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, (u32 *)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 (copy_inst_from_kernel_nofault(&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((u32 *)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, (u32 *)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 (copy_inst_from_kernel_nofault(&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_RAW_NOP());
166
167 if (copy_inst_from_kernel_nofault(&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_RAW_MFLR(_R0))) &&
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 (copy_inst_from_kernel_nofault(&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 %08lx 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((u32 *)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_RAW_NOP());
282
283 if (patch_instruction((u32 *)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])
340 break;
341 else if (ftrace_tramps[i] == tramp)
342 return 0;
343
344 /* Is this a known plt tramp? */
345 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
346 if (!ftrace_plt_tramps[i])
347 break;
348 else if (ftrace_plt_tramps[i] == tramp)
349 return -1;
350
351 /* New trampoline -- read where this goes */
352 if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
353 pr_debug("Fetching opcode failed.\n");
354 return -1;
355 }
356
357 /* Is this a 24 bit branch? */
358 if (!is_b_op(op)) {
359 pr_debug("Trampoline is not a long branch tramp.\n");
360 return -1;
361 }
362
363 /* lets find where the pointer goes */
364 ptr = find_bl_target(tramp, op);
365
366 if (ptr != ppc_global_function_entry((void *)_mcount)) {
367 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
368 return -1;
369 }
370
371 /* Let's re-write the tramp to go to ftrace_[regs_]caller */
372 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
373 ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
374 #else
375 ptr = ppc_global_function_entry((void *)ftrace_caller);
376 #endif
377 if (create_branch(&instr, (void *)tramp, ptr, 0)) {
378 pr_debug("%ps is not reachable from existing mcount tramp\n",
379 (void *)ptr);
380 return -1;
381 }
382
383 if (patch_branch((u32 *)tramp, ptr, 0)) {
384 pr_debug("REL24 out of range!\n");
385 return -1;
386 }
387
388 if (add_ftrace_tramp(tramp)) {
389 pr_debug("No tramp locations left\n");
390 return -1;
391 }
392
393 return 0;
394 }
395
__ftrace_make_nop_kernel(struct dyn_ftrace * rec,unsigned long addr)396 static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
397 {
398 unsigned long tramp, ip = rec->ip;
399 struct ppc_inst op;
400
401 /* Read where this goes */
402 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
403 pr_err("Fetching opcode failed.\n");
404 return -EFAULT;
405 }
406
407 /* Make sure that that this is still a 24bit jump */
408 if (!is_bl_op(op)) {
409 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
410 return -EINVAL;
411 }
412
413 /* Let's find where the pointer goes */
414 tramp = find_bl_target(ip, op);
415
416 pr_devel("ip:%lx jumps to %lx", ip, tramp);
417
418 if (setup_mcount_compiler_tramp(tramp)) {
419 /* Are other trampolines reachable? */
420 if (!find_ftrace_tramp(ip)) {
421 pr_err("No ftrace trampolines reachable from %ps\n",
422 (void *)ip);
423 return -EINVAL;
424 }
425 }
426
427 if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
428 pr_err("Patching NOP failed.\n");
429 return -EPERM;
430 }
431
432 return 0;
433 }
434
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)435 int ftrace_make_nop(struct module *mod,
436 struct dyn_ftrace *rec, unsigned long addr)
437 {
438 unsigned long ip = rec->ip;
439 struct ppc_inst old, new;
440
441 /*
442 * If the calling address is more that 24 bits away,
443 * then we had to use a trampoline to make the call.
444 * Otherwise just update the call site.
445 */
446 if (test_24bit_addr(ip, addr)) {
447 /* within range */
448 old = ftrace_call_replace(ip, addr, 1);
449 new = ppc_inst(PPC_RAW_NOP());
450 return ftrace_modify_code(ip, old, new);
451 } else if (core_kernel_text(ip))
452 return __ftrace_make_nop_kernel(rec, addr);
453
454 #ifdef CONFIG_MODULES
455 /*
456 * Out of range jumps are called from modules.
457 * We should either already have a pointer to the module
458 * or it has been passed in.
459 */
460 if (!rec->arch.mod) {
461 if (!mod) {
462 pr_err("No module loaded addr=%lx\n", addr);
463 return -EFAULT;
464 }
465 rec->arch.mod = mod;
466 } else if (mod) {
467 if (mod != rec->arch.mod) {
468 pr_err("Record mod %p not equal to passed in mod %p\n",
469 rec->arch.mod, mod);
470 return -EINVAL;
471 }
472 /* nothing to do if mod == rec->arch.mod */
473 } else
474 mod = rec->arch.mod;
475
476 return __ftrace_make_nop(mod, rec, addr);
477 #else
478 /* We should not get here without modules */
479 return -EINVAL;
480 #endif /* CONFIG_MODULES */
481 }
482
483 #ifdef CONFIG_MODULES
484 #ifdef CONFIG_PPC64
485 /*
486 * Examine the existing instructions for __ftrace_make_call.
487 * They should effectively be a NOP, and follow formal constraints,
488 * depending on the ABI. Return false if they don't.
489 */
490 #ifndef CONFIG_MPROFILE_KERNEL
491 static int
expected_nop_sequence(void * ip,struct ppc_inst op0,struct ppc_inst op1)492 expected_nop_sequence(void *ip, struct ppc_inst op0, struct ppc_inst op1)
493 {
494 /*
495 * We expect to see:
496 *
497 * b +8
498 * ld r2,XX(r1)
499 *
500 * The load offset is different depending on the ABI. For simplicity
501 * just mask it out when doing the compare.
502 */
503 if (!ppc_inst_equal(op0, ppc_inst(0x48000008)) ||
504 (ppc_inst_val(op1) & 0xffff0000) != 0xe8410000)
505 return 0;
506 return 1;
507 }
508 #else
509 static int
expected_nop_sequence(void * ip,struct ppc_inst op0,struct ppc_inst op1)510 expected_nop_sequence(void *ip, struct ppc_inst op0, struct ppc_inst op1)
511 {
512 /* look for patched "NOP" on ppc64 with -mprofile-kernel */
513 if (!ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())))
514 return 0;
515 return 1;
516 }
517 #endif
518
519 static int
__ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)520 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
521 {
522 struct ppc_inst op[2];
523 struct ppc_inst instr;
524 void *ip = (void *)rec->ip;
525 unsigned long entry, ptr, tramp;
526 struct module *mod = rec->arch.mod;
527
528 /* read where this goes */
529 if (copy_inst_from_kernel_nofault(op, ip))
530 return -EFAULT;
531
532 if (copy_inst_from_kernel_nofault(op + 1, ip + 4))
533 return -EFAULT;
534
535 if (!expected_nop_sequence(ip, op[0], op[1])) {
536 pr_err("Unexpected call sequence at %p: %s %s\n",
537 ip, ppc_inst_as_str(op[0]), ppc_inst_as_str(op[1]));
538 return -EINVAL;
539 }
540
541 /* If we never set up ftrace trampoline(s), then bail */
542 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
543 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
544 #else
545 if (!mod->arch.tramp) {
546 #endif
547 pr_err("No ftrace trampoline\n");
548 return -EINVAL;
549 }
550
551 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
552 if (rec->flags & FTRACE_FL_REGS)
553 tramp = mod->arch.tramp_regs;
554 else
555 #endif
556 tramp = mod->arch.tramp;
557
558 if (module_trampoline_target(mod, tramp, &ptr)) {
559 pr_err("Failed to get trampoline target\n");
560 return -EFAULT;
561 }
562
563 pr_devel("trampoline target %lx", ptr);
564
565 entry = ppc_global_function_entry((void *)addr);
566 /* This should match what was called */
567 if (ptr != entry) {
568 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
569 return -EINVAL;
570 }
571
572 /* Ensure branch is within 24 bits */
573 if (create_branch(&instr, ip, tramp, BRANCH_SET_LINK)) {
574 pr_err("Branch out of range\n");
575 return -EINVAL;
576 }
577
578 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
579 pr_err("REL24 out of range!\n");
580 return -EINVAL;
581 }
582
583 return 0;
584 }
585
586 #else /* !CONFIG_PPC64: */
587 static int
588 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
589 {
590 int err;
591 struct ppc_inst op;
592 u32 *ip = (u32 *)rec->ip;
593
594 /* read where this goes */
595 if (copy_inst_from_kernel_nofault(&op, ip))
596 return -EFAULT;
597
598 /* It should be pointing to a nop */
599 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
600 pr_err("Expected NOP but have %s\n", ppc_inst_as_str(op));
601 return -EINVAL;
602 }
603
604 /* If we never set up a trampoline to ftrace_caller, then bail */
605 if (!rec->arch.mod->arch.tramp) {
606 pr_err("No ftrace trampoline\n");
607 return -EINVAL;
608 }
609
610 /* create the branch to the trampoline */
611 err = create_branch(&op, ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
612 if (err) {
613 pr_err("REL24 out of range!\n");
614 return -EINVAL;
615 }
616
617 pr_devel("write to %lx\n", rec->ip);
618
619 if (patch_instruction(ip, op))
620 return -EPERM;
621
622 return 0;
623 }
624 #endif /* CONFIG_PPC64 */
625 #endif /* CONFIG_MODULES */
626
627 static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
628 {
629 struct ppc_inst op;
630 void *ip = (void *)rec->ip;
631 unsigned long tramp, entry, ptr;
632
633 /* Make sure we're being asked to patch branch to a known ftrace addr */
634 entry = ppc_global_function_entry((void *)ftrace_caller);
635 ptr = ppc_global_function_entry((void *)addr);
636
637 if (ptr != entry) {
638 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
639 entry = ppc_global_function_entry((void *)ftrace_regs_caller);
640 if (ptr != entry) {
641 #endif
642 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
643 return -EINVAL;
644 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
645 }
646 #endif
647 }
648
649 /* Make sure we have a nop */
650 if (copy_inst_from_kernel_nofault(&op, ip)) {
651 pr_err("Unable to read ftrace location %p\n", ip);
652 return -EFAULT;
653 }
654
655 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
656 pr_err("Unexpected call sequence at %p: %s\n", ip, ppc_inst_as_str(op));
657 return -EINVAL;
658 }
659
660 tramp = find_ftrace_tramp((unsigned long)ip);
661 if (!tramp) {
662 pr_err("No ftrace trampolines reachable from %ps\n", ip);
663 return -EINVAL;
664 }
665
666 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
667 pr_err("Error patching branch to ftrace tramp!\n");
668 return -EINVAL;
669 }
670
671 return 0;
672 }
673
674 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
675 {
676 unsigned long ip = rec->ip;
677 struct ppc_inst old, new;
678
679 /*
680 * If the calling address is more that 24 bits away,
681 * then we had to use a trampoline to make the call.
682 * Otherwise just update the call site.
683 */
684 if (test_24bit_addr(ip, addr)) {
685 /* within range */
686 old = ppc_inst(PPC_RAW_NOP());
687 new = ftrace_call_replace(ip, addr, 1);
688 return ftrace_modify_code(ip, old, new);
689 } else if (core_kernel_text(ip))
690 return __ftrace_make_call_kernel(rec, addr);
691
692 #ifdef CONFIG_MODULES
693 /*
694 * Out of range jumps are called from modules.
695 * Being that we are converting from nop, it had better
696 * already have a module defined.
697 */
698 if (!rec->arch.mod) {
699 pr_err("No module loaded\n");
700 return -EINVAL;
701 }
702
703 return __ftrace_make_call(rec, addr);
704 #else
705 /* We should not get here without modules */
706 return -EINVAL;
707 #endif /* CONFIG_MODULES */
708 }
709
710 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
711 #ifdef CONFIG_MODULES
712 static int
713 __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
714 unsigned long addr)
715 {
716 struct ppc_inst op;
717 unsigned long ip = rec->ip;
718 unsigned long entry, ptr, tramp;
719 struct module *mod = rec->arch.mod;
720
721 /* If we never set up ftrace trampolines, then bail */
722 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
723 pr_err("No ftrace trampoline\n");
724 return -EINVAL;
725 }
726
727 /* read where this goes */
728 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
729 pr_err("Fetching opcode failed.\n");
730 return -EFAULT;
731 }
732
733 /* Make sure that that this is still a 24bit jump */
734 if (!is_bl_op(op)) {
735 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
736 return -EINVAL;
737 }
738
739 /* lets find where the pointer goes */
740 tramp = find_bl_target(ip, op);
741 entry = ppc_global_function_entry((void *)old_addr);
742
743 pr_devel("ip:%lx jumps to %lx", ip, tramp);
744
745 if (tramp != entry) {
746 /* old_addr is not within range, so we must have used a trampoline */
747 if (module_trampoline_target(mod, tramp, &ptr)) {
748 pr_err("Failed to get trampoline target\n");
749 return -EFAULT;
750 }
751
752 pr_devel("trampoline target %lx", ptr);
753
754 /* This should match what was called */
755 if (ptr != entry) {
756 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
757 return -EINVAL;
758 }
759 }
760
761 /* The new target may be within range */
762 if (test_24bit_addr(ip, addr)) {
763 /* within range */
764 if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
765 pr_err("REL24 out of range!\n");
766 return -EINVAL;
767 }
768
769 return 0;
770 }
771
772 if (rec->flags & FTRACE_FL_REGS)
773 tramp = mod->arch.tramp_regs;
774 else
775 tramp = mod->arch.tramp;
776
777 if (module_trampoline_target(mod, tramp, &ptr)) {
778 pr_err("Failed to get trampoline target\n");
779 return -EFAULT;
780 }
781
782 pr_devel("trampoline target %lx", ptr);
783
784 entry = ppc_global_function_entry((void *)addr);
785 /* This should match what was called */
786 if (ptr != entry) {
787 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
788 return -EINVAL;
789 }
790
791 /* Ensure branch is within 24 bits */
792 if (create_branch(&op, (u32 *)ip, tramp, BRANCH_SET_LINK)) {
793 pr_err("Branch out of range\n");
794 return -EINVAL;
795 }
796
797 if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
798 pr_err("REL24 out of range!\n");
799 return -EINVAL;
800 }
801
802 return 0;
803 }
804 #endif
805
806 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
807 unsigned long addr)
808 {
809 unsigned long ip = rec->ip;
810 struct ppc_inst old, new;
811
812 /*
813 * If the calling address is more that 24 bits away,
814 * then we had to use a trampoline to make the call.
815 * Otherwise just update the call site.
816 */
817 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
818 /* within range */
819 old = ftrace_call_replace(ip, old_addr, 1);
820 new = ftrace_call_replace(ip, addr, 1);
821 return ftrace_modify_code(ip, old, new);
822 } else if (core_kernel_text(ip)) {
823 /*
824 * We always patch out of range locations to go to the regs
825 * variant, so there is nothing to do here
826 */
827 return 0;
828 }
829
830 #ifdef CONFIG_MODULES
831 /*
832 * Out of range jumps are called from modules.
833 */
834 if (!rec->arch.mod) {
835 pr_err("No module loaded\n");
836 return -EINVAL;
837 }
838
839 return __ftrace_modify_call(rec, old_addr, addr);
840 #else
841 /* We should not get here without modules */
842 return -EINVAL;
843 #endif /* CONFIG_MODULES */
844 }
845 #endif
846
847 int ftrace_update_ftrace_func(ftrace_func_t func)
848 {
849 unsigned long ip = (unsigned long)(&ftrace_call);
850 struct ppc_inst old, new;
851 int ret;
852
853 old = ppc_inst_read((u32 *)&ftrace_call);
854 new = ftrace_call_replace(ip, (unsigned long)func, 1);
855 ret = ftrace_modify_code(ip, old, new);
856
857 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
858 /* Also update the regs callback function */
859 if (!ret) {
860 ip = (unsigned long)(&ftrace_regs_call);
861 old = ppc_inst_read((u32 *)&ftrace_regs_call);
862 new = ftrace_call_replace(ip, (unsigned long)func, 1);
863 ret = ftrace_modify_code(ip, old, new);
864 }
865 #endif
866
867 return ret;
868 }
869
870 /*
871 * Use the default ftrace_modify_all_code, but without
872 * stop_machine().
873 */
874 void arch_ftrace_update_code(int command)
875 {
876 ftrace_modify_all_code(command);
877 }
878
879 #ifdef CONFIG_PPC64
880 #define PACATOC offsetof(struct paca_struct, kernel_toc)
881
882 extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
883
884 int __init ftrace_dyn_arch_init(void)
885 {
886 int i;
887 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
888 u32 stub_insns[] = {
889 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */
890 0x3d8c0000, /* addis r12,r12,<high> */
891 0x398c0000, /* addi r12,r12,<low> */
892 0x7d8903a6, /* mtctr r12 */
893 0x4e800420, /* bctr */
894 };
895 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
896 unsigned long addr = ppc_global_function_entry((void *)ftrace_regs_caller);
897 #else
898 unsigned long addr = ppc_global_function_entry((void *)ftrace_caller);
899 #endif
900 long reladdr = addr - kernel_toc_addr();
901
902 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
903 pr_err("Address of %ps out of range of kernel_toc.\n",
904 (void *)addr);
905 return -1;
906 }
907
908 for (i = 0; i < 2; i++) {
909 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
910 tramp[i][1] |= PPC_HA(reladdr);
911 tramp[i][2] |= PPC_LO(reladdr);
912 add_ftrace_tramp((unsigned long)tramp[i]);
913 }
914
915 return 0;
916 }
917 #else
918 int __init ftrace_dyn_arch_init(void)
919 {
920 return 0;
921 }
922 #endif
923 #endif /* CONFIG_DYNAMIC_FTRACE */
924
925 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
926
927 extern void ftrace_graph_call(void);
928 extern void ftrace_graph_stub(void);
929
930 int ftrace_enable_ftrace_graph_caller(void)
931 {
932 unsigned long ip = (unsigned long)(&ftrace_graph_call);
933 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
934 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
935 struct ppc_inst old, new;
936
937 old = ftrace_call_replace(ip, stub, 0);
938 new = ftrace_call_replace(ip, addr, 0);
939
940 return ftrace_modify_code(ip, old, new);
941 }
942
943 int ftrace_disable_ftrace_graph_caller(void)
944 {
945 unsigned long ip = (unsigned long)(&ftrace_graph_call);
946 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
947 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
948 struct ppc_inst old, new;
949
950 old = ftrace_call_replace(ip, addr, 0);
951 new = ftrace_call_replace(ip, stub, 0);
952
953 return ftrace_modify_code(ip, old, new);
954 }
955
956 /*
957 * Hook the return address and push it in the stack of return addrs
958 * in current thread info. Return the address we want to divert to.
959 */
960 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
961 unsigned long sp)
962 {
963 unsigned long return_hooker;
964
965 if (unlikely(ftrace_graph_is_dead()))
966 goto out;
967
968 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
969 goto out;
970
971 return_hooker = ppc_function_entry(return_to_handler);
972
973 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
974 parent = return_hooker;
975 out:
976 return parent;
977 }
978 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
979
980 #ifdef PPC64_ELF_ABI_v1
981 char *arch_ftrace_match_adjust(char *str, const char *search)
982 {
983 if (str[0] == '.' && search[0] != '.')
984 return str + 1;
985 else
986 return str;
987 }
988 #endif /* PPC64_ELF_ABI_v1 */
989