 | struct dyn_ftrace *rec, unsigned long addr) | |
145 | { | |
0d098a7d | 146 | unsigned const char *new, *old; |
31e88909 SR |
147 | unsigned long ip = rec->ip; |
148 | ||
149 | old = ftrace_call_replace(ip, addr); | |
150 | new = ftrace_nop_replace(); | |
151 | ||
8a4d0a68 SR |
152 | /* |
153 | * On boot up, and when modules are loaded, the MCOUNT_ADDR | |
154 | * is converted to a nop, and will never become MCOUNT_ADDR | |
155 | * again. This code is either running before SMP (on boot up) | |
156 | * or before the code will ever be executed (module load). | |
157 | * We do not want to use the breakpoint version in this case, | |
158 | * just modify the code directly. | |
159 | */ | |
160 | if (addr == MCOUNT_ADDR) | |
161 | return ftrace_modify_code_direct(rec->ip, old, new); | |
162 | ||
b05086c7 SRRH |
163 | ftrace_expected = NULL; |
164 | ||
8a4d0a68 SR |
165 | /* Normal cases use add_brk_on_nop */ |
166 | WARN_ONCE(1, "invalid use of ftrace_make_nop"); | |
167 | return -EINVAL; | |
31e88909 SR |
168 | } |
169 | ||
170 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
171 | { | |
0d098a7d | 172 | unsigned const char *new, *old; |
31e88909 SR |
173 | unsigned long ip = rec->ip; |
174 | ||
175 | old = ftrace_nop_replace(); | |
176 | new = ftrace_call_replace(ip, addr); | |
177 | ||
8a4d0a68 SR |
178 | /* Should only be called when module is loaded */ |
179 | return ftrace_modify_code_direct(rec->ip, old, new); | |
d61f82d0 SR |
180 | } |
181 | ||
a192cd04 SR |
182 | /* |
183 | * The modifying_ftrace_code is used to tell the breakpoint | |
184 | * handler to call ftrace_int3_handler(). If it fails to | |
185 | * call this handler for a breakpoint added by ftrace, then | |
186 | * the kernel may crash. | |
187 | * | |
188 | * As atomic_writes on x86 do not need a barrier, we do not | |
189 | * need to add smp_mb()s for this to work. It is also considered | |
190 | * that we can not read the modifying_ftrace_code before | |
191 | * executing the breakpoint. That would be quite remarkable if | |
192 | * it could do that. Here's the flow that is required: | |
193 | * | |
194 | * CPU-0 CPU-1 | |
195 | * | |
196 | * atomic_inc(mfc); | |
197 | * write int3s | |
198 | * <trap-int3> // implicit (r)mb | |
199 | * if (atomic_read(mfc)) | |
200 | * call ftrace_int3_handler() | |
201 | * | |
202 | * Then when we are finished: | |
203 | * | |
204 | * atomic_dec(mfc); | |
205 | * | |
206 | * If we hit a breakpoint that was not set by ftrace, it does not | |
207 | * matter if ftrace_int3_handler() is called or not. It will | |
208 | * simply be ignored. But it is crucial that a ftrace nop/caller | |
209 | * breakpoint is handled. No other user should ever place a | |
210 | * breakpoint on an ftrace nop/caller location. It must only | |
211 | * be done by this code. | |
212 | */ | |
213 | atomic_t modifying_ftrace_code __read_mostly; | |
08d636b6 | 214 | |
8a4d0a68 SR |
215 | static int |
216 | ftrace_modify_code(unsigned long ip, unsigned const char *old_code, | |
217 | unsigned const char *new_code); | |
218 | ||
08f6fba5 SR |
219 | /* |
220 | * Should never be called: | |
221 | * As it is only called by __ftrace_replace_code() which is called by | |
222 | * ftrace_replace_code() that x86 overrides, and by ftrace_update_code() | |
223 | * which is called to turn mcount into nops or nops into function calls | |
224 | * but not to convert a function from not using regs to one that uses | |
225 | * regs, which ftrace_modify_call() is for. | |
226 | */ | |
227 | int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, | |
228 | unsigned long addr) | |
229 | { | |
230 | WARN_ON(1); | |
b05086c7 | 231 | ftrace_expected = NULL; |
08f6fba5 SR |
232 | return -EINVAL; |
233 | } | |
08f6fba5 | 234 | |
87fbb2ac SRRH |
235 | static unsigned long ftrace_update_func; |
236 | ||
237 | static int update_ftrace_func(unsigned long ip, void *new) | |
8a4d0a68 | 238 | { |
87fbb2ac | 239 | unsigned char old[MCOUNT_INSN_SIZE]; |
8a4d0a68 SR |
240 | int ret; |
241 | ||
87fbb2ac SRRH |
242 | memcpy(old, (void *)ip, MCOUNT_INSN_SIZE); |
243 | ||
244 | ftrace_update_func = ip; | |
245 | /* Make sure the breakpoints see the ftrace_update_func update */ | |
246 | smp_wmb(); | |
8a4d0a68 SR |
247 | |
248 | /* See comment above by declaration of modifying_ftrace_code */ | |
249 | atomic_inc(&modifying_ftrace_code); | |
250 | ||
251 | ret = ftrace_modify_code(ip, old, new); | |
252 | ||
87fbb2ac SRRH |
253 | atomic_dec(&modifying_ftrace_code); |
254 | ||
255 | return ret; | |
256 | } | |
257 | ||
258 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
259 | { | |
260 | unsigned long ip = (unsigned long)(&ftrace_call); | |
261 | unsigned char *new; | |
262 | int ret; | |
263 | ||
264 | new = ftrace_call_replace(ip, (unsigned long)func); | |
265 | ret = update_ftrace_func(ip, new); | |
266 | ||
08f6fba5 SR |
267 | /* Also update the regs callback function */ |
268 | if (!ret) { | |
269 | ip = (unsigned long)(&ftrace_regs_call); | |
08f6fba5 | 270 | new = ftrace_call_replace(ip, (unsigned long)func); |
87fbb2ac | 271 | ret = update_ftrace_func(ip, new); |
08f6fba5 | 272 | } |
08f6fba5 | 273 | |
8a4d0a68 SR |
274 | return ret; |
275 | } | |
276 | ||
ab4ead02 KH |
277 | static int is_ftrace_caller(unsigned long ip) |
278 | { | |
87fbb2ac | 279 | if (ip == ftrace_update_func) |
ab4ead02 KH |
280 | return 1; |
281 | ||
282 | return 0; | |
283 | } | |
284 | ||
08d636b6 SR |
285 | /* |
286 | * A breakpoint was added to the code address we are about to | |
287 | * modify, and this is the handle that will just skip over it. | |
288 | * We are either changing a nop into a trace call, or a trace | |
289 | * call to a nop. While the change is taking place, we treat | |
290 | * it just like it was a nop. | |
291 | */ | |
292 | int ftrace_int3_handler(struct pt_regs *regs) | |
293 | { | |
ab4ead02 KH |
294 | unsigned long ip; |
295 | ||
08d636b6 SR |
296 | if (WARN_ON_ONCE(!regs)) |
297 | return 0; | |
298 | ||
ab4ead02 KH |
299 | ip = regs->ip - 1; |
300 | if (!ftrace_location(ip) && !is_ftrace_caller(ip)) | |
08d636b6 SR |
301 | return 0; |
302 | ||
303 | regs->ip += MCOUNT_INSN_SIZE - 1; | |
304 | ||
305 | return 1; | |
306 | } | |
307 | ||
308 | static int ftrace_write(unsigned long ip, const char *val, int size) | |
309 | { | |
964f7b6b | 310 | ip = text_ip_addr(ip); |
08d636b6 | 311 | |
92550405 SRRH |
312 | if (probe_kernel_write((void *)ip, val, size)) |
313 | return -EPERM; | |
314 | ||
315 | return 0; | |
08d636b6 SR |
316 | } |
317 | ||
318 | static int add_break(unsigned long ip, const char *old) | |
319 | { | |
320 | unsigned char replaced[MCOUNT_INSN_SIZE]; | |
321 | unsigned char brk = BREAKPOINT_INSTRUCTION; | |
322 | ||
323 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) | |
324 | return -EFAULT; | |
325 | ||
b05086c7 SRRH |
326 | ftrace_expected = old; |
327 | ||
08d636b6 SR |
328 | /* Make sure it is what we expect it to be */ |
329 | if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0) | |
330 | return -EINVAL; | |
331 | ||
92550405 | 332 | return ftrace_write(ip, &brk, 1); |
08d636b6 SR |
333 | } |
334 | ||
335 | static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr) | |
336 | { | |
337 | unsigned const char *old; | |
338 | unsigned long ip = rec->ip; | |
339 | ||
340 | old = ftrace_call_replace(ip, addr); | |
341 | ||
342 | return add_break(rec->ip, old); | |
343 | } | |
344 | ||
345 | ||
346 | static int add_brk_on_nop(struct dyn_ftrace *rec) | |
347 | { | |
348 | unsigned const char *old; | |
349 | ||
350 | old = ftrace_nop_replace(); | |
351 | ||
352 | return add_break(rec->ip, old); | |
353 | } | |
354 | ||
355 | static int add_breakpoints(struct dyn_ftrace *rec, int enable) | |
356 | { | |
357 | unsigned long ftrace_addr; | |
358 | int ret; | |
359 | ||
7413af1f | 360 | ftrace_addr = ftrace_get_addr_curr(rec); |
08d636b6 | 361 | |
94792ea0 | 362 | ret = ftrace_test_record(rec, enable); |
08d636b6 SR |
363 | |
364 | switch (ret) { | |
365 | case FTRACE_UPDATE_IGNORE: | |
366 | return 0; | |
367 | ||
368 | case FTRACE_UPDATE_MAKE_CALL: | |
369 | /* converting nop to call */ | |
370 | return add_brk_on_nop(rec); | |
371 | ||
08f6fba5 | 372 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
373 | case FTRACE_UPDATE_MAKE_NOP: |
374 | /* converting a call to a nop */ | |
375 | return add_brk_on_call(rec, ftrace_addr); | |
376 | } | |
377 | return 0; | |
378 | } | |
379 | ||
380 | /* | |
381 | * On error, we need to remove breakpoints. This needs to | |
382 | * be done caefully. If the address does not currently have a | |
383 | * breakpoint, we know we are done. Otherwise, we look at the | |
384 | * remaining 4 bytes of the instruction. If it matches a nop | |
385 | * we replace the breakpoint with the nop. Otherwise we replace | |
386 | * it with the call instruction. | |
387 | */ | |
388 | static int remove_breakpoint(struct dyn_ftrace *rec) | |
389 | { | |
390 | unsigned char ins[MCOUNT_INSN_SIZE]; | |
391 | unsigned char brk = BREAKPOINT_INSTRUCTION; | |
392 | const unsigned char *nop; | |
393 | unsigned long ftrace_addr; | |
394 | unsigned long ip = rec->ip; | |
395 | ||
396 | /* If we fail the read, just give up */ | |
397 | if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE)) | |
398 | return -EFAULT; | |
399 | ||
400 | /* If this does not have a breakpoint, we are done */ | |
401 | if (ins[0] != brk) | |
7f11f5ec | 402 | return 0; |
08d636b6 SR |
403 | |
404 | nop = ftrace_nop_replace(); | |
405 | ||
406 | /* | |
407 | * If the last 4 bytes of the instruction do not match | |
408 | * a nop, then we assume that this is a call to ftrace_addr. | |
409 | */ | |
410 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) { | |
411 | /* | |
412 | * For extra paranoidism, we check if the breakpoint is on | |
413 | * a call that would actually jump to the ftrace_addr. | |
414 | * If not, don't touch the breakpoint, we make just create | |
415 | * a disaster. | |
416 | */ | |
7413af1f | 417 | ftrace_addr = ftrace_get_addr_new(rec); |
08f6fba5 SR |
418 | nop = ftrace_call_replace(ip, ftrace_addr); |
419 | ||
420 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0) | |
421 | goto update; | |
422 | ||
423 | /* Check both ftrace_addr and ftrace_old_addr */ | |
7413af1f | 424 | ftrace_addr = ftrace_get_addr_curr(rec); |
08d636b6 SR |
425 | nop = ftrace_call_replace(ip, ftrace_addr); |
426 | ||
b05086c7 SRRH |
427 | ftrace_expected = nop; |
428 | ||
08d636b6 SR |
429 | if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) |
430 | return -EINVAL; | |
431 | } | |
432 | ||
08f6fba5 | 433 | update: |
c932c6b7 | 434 | return ftrace_write(ip, nop, 1); |
08d636b6 SR |
435 | } |
436 | ||
437 | static int add_update_code(unsigned long ip, unsigned const char *new) | |
438 | { | |
439 | /* skip breakpoint */ | |
440 | ip++; | |
441 | new++; | |
92550405 | 442 | return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1); |
08d636b6 SR |
443 | } |
444 | ||
445 | static int add_update_call(struct dyn_ftrace *rec, unsigned long addr) | |
446 | { | |
447 | unsigned long ip = rec->ip; | |
448 | unsigned const char *new; | |
449 | ||
450 | new = ftrace_call_replace(ip, addr); | |
451 | return add_update_code(ip, new); | |
452 | } | |
453 | ||
454 | static int add_update_nop(struct dyn_ftrace *rec) | |
455 | { | |
456 | unsigned long ip = rec->ip; | |
457 | unsigned const char *new; | |
458 | ||
459 | new = ftrace_nop_replace(); | |
460 | return add_update_code(ip, new); | |
461 | } | |
462 | ||
463 | static int add_update(struct dyn_ftrace *rec, int enable) | |
464 | { | |
465 | unsigned long ftrace_addr; | |
466 | int ret; | |
467 | ||
468 | ret = ftrace_test_record(rec, enable); | |
469 | ||
7413af1f | 470 | ftrace_addr = ftrace_get_addr_new(rec); |
08d636b6 SR |
471 | |
472 | switch (ret) { | |
473 | case FTRACE_UPDATE_IGNORE: | |
474 | return 0; | |
475 | ||
08f6fba5 | 476 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
477 | case FTRACE_UPDATE_MAKE_CALL: |
478 | /* converting nop to call */ | |
479 | return add_update_call(rec, ftrace_addr); | |
480 | ||
481 | case FTRACE_UPDATE_MAKE_NOP: | |
482 | /* converting a call to a nop */ | |
483 | return add_update_nop(rec); | |
484 | } | |
485 | ||
486 | return 0; | |
487 | } | |
488 | ||
489 | static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr) | |
490 | { | |
491 | unsigned long ip = rec->ip; | |
492 | unsigned const char *new; | |
493 | ||
494 | new = ftrace_call_replace(ip, addr); | |
495 | ||
92550405 | 496 | return ftrace_write(ip, new, 1); |
08d636b6 SR |
497 | } |
498 | ||
499 | static int finish_update_nop(struct dyn_ftrace *rec) | |
500 | { | |
501 | unsigned long ip = rec->ip; | |
502 | unsigned const char *new; | |
503 | ||
504 | new = ftrace_nop_replace(); | |
505 | ||
92550405 | 506 | return ftrace_write(ip, new, 1); |
08d636b6 SR |
507 | } |
508 | ||
509 | static int finish_update(struct dyn_ftrace *rec, int enable) | |
510 | { | |
511 | unsigned long ftrace_addr; | |
512 | int ret; | |
513 | ||
514 | ret = ftrace_update_record(rec, enable); | |
515 | ||
7413af1f | 516 | ftrace_addr = ftrace_get_addr_new(rec); |
08d636b6 SR |
517 | |
518 | switch (ret) { | |
519 | case FTRACE_UPDATE_IGNORE: | |
520 | return 0; | |
521 | ||
08f6fba5 | 522 | case FTRACE_UPDATE_MODIFY_CALL: |
08d636b6 SR |
523 | case FTRACE_UPDATE_MAKE_CALL: |
524 | /* converting nop to call */ | |
525 | return finish_update_call(rec, ftrace_addr); | |
526 | ||
527 | case FTRACE_UPDATE_MAKE_NOP: | |
528 | /* converting a call to a nop */ | |
529 | return finish_update_nop(rec); | |
530 | } | |
531 | ||
532 | return 0; | |
533 | } | |
534 | ||
535 | static void do_sync_core(void *data) | |
536 | { | |
537 | sync_core(); | |
538 | } | |
539 | ||
540 | static void run_sync(void) | |
541 | { | |
542 | int enable_irqs = irqs_disabled(); | |
543 | ||
8a1115ff | 544 | /* We may be called with interrupts disabled (on bootup). */ |
08d636b6 SR |
545 | if (enable_irqs) |
546 | local_irq_enable(); | |
547 | on_each_cpu(do_sync_core, NULL, 1); | |
548 | if (enable_irqs) | |
549 | local_irq_disable(); | |
550 | } | |
551 | ||
e4f5d544 | 552 | void ftrace_replace_code(int enable) |
08d636b6 SR |
553 | { |
554 | struct ftrace_rec_iter *iter; | |
555 | struct dyn_ftrace *rec; | |
556 | const char *report = "adding breakpoints"; | |
557 | int count = 0; | |
558 | int ret; | |
559 | ||
560 | for_ftrace_rec_iter(iter) { | |
561 | rec = ftrace_rec_iter_record(iter); | |
562 | ||
563 | ret = add_breakpoints(rec, enable); | |
564 | if (ret) | |
565 | goto remove_breakpoints; | |
566 | count++; | |
567 | } | |
568 | ||
569 | run_sync(); | |
570 | ||
571 | report = "updating code"; | |
883a1e86 | 572 | count = 0; |
08d636b6 SR |
573 | |
574 | for_ftrace_rec_iter(iter) { | |
575 | rec = ftrace_rec_iter_record(iter); | |
576 | ||
577 | ret = add_update(rec, enable); | |
578 | if (ret) | |
579 | goto remove_breakpoints; | |
883a1e86 | 580 | count++; |
08d636b6 SR |
581 | } |
582 | ||
583 | run_sync(); | |
584 | ||
585 | report = "removing breakpoints"; | |
883a1e86 | 586 | count = 0; |
08d636b6 SR |
587 | |
588 | for_ftrace_rec_iter(iter) { | |
589 | rec = ftrace_rec_iter_record(iter); | |
590 | ||
591 | ret = finish_update(rec, enable); | |
592 | if (ret) | |
593 | goto remove_breakpoints; | |
883a1e86 | 594 | count++; |
08d636b6 SR |
595 | } |
596 | ||
597 | run_sync(); | |
598 | ||
599 | return; | |
600 | ||
601 | remove_breakpoints: | |
74bb8c45 | 602 | pr_warn("Failed on %s (%d):\n", report, count); |
4fd3279b | 603 | ftrace_bug(ret, rec); |
08d636b6 SR |
604 | for_ftrace_rec_iter(iter) { |
605 | rec = ftrace_rec_iter_record(iter); | |
7f11f5ec PM |
606 | /* |
607 | * Breakpoints are handled only when this function is in | |
608 | * progress. The system could not work with them. | |
609 | */ | |
610 | if (remove_breakpoint(rec)) | |
611 | BUG(); | |
08d636b6 | 612 | } |
c932c6b7 | 613 | run_sync(); |
08d636b6 SR |
614 | } |
615 | ||
8a4d0a68 SR |
616 | static int |
617 | ftrace_modify_code(unsigned long ip, unsigned const char *old_code, | |
618 | unsigned const char *new_code) | |
619 | { | |
620 | int ret; | |
621 | ||
622 | ret = add_break(ip, old_code); | |
623 | if (ret) | |
624 | goto out; | |
625 | ||
626 | run_sync(); | |
627 | ||
628 | ret = add_update_code(ip, new_code); | |
629 | if (ret) | |
630 | goto fail_update; | |
631 | ||
632 | run_sync(); | |
633 | ||
634 | ret = ftrace_write(ip, new_code, 1); | |
7f11f5ec PM |
635 | /* |
636 | * The breakpoint is handled only when this function is in progress. | |
637 | * The system could not work if we could not remove it. | |
638 | */ | |
639 | BUG_ON(ret); | |
8a4d0a68 | 640 | out: |
12729f14 | 641 | run_sync(); |
8a4d0a68 SR |
642 | return ret; |
643 | ||
644 | fail_update: | |
7f11f5ec PM |
645 | /* Also here the system could not work with the breakpoint */ |
646 | if (ftrace_write(ip, old_code, 1)) | |
647 | BUG(); | |
8a4d0a68 SR |
648 | goto out; |
649 | } | |
650 | ||
08d636b6 SR |
651 | void arch_ftrace_update_code(int command) |
652 | { | |
a192cd04 SR |
653 | /* See comment above by declaration of modifying_ftrace_code */ |
654 | atomic_inc(&modifying_ftrace_code); | |
08d636b6 | 655 | |
e4f5d544 | 656 | ftrace_modify_all_code(command); |
08d636b6 | 657 | |
a192cd04 | 658 | atomic_dec(&modifying_ftrace_code); |
08d636b6 SR |
659 | } |
660 | ||
3a36cb11 | 661 | int __init ftrace_dyn_arch_init(void) |
3d083395 | 662 | { |
3d083395 SR |
663 | return 0; |
664 | } | |
5a45cfe1 | 665 | |
f3bea491 | 666 | #if defined(CONFIG_X86_64) || defined(CONFIG_FUNCTION_GRAPH_TRACER) |
87fbb2ac | 667 | static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr) |
5a45cfe1 | 668 | { |
87fbb2ac | 669 | static union ftrace_code_union calc; |
5a45cfe1 | 670 | |
87fbb2ac SRRH |
671 | /* Jmp not a call (ignore the .e8) */ |
672 | calc.e8 = 0xe9; | |
673 | calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); | |
5a45cfe1 | 674 | |
87fbb2ac SRRH |
675 | /* |
676 | * ftrace external locks synchronize the access to the static variable. | |
677 | */ | |
678 | return calc.code; | |
679 | } | |
f3bea491 SRRH |
680 | #endif |
681 | ||
682 | /* Currently only x86_64 supports dynamic trampolines */ | |
683 | #ifdef CONFIG_X86_64 | |
684 | ||
685 | #ifdef CONFIG_MODULES | |
686 | #include <linux/moduleloader.h> | |
687 | /* Module allocation simplifies allocating memory for code */ | |
688 | static inline void *alloc_tramp(unsigned long size) | |
689 | { | |
690 | return module_alloc(size); | |
691 | } | |
692 | static inline void tramp_free(void *tramp) | |
693 | { | |
be1f221c | 694 | module_memfree(tramp); |
f3bea491 SRRH |
695 | } |
696 | #else | |
697 | /* Trampolines can only be created if modules are supported */ | |
698 | static inline void *alloc_tramp(unsigned long size) | |
699 | { | |
700 | return NULL; | |
701 | } | |
702 | static inline void tramp_free(void *tramp) { } | |
703 | #endif | |
704 | ||
705 | /* Defined as markers to the end of the ftrace default trampolines */ | |
f3bea491 | 706 | extern void ftrace_regs_caller_end(void); |
f1b92bb6 | 707 | extern void ftrace_epilogue(void); |
f3bea491 SRRH |
708 | extern void ftrace_caller_op_ptr(void); |
709 | extern void ftrace_regs_caller_op_ptr(void); | |
710 | ||
711 | /* movq function_trace_op(%rip), %rdx */ | |
712 | /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */ | |
713 | #define OP_REF_SIZE 7 | |
714 | ||
715 | /* | |
716 | * The ftrace_ops is passed to the function callback. Since the | |
717 | * trampoline only services a single ftrace_ops, we can pass in | |
718 | * that ops directly. | |
719 | * | |
720 | * The ftrace_op_code_union is used to create a pointer to the | |
721 | * ftrace_ops that will be passed to the callback function. | |
722 | */ | |
723 | union ftrace_op_code_union { | |
724 | char code[OP_REF_SIZE]; | |
725 | struct { | |
726 | char op[3]; | |
727 | int offset; | |
728 | } __attribute__((packed)); | |
729 | }; | |
730 | ||
aec0be2d SRRH |
731 | static unsigned long |
732 | create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) | |
f3bea491 SRRH |
733 | { |
734 | unsigned const char *jmp; | |
735 | unsigned long start_offset; | |
736 | unsigned long end_offset; | |
737 | unsigned long op_offset; | |
738 | unsigned long offset; | |
739 | unsigned long size; | |
740 | unsigned long ip; | |
741 | unsigned long *ptr; | |
742 | void *trampoline; | |
743 | /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */ | |
744 | unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 }; | |
745 | union ftrace_op_code_union op_ptr; | |
746 | int ret; | |
747 | ||
748 | if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { | |
749 | start_offset = (unsigned long)ftrace_regs_caller; | |
750 | end_offset = (unsigned long)ftrace_regs_caller_end; | |
751 | op_offset = (unsigned long)ftrace_regs_caller_op_ptr; | |
752 | } else { | |
753 | start_offset = (unsigned long)ftrace_caller; | |
f1b92bb6 | 754 | end_offset = (unsigned long)ftrace_epilogue; |
f3bea491 SRRH |
755 | op_offset = (unsigned long)ftrace_caller_op_ptr; |
756 | } | |
757 | ||
758 | size = end_offset - start_offset; | |
759 | ||
760 | /* | |
761 | * Allocate enough size to store the ftrace_caller code, | |
f1b92bb6 | 762 | * the jmp to ftrace_epilogue, as well as the address of |
f3bea491 SRRH |
763 | * the ftrace_ops this trampoline is used for. |
764 | */ | |
765 | trampoline = alloc_tramp(size + MCOUNT_INSN_SIZE + sizeof(void *)); | |
766 | if (!trampoline) | |
767 | return 0; | |
768 | ||
aec0be2d SRRH |
769 | *tramp_size = size + MCOUNT_INSN_SIZE + sizeof(void *); |
770 | ||
f3bea491 SRRH |
771 | /* Copy ftrace_caller onto the trampoline memory */ |
772 | ret = probe_kernel_read(trampoline, (void *)start_offset, size); | |
773 | if (WARN_ON(ret < 0)) { | |
774 | tramp_free(trampoline); | |
775 | return 0; | |
776 | } | |
777 | ||
778 | ip = (unsigned long)trampoline + size; | |
779 | ||
f1b92bb6 BP |
780 | /* The trampoline ends with a jmp to ftrace_epilogue */ |
781 | jmp = ftrace_jmp_replace(ip, (unsigned long)ftrace_epilogue); | |
f3bea491 SRRH |
782 | memcpy(trampoline + size, jmp, MCOUNT_INSN_SIZE); |
783 | ||
784 | /* | |
785 | * The address of the ftrace_ops that is used for this trampoline | |
786 | * is stored at the end of the trampoline. This will be used to | |
787 | * load the third parameter for the callback. Basically, that | |
788 | * location at the end of the trampoline takes the place of | |
789 | * the global function_trace_op variable. | |
790 | */ | |
791 | ||
792 | ptr = (unsigned long *)(trampoline + size + MCOUNT_INSN_SIZE); | |
793 | *ptr = (unsigned long)ops; | |
794 | ||
795 | op_offset -= start_offset; | |
796 | memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE); | |
797 | ||
798 | /* Are we pointing to the reference? */ | |
799 | if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) { | |
800 | tramp_free(trampoline); | |
801 | return 0; | |
802 | } | |
803 | ||
804 | /* Load the contents of ptr into the callback parameter */ | |
805 | offset = (unsigned long)ptr; | |
806 | offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE; | |
807 | ||
808 | op_ptr.offset = offset; | |
809 | ||
810 | /* put in the new offset to the ftrace_ops */ | |
811 | memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE); | |
812 | ||
813 | /* ALLOC_TRAMP flags lets us know we created it */ | |
814 | ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP; | |
815 | ||
816 | return (unsigned long)trampoline; | |
817 | } | |
818 | ||
15d5b02c SRRH |
819 | static unsigned long calc_trampoline_call_offset(bool save_regs) |
820 | { | |
821 | unsigned long start_offset; | |
822 | unsigned long call_offset; | |
823 | ||
824 | if (save_regs) { | |
825 | start_offset = (unsigned long)ftrace_regs_caller; | |
826 | call_offset = (unsigned long)ftrace_regs_call; | |
827 | } else { | |
828 | start_offset = (unsigned long)ftrace_caller; | |
829 | call_offset = (unsigned long)ftrace_call; | |
830 | } | |
831 | ||
832 | return call_offset - start_offset; | |
833 | } | |
834 | ||
f3bea491 SRRH |
835 | void arch_ftrace_update_trampoline(struct ftrace_ops *ops) |
836 | { | |
837 | ftrace_func_t func; | |
838 | unsigned char *new; | |
f3bea491 SRRH |
839 | unsigned long offset; |
840 | unsigned long ip; | |
aec0be2d | 841 | unsigned int size; |
f3bea491 SRRH |
842 | int ret; |
843 | ||
844 | if (ops->trampoline) { | |
845 | /* | |
846 | * The ftrace_ops caller may set up its own trampoline. | |
847 | * In such a case, this code must not modify it. | |
848 | */ | |
849 | if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
850 | return; | |
851 | } else { | |
aec0be2d | 852 | ops->trampoline = create_trampoline(ops, &size); |
f3bea491 SRRH |
853 | if (!ops->trampoline) |
854 | return; | |
aec0be2d | 855 | ops->trampoline_size = size; |
f3bea491 SRRH |
856 | } |
857 | ||
15d5b02c | 858 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); |
f3bea491 SRRH |
859 | ip = ops->trampoline + offset; |
860 | ||
861 | func = ftrace_ops_get_func(ops); | |
862 | ||
863 | /* Do a safe modify in case the trampoline is executing */ | |
864 | new = ftrace_call_replace(ip, (unsigned long)func); | |
865 | ret = update_ftrace_func(ip, new); | |
866 | ||
867 | /* The update should never fail */ | |
868 | WARN_ON(ret); | |
869 | } | |
15d5b02c SRRH |
870 | |
871 | /* Return the address of the function the trampoline calls */ | |
872 | static void *addr_from_call(void *ptr) | |
873 | { | |
874 | union ftrace_code_union calc; | |
875 | int ret; | |
876 | ||
877 | ret = probe_kernel_read(&calc, ptr, MCOUNT_INSN_SIZE); | |
878 | if (WARN_ON_ONCE(ret < 0)) | |
879 | return NULL; | |
880 | ||
881 | /* Make sure this is a call */ | |
882 | if (WARN_ON_ONCE(calc.e8 != 0xe8)) { | |
883 | pr_warn("Expected e8, got %x\n", calc.e8); | |
884 | return NULL; | |
885 | } | |
886 | ||
887 | return ptr + MCOUNT_INSN_SIZE + calc.offset; | |
888 | } | |
889 | ||
6a06bdbf | 890 | void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, |
15d5b02c SRRH |
891 | unsigned long frame_pointer); |
892 | ||
893 | /* | |
894 | * If the ops->trampoline was not allocated, then it probably | |
895 | * has a static trampoline func, or is the ftrace caller itself. | |
896 | */ | |
897 | static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) | |
898 | { | |
899 | unsigned long offset; | |
900 | bool save_regs = rec->flags & FTRACE_FL_REGS_EN; | |
901 | void *ptr; | |
902 | ||
903 | if (ops && ops->trampoline) { | |
904 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
905 | /* | |
906 | * We only know about function graph tracer setting as static | |
907 | * trampoline. | |
908 | */ | |
909 | if (ops->trampoline == FTRACE_GRAPH_ADDR) | |
910 | return (void *)prepare_ftrace_return; | |
911 | #endif | |
912 | return NULL; | |
913 | } | |
914 | ||
915 | offset = calc_trampoline_call_offset(save_regs); | |
916 | ||
917 | if (save_regs) | |
918 | ptr = (void *)FTRACE_REGS_ADDR + offset; | |
919 | else | |
920 | ptr = (void *)FTRACE_ADDR + offset; | |
921 | ||
922 | return addr_from_call(ptr); | |
923 | } | |
924 | ||
925 | void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec) | |
926 | { | |
927 | unsigned long offset; | |
928 | ||
929 | /* If we didn't allocate this trampoline, consider it static */ | |
930 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
931 | return static_tramp_func(ops, rec); | |
932 | ||
933 | offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS); | |
934 | return addr_from_call((void *)ops->trampoline + offset); | |
935 | } | |
936 | ||
12cce594 SRRH |
937 | void arch_ftrace_trampoline_free(struct ftrace_ops *ops) |
938 | { | |
939 | if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) | |
940 | return; | |
941 | ||
942 | tramp_free((void *)ops->trampoline); | |
943 | ops->trampoline = 0; | |
944 | } | |
15d5b02c | 945 | |
f3bea491 SRRH |
946 | #endif /* CONFIG_X86_64 */ |
947 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
948 | ||
949 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
950 | ||
951 | #ifdef CONFIG_DYNAMIC_FTRACE | |
952 | extern void ftrace_graph_call(void); | |
5a45cfe1 | 953 | |
87fbb2ac SRRH |
954 | static int ftrace_mod_jmp(unsigned long ip, void *func) |
955 | { | |
956 | unsigned char *new; | |
5a45cfe1 | 957 | |
87fbb2ac | 958 | new = ftrace_jmp_replace(ip, (unsigned long)func); |
5a45cfe1 | 959 | |
87fbb2ac | 960 | return update_ftrace_func(ip, new); |
5a45cfe1 SR |
961 | } |
962 | ||
963 | int ftrace_enable_ftrace_graph_caller(void) | |
964 | { | |
965 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 966 | |
87fbb2ac | 967 | return ftrace_mod_jmp(ip, &ftrace_graph_caller); |
5a45cfe1 SR |
968 | } |
969 | ||
970 | int ftrace_disable_ftrace_graph_caller(void) | |
971 | { | |
972 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
5a45cfe1 | 973 | |
87fbb2ac | 974 | return ftrace_mod_jmp(ip, &ftrace_stub); |
5a45cfe1 SR |
975 | } |
976 | ||
e7d3737e FW |
977 | #endif /* !CONFIG_DYNAMIC_FTRACE */ |
978 | ||
e7d3737e FW |
979 | /* |
980 | * Hook the return address and push it in the stack of return addrs | |
981 | * in current thread info. | |
982 | */ | |
6a06bdbf | 983 | void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, |
71e308a2 | 984 | unsigned long frame_pointer) |
e7d3737e FW |
985 | { |
986 | unsigned long old; | |
e7d3737e | 987 | int faulted; |
287b6e68 | 988 | struct ftrace_graph_ent trace; |
e7d3737e FW |
989 | unsigned long return_hooker = (unsigned long) |
990 | &return_to_handler; | |
991 | ||
84b2bc7f SRRH |
992 | if (unlikely(ftrace_graph_is_dead())) |
993 | return; | |
994 | ||
380c4b14 | 995 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
e7d3737e FW |
996 | return; |
997 | ||
998 | /* | |
999 | * Protect against fault, even if it shouldn't | |
1000 | * happen. This tool is too much intrusive to | |
1001 | * ignore such a protection. | |
1002 | */ | |
1003 | asm volatile( | |
96665788 SR |
1004 | "1: " _ASM_MOV " (%[parent]), %[old]\n" |
1005 | "2: " _ASM_MOV " %[return_hooker], (%[parent])\n" | |
e7d3737e | 1006 | " movl $0, %[faulted]\n" |
e3944bfa | 1007 | "3:\n" |
e7d3737e FW |
1008 | |
1009 | ".section .fixup, \"ax\"\n" | |
e3944bfa SR |
1010 | "4: movl $1, %[faulted]\n" |
1011 | " jmp 3b\n" | |
e7d3737e FW |
1012 | ".previous\n" |
1013 | ||
e3944bfa SR |
1014 | _ASM_EXTABLE(1b, 4b) |
1015 | _ASM_EXTABLE(2b, 4b) | |
e7d3737e | 1016 | |
aa512a27 | 1017 | : [old] "=&r" (old), [faulted] "=r" (faulted) |
96665788 | 1018 | : [parent] "r" (parent), [return_hooker] "r" (return_hooker) |
e7d3737e FW |
1019 | : "memory" |
1020 | ); | |
1021 | ||
14a866c5 SR |
1022 | if (unlikely(faulted)) { |
1023 | ftrace_graph_stop(); | |
1024 | WARN_ON(1); | |
e7d3737e FW |
1025 | return; |
1026 | } | |
1027 | ||
287b6e68 | 1028 | trace.func = self_addr; |
722b3c74 | 1029 | trace.depth = current->curr_ret_stack + 1; |
287b6e68 | 1030 | |
e49dc19c SR |
1031 | /* Only trace if the calling function expects to */ |
1032 | if (!ftrace_graph_entry(&trace)) { | |
e49dc19c | 1033 | *parent = old; |
722b3c74 SR |
1034 | return; |
1035 | } | |
1036 | ||
1037 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, | |
471bd10f | 1038 | frame_pointer, parent) == -EBUSY) { |
722b3c74 SR |
1039 | *parent = old; |
1040 | return; | |
e49dc19c | 1041 | } |
e7d3737e | 1042 | } |
fb52607a | 1043 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |