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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/cacheflush.h>
26#include <asm/code-patching.h>
27#include <asm/ftrace.h>
28#include <asm/syscall.h>
29#include <asm/inst.h>
30
31/*
32 * We generally only have a single long_branch tramp and at most 2 or 3 plt
33 * tramps generated. But, we don't use the plt tramps currently. We also allot
34 * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
35 * tramps in total. Set aside 8 just to be sure.
36 */
37#define NUM_FTRACE_TRAMPS 8
38static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
39
40static ppc_inst_t
41ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
42{
43 ppc_inst_t op;
44
45 addr = ppc_function_entry((void *)addr);
46
47 /* if (link) set op to 'bl' else 'b' */
48 create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
49
50 return op;
51}
52
53static inline int
54ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
55{
56 ppc_inst_t replaced;
57
58 /*
59 * Note:
60 * We are paranoid about modifying text, as if a bug was to happen, it
61 * could cause us to read or write to someplace that could cause harm.
62 * Carefully read and modify the code with probe_kernel_*(), and make
63 * sure what we read is what we expected it to be before modifying it.
64 */
65
66 /* read the text we want to modify */
67 if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
68 return -EFAULT;
69
70 /* Make sure it is what we expect it to be */
71 if (!ppc_inst_equal(replaced, old)) {
72 pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
73 ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
74 return -EINVAL;
75 }
76
77 /* replace the text with the new text */
78 return patch_instruction((u32 *)ip, new);
79}
80
81/*
82 * Helper functions that are the same for both PPC64 and PPC32.
83 */
84static int test_24bit_addr(unsigned long ip, unsigned long addr)
85{
86 addr = ppc_function_entry((void *)addr);
87
88 return is_offset_in_branch_range(addr - ip);
89}
90
91static int is_bl_op(ppc_inst_t op)
92{
93 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
94}
95
96static int is_b_op(ppc_inst_t op)
97{
98 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
99}
100
101static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
102{
103 int offset;
104
105 offset = PPC_LI(ppc_inst_val(op));
106 /* make it signed */
107 if (offset & 0x02000000)
108 offset |= 0xfe000000;
109
110 return ip + (long)offset;
111}
112
113#ifdef CONFIG_MODULES
114static int
115__ftrace_make_nop(struct module *mod,
116 struct dyn_ftrace *rec, unsigned long addr)
117{
118 unsigned long entry, ptr, tramp;
119 unsigned long ip = rec->ip;
120 ppc_inst_t op, pop;
121
122 /* read where this goes */
123 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
124 pr_err("Fetching opcode failed.\n");
125 return -EFAULT;
126 }
127
128 /* Make sure that this is still a 24bit jump */
129 if (!is_bl_op(op)) {
130 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
131 return -EINVAL;
132 }
133
134 /* lets find where the pointer goes */
135 tramp = find_bl_target(ip, op);
136
137 pr_devel("ip:%lx jumps to %lx", ip, tramp);
138
139 if (module_trampoline_target(mod, tramp, &ptr)) {
140 pr_err("Failed to get trampoline target\n");
141 return -EFAULT;
142 }
143
144 pr_devel("trampoline target %lx", ptr);
145
146 entry = ppc_global_function_entry((void *)addr);
147 /* This should match what was called */
148 if (ptr != entry) {
149 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
150 return -EINVAL;
151 }
152
153 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
154 if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
155 pr_err("Fetching instruction at %lx failed.\n", ip - 4);
156 return -EFAULT;
157 }
158
159 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
160 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
161 !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
162 pr_err("Unexpected instruction %08lx around bl _mcount\n",
163 ppc_inst_as_ulong(op));
164 return -EINVAL;
165 }
166 } else if (IS_ENABLED(CONFIG_PPC64)) {
167 /*
168 * Check what is in the next instruction. We can see ld r2,40(r1), but
169 * on first pass after boot we will see mflr r0.
170 */
171 if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
172 pr_err("Fetching op failed.\n");
173 return -EFAULT;
174 }
175
176 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
177 pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
178 ppc_inst_as_ulong(op));
179 return -EINVAL;
180 }
181 }
182
183 /*
184 * When using -mprofile-kernel or PPC32 there is no load to jump over.
185 *
186 * Otherwise our original call site looks like:
187 *
188 * bl <tramp>
189 * ld r2,XX(r1)
190 *
191 * Milton Miller pointed out that we can not simply nop the branch.
192 * If a task was preempted when calling a trace function, the nops
193 * will remove the way to restore the TOC in r2 and the r2 TOC will
194 * get corrupted.
195 *
196 * Use a b +8 to jump over the load.
197 */
198 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
199 pop = ppc_inst(PPC_RAW_NOP());
200 else
201 pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
202
203 if (patch_instruction((u32 *)ip, pop)) {
204 pr_err("Patching NOP failed.\n");
205 return -EPERM;
206 }
207
208 return 0;
209}
210#else
211static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
212{
213 return 0;
214}
215#endif /* CONFIG_MODULES */
216
217static unsigned long find_ftrace_tramp(unsigned long ip)
218{
219 int i;
220
221 /*
222 * We have the compiler generated long_branch tramps at the end
223 * and we prefer those
224 */
225 for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
226 if (!ftrace_tramps[i])
227 continue;
228 else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
229 return ftrace_tramps[i];
230
231 return 0;
232}
233
234static int add_ftrace_tramp(unsigned long tramp)
235{
236 int i;
237
238 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
239 if (!ftrace_tramps[i]) {
240 ftrace_tramps[i] = tramp;
241 return 0;
242 }
243
244 return -1;
245}
246
247/*
248 * If this is a compiler generated long_branch trampoline (essentially, a
249 * trampoline that has a branch to _mcount()), we re-write the branch to
250 * instead go to ftrace_[regs_]caller() and note down the location of this
251 * trampoline.
252 */
253static int setup_mcount_compiler_tramp(unsigned long tramp)
254{
255 int i;
256 ppc_inst_t op;
257 unsigned long ptr;
258
259 /* Is this a known long jump tramp? */
260 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
261 if (ftrace_tramps[i] == tramp)
262 return 0;
263
264 /* New trampoline -- read where this goes */
265 if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
266 pr_debug("Fetching opcode failed.\n");
267 return -1;
268 }
269
270 /* Is this a 24 bit branch? */
271 if (!is_b_op(op)) {
272 pr_debug("Trampoline is not a long branch tramp.\n");
273 return -1;
274 }
275
276 /* lets find where the pointer goes */
277 ptr = find_bl_target(tramp, op);
278
279 if (ptr != ppc_global_function_entry((void *)_mcount)) {
280 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
281 return -1;
282 }
283
284 /* Let's re-write the tramp to go to ftrace_[regs_]caller */
285 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
286 ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
287 else
288 ptr = ppc_global_function_entry((void *)ftrace_caller);
289
290 if (patch_branch((u32 *)tramp, ptr, 0)) {
291 pr_debug("REL24 out of range!\n");
292 return -1;
293 }
294
295 if (add_ftrace_tramp(tramp)) {
296 pr_debug("No tramp locations left\n");
297 return -1;
298 }
299
300 return 0;
301}
302
303static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
304{
305 unsigned long tramp, ip = rec->ip;
306 ppc_inst_t op;
307
308 /* Read where this goes */
309 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
310 pr_err("Fetching opcode failed.\n");
311 return -EFAULT;
312 }
313
314 /* Make sure that this is still a 24bit jump */
315 if (!is_bl_op(op)) {
316 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
317 return -EINVAL;
318 }
319
320 /* Let's find where the pointer goes */
321 tramp = find_bl_target(ip, op);
322
323 pr_devel("ip:%lx jumps to %lx", ip, tramp);
324
325 if (setup_mcount_compiler_tramp(tramp)) {
326 /* Are other trampolines reachable? */
327 if (!find_ftrace_tramp(ip)) {
328 pr_err("No ftrace trampolines reachable from %ps\n",
329 (void *)ip);
330 return -EINVAL;
331 }
332 }
333
334 if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
335 pr_err("Patching NOP failed.\n");
336 return -EPERM;
337 }
338
339 return 0;
340}
341
342int ftrace_make_nop(struct module *mod,
343 struct dyn_ftrace *rec, unsigned long addr)
344{
345 unsigned long ip = rec->ip;
346 ppc_inst_t old, new;
347
348 /*
349 * If the calling address is more that 24 bits away,
350 * then we had to use a trampoline to make the call.
351 * Otherwise just update the call site.
352 */
353 if (test_24bit_addr(ip, addr)) {
354 /* within range */
355 old = ftrace_call_replace(ip, addr, 1);
356 new = ppc_inst(PPC_RAW_NOP());
357 return ftrace_modify_code(ip, old, new);
358 } else if (core_kernel_text(ip)) {
359 return __ftrace_make_nop_kernel(rec, addr);
360 } else if (!IS_ENABLED(CONFIG_MODULES)) {
361 return -EINVAL;
362 }
363
364 /*
365 * Out of range jumps are called from modules.
366 * We should either already have a pointer to the module
367 * or it has been passed in.
368 */
369 if (!rec->arch.mod) {
370 if (!mod) {
371 pr_err("No module loaded addr=%lx\n", addr);
372 return -EFAULT;
373 }
374 rec->arch.mod = mod;
375 } else if (mod) {
376 if (mod != rec->arch.mod) {
377 pr_err("Record mod %p not equal to passed in mod %p\n",
378 rec->arch.mod, mod);
379 return -EINVAL;
380 }
381 /* nothing to do if mod == rec->arch.mod */
382 } else
383 mod = rec->arch.mod;
384
385 return __ftrace_make_nop(mod, rec, addr);
386}
387
388#ifdef CONFIG_MODULES
389/*
390 * Examine the existing instructions for __ftrace_make_call.
391 * They should effectively be a NOP, and follow formal constraints,
392 * depending on the ABI. Return false if they don't.
393 */
394static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
395{
396 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
397 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
398 else
399 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
400 ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
401}
402
403static int
404__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
405{
406 ppc_inst_t op[2];
407 void *ip = (void *)rec->ip;
408 unsigned long entry, ptr, tramp;
409 struct module *mod = rec->arch.mod;
410
411 /* read where this goes */
412 if (copy_inst_from_kernel_nofault(op, ip))
413 return -EFAULT;
414
415 if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
416 copy_inst_from_kernel_nofault(op + 1, ip + 4))
417 return -EFAULT;
418
419 if (!expected_nop_sequence(ip, op[0], op[1])) {
420 pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
421 ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
422 return -EINVAL;
423 }
424
425 /* If we never set up ftrace trampoline(s), then bail */
426 if (!mod->arch.tramp ||
427 (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
428 pr_err("No ftrace trampoline\n");
429 return -EINVAL;
430 }
431
432 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
433 tramp = mod->arch.tramp_regs;
434 else
435 tramp = mod->arch.tramp;
436
437 if (module_trampoline_target(mod, tramp, &ptr)) {
438 pr_err("Failed to get trampoline target\n");
439 return -EFAULT;
440 }
441
442 pr_devel("trampoline target %lx", ptr);
443
444 entry = ppc_global_function_entry((void *)addr);
445 /* This should match what was called */
446 if (ptr != entry) {
447 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
448 return -EINVAL;
449 }
450
451 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
452 pr_err("REL24 out of range!\n");
453 return -EINVAL;
454 }
455
456 return 0;
457}
458#else
459static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
460{
461 return 0;
462}
463#endif /* CONFIG_MODULES */
464
465static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
466{
467 ppc_inst_t op;
468 void *ip = (void *)rec->ip;
469 unsigned long tramp, entry, ptr;
470
471 /* Make sure we're being asked to patch branch to a known ftrace addr */
472 entry = ppc_global_function_entry((void *)ftrace_caller);
473 ptr = ppc_global_function_entry((void *)addr);
474
475 if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
476 entry = ppc_global_function_entry((void *)ftrace_regs_caller);
477
478 if (ptr != entry) {
479 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
480 return -EINVAL;
481 }
482
483 /* Make sure we have a nop */
484 if (copy_inst_from_kernel_nofault(&op, ip)) {
485 pr_err("Unable to read ftrace location %p\n", ip);
486 return -EFAULT;
487 }
488
489 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
490 pr_err("Unexpected call sequence at %p: %08lx\n",
491 ip, ppc_inst_as_ulong(op));
492 return -EINVAL;
493 }
494
495 tramp = find_ftrace_tramp((unsigned long)ip);
496 if (!tramp) {
497 pr_err("No ftrace trampolines reachable from %ps\n", ip);
498 return -EINVAL;
499 }
500
501 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
502 pr_err("Error patching branch to ftrace tramp!\n");
503 return -EINVAL;
504 }
505
506 return 0;
507}
508
509int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
510{
511 unsigned long ip = rec->ip;
512 ppc_inst_t old, new;
513
514 /*
515 * If the calling address is more that 24 bits away,
516 * then we had to use a trampoline to make the call.
517 * Otherwise just update the call site.
518 */
519 if (test_24bit_addr(ip, addr)) {
520 /* within range */
521 old = ppc_inst(PPC_RAW_NOP());
522 new = ftrace_call_replace(ip, addr, 1);
523 return ftrace_modify_code(ip, old, new);
524 } else if (core_kernel_text(ip)) {
525 return __ftrace_make_call_kernel(rec, addr);
526 } else if (!IS_ENABLED(CONFIG_MODULES)) {
527 /* We should not get here without modules */
528 return -EINVAL;
529 }
530
531 /*
532 * Out of range jumps are called from modules.
533 * Being that we are converting from nop, it had better
534 * already have a module defined.
535 */
536 if (!rec->arch.mod) {
537 pr_err("No module loaded\n");
538 return -EINVAL;
539 }
540
541 return __ftrace_make_call(rec, addr);
542}
543
544#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
545#ifdef CONFIG_MODULES
546static int
547__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
548 unsigned long addr)
549{
550 ppc_inst_t op;
551 unsigned long ip = rec->ip;
552 unsigned long entry, ptr, tramp;
553 struct module *mod = rec->arch.mod;
554
555 /* If we never set up ftrace trampolines, then bail */
556 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
557 pr_err("No ftrace trampoline\n");
558 return -EINVAL;
559 }
560
561 /* read where this goes */
562 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
563 pr_err("Fetching opcode failed.\n");
564 return -EFAULT;
565 }
566
567 /* Make sure that this is still a 24bit jump */
568 if (!is_bl_op(op)) {
569 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
570 return -EINVAL;
571 }
572
573 /* lets find where the pointer goes */
574 tramp = find_bl_target(ip, op);
575 entry = ppc_global_function_entry((void *)old_addr);
576
577 pr_devel("ip:%lx jumps to %lx", ip, tramp);
578
579 if (tramp != entry) {
580 /* old_addr is not within range, so we must have used a trampoline */
581 if (module_trampoline_target(mod, tramp, &ptr)) {
582 pr_err("Failed to get trampoline target\n");
583 return -EFAULT;
584 }
585
586 pr_devel("trampoline target %lx", ptr);
587
588 /* This should match what was called */
589 if (ptr != entry) {
590 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
591 return -EINVAL;
592 }
593 }
594
595 /* The new target may be within range */
596 if (test_24bit_addr(ip, addr)) {
597 /* within range */
598 if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
599 pr_err("REL24 out of range!\n");
600 return -EINVAL;
601 }
602
603 return 0;
604 }
605
606 if (rec->flags & FTRACE_FL_REGS)
607 tramp = mod->arch.tramp_regs;
608 else
609 tramp = mod->arch.tramp;
610
611 if (module_trampoline_target(mod, tramp, &ptr)) {
612 pr_err("Failed to get trampoline target\n");
613 return -EFAULT;
614 }
615
616 pr_devel("trampoline target %lx", ptr);
617
618 entry = ppc_global_function_entry((void *)addr);
619 /* This should match what was called */
620 if (ptr != entry) {
621 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
622 return -EINVAL;
623 }
624
625 if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
626 pr_err("REL24 out of range!\n");
627 return -EINVAL;
628 }
629
630 return 0;
631}
632#else
633static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
634{
635 return 0;
636}
637#endif
638
639int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
640 unsigned long addr)
641{
642 unsigned long ip = rec->ip;
643 ppc_inst_t old, new;
644
645 /*
646 * If the calling address is more that 24 bits away,
647 * then we had to use a trampoline to make the call.
648 * Otherwise just update the call site.
649 */
650 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
651 /* within range */
652 old = ftrace_call_replace(ip, old_addr, 1);
653 new = ftrace_call_replace(ip, addr, 1);
654 return ftrace_modify_code(ip, old, new);
655 } else if (core_kernel_text(ip)) {
656 /*
657 * We always patch out of range locations to go to the regs
658 * variant, so there is nothing to do here
659 */
660 return 0;
661 } else if (!IS_ENABLED(CONFIG_MODULES)) {
662 /* We should not get here without modules */
663 return -EINVAL;
664 }
665
666 /*
667 * Out of range jumps are called from modules.
668 */
669 if (!rec->arch.mod) {
670 pr_err("No module loaded\n");
671 return -EINVAL;
672 }
673
674 return __ftrace_modify_call(rec, old_addr, addr);
675}
676#endif
677
678int ftrace_update_ftrace_func(ftrace_func_t func)
679{
680 unsigned long ip = (unsigned long)(&ftrace_call);
681 ppc_inst_t old, new;
682 int ret;
683
684 old = ppc_inst_read((u32 *)&ftrace_call);
685 new = ftrace_call_replace(ip, (unsigned long)func, 1);
686 ret = ftrace_modify_code(ip, old, new);
687
688 /* Also update the regs callback function */
689 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
690 ip = (unsigned long)(&ftrace_regs_call);
691 old = ppc_inst_read((u32 *)&ftrace_regs_call);
692 new = ftrace_call_replace(ip, (unsigned long)func, 1);
693 ret = ftrace_modify_code(ip, old, new);
694 }
695
696 return ret;
697}
698
699/*
700 * Use the default ftrace_modify_all_code, but without
701 * stop_machine().
702 */
703void arch_ftrace_update_code(int command)
704{
705 ftrace_modify_all_code(command);
706}
707
708#ifdef CONFIG_PPC64
709#define PACATOC offsetof(struct paca_struct, kernel_toc)
710
711extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
712
713void ftrace_free_init_tramp(void)
714{
715 int i;
716
717 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
718 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
719 ftrace_tramps[i] = 0;
720 return;
721 }
722}
723
724int __init ftrace_dyn_arch_init(void)
725{
726 int i;
727 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
728 u32 stub_insns[] = {
729 PPC_RAW_LD(_R12, _R13, PACATOC),
730 PPC_RAW_ADDIS(_R12, _R12, 0),
731 PPC_RAW_ADDI(_R12, _R12, 0),
732 PPC_RAW_MTCTR(_R12),
733 PPC_RAW_BCTR()
734 };
735 unsigned long addr;
736 long reladdr;
737
738 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
739 addr = ppc_global_function_entry((void *)ftrace_regs_caller);
740 else
741 addr = ppc_global_function_entry((void *)ftrace_caller);
742
743 reladdr = addr - kernel_toc_addr();
744
745 if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {
746 pr_err("Address of %ps out of range of kernel_toc.\n",
747 (void *)addr);
748 return -1;
749 }
750
751 for (i = 0; i < 2; i++) {
752 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
753 tramp[i][1] |= PPC_HA(reladdr);
754 tramp[i][2] |= PPC_LO(reladdr);
755 add_ftrace_tramp((unsigned long)tramp[i]);
756 }
757
758 return 0;
759}
760#endif
761
762#ifdef CONFIG_FUNCTION_GRAPH_TRACER
763
764extern void ftrace_graph_call(void);
765extern void ftrace_graph_stub(void);
766
767static int ftrace_modify_ftrace_graph_caller(bool enable)
768{
769 unsigned long ip = (unsigned long)(&ftrace_graph_call);
770 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
771 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
772 ppc_inst_t old, new;
773
774 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
775 return 0;
776
777 old = ftrace_call_replace(ip, enable ? stub : addr, 0);
778 new = ftrace_call_replace(ip, enable ? addr : stub, 0);
779
780 return ftrace_modify_code(ip, old, new);
781}
782
783int ftrace_enable_ftrace_graph_caller(void)
784{
785 return ftrace_modify_ftrace_graph_caller(true);
786}
787
788int ftrace_disable_ftrace_graph_caller(void)
789{
790 return ftrace_modify_ftrace_graph_caller(false);
791}
792
793/*
794 * Hook the return address and push it in the stack of return addrs
795 * in current thread info. Return the address we want to divert to.
796 */
797static unsigned long
798__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
799{
800 unsigned long return_hooker;
801 int bit;
802
803 if (unlikely(ftrace_graph_is_dead()))
804 goto out;
805
806 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
807 goto out;
808
809 bit = ftrace_test_recursion_trylock(ip, parent);
810 if (bit < 0)
811 goto out;
812
813 return_hooker = ppc_function_entry(return_to_handler);
814
815 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
816 parent = return_hooker;
817
818 ftrace_test_recursion_unlock(bit);
819out:
820 return parent;
821}
822
823#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
824void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
825 struct ftrace_ops *op, struct ftrace_regs *fregs)
826{
827 fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
828}
829#else
830unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
831 unsigned long sp)
832{
833 return __prepare_ftrace_return(parent, ip, sp);
834}
835#endif
836#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
837
838#ifdef CONFIG_PPC64_ELF_ABI_V1
839char *arch_ftrace_match_adjust(char *str, const char *search)
840{
841 if (str[0] == '.' && search[0] != '.')
842 return str + 1;
843 else
844 return str;
845}
846#endif /* CONFIG_PPC64_ELF_ABI_V1 */
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/cacheflush.h>
26#include <asm/text-patching.h>
27#include <asm/ftrace.h>
28#include <asm/syscall.h>
29#include <asm/inst.h>
30#include <asm/sections.h>
31
32#define NUM_FTRACE_TRAMPS 2
33static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
34
35unsigned long ftrace_call_adjust(unsigned long addr)
36{
37 if (addr >= (unsigned long)__exittext_begin && addr < (unsigned long)__exittext_end)
38 return 0;
39
40 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY) &&
41 !IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) {
42 addr += MCOUNT_INSN_SIZE;
43 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS))
44 addr += MCOUNT_INSN_SIZE;
45 }
46
47 return addr;
48}
49
50static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
51{
52 ppc_inst_t op;
53
54 WARN_ON(!is_offset_in_branch_range(addr - ip));
55 create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
56
57 return op;
58}
59
60static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
61{
62 if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
63 pr_err("0x%lx: fetching instruction failed\n", ip);
64 return -EFAULT;
65 }
66
67 return 0;
68}
69
70static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
71{
72 ppc_inst_t op;
73 int ret;
74
75 ret = ftrace_read_inst(ip, &op);
76 if (!ret && !ppc_inst_equal(op, inst)) {
77 pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
78 ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
79 ret = -EINVAL;
80 }
81
82 return ret;
83}
84
85static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
86{
87 int ret = ftrace_validate_inst(ip, old);
88
89 if (!ret && !ppc_inst_equal(old, new))
90 ret = patch_instruction((u32 *)ip, new);
91
92 return ret;
93}
94
95static int is_bl_op(ppc_inst_t op)
96{
97 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
98}
99
100static unsigned long find_ftrace_tramp(unsigned long ip)
101{
102 int i;
103
104 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
105 if (!ftrace_tramps[i])
106 continue;
107 else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
108 return ftrace_tramps[i];
109
110 return 0;
111}
112
113#ifdef CONFIG_MODULES
114static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long addr)
115{
116 struct module *mod = NULL;
117
118 preempt_disable();
119 mod = __module_text_address(ip);
120 preempt_enable();
121
122 if (!mod)
123 pr_err("No module loaded at addr=%lx\n", ip);
124
125 return (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs);
126}
127#else
128static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long addr)
129{
130 return 0;
131}
132#endif
133
134static unsigned long ftrace_get_ool_stub(struct dyn_ftrace *rec)
135{
136#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
137 return rec->arch.ool_stub;
138#else
139 BUILD_BUG();
140#endif
141}
142
143static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
144{
145 unsigned long ip;
146 unsigned long stub;
147
148 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
149 ip = ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE; /* second instruction in stub */
150 else
151 ip = rec->ip;
152
153 if (!is_offset_in_branch_range(addr - ip) && addr != FTRACE_ADDR &&
154 addr != FTRACE_REGS_ADDR) {
155 /* This can only happen with ftrace direct */
156 if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS)) {
157 pr_err("0x%lx (0x%lx): Unexpected target address 0x%lx\n",
158 ip, rec->ip, addr);
159 return -EINVAL;
160 }
161 addr = FTRACE_ADDR;
162 }
163
164 if (is_offset_in_branch_range(addr - ip))
165 /* Within range */
166 stub = addr;
167 else if (core_kernel_text(ip))
168 /* We would be branching to one of our ftrace stubs */
169 stub = find_ftrace_tramp(ip);
170 else
171 stub = ftrace_lookup_module_stub(ip, addr);
172
173 if (!stub) {
174 pr_err("0x%lx (0x%lx): No ftrace stubs reachable\n", ip, rec->ip);
175 return -EINVAL;
176 }
177
178 *call_inst = ftrace_create_branch_inst(ip, stub, 1);
179 return 0;
180}
181
182static int ftrace_init_ool_stub(struct module *mod, struct dyn_ftrace *rec)
183{
184#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
185 static int ool_stub_text_index, ool_stub_text_end_index, ool_stub_inittext_index;
186 int ret = 0, ool_stub_count, *ool_stub_index;
187 ppc_inst_t inst;
188 /*
189 * See ftrace_entry.S if changing the below instruction sequence, as we rely on
190 * decoding the last branch instruction here to recover the correct function ip.
191 */
192 struct ftrace_ool_stub *ool_stub, ool_stub_template = {
193 .insn = {
194 PPC_RAW_MFLR(_R0),
195 PPC_RAW_NOP(), /* bl ftrace_caller */
196 PPC_RAW_MTLR(_R0),
197 PPC_RAW_NOP() /* b rec->ip + 4 */
198 }
199 };
200
201 WARN_ON(rec->arch.ool_stub);
202
203 if (is_kernel_inittext(rec->ip)) {
204 ool_stub = ftrace_ool_stub_inittext;
205 ool_stub_index = &ool_stub_inittext_index;
206 ool_stub_count = ftrace_ool_stub_inittext_count;
207 } else if (is_kernel_text(rec->ip)) {
208 /*
209 * ftrace records are sorted, so we first use up the stub area within .text
210 * (ftrace_ool_stub_text) before using the area at the end of .text
211 * (ftrace_ool_stub_text_end), unless the stub is out of range of the record.
212 */
213 if (ool_stub_text_index >= ftrace_ool_stub_text_count ||
214 !is_offset_in_branch_range((long)rec->ip -
215 (long)&ftrace_ool_stub_text[ool_stub_text_index])) {
216 ool_stub = ftrace_ool_stub_text_end;
217 ool_stub_index = &ool_stub_text_end_index;
218 ool_stub_count = ftrace_ool_stub_text_end_count;
219 } else {
220 ool_stub = ftrace_ool_stub_text;
221 ool_stub_index = &ool_stub_text_index;
222 ool_stub_count = ftrace_ool_stub_text_count;
223 }
224#ifdef CONFIG_MODULES
225 } else if (mod) {
226 ool_stub = mod->arch.ool_stubs;
227 ool_stub_index = &mod->arch.ool_stub_index;
228 ool_stub_count = mod->arch.ool_stub_count;
229#endif
230 } else {
231 return -EINVAL;
232 }
233
234 ool_stub += (*ool_stub_index)++;
235
236 if (WARN_ON(*ool_stub_index > ool_stub_count))
237 return -EINVAL;
238
239 if (!is_offset_in_branch_range((long)rec->ip - (long)&ool_stub->insn[0]) ||
240 !is_offset_in_branch_range((long)(rec->ip + MCOUNT_INSN_SIZE) -
241 (long)&ool_stub->insn[3])) {
242 pr_err("%s: ftrace ool stub out of range (%p -> %p).\n",
243 __func__, (void *)rec->ip, (void *)&ool_stub->insn[0]);
244 return -EINVAL;
245 }
246
247 rec->arch.ool_stub = (unsigned long)&ool_stub->insn[0];
248
249 /* bl ftrace_caller */
250 if (!mod)
251 ret = ftrace_get_call_inst(rec, (unsigned long)ftrace_caller, &inst);
252#ifdef CONFIG_MODULES
253 else
254 /*
255 * We can't use ftrace_get_call_inst() since that uses
256 * __module_text_address(rec->ip) to look up the module.
257 * But, since the module is not fully formed at this stage,
258 * the lookup fails. We know the target though, so generate
259 * the branch inst directly.
260 */
261 inst = ftrace_create_branch_inst(ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE,
262 mod->arch.tramp, 1);
263#endif
264 ool_stub_template.insn[1] = ppc_inst_val(inst);
265
266 /* b rec->ip + 4 */
267 if (!ret && create_branch(&inst, &ool_stub->insn[3], rec->ip + MCOUNT_INSN_SIZE, 0))
268 return -EINVAL;
269 ool_stub_template.insn[3] = ppc_inst_val(inst);
270
271 if (!ret)
272 ret = patch_instructions((u32 *)ool_stub, (u32 *)&ool_stub_template,
273 sizeof(ool_stub_template), false);
274
275 return ret;
276#else /* !CONFIG_PPC_FTRACE_OUT_OF_LINE */
277 BUILD_BUG();
278#endif
279}
280
281#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
282static const struct ftrace_ops *powerpc_rec_get_ops(struct dyn_ftrace *rec)
283{
284 const struct ftrace_ops *ops = NULL;
285
286 if (rec->flags & FTRACE_FL_CALL_OPS_EN) {
287 ops = ftrace_find_unique_ops(rec);
288 WARN_ON_ONCE(!ops);
289 }
290
291 if (!ops)
292 ops = &ftrace_list_ops;
293
294 return ops;
295}
296
297static int ftrace_rec_set_ops(struct dyn_ftrace *rec, const struct ftrace_ops *ops)
298{
299 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
300 return patch_ulong((void *)(ftrace_get_ool_stub(rec) - sizeof(unsigned long)),
301 (unsigned long)ops);
302 else
303 return patch_ulong((void *)(rec->ip - MCOUNT_INSN_SIZE - sizeof(unsigned long)),
304 (unsigned long)ops);
305}
306
307static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec)
308{
309 return ftrace_rec_set_ops(rec, &ftrace_nop_ops);
310}
311
312static int ftrace_rec_update_ops(struct dyn_ftrace *rec)
313{
314 return ftrace_rec_set_ops(rec, powerpc_rec_get_ops(rec));
315}
316#else
317static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) { return 0; }
318static int ftrace_rec_update_ops(struct dyn_ftrace *rec) { return 0; }
319#endif
320
321#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
322int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
323{
324 /* This should never be called since we override ftrace_replace_code() */
325 WARN_ON(1);
326 return -EINVAL;
327}
328#endif
329
330int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
331{
332 ppc_inst_t old, new;
333 unsigned long ip = rec->ip;
334 int ret = 0;
335
336 /* This can only ever be called during module load */
337 if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(ip)))
338 return -EINVAL;
339
340 old = ppc_inst(PPC_RAW_NOP());
341 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) {
342 ip = ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE; /* second instruction in stub */
343 ret = ftrace_get_call_inst(rec, (unsigned long)ftrace_caller, &old);
344 }
345
346 ret |= ftrace_get_call_inst(rec, addr, &new);
347
348 if (!ret)
349 ret = ftrace_modify_code(ip, old, new);
350
351 ret = ftrace_rec_update_ops(rec);
352 if (ret)
353 return ret;
354
355 if (!ret && IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
356 ret = ftrace_modify_code(rec->ip, ppc_inst(PPC_RAW_NOP()),
357 ppc_inst(PPC_RAW_BRANCH((long)ftrace_get_ool_stub(rec) - (long)rec->ip)));
358
359 return ret;
360}
361
362int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
363{
364 /*
365 * This should never be called since we override ftrace_replace_code(),
366 * as well as ftrace_init_nop()
367 */
368 WARN_ON(1);
369 return -EINVAL;
370}
371
372void ftrace_replace_code(int enable)
373{
374 ppc_inst_t old, new, call_inst, new_call_inst;
375 ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
376 unsigned long ip, new_addr, addr;
377 struct ftrace_rec_iter *iter;
378 struct dyn_ftrace *rec;
379 int ret = 0, update;
380
381 for_ftrace_rec_iter(iter) {
382 rec = ftrace_rec_iter_record(iter);
383 ip = rec->ip;
384
385 if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
386 continue;
387
388 addr = ftrace_get_addr_curr(rec);
389 new_addr = ftrace_get_addr_new(rec);
390 update = ftrace_update_record(rec, enable);
391
392 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) && update != FTRACE_UPDATE_IGNORE) {
393 ip = ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE;
394 ret = ftrace_get_call_inst(rec, (unsigned long)ftrace_caller, &nop_inst);
395 if (ret)
396 goto out;
397 }
398
399 switch (update) {
400 case FTRACE_UPDATE_IGNORE:
401 default:
402 continue;
403 case FTRACE_UPDATE_MODIFY_CALL:
404 ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
405 ret |= ftrace_get_call_inst(rec, addr, &call_inst);
406 ret |= ftrace_rec_update_ops(rec);
407 old = call_inst;
408 new = new_call_inst;
409 break;
410 case FTRACE_UPDATE_MAKE_NOP:
411 ret = ftrace_get_call_inst(rec, addr, &call_inst);
412 ret |= ftrace_rec_set_nop_ops(rec);
413 old = call_inst;
414 new = nop_inst;
415 break;
416 case FTRACE_UPDATE_MAKE_CALL:
417 ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
418 ret |= ftrace_rec_update_ops(rec);
419 old = nop_inst;
420 new = call_inst;
421 break;
422 }
423
424 if (!ret)
425 ret = ftrace_modify_code(ip, old, new);
426
427 if (!ret && IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) &&
428 (update == FTRACE_UPDATE_MAKE_NOP || update == FTRACE_UPDATE_MAKE_CALL)) {
429 /* Update the actual ftrace location */
430 call_inst = ppc_inst(PPC_RAW_BRANCH((long)ftrace_get_ool_stub(rec) -
431 (long)rec->ip));
432 nop_inst = ppc_inst(PPC_RAW_NOP());
433 ip = rec->ip;
434
435 if (update == FTRACE_UPDATE_MAKE_NOP)
436 ret = ftrace_modify_code(ip, call_inst, nop_inst);
437 else
438 ret = ftrace_modify_code(ip, nop_inst, call_inst);
439
440 if (ret)
441 goto out;
442 }
443
444 if (ret)
445 goto out;
446 }
447
448out:
449 if (ret)
450 ftrace_bug(ret, rec);
451 return;
452}
453
454int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
455{
456 unsigned long addr, ip = rec->ip;
457 ppc_inst_t old, new;
458 int ret = 0;
459
460 /* Verify instructions surrounding the ftrace location */
461 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
462 /* Expect nops */
463 if (!IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
464 ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
465 if (!ret)
466 ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
467 } else if (IS_ENABLED(CONFIG_PPC32)) {
468 /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
469 ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
470 if (ret)
471 return ret;
472 ret = ftrace_modify_code(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)),
473 ppc_inst(PPC_RAW_NOP()));
474 } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
475 /* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */
476 ret = ftrace_read_inst(ip - 4, &old);
477 if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) {
478 /* Gcc v5.x emit the additional 'std' instruction, gcc v6.x don't */
479 ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
480 if (ret)
481 return ret;
482 ret = ftrace_modify_code(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16)),
483 ppc_inst(PPC_RAW_NOP()));
484 }
485 } else {
486 return -EINVAL;
487 }
488
489 if (ret)
490 return ret;
491
492 /* Set up out-of-line stub */
493 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
494 return ftrace_init_ool_stub(mod, rec);
495
496 /* Nop-out the ftrace location */
497 new = ppc_inst(PPC_RAW_NOP());
498 addr = MCOUNT_ADDR;
499 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
500 /* we instead patch-in the 'mflr r0' */
501 old = ppc_inst(PPC_RAW_NOP());
502 new = ppc_inst(PPC_RAW_MFLR(_R0));
503 ret = ftrace_modify_code(ip - 4, old, new);
504 } else if (is_offset_in_branch_range(addr - ip)) {
505 /* Within range */
506 old = ftrace_create_branch_inst(ip, addr, 1);
507 ret = ftrace_modify_code(ip, old, new);
508 } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
509 /*
510 * We would be branching to a linker-generated stub, or to the module _mcount
511 * stub. Let's just confirm we have a 'bl' here.
512 */
513 ret = ftrace_read_inst(ip, &old);
514 if (ret)
515 return ret;
516 if (!is_bl_op(old)) {
517 pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
518 return -EINVAL;
519 }
520 ret = patch_instruction((u32 *)ip, new);
521 } else {
522 return -EINVAL;
523 }
524
525 return ret;
526}
527
528int ftrace_update_ftrace_func(ftrace_func_t func)
529{
530 unsigned long ip = (unsigned long)(&ftrace_call);
531 ppc_inst_t old, new;
532 int ret;
533
534 /*
535 * When using CALL_OPS, the function to call is associated with the
536 * call site, and we don't have a global function pointer to update.
537 */
538 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS))
539 return 0;
540
541 old = ppc_inst_read((u32 *)&ftrace_call);
542 new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
543 ret = ftrace_modify_code(ip, old, new);
544
545 /* Also update the regs callback function */
546 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
547 ip = (unsigned long)(&ftrace_regs_call);
548 old = ppc_inst_read((u32 *)&ftrace_regs_call);
549 new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
550 ret = ftrace_modify_code(ip, old, new);
551 }
552
553 return ret;
554}
555
556/*
557 * Use the default ftrace_modify_all_code, but without
558 * stop_machine().
559 */
560void arch_ftrace_update_code(int command)
561{
562 ftrace_modify_all_code(command);
563}
564
565void ftrace_free_init_tramp(void)
566{
567 int i;
568
569 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
570 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
571 ftrace_tramps[i] = 0;
572 return;
573 }
574}
575
576static void __init add_ftrace_tramp(unsigned long tramp)
577{
578 int i;
579
580 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
581 if (!ftrace_tramps[i]) {
582 ftrace_tramps[i] = tramp;
583 return;
584 }
585}
586
587int __init ftrace_dyn_arch_init(void)
588{
589 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
590 unsigned long addr = FTRACE_REGS_ADDR;
591 long reladdr;
592 int i;
593 u32 stub_insns[] = {
594#ifdef CONFIG_PPC_KERNEL_PCREL
595 /* pla r12,addr */
596 PPC_PREFIX_MLS | __PPC_PRFX_R(1),
597 PPC_INST_PADDI | ___PPC_RT(_R12),
598 PPC_RAW_MTCTR(_R12),
599 PPC_RAW_BCTR()
600#elif defined(CONFIG_PPC64)
601 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
602 PPC_RAW_ADDIS(_R12, _R12, 0),
603 PPC_RAW_ADDI(_R12, _R12, 0),
604 PPC_RAW_MTCTR(_R12),
605 PPC_RAW_BCTR()
606#else
607 PPC_RAW_LIS(_R12, 0),
608 PPC_RAW_ADDI(_R12, _R12, 0),
609 PPC_RAW_MTCTR(_R12),
610 PPC_RAW_BCTR()
611#endif
612 };
613
614 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
615 for (i = 0; i < 2; i++) {
616 reladdr = addr - (unsigned long)tramp[i];
617
618 if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
619 pr_err("Address of %ps out of range of pcrel address.\n",
620 (void *)addr);
621 return -1;
622 }
623
624 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
625 tramp[i][0] |= IMM_H18(reladdr);
626 tramp[i][1] |= IMM_L(reladdr);
627 add_ftrace_tramp((unsigned long)tramp[i]);
628 }
629 } else if (IS_ENABLED(CONFIG_PPC64)) {
630 reladdr = addr - kernel_toc_addr();
631
632 if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
633 pr_err("Address of %ps out of range of kernel_toc.\n",
634 (void *)addr);
635 return -1;
636 }
637
638 for (i = 0; i < 2; i++) {
639 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
640 tramp[i][1] |= PPC_HA(reladdr);
641 tramp[i][2] |= PPC_LO(reladdr);
642 add_ftrace_tramp((unsigned long)tramp[i]);
643 }
644 } else {
645 for (i = 0; i < 2; i++) {
646 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
647 tramp[i][0] |= PPC_HA(addr);
648 tramp[i][1] |= PPC_LO(addr);
649 add_ftrace_tramp((unsigned long)tramp[i]);
650 }
651 }
652
653 return 0;
654}
655
656#ifdef CONFIG_FUNCTION_GRAPH_TRACER
657void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
658 struct ftrace_ops *op, struct ftrace_regs *fregs)
659{
660 unsigned long sp = arch_ftrace_regs(fregs)->regs.gpr[1];
661 int bit;
662
663 if (unlikely(ftrace_graph_is_dead()))
664 goto out;
665
666 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
667 goto out;
668
669 bit = ftrace_test_recursion_trylock(ip, parent_ip);
670 if (bit < 0)
671 goto out;
672
673 if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
674 parent_ip = ppc_function_entry(return_to_handler);
675
676 ftrace_test_recursion_unlock(bit);
677out:
678 arch_ftrace_regs(fregs)->regs.link = parent_ip;
679}
680#endif /* CONFIG_FUNCTION_GRAPH_TRACER */