1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Code for replacing ftrace calls with jumps.
4 *
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
6 *
7 * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
8 *
9 * Added function graph tracer code, taken from x86 that was written
10 * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
11 *
12 */
13
14 #define pr_fmt(fmt) "ftrace-powerpc: " fmt
15
16 #include <linux/spinlock.h>
17 #include <linux/hardirq.h>
18 #include <linux/uaccess.h>
19 #include <linux/module.h>
20 #include <linux/ftrace.h>
21 #include <linux/percpu.h>
22 #include <linux/init.h>
23 #include <linux/list.h>
24
25 #include <asm/asm-prototypes.h>
26 #include <asm/cacheflush.h>
27 #include <asm/code-patching.h>
28 #include <asm/ftrace.h>
29 #include <asm/syscall.h>
30 #include <asm/inst.h>
31
32
33 #ifdef CONFIG_DYNAMIC_FTRACE
34
35 /*
36 * We generally only have a single long_branch tramp and at most 2 or 3 plt
37 * tramps generated. But, we don't use the plt tramps currently. We also allot
38 * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
39 * tramps in total. Set aside 8 just to be sure.
40 */
41 #define NUM_FTRACE_TRAMPS 8
42 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
43
44 static struct ppc_inst
ftrace_call_replace(unsigned long ip,unsigned long addr,int link)45 ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
46 {
47 struct ppc_inst op;
48
49 addr = ppc_function_entry((void *)addr);
50
51 /* if (link) set op to 'bl' else 'b' */
52 create_branch(&op, (struct ppc_inst *)ip, addr, link ? 1 : 0);
53
54 return op;
55 }
56
57 static int
ftrace_modify_code(unsigned long ip,struct ppc_inst old,struct ppc_inst new)58 ftrace_modify_code(unsigned long ip, struct ppc_inst old, struct ppc_inst new)
59 {
60 struct ppc_inst replaced;
61
62 /*
63 * Note:
64 * We are paranoid about modifying text, as if a bug was to happen, it
65 * could cause us to read or write to someplace that could cause harm.
66 * Carefully read and modify the code with probe_kernel_*(), and make
67 * sure what we read is what we expected it to be before modifying it.
68 */
69
70 /* read the text we want to modify */
71 if (probe_kernel_read_inst(&replaced, (void *)ip))
72 return -EFAULT;
73
74 /* Make sure it is what we expect it to be */
75 if (!ppc_inst_equal(replaced, old)) {
76 pr_err("%p: replaced (%s) != old (%s)",
77 (void *)ip, ppc_inst_as_str(replaced), ppc_inst_as_str(old));
78 return -EINVAL;
79 }
80
81 /* replace the text with the new text */
82 if (patch_instruction((struct ppc_inst *)ip, new))
83 return -EPERM;
84
85 return 0;
86 }
87
88 /*
89 * Helper functions that are the same for both PPC64 and PPC32.
90 */
test_24bit_addr(unsigned long ip,unsigned long addr)91 static int test_24bit_addr(unsigned long ip, unsigned long addr)
92 {
93 struct ppc_inst op;
94 addr = ppc_function_entry((void *)addr);
95
96 /* use the create_branch to verify that this offset can be branched */
97 return create_branch(&op, (struct ppc_inst *)ip, addr, 0) == 0;
98 }
99
is_bl_op(struct ppc_inst op)100 static int is_bl_op(struct ppc_inst op)
101 {
102 return (ppc_inst_val(op) & 0xfc000003) == 0x48000001;
103 }
104
is_b_op(struct ppc_inst op)105 static int is_b_op(struct ppc_inst op)
106 {
107 return (ppc_inst_val(op) & 0xfc000003) == 0x48000000;
108 }
109
find_bl_target(unsigned long ip,struct ppc_inst op)110 static unsigned long find_bl_target(unsigned long ip, struct ppc_inst op)
111 {
112 int offset;
113
114 offset = (ppc_inst_val(op) & 0x03fffffc);
115 /* make it signed */
116 if (offset & 0x02000000)
117 offset |= 0xfe000000;
118
119 return ip + (long)offset;
120 }
121
122 #ifdef CONFIG_MODULES
123 #ifdef CONFIG_PPC64
124 static int
__ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)125 __ftrace_make_nop(struct module *mod,
126 struct dyn_ftrace *rec, unsigned long addr)
127 {
128 unsigned long entry, ptr, tramp;
129 unsigned long ip = rec->ip;
130 struct ppc_inst op, pop;
131
132 /* read where this goes */
133 if (probe_kernel_read_inst(&op, (void *)ip)) {
134 pr_err("Fetching opcode failed.\n");
135 return -EFAULT;
136 }
137
138 /* Make sure that that this is still a 24bit jump */
139 if (!is_bl_op(op)) {
140 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
141 return -EINVAL;
142 }
143
144 /* lets find where the pointer goes */
145 tramp = find_bl_target(ip, op);
146
147 pr_devel("ip:%lx jumps to %lx", ip, tramp);
148
149 if (module_trampoline_target(mod, tramp, &ptr)) {
150 pr_err("Failed to get trampoline target\n");
151 return -EFAULT;
152 }
153
154 pr_devel("trampoline target %lx", ptr);
155
156 entry = ppc_global_function_entry((void *)addr);
157 /* This should match what was called */
158 if (ptr != entry) {
159 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
160 return -EINVAL;
161 }
162
163 #ifdef CONFIG_MPROFILE_KERNEL
164 /* When using -mkernel_profile there is no load to jump over */
165 pop = ppc_inst(PPC_INST_NOP);
166
167 if (probe_kernel_read_inst(&op, (void *)(ip - 4))) {
168 pr_err("Fetching instruction at %lx failed.\n", ip - 4);
169 return -EFAULT;
170 }
171
172 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
173 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_MFLR)) &&
174 !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
175 pr_err("Unexpected instruction %s around bl _mcount\n",
176 ppc_inst_as_str(op));
177 return -EINVAL;
178 }
179 #else
180 /*
181 * Our original call site looks like:
182 *
183 * bl <tramp>
184 * ld r2,XX(r1)
185 *
186 * Milton Miller pointed out that we can not simply nop the branch.
187 * If a task was preempted when calling a trace function, the nops
188 * will remove the way to restore the TOC in r2 and the r2 TOC will
189 * get corrupted.
190 *
191 * Use a b +8 to jump over the load.
192 */
193
194 pop = ppc_inst(PPC_INST_BRANCH | 8); /* b +8 */
195
196 /*
197 * Check what is in the next instruction. We can see ld r2,40(r1), but
198 * on first pass after boot we will see mflr r0.
199 */
200 if (probe_kernel_read_inst(&op, (void *)(ip + 4))) {
201 pr_err("Fetching op failed.\n");
202 return -EFAULT;
203 }
204
205 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
206 pr_err("Expected %08x found %s\n", PPC_INST_LD_TOC, ppc_inst_as_str(op));
207 return -EINVAL;
208 }
209 #endif /* CONFIG_MPROFILE_KERNEL */
210
211 if (patch_instruction((struct ppc_inst *)ip, pop)) {
212 pr_err("Patching NOP failed.\n");
213 return -EPERM;
214 }
215
216 return 0;
217 }
218
219 #else /* !PPC64 */
220 static int
__ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)221 __ftrace_make_nop(struct module *mod,
222 struct dyn_ftrace *rec, unsigned long addr)
223 {
224 struct ppc_inst op;
225 unsigned int jmp[4];
226 unsigned long ip = rec->ip;
227 unsigned long tramp;
228
229 if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
230 return -EFAULT;
231
232 /* Make sure that that this is still a 24bit jump */
233 if (!is_bl_op(op)) {
234 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
235 return -EINVAL;
236 }
237
238 /* lets find where the pointer goes */
239 tramp = find_bl_target(ip, op);
240
241 /*
242 * On PPC32 the trampoline looks like:
243 * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
244 * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
245 * 0x7d, 0x89, 0x03, 0xa6 mtctr r12
246 * 0x4e, 0x80, 0x04, 0x20 bctr
247 */
248
249 pr_devel("ip:%lx jumps to %lx", ip, tramp);
250
251 /* Find where the trampoline jumps to */
252 if (copy_from_kernel_nofault(jmp, (void *)tramp, sizeof(jmp))) {
253 pr_err("Failed to read %lx\n", tramp);
254 return -EFAULT;
255 }
256
257 pr_devel(" %08x %08x ", jmp[0], jmp[1]);
258
259 /* verify that this is what we expect it to be */
260 if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
261 ((jmp[1] & 0xffff0000) != 0x398c0000) ||
262 (jmp[2] != 0x7d8903a6) ||
263 (jmp[3] != 0x4e800420)) {
264 pr_err("Not a trampoline\n");
265 return -EINVAL;
266 }
267
268 tramp = (jmp[1] & 0xffff) |
269 ((jmp[0] & 0xffff) << 16);
270 if (tramp & 0x8000)
271 tramp -= 0x10000;
272
273 pr_devel(" %lx ", tramp);
274
275 if (tramp != addr) {
276 pr_err("Trampoline location %08lx does not match addr\n",
277 tramp);
278 return -EINVAL;
279 }
280
281 op = ppc_inst(PPC_INST_NOP);
282
283 if (patch_instruction((struct ppc_inst *)ip, op))
284 return -EPERM;
285
286 return 0;
287 }
288 #endif /* PPC64 */
289 #endif /* CONFIG_MODULES */
290
find_ftrace_tramp(unsigned long ip)291 static unsigned long find_ftrace_tramp(unsigned long ip)
292 {
293 int i;
294 struct ppc_inst instr;
295
296 /*
297 * We have the compiler generated long_branch tramps at the end
298 * and we prefer those
299 */
300 for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
301 if (!ftrace_tramps[i])
302 continue;
303 else if (create_branch(&instr, (void *)ip,
304 ftrace_tramps[i], 0) == 0)
305 return ftrace_tramps[i];
306
307 return 0;
308 }
309
add_ftrace_tramp(unsigned long tramp)310 static int add_ftrace_tramp(unsigned long tramp)
311 {
312 int i;
313
314 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
315 if (!ftrace_tramps[i]) {
316 ftrace_tramps[i] = tramp;
317 return 0;
318 }
319
320 return -1;
321 }
322
323 /*
324 * If this is a compiler generated long_branch trampoline (essentially, a
325 * trampoline that has a branch to _mcount()), we re-write the branch to
326 * instead go to ftrace_[regs_]caller() and note down the location of this
327 * trampoline.
328 */
setup_mcount_compiler_tramp(unsigned long tramp)329 static int setup_mcount_compiler_tramp(unsigned long tramp)
330 {
331 int i;
332 struct ppc_inst op;
333 unsigned long ptr;
334 struct ppc_inst instr;
335 static unsigned long ftrace_plt_tramps[NUM_FTRACE_TRAMPS];
336
337 /* Is this a known long jump tramp? */
338 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
339 if (ftrace_tramps[i] == tramp)
340 return 0;
341
342 /* Is this a known plt tramp? */
343 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
344 if (!ftrace_plt_tramps[i])
345 break;
346 else if (ftrace_plt_tramps[i] == tramp)
347 return -1;
348
349 /* New trampoline -- read where this goes */
350 if (probe_kernel_read_inst(&op, (void *)tramp)) {
351 pr_debug("Fetching opcode failed.\n");
352 return -1;
353 }
354
355 /* Is this a 24 bit branch? */
356 if (!is_b_op(op)) {
357 pr_debug("Trampoline is not a long branch tramp.\n");
358 return -1;
359 }
360
361 /* lets find where the pointer goes */
362 ptr = find_bl_target(tramp, op);
363
364 if (ptr != ppc_global_function_entry((void *)_mcount)) {
365 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
366 return -1;
367 }
368
369 /* Let's re-write the tramp to go to ftrace_[regs_]caller */
370 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
371 ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
372 #else
373 ptr = ppc_global_function_entry((void *)ftrace_caller);
374 #endif
375 if (create_branch(&instr, (void *)tramp, ptr, 0)) {
376 pr_debug("%ps is not reachable from existing mcount tramp\n",
377 (void *)ptr);
378 return -1;
379 }
380
381 if (patch_branch((struct ppc_inst *)tramp, ptr, 0)) {
382 pr_debug("REL24 out of range!\n");
383 return -1;
384 }
385
386 if (add_ftrace_tramp(tramp)) {
387 pr_debug("No tramp locations left\n");
388 return -1;
389 }
390
391 return 0;
392 }
393
__ftrace_make_nop_kernel(struct dyn_ftrace * rec,unsigned long addr)394 static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
395 {
396 unsigned long tramp, ip = rec->ip;
397 struct ppc_inst op;
398
399 /* Read where this goes */
400 if (probe_kernel_read_inst(&op, (void *)ip)) {
401 pr_err("Fetching opcode failed.\n");
402 return -EFAULT;
403 }
404
405 /* Make sure that that this is still a 24bit jump */
406 if (!is_bl_op(op)) {
407 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
408 return -EINVAL;
409 }
410
411 /* Let's find where the pointer goes */
412 tramp = find_bl_target(ip, op);
413
414 pr_devel("ip:%lx jumps to %lx", ip, tramp);
415
416 if (setup_mcount_compiler_tramp(tramp)) {
417 /* Are other trampolines reachable? */
418 if (!find_ftrace_tramp(ip)) {
419 pr_err("No ftrace trampolines reachable from %ps\n",
420 (void *)ip);
421 return -EINVAL;
422 }
423 }
424
425 if (patch_instruction((struct ppc_inst *)ip, ppc_inst(PPC_INST_NOP))) {
426 pr_err("Patching NOP failed.\n");
427 return -EPERM;
428 }
429
430 return 0;
431 }
432
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)433 int ftrace_make_nop(struct module *mod,
434 struct dyn_ftrace *rec, unsigned long addr)
435 {
436 unsigned long ip = rec->ip;
437 struct ppc_inst old, new;
438
439 /*
440 * If the calling address is more that 24 bits away,
441 * then we had to use a trampoline to make the call.
442 * Otherwise just update the call site.
443 */
444 if (test_24bit_addr(ip, addr)) {
445 /* within range */
446 old = ftrace_call_replace(ip, addr, 1);
447 new = ppc_inst(PPC_INST_NOP);
448 return ftrace_modify_code(ip, old, new);
449 } else if (core_kernel_text(ip))
450 return __ftrace_make_nop_kernel(rec, addr);
451
452 #ifdef CONFIG_MODULES
453 /*
454 * Out of range jumps are called from modules.
455 * We should either already have a pointer to the module
456 * or it has been passed in.
457 */
458 if (!rec->arch.mod) {
459 if (!mod) {
460 pr_err("No module loaded addr=%lx\n", addr);
461 return -EFAULT;
462 }
463 rec->arch.mod = mod;
464 } else if (mod) {
465 if (mod != rec->arch.mod) {
466 pr_err("Record mod %p not equal to passed in mod %p\n",
467 rec->arch.mod, mod);
468 return -EINVAL;
469 }
470 /* nothing to do if mod == rec->arch.mod */
471 } else
472 mod = rec->arch.mod;
473
474 return __ftrace_make_nop(mod, rec, addr);
475 #else
476 /* We should not get here without modules */
477 return -EINVAL;
478 #endif /* CONFIG_MODULES */
479 }
480
481 #ifdef CONFIG_MODULES
482 #ifdef CONFIG_PPC64
483 /*
484 * Examine the existing instructions for __ftrace_make_call.
485 * They should effectively be a NOP, and follow formal constraints,
486 * depending on the ABI. Return false if they don't.
487 */
488 #ifndef CONFIG_MPROFILE_KERNEL
489 static int
expected_nop_sequence(void * ip,struct ppc_inst op0,struct ppc_inst op1)490 expected_nop_sequence(void *ip, struct ppc_inst op0, struct ppc_inst op1)
491 {
492 /*
493 * We expect to see:
494 *
495 * b +8
496 * ld r2,XX(r1)
497 *
498 * The load offset is different depending on the ABI. For simplicity
499 * just mask it out when doing the compare.
500 */
501 if (!ppc_inst_equal(op0, ppc_inst(0x48000008)) ||
502 (ppc_inst_val(op1) & 0xffff0000) != 0xe8410000)
503 return 0;
504 return 1;
505 }
506 #else
507 static int
expected_nop_sequence(void * ip,struct ppc_inst op0,struct ppc_inst op1)508 expected_nop_sequence(void *ip, struct ppc_inst op0, struct ppc_inst op1)
509 {
510 /* look for patched "NOP" on ppc64 with -mprofile-kernel */
511 if (!ppc_inst_equal(op0, ppc_inst(PPC_INST_NOP)))
512 return 0;
513 return 1;
514 }
515 #endif
516
517 static int
__ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)518 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
519 {
520 struct ppc_inst op[2];
521 struct ppc_inst instr;
522 void *ip = (void *)rec->ip;
523 unsigned long entry, ptr, tramp;
524 struct module *mod = rec->arch.mod;
525
526 /* read where this goes */
527 if (probe_kernel_read_inst(op, ip))
528 return -EFAULT;
529
530 if (probe_kernel_read_inst(op + 1, ip + 4))
531 return -EFAULT;
532
533 if (!expected_nop_sequence(ip, op[0], op[1])) {
534 pr_err("Unexpected call sequence at %p: %s %s\n",
535 ip, ppc_inst_as_str(op[0]), ppc_inst_as_str(op[1]));
536 return -EINVAL;
537 }
538
539 /* If we never set up ftrace trampoline(s), then bail */
540 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
541 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
542 #else
543 if (!mod->arch.tramp) {
544 #endif
545 pr_err("No ftrace trampoline\n");
546 return -EINVAL;
547 }
548
549 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
550 if (rec->flags & FTRACE_FL_REGS)
551 tramp = mod->arch.tramp_regs;
552 else
553 #endif
554 tramp = mod->arch.tramp;
555
556 if (module_trampoline_target(mod, tramp, &ptr)) {
557 pr_err("Failed to get trampoline target\n");
558 return -EFAULT;
559 }
560
561 pr_devel("trampoline target %lx", ptr);
562
563 entry = ppc_global_function_entry((void *)addr);
564 /* This should match what was called */
565 if (ptr != entry) {
566 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
567 return -EINVAL;
568 }
569
570 /* Ensure branch is within 24 bits */
571 if (create_branch(&instr, ip, tramp, BRANCH_SET_LINK)) {
572 pr_err("Branch out of range\n");
573 return -EINVAL;
574 }
575
576 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
577 pr_err("REL24 out of range!\n");
578 return -EINVAL;
579 }
580
581 return 0;
582 }
583
584 #else /* !CONFIG_PPC64: */
585 static int
586 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
587 {
588 int err;
589 struct ppc_inst op;
590 unsigned long ip = rec->ip;
591
592 /* read where this goes */
593 if (probe_kernel_read_inst(&op, (void *)ip))
594 return -EFAULT;
595
596 /* It should be pointing to a nop */
597 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_NOP))) {
598 pr_err("Expected NOP but have %s\n", ppc_inst_as_str(op));
599 return -EINVAL;
600 }
601
602 /* If we never set up a trampoline to ftrace_caller, then bail */
603 if (!rec->arch.mod->arch.tramp) {
604 pr_err("No ftrace trampoline\n");
605 return -EINVAL;
606 }
607
608 /* create the branch to the trampoline */
609 err = create_branch(&op, (struct ppc_inst *)ip,
610 rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
611 if (err) {
612 pr_err("REL24 out of range!\n");
613 return -EINVAL;
614 }
615
616 pr_devel("write to %lx\n", rec->ip);
617
618 if (patch_instruction((struct ppc_inst *)ip, op))
619 return -EPERM;
620
621 return 0;
622 }
623 #endif /* CONFIG_PPC64 */
624 #endif /* CONFIG_MODULES */
625
626 static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
627 {
628 struct ppc_inst op;
629 void *ip = (void *)rec->ip;
630 unsigned long tramp, entry, ptr;
631
632 /* Make sure we're being asked to patch branch to a known ftrace addr */
633 entry = ppc_global_function_entry((void *)ftrace_caller);
634 ptr = ppc_global_function_entry((void *)addr);
635
636 if (ptr != entry) {
637 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
638 entry = ppc_global_function_entry((void *)ftrace_regs_caller);
639 if (ptr != entry) {
640 #endif
641 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
642 return -EINVAL;
643 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
644 }
645 #endif
646 }
647
648 /* Make sure we have a nop */
649 if (probe_kernel_read_inst(&op, ip)) {
650 pr_err("Unable to read ftrace location %p\n", ip);
651 return -EFAULT;
652 }
653
654 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_NOP))) {
655 pr_err("Unexpected call sequence at %p: %s\n", ip, ppc_inst_as_str(op));
656 return -EINVAL;
657 }
658
659 tramp = find_ftrace_tramp((unsigned long)ip);
660 if (!tramp) {
661 pr_err("No ftrace trampolines reachable from %ps\n", ip);
662 return -EINVAL;
663 }
664
665 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
666 pr_err("Error patching branch to ftrace tramp!\n");
667 return -EINVAL;
668 }
669
670 return 0;
671 }
672
673 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
674 {
675 unsigned long ip = rec->ip;
676 struct ppc_inst old, new;
677
678 /*
679 * If the calling address is more that 24 bits away,
680 * then we had to use a trampoline to make the call.
681 * Otherwise just update the call site.
682 */
683 if (test_24bit_addr(ip, addr)) {
684 /* within range */
685 old = ppc_inst(PPC_INST_NOP);
686 new = ftrace_call_replace(ip, addr, 1);
687 return ftrace_modify_code(ip, old, new);
688 } else if (core_kernel_text(ip))
689 return __ftrace_make_call_kernel(rec, addr);
690
691 #ifdef CONFIG_MODULES
692 /*
693 * Out of range jumps are called from modules.
694 * Being that we are converting from nop, it had better
695 * already have a module defined.
696 */
697 if (!rec->arch.mod) {
698 pr_err("No module loaded\n");
699 return -EINVAL;
700 }
701
702 return __ftrace_make_call(rec, addr);
703 #else
704 /* We should not get here without modules */
705 return -EINVAL;
706 #endif /* CONFIG_MODULES */
707 }
708
709 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
710 #ifdef CONFIG_MODULES
711 static int
712 __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
713 unsigned long addr)
714 {
715 struct ppc_inst op;
716 unsigned long ip = rec->ip;
717 unsigned long entry, ptr, tramp;
718 struct module *mod = rec->arch.mod;
719
720 /* If we never set up ftrace trampolines, then bail */
721 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
722 pr_err("No ftrace trampoline\n");
723 return -EINVAL;
724 }
725
726 /* read where this goes */
727 if (probe_kernel_read_inst(&op, (void *)ip)) {
728 pr_err("Fetching opcode failed.\n");
729 return -EFAULT;
730 }
731
732 /* Make sure that that this is still a 24bit jump */
733 if (!is_bl_op(op)) {
734 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
735 return -EINVAL;
736 }
737
738 /* lets find where the pointer goes */
739 tramp = find_bl_target(ip, op);
740 entry = ppc_global_function_entry((void *)old_addr);
741
742 pr_devel("ip:%lx jumps to %lx", ip, tramp);
743
744 if (tramp != entry) {
745 /* old_addr is not within range, so we must have used a trampoline */
746 if (module_trampoline_target(mod, tramp, &ptr)) {
747 pr_err("Failed to get trampoline target\n");
748 return -EFAULT;
749 }
750
751 pr_devel("trampoline target %lx", ptr);
752
753 /* This should match what was called */
754 if (ptr != entry) {
755 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
756 return -EINVAL;
757 }
758 }
759
760 /* The new target may be within range */
761 if (test_24bit_addr(ip, addr)) {
762 /* within range */
763 if (patch_branch((struct ppc_inst *)ip, addr, BRANCH_SET_LINK)) {
764 pr_err("REL24 out of range!\n");
765 return -EINVAL;
766 }
767
768 return 0;
769 }
770
771 if (rec->flags & FTRACE_FL_REGS)
772 tramp = mod->arch.tramp_regs;
773 else
774 tramp = mod->arch.tramp;
775
776 if (module_trampoline_target(mod, tramp, &ptr)) {
777 pr_err("Failed to get trampoline target\n");
778 return -EFAULT;
779 }
780
781 pr_devel("trampoline target %lx", ptr);
782
783 entry = ppc_global_function_entry((void *)addr);
784 /* This should match what was called */
785 if (ptr != entry) {
786 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
787 return -EINVAL;
788 }
789
790 /* Ensure branch is within 24 bits */
791 if (create_branch(&op, (struct ppc_inst *)ip, tramp, BRANCH_SET_LINK)) {
792 pr_err("Branch out of range\n");
793 return -EINVAL;
794 }
795
796 if (patch_branch((struct ppc_inst *)ip, tramp, BRANCH_SET_LINK)) {
797 pr_err("REL24 out of range!\n");
798 return -EINVAL;
799 }
800
801 return 0;
802 }
803 #endif
804
805 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
806 unsigned long addr)
807 {
808 unsigned long ip = rec->ip;
809 struct ppc_inst old, new;
810
811 /*
812 * If the calling address is more that 24 bits away,
813 * then we had to use a trampoline to make the call.
814 * Otherwise just update the call site.
815 */
816 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
817 /* within range */
818 old = ftrace_call_replace(ip, old_addr, 1);
819 new = ftrace_call_replace(ip, addr, 1);
820 return ftrace_modify_code(ip, old, new);
821 } else if (core_kernel_text(ip)) {
822 /*
823 * We always patch out of range locations to go to the regs
824 * variant, so there is nothing to do here
825 */
826 return 0;
827 }
828
829 #ifdef CONFIG_MODULES
830 /*
831 * Out of range jumps are called from modules.
832 */
833 if (!rec->arch.mod) {
834 pr_err("No module loaded\n");
835 return -EINVAL;
836 }
837
838 return __ftrace_modify_call(rec, old_addr, addr);
839 #else
840 /* We should not get here without modules */
841 return -EINVAL;
842 #endif /* CONFIG_MODULES */
843 }
844 #endif
845
846 int ftrace_update_ftrace_func(ftrace_func_t func)
847 {
848 unsigned long ip = (unsigned long)(&ftrace_call);
849 struct ppc_inst old, new;
850 int ret;
851
852 old = ppc_inst_read((struct ppc_inst *)&ftrace_call);
853 new = ftrace_call_replace(ip, (unsigned long)func, 1);
854 ret = ftrace_modify_code(ip, old, new);
855
856 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
857 /* Also update the regs callback function */
858 if (!ret) {
859 ip = (unsigned long)(&ftrace_regs_call);
860 old = ppc_inst_read((struct ppc_inst *)&ftrace_regs_call);
861 new = ftrace_call_replace(ip, (unsigned long)func, 1);
862 ret = ftrace_modify_code(ip, old, new);
863 }
864 #endif
865
866 return ret;
867 }
868
869 /*
870 * Use the default ftrace_modify_all_code, but without
871 * stop_machine().
872 */
873 void arch_ftrace_update_code(int command)
874 {
875 ftrace_modify_all_code(command);
876 }
877
878 #ifdef CONFIG_PPC64
879 #define PACATOC offsetof(struct paca_struct, kernel_toc)
880
881 extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
882
883 void ftrace_free_init_tramp(void)
884 {
885 int i;
886
887 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
888 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
889 ftrace_tramps[i] = 0;
890 return;
891 }
892 }
893
894 int __init ftrace_dyn_arch_init(void)
895 {
896 int i;
897 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
898 u32 stub_insns[] = {
899 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */
900 0x3d8c0000, /* addis r12,r12,<high> */
901 0x398c0000, /* addi r12,r12,<low> */
902 0x7d8903a6, /* mtctr r12 */
903 0x4e800420, /* bctr */
904 };
905 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
906 unsigned long addr = ppc_global_function_entry((void *)ftrace_regs_caller);
907 #else
908 unsigned long addr = ppc_global_function_entry((void *)ftrace_caller);
909 #endif
910 long reladdr = addr - kernel_toc_addr();
911
912 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
913 pr_err("Address of %ps out of range of kernel_toc.\n",
914 (void *)addr);
915 return -1;
916 }
917
918 for (i = 0; i < 2; i++) {
919 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
920 tramp[i][1] |= PPC_HA(reladdr);
921 tramp[i][2] |= PPC_LO(reladdr);
922 add_ftrace_tramp((unsigned long)tramp[i]);
923 }
924
925 return 0;
926 }
927 #else
928 int __init ftrace_dyn_arch_init(void)
929 {
930 return 0;
931 }
932 #endif
933 #endif /* CONFIG_DYNAMIC_FTRACE */
934
935 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
936
937 extern void ftrace_graph_call(void);
938 extern void ftrace_graph_stub(void);
939
940 int ftrace_enable_ftrace_graph_caller(void)
941 {
942 unsigned long ip = (unsigned long)(&ftrace_graph_call);
943 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
944 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
945 struct ppc_inst old, new;
946
947 old = ftrace_call_replace(ip, stub, 0);
948 new = ftrace_call_replace(ip, addr, 0);
949
950 return ftrace_modify_code(ip, old, new);
951 }
952
953 int ftrace_disable_ftrace_graph_caller(void)
954 {
955 unsigned long ip = (unsigned long)(&ftrace_graph_call);
956 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
957 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
958 struct ppc_inst old, new;
959
960 old = ftrace_call_replace(ip, addr, 0);
961 new = ftrace_call_replace(ip, stub, 0);
962
963 return ftrace_modify_code(ip, old, new);
964 }
965
966 /*
967 * Hook the return address and push it in the stack of return addrs
968 * in current thread info. Return the address we want to divert to.
969 */
970 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
971 unsigned long sp)
972 {
973 unsigned long return_hooker;
974
975 if (unlikely(ftrace_graph_is_dead()))
976 goto out;
977
978 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
979 goto out;
980
981 return_hooker = ppc_function_entry(return_to_handler);
982
983 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
984 parent = return_hooker;
985 out:
986 return parent;
987 }
988 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
989
990 #ifdef PPC64_ELF_ABI_v1
991 char *arch_ftrace_match_adjust(char *str, const char *search)
992 {
993 if (str[0] == '.' && search[0] != '.')
994 return str + 1;
995 else
996 return str;
997 }
998 #endif /* PPC64_ELF_ABI_v1 */
999