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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
40unsigned long ftrace_call_adjust(unsigned long addr)
41{
42 return addr;
43}
44
45static ppc_inst_t
46ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
47{
48 ppc_inst_t op;
49
50 addr = ppc_function_entry((void *)addr);
51
52 /* if (link) set op to 'bl' else 'b' */
53 create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
54
55 return op;
56}
57
58static inline int
59ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
60{
61 ppc_inst_t replaced;
62
63 /*
64 * Note:
65 * We are paranoid about modifying text, as if a bug was to happen, it
66 * could cause us to read or write to someplace that could cause harm.
67 * Carefully read and modify the code with probe_kernel_*(), and make
68 * sure what we read is what we expected it to be before modifying it.
69 */
70
71 /* read the text we want to modify */
72 if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
73 return -EFAULT;
74
75 /* Make sure it is what we expect it to be */
76 if (!ppc_inst_equal(replaced, old)) {
77 pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
78 ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
79 return -EINVAL;
80 }
81
82 /* replace the text with the new text */
83 return patch_instruction((u32 *)ip, new);
84}
85
86/*
87 * Helper functions that are the same for both PPC64 and PPC32.
88 */
89static int test_24bit_addr(unsigned long ip, unsigned long addr)
90{
91 addr = ppc_function_entry((void *)addr);
92
93 return is_offset_in_branch_range(addr - ip);
94}
95
96static int is_bl_op(ppc_inst_t op)
97{
98 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
99}
100
101static int is_b_op(ppc_inst_t op)
102{
103 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
104}
105
106static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
107{
108 int offset;
109
110 offset = PPC_LI(ppc_inst_val(op));
111 /* make it signed */
112 if (offset & 0x02000000)
113 offset |= 0xfe000000;
114
115 return ip + (long)offset;
116}
117
118#ifdef CONFIG_MODULES
119static int
120__ftrace_make_nop(struct module *mod,
121 struct dyn_ftrace *rec, unsigned long addr)
122{
123 unsigned long entry, ptr, tramp;
124 unsigned long ip = rec->ip;
125 ppc_inst_t op, pop;
126
127 /* read where this goes */
128 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
129 pr_err("Fetching opcode failed.\n");
130 return -EFAULT;
131 }
132
133 /* Make sure that this is still a 24bit jump */
134 if (!is_bl_op(op)) {
135 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
136 return -EINVAL;
137 }
138
139 /* lets find where the pointer goes */
140 tramp = find_bl_target(ip, op);
141
142 pr_devel("ip:%lx jumps to %lx", ip, tramp);
143
144 if (module_trampoline_target(mod, tramp, &ptr)) {
145 pr_err("Failed to get trampoline target\n");
146 return -EFAULT;
147 }
148
149 pr_devel("trampoline target %lx", ptr);
150
151 entry = ppc_global_function_entry((void *)addr);
152 /* This should match what was called */
153 if (ptr != entry) {
154 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
155 return -EINVAL;
156 }
157
158 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
159 if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
160 pr_err("Fetching instruction at %lx failed.\n", ip - 4);
161 return -EFAULT;
162 }
163
164 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
165 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
166 !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
167 pr_err("Unexpected instruction %08lx around bl _mcount\n",
168 ppc_inst_as_ulong(op));
169 return -EINVAL;
170 }
171 } else if (IS_ENABLED(CONFIG_PPC64)) {
172 /*
173 * Check what is in the next instruction. We can see ld r2,40(r1), but
174 * on first pass after boot we will see mflr r0.
175 */
176 if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
177 pr_err("Fetching op failed.\n");
178 return -EFAULT;
179 }
180
181 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
182 pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
183 ppc_inst_as_ulong(op));
184 return -EINVAL;
185 }
186 }
187
188 /*
189 * When using -mprofile-kernel or PPC32 there is no load to jump over.
190 *
191 * Otherwise our original call site looks like:
192 *
193 * bl <tramp>
194 * ld r2,XX(r1)
195 *
196 * Milton Miller pointed out that we can not simply nop the branch.
197 * If a task was preempted when calling a trace function, the nops
198 * will remove the way to restore the TOC in r2 and the r2 TOC will
199 * get corrupted.
200 *
201 * Use a b +8 to jump over the load.
202 */
203 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
204 pop = ppc_inst(PPC_RAW_NOP());
205 else
206 pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
207
208 if (patch_instruction((u32 *)ip, pop)) {
209 pr_err("Patching NOP failed.\n");
210 return -EPERM;
211 }
212
213 return 0;
214}
215#else
216static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
217{
218 return 0;
219}
220#endif /* CONFIG_MODULES */
221
222static unsigned long find_ftrace_tramp(unsigned long ip)
223{
224 int i;
225
226 /*
227 * We have the compiler generated long_branch tramps at the end
228 * and we prefer those
229 */
230 for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
231 if (!ftrace_tramps[i])
232 continue;
233 else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
234 return ftrace_tramps[i];
235
236 return 0;
237}
238
239static int add_ftrace_tramp(unsigned long tramp)
240{
241 int i;
242
243 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
244 if (!ftrace_tramps[i]) {
245 ftrace_tramps[i] = tramp;
246 return 0;
247 }
248
249 return -1;
250}
251
252/*
253 * If this is a compiler generated long_branch trampoline (essentially, a
254 * trampoline that has a branch to _mcount()), we re-write the branch to
255 * instead go to ftrace_[regs_]caller() and note down the location of this
256 * trampoline.
257 */
258static int setup_mcount_compiler_tramp(unsigned long tramp)
259{
260 int i;
261 ppc_inst_t op;
262 unsigned long ptr;
263
264 /* Is this a known long jump tramp? */
265 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
266 if (ftrace_tramps[i] == tramp)
267 return 0;
268
269 /* New trampoline -- read where this goes */
270 if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
271 pr_debug("Fetching opcode failed.\n");
272 return -1;
273 }
274
275 /* Is this a 24 bit branch? */
276 if (!is_b_op(op)) {
277 pr_debug("Trampoline is not a long branch tramp.\n");
278 return -1;
279 }
280
281 /* lets find where the pointer goes */
282 ptr = find_bl_target(tramp, op);
283
284 if (ptr != ppc_global_function_entry((void *)_mcount)) {
285 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
286 return -1;
287 }
288
289 /* Let's re-write the tramp to go to ftrace_[regs_]caller */
290 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
291 ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
292 else
293 ptr = ppc_global_function_entry((void *)ftrace_caller);
294
295 if (patch_branch((u32 *)tramp, ptr, 0)) {
296 pr_debug("REL24 out of range!\n");
297 return -1;
298 }
299
300 if (add_ftrace_tramp(tramp)) {
301 pr_debug("No tramp locations left\n");
302 return -1;
303 }
304
305 return 0;
306}
307
308static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
309{
310 unsigned long tramp, ip = rec->ip;
311 ppc_inst_t op;
312
313 /* Read where this goes */
314 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
315 pr_err("Fetching opcode failed.\n");
316 return -EFAULT;
317 }
318
319 /* Make sure that this is still a 24bit jump */
320 if (!is_bl_op(op)) {
321 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
322 return -EINVAL;
323 }
324
325 /* Let's find where the pointer goes */
326 tramp = find_bl_target(ip, op);
327
328 pr_devel("ip:%lx jumps to %lx", ip, tramp);
329
330 if (setup_mcount_compiler_tramp(tramp)) {
331 /* Are other trampolines reachable? */
332 if (!find_ftrace_tramp(ip)) {
333 pr_err("No ftrace trampolines reachable from %ps\n",
334 (void *)ip);
335 return -EINVAL;
336 }
337 }
338
339 if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
340 pr_err("Patching NOP failed.\n");
341 return -EPERM;
342 }
343
344 return 0;
345}
346
347int ftrace_make_nop(struct module *mod,
348 struct dyn_ftrace *rec, unsigned long addr)
349{
350 unsigned long ip = rec->ip;
351 ppc_inst_t old, new;
352
353 /*
354 * If the calling address is more that 24 bits away,
355 * then we had to use a trampoline to make the call.
356 * Otherwise just update the call site.
357 */
358 if (test_24bit_addr(ip, addr)) {
359 /* within range */
360 old = ftrace_call_replace(ip, addr, 1);
361 new = ppc_inst(PPC_RAW_NOP());
362 return ftrace_modify_code(ip, old, new);
363 } else if (core_kernel_text(ip)) {
364 return __ftrace_make_nop_kernel(rec, addr);
365 } else if (!IS_ENABLED(CONFIG_MODULES)) {
366 return -EINVAL;
367 }
368
369 /*
370 * Out of range jumps are called from modules.
371 * We should either already have a pointer to the module
372 * or it has been passed in.
373 */
374 if (!rec->arch.mod) {
375 if (!mod) {
376 pr_err("No module loaded addr=%lx\n", addr);
377 return -EFAULT;
378 }
379 rec->arch.mod = mod;
380 } else if (mod) {
381 if (mod != rec->arch.mod) {
382 pr_err("Record mod %p not equal to passed in mod %p\n",
383 rec->arch.mod, mod);
384 return -EINVAL;
385 }
386 /* nothing to do if mod == rec->arch.mod */
387 } else
388 mod = rec->arch.mod;
389
390 return __ftrace_make_nop(mod, rec, addr);
391}
392
393#ifdef CONFIG_MODULES
394/*
395 * Examine the existing instructions for __ftrace_make_call.
396 * They should effectively be a NOP, and follow formal constraints,
397 * depending on the ABI. Return false if they don't.
398 */
399static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
400{
401 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
402 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
403 else
404 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
405 ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
406}
407
408static int
409__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
410{
411 ppc_inst_t op[2];
412 void *ip = (void *)rec->ip;
413 unsigned long entry, ptr, tramp;
414 struct module *mod = rec->arch.mod;
415
416 /* read where this goes */
417 if (copy_inst_from_kernel_nofault(op, ip))
418 return -EFAULT;
419
420 if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
421 copy_inst_from_kernel_nofault(op + 1, ip + 4))
422 return -EFAULT;
423
424 if (!expected_nop_sequence(ip, op[0], op[1])) {
425 pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
426 ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
427 return -EINVAL;
428 }
429
430 /* If we never set up ftrace trampoline(s), then bail */
431 if (!mod->arch.tramp ||
432 (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
433 pr_err("No ftrace trampoline\n");
434 return -EINVAL;
435 }
436
437 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
438 tramp = mod->arch.tramp_regs;
439 else
440 tramp = mod->arch.tramp;
441
442 if (module_trampoline_target(mod, tramp, &ptr)) {
443 pr_err("Failed to get trampoline target\n");
444 return -EFAULT;
445 }
446
447 pr_devel("trampoline target %lx", ptr);
448
449 entry = ppc_global_function_entry((void *)addr);
450 /* This should match what was called */
451 if (ptr != entry) {
452 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
453 return -EINVAL;
454 }
455
456 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
457 pr_err("REL24 out of range!\n");
458 return -EINVAL;
459 }
460
461 return 0;
462}
463#else
464static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
465{
466 return 0;
467}
468#endif /* CONFIG_MODULES */
469
470static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
471{
472 ppc_inst_t op;
473 void *ip = (void *)rec->ip;
474 unsigned long tramp, entry, ptr;
475
476 /* Make sure we're being asked to patch branch to a known ftrace addr */
477 entry = ppc_global_function_entry((void *)ftrace_caller);
478 ptr = ppc_global_function_entry((void *)addr);
479
480 if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
481 entry = ppc_global_function_entry((void *)ftrace_regs_caller);
482
483 if (ptr != entry) {
484 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
485 return -EINVAL;
486 }
487
488 /* Make sure we have a nop */
489 if (copy_inst_from_kernel_nofault(&op, ip)) {
490 pr_err("Unable to read ftrace location %p\n", ip);
491 return -EFAULT;
492 }
493
494 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
495 pr_err("Unexpected call sequence at %p: %08lx\n",
496 ip, ppc_inst_as_ulong(op));
497 return -EINVAL;
498 }
499
500 tramp = find_ftrace_tramp((unsigned long)ip);
501 if (!tramp) {
502 pr_err("No ftrace trampolines reachable from %ps\n", ip);
503 return -EINVAL;
504 }
505
506 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
507 pr_err("Error patching branch to ftrace tramp!\n");
508 return -EINVAL;
509 }
510
511 return 0;
512}
513
514int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
515{
516 unsigned long ip = rec->ip;
517 ppc_inst_t old, new;
518
519 /*
520 * If the calling address is more that 24 bits away,
521 * then we had to use a trampoline to make the call.
522 * Otherwise just update the call site.
523 */
524 if (test_24bit_addr(ip, addr)) {
525 /* within range */
526 old = ppc_inst(PPC_RAW_NOP());
527 new = ftrace_call_replace(ip, addr, 1);
528 return ftrace_modify_code(ip, old, new);
529 } else if (core_kernel_text(ip)) {
530 return __ftrace_make_call_kernel(rec, addr);
531 } else if (!IS_ENABLED(CONFIG_MODULES)) {
532 /* We should not get here without modules */
533 return -EINVAL;
534 }
535
536 /*
537 * Out of range jumps are called from modules.
538 * Being that we are converting from nop, it had better
539 * already have a module defined.
540 */
541 if (!rec->arch.mod) {
542 pr_err("No module loaded\n");
543 return -EINVAL;
544 }
545
546 return __ftrace_make_call(rec, addr);
547}
548
549#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
550#ifdef CONFIG_MODULES
551static int
552__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
553 unsigned long addr)
554{
555 ppc_inst_t op;
556 unsigned long ip = rec->ip;
557 unsigned long entry, ptr, tramp;
558 struct module *mod = rec->arch.mod;
559
560 /* If we never set up ftrace trampolines, then bail */
561 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
562 pr_err("No ftrace trampoline\n");
563 return -EINVAL;
564 }
565
566 /* read where this goes */
567 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
568 pr_err("Fetching opcode failed.\n");
569 return -EFAULT;
570 }
571
572 /* Make sure that this is still a 24bit jump */
573 if (!is_bl_op(op)) {
574 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
575 return -EINVAL;
576 }
577
578 /* lets find where the pointer goes */
579 tramp = find_bl_target(ip, op);
580 entry = ppc_global_function_entry((void *)old_addr);
581
582 pr_devel("ip:%lx jumps to %lx", ip, tramp);
583
584 if (tramp != entry) {
585 /* old_addr is not within range, so we must have used a trampoline */
586 if (module_trampoline_target(mod, tramp, &ptr)) {
587 pr_err("Failed to get trampoline target\n");
588 return -EFAULT;
589 }
590
591 pr_devel("trampoline target %lx", ptr);
592
593 /* This should match what was called */
594 if (ptr != entry) {
595 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
596 return -EINVAL;
597 }
598 }
599
600 /* The new target may be within range */
601 if (test_24bit_addr(ip, addr)) {
602 /* within range */
603 if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
604 pr_err("REL24 out of range!\n");
605 return -EINVAL;
606 }
607
608 return 0;
609 }
610
611 if (rec->flags & FTRACE_FL_REGS)
612 tramp = mod->arch.tramp_regs;
613 else
614 tramp = mod->arch.tramp;
615
616 if (module_trampoline_target(mod, tramp, &ptr)) {
617 pr_err("Failed to get trampoline target\n");
618 return -EFAULT;
619 }
620
621 pr_devel("trampoline target %lx", ptr);
622
623 entry = ppc_global_function_entry((void *)addr);
624 /* This should match what was called */
625 if (ptr != entry) {
626 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
627 return -EINVAL;
628 }
629
630 if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
631 pr_err("REL24 out of range!\n");
632 return -EINVAL;
633 }
634
635 return 0;
636}
637#else
638static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
639{
640 return 0;
641}
642#endif
643
644int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
645 unsigned long addr)
646{
647 unsigned long ip = rec->ip;
648 ppc_inst_t old, new;
649
650 /*
651 * If the calling address is more that 24 bits away,
652 * then we had to use a trampoline to make the call.
653 * Otherwise just update the call site.
654 */
655 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
656 /* within range */
657 old = ftrace_call_replace(ip, old_addr, 1);
658 new = ftrace_call_replace(ip, addr, 1);
659 return ftrace_modify_code(ip, old, new);
660 } else if (core_kernel_text(ip)) {
661 /*
662 * We always patch out of range locations to go to the regs
663 * variant, so there is nothing to do here
664 */
665 return 0;
666 } else if (!IS_ENABLED(CONFIG_MODULES)) {
667 /* We should not get here without modules */
668 return -EINVAL;
669 }
670
671 /*
672 * Out of range jumps are called from modules.
673 */
674 if (!rec->arch.mod) {
675 pr_err("No module loaded\n");
676 return -EINVAL;
677 }
678
679 return __ftrace_modify_call(rec, old_addr, addr);
680}
681#endif
682
683int ftrace_update_ftrace_func(ftrace_func_t func)
684{
685 unsigned long ip = (unsigned long)(&ftrace_call);
686 ppc_inst_t old, new;
687 int ret;
688
689 old = ppc_inst_read((u32 *)&ftrace_call);
690 new = ftrace_call_replace(ip, (unsigned long)func, 1);
691 ret = ftrace_modify_code(ip, old, new);
692
693 /* Also update the regs callback function */
694 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
695 ip = (unsigned long)(&ftrace_regs_call);
696 old = ppc_inst_read((u32 *)&ftrace_regs_call);
697 new = ftrace_call_replace(ip, (unsigned long)func, 1);
698 ret = ftrace_modify_code(ip, old, new);
699 }
700
701 return ret;
702}
703
704/*
705 * Use the default ftrace_modify_all_code, but without
706 * stop_machine().
707 */
708void arch_ftrace_update_code(int command)
709{
710 ftrace_modify_all_code(command);
711}
712
713#ifdef CONFIG_PPC64
714#define PACATOC offsetof(struct paca_struct, kernel_toc)
715
716extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
717
718void ftrace_free_init_tramp(void)
719{
720 int i;
721
722 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
723 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
724 ftrace_tramps[i] = 0;
725 return;
726 }
727}
728
729int __init ftrace_dyn_arch_init(void)
730{
731 int i;
732 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
733 u32 stub_insns[] = {
734 PPC_RAW_LD(_R12, _R13, PACATOC),
735 PPC_RAW_ADDIS(_R12, _R12, 0),
736 PPC_RAW_ADDI(_R12, _R12, 0),
737 PPC_RAW_MTCTR(_R12),
738 PPC_RAW_BCTR()
739 };
740 unsigned long addr;
741 long reladdr;
742
743 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
744 addr = ppc_global_function_entry((void *)ftrace_regs_caller);
745 else
746 addr = ppc_global_function_entry((void *)ftrace_caller);
747
748 reladdr = addr - kernel_toc_addr();
749
750 if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {
751 pr_err("Address of %ps out of range of kernel_toc.\n",
752 (void *)addr);
753 return -1;
754 }
755
756 for (i = 0; i < 2; i++) {
757 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
758 tramp[i][1] |= PPC_HA(reladdr);
759 tramp[i][2] |= PPC_LO(reladdr);
760 add_ftrace_tramp((unsigned long)tramp[i]);
761 }
762
763 return 0;
764}
765#endif
766
767#ifdef CONFIG_FUNCTION_GRAPH_TRACER
768
769extern void ftrace_graph_call(void);
770extern void ftrace_graph_stub(void);
771
772static int ftrace_modify_ftrace_graph_caller(bool enable)
773{
774 unsigned long ip = (unsigned long)(&ftrace_graph_call);
775 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
776 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
777 ppc_inst_t old, new;
778
779 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
780 return 0;
781
782 old = ftrace_call_replace(ip, enable ? stub : addr, 0);
783 new = ftrace_call_replace(ip, enable ? addr : stub, 0);
784
785 return ftrace_modify_code(ip, old, new);
786}
787
788int ftrace_enable_ftrace_graph_caller(void)
789{
790 return ftrace_modify_ftrace_graph_caller(true);
791}
792
793int ftrace_disable_ftrace_graph_caller(void)
794{
795 return ftrace_modify_ftrace_graph_caller(false);
796}
797
798/*
799 * Hook the return address and push it in the stack of return addrs
800 * in current thread info. Return the address we want to divert to.
801 */
802static unsigned long
803__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
804{
805 unsigned long return_hooker;
806 int bit;
807
808 if (unlikely(ftrace_graph_is_dead()))
809 goto out;
810
811 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
812 goto out;
813
814 bit = ftrace_test_recursion_trylock(ip, parent);
815 if (bit < 0)
816 goto out;
817
818 return_hooker = ppc_function_entry(return_to_handler);
819
820 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
821 parent = return_hooker;
822
823 ftrace_test_recursion_unlock(bit);
824out:
825 return parent;
826}
827
828#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
829void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
830 struct ftrace_ops *op, struct ftrace_regs *fregs)
831{
832 fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
833}
834#else
835unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
836 unsigned long sp)
837{
838 return __prepare_ftrace_return(parent, ip, sp);
839}
840#endif
841#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
842
843#ifdef CONFIG_PPC64_ELF_ABI_V1
844char *arch_ftrace_match_adjust(char *str, const char *search)
845{
846 if (str[0] == '.' && search[0] != '.')
847 return str + 1;
848 else
849 return str;
850}
851#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
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
40unsigned long ftrace_call_adjust(unsigned long addr)
41{
42 return addr;
43}
44
45static ppc_inst_t
46ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
47{
48 ppc_inst_t op;
49
50 addr = ppc_function_entry((void *)addr);
51
52 /* if (link) set op to 'bl' else 'b' */
53 create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
54
55 return op;
56}
57
58static inline int
59ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
60{
61 ppc_inst_t replaced;
62
63 /*
64 * Note:
65 * We are paranoid about modifying text, as if a bug was to happen, it
66 * could cause us to read or write to someplace that could cause harm.
67 * Carefully read and modify the code with probe_kernel_*(), and make
68 * sure what we read is what we expected it to be before modifying it.
69 */
70
71 /* read the text we want to modify */
72 if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
73 return -EFAULT;
74
75 /* Make sure it is what we expect it to be */
76 if (!ppc_inst_equal(replaced, old)) {
77 pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
78 ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
79 return -EINVAL;
80 }
81
82 /* replace the text with the new text */
83 return patch_instruction((u32 *)ip, new);
84}
85
86/*
87 * Helper functions that are the same for both PPC64 and PPC32.
88 */
89static int test_24bit_addr(unsigned long ip, unsigned long addr)
90{
91 addr = ppc_function_entry((void *)addr);
92
93 return is_offset_in_branch_range(addr - ip);
94}
95
96static int is_bl_op(ppc_inst_t op)
97{
98 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
99}
100
101static int is_b_op(ppc_inst_t op)
102{
103 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
104}
105
106static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
107{
108 int offset;
109
110 offset = PPC_LI(ppc_inst_val(op));
111 /* make it signed */
112 if (offset & 0x02000000)
113 offset |= 0xfe000000;
114
115 return ip + (long)offset;
116}
117
118#ifdef CONFIG_MODULES
119static struct module *ftrace_lookup_module(struct dyn_ftrace *rec)
120{
121 struct module *mod;
122
123 preempt_disable();
124 mod = __module_text_address(rec->ip);
125 preempt_enable();
126
127 if (!mod)
128 pr_err("No module loaded at addr=%lx\n", rec->ip);
129
130 return mod;
131}
132
133static int
134__ftrace_make_nop(struct module *mod,
135 struct dyn_ftrace *rec, unsigned long addr)
136{
137 unsigned long entry, ptr, tramp;
138 unsigned long ip = rec->ip;
139 ppc_inst_t op, pop;
140
141 if (!mod) {
142 mod = ftrace_lookup_module(rec);
143 if (!mod)
144 return -EINVAL;
145 }
146
147 /* read where this goes */
148 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
149 pr_err("Fetching opcode failed.\n");
150 return -EFAULT;
151 }
152
153 /* Make sure that this is still a 24bit jump */
154 if (!is_bl_op(op)) {
155 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
156 return -EINVAL;
157 }
158
159 /* lets find where the pointer goes */
160 tramp = find_bl_target(ip, op);
161
162 pr_devel("ip:%lx jumps to %lx", ip, tramp);
163
164 if (module_trampoline_target(mod, tramp, &ptr)) {
165 pr_err("Failed to get trampoline target\n");
166 return -EFAULT;
167 }
168
169 pr_devel("trampoline target %lx", ptr);
170
171 entry = ppc_global_function_entry((void *)addr);
172 /* This should match what was called */
173 if (ptr != entry) {
174 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
175 return -EINVAL;
176 }
177
178 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
179 if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
180 pr_err("Fetching instruction at %lx failed.\n", ip - 4);
181 return -EFAULT;
182 }
183
184 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
185 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
186 !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
187 pr_err("Unexpected instruction %08lx around bl _mcount\n",
188 ppc_inst_as_ulong(op));
189 return -EINVAL;
190 }
191 } else if (IS_ENABLED(CONFIG_PPC64)) {
192 /*
193 * Check what is in the next instruction. We can see ld r2,40(r1), but
194 * on first pass after boot we will see mflr r0.
195 */
196 if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
197 pr_err("Fetching op failed.\n");
198 return -EFAULT;
199 }
200
201 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
202 pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
203 ppc_inst_as_ulong(op));
204 return -EINVAL;
205 }
206 }
207
208 /*
209 * When using -mprofile-kernel or PPC32 there is no load to jump over.
210 *
211 * Otherwise our original call site looks like:
212 *
213 * bl <tramp>
214 * ld r2,XX(r1)
215 *
216 * Milton Miller pointed out that we can not simply nop the branch.
217 * If a task was preempted when calling a trace function, the nops
218 * will remove the way to restore the TOC in r2 and the r2 TOC will
219 * get corrupted.
220 *
221 * Use a b +8 to jump over the load.
222 */
223 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
224 pop = ppc_inst(PPC_RAW_NOP());
225 else
226 pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
227
228 if (patch_instruction((u32 *)ip, pop)) {
229 pr_err("Patching NOP failed.\n");
230 return -EPERM;
231 }
232
233 return 0;
234}
235#else
236static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
237{
238 return 0;
239}
240#endif /* CONFIG_MODULES */
241
242static unsigned long find_ftrace_tramp(unsigned long ip)
243{
244 int i;
245
246 /*
247 * We have the compiler generated long_branch tramps at the end
248 * and we prefer those
249 */
250 for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
251 if (!ftrace_tramps[i])
252 continue;
253 else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
254 return ftrace_tramps[i];
255
256 return 0;
257}
258
259static int add_ftrace_tramp(unsigned long tramp)
260{
261 int i;
262
263 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
264 if (!ftrace_tramps[i]) {
265 ftrace_tramps[i] = tramp;
266 return 0;
267 }
268
269 return -1;
270}
271
272/*
273 * If this is a compiler generated long_branch trampoline (essentially, a
274 * trampoline that has a branch to _mcount()), we re-write the branch to
275 * instead go to ftrace_[regs_]caller() and note down the location of this
276 * trampoline.
277 */
278static int setup_mcount_compiler_tramp(unsigned long tramp)
279{
280 int i;
281 ppc_inst_t op;
282 unsigned long ptr;
283
284 /* Is this a known long jump tramp? */
285 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
286 if (ftrace_tramps[i] == tramp)
287 return 0;
288
289 /* New trampoline -- read where this goes */
290 if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
291 pr_debug("Fetching opcode failed.\n");
292 return -1;
293 }
294
295 /* Is this a 24 bit branch? */
296 if (!is_b_op(op)) {
297 pr_debug("Trampoline is not a long branch tramp.\n");
298 return -1;
299 }
300
301 /* lets find where the pointer goes */
302 ptr = find_bl_target(tramp, op);
303
304 if (ptr != ppc_global_function_entry((void *)_mcount)) {
305 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
306 return -1;
307 }
308
309 /* Let's re-write the tramp to go to ftrace_[regs_]caller */
310 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
311 ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
312 else
313 ptr = ppc_global_function_entry((void *)ftrace_caller);
314
315 if (patch_branch((u32 *)tramp, ptr, 0)) {
316 pr_debug("REL24 out of range!\n");
317 return -1;
318 }
319
320 if (add_ftrace_tramp(tramp)) {
321 pr_debug("No tramp locations left\n");
322 return -1;
323 }
324
325 return 0;
326}
327
328static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
329{
330 unsigned long tramp, ip = rec->ip;
331 ppc_inst_t op;
332
333 /* Read where this goes */
334 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
335 pr_err("Fetching opcode failed.\n");
336 return -EFAULT;
337 }
338
339 /* Make sure that this is still a 24bit jump */
340 if (!is_bl_op(op)) {
341 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
342 return -EINVAL;
343 }
344
345 /* Let's find where the pointer goes */
346 tramp = find_bl_target(ip, op);
347
348 pr_devel("ip:%lx jumps to %lx", ip, tramp);
349
350 if (setup_mcount_compiler_tramp(tramp)) {
351 /* Are other trampolines reachable? */
352 if (!find_ftrace_tramp(ip)) {
353 pr_err("No ftrace trampolines reachable from %ps\n",
354 (void *)ip);
355 return -EINVAL;
356 }
357 }
358
359 if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
360 pr_err("Patching NOP failed.\n");
361 return -EPERM;
362 }
363
364 return 0;
365}
366
367int ftrace_make_nop(struct module *mod,
368 struct dyn_ftrace *rec, unsigned long addr)
369{
370 unsigned long ip = rec->ip;
371 ppc_inst_t old, new;
372
373 /*
374 * If the calling address is more that 24 bits away,
375 * then we had to use a trampoline to make the call.
376 * Otherwise just update the call site.
377 */
378 if (test_24bit_addr(ip, addr)) {
379 /* within range */
380 old = ftrace_call_replace(ip, addr, 1);
381 new = ppc_inst(PPC_RAW_NOP());
382 return ftrace_modify_code(ip, old, new);
383 } else if (core_kernel_text(ip)) {
384 return __ftrace_make_nop_kernel(rec, addr);
385 } else if (!IS_ENABLED(CONFIG_MODULES)) {
386 return -EINVAL;
387 }
388
389 return __ftrace_make_nop(mod, rec, addr);
390}
391
392#ifdef CONFIG_MODULES
393/*
394 * Examine the existing instructions for __ftrace_make_call.
395 * They should effectively be a NOP, and follow formal constraints,
396 * depending on the ABI. Return false if they don't.
397 */
398static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
399{
400 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
401 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
402 else
403 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
404 ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
405}
406
407static int
408__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
409{
410 ppc_inst_t op[2];
411 void *ip = (void *)rec->ip;
412 unsigned long entry, ptr, tramp;
413 struct module *mod = ftrace_lookup_module(rec);
414
415 if (!mod)
416 return -EINVAL;
417
418 /* read where this goes */
419 if (copy_inst_from_kernel_nofault(op, ip))
420 return -EFAULT;
421
422 if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
423 copy_inst_from_kernel_nofault(op + 1, ip + 4))
424 return -EFAULT;
425
426 if (!expected_nop_sequence(ip, op[0], op[1])) {
427 pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
428 ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
429 return -EINVAL;
430 }
431
432 /* If we never set up ftrace trampoline(s), then bail */
433 if (!mod->arch.tramp ||
434 (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
435 pr_err("No ftrace trampoline\n");
436 return -EINVAL;
437 }
438
439 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
440 tramp = mod->arch.tramp_regs;
441 else
442 tramp = mod->arch.tramp;
443
444 if (module_trampoline_target(mod, tramp, &ptr)) {
445 pr_err("Failed to get trampoline target\n");
446 return -EFAULT;
447 }
448
449 pr_devel("trampoline target %lx", ptr);
450
451 entry = ppc_global_function_entry((void *)addr);
452 /* This should match what was called */
453 if (ptr != entry) {
454 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
455 return -EINVAL;
456 }
457
458 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
459 pr_err("REL24 out of range!\n");
460 return -EINVAL;
461 }
462
463 return 0;
464}
465#else
466static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
467{
468 return 0;
469}
470#endif /* CONFIG_MODULES */
471
472static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
473{
474 ppc_inst_t op;
475 void *ip = (void *)rec->ip;
476 unsigned long tramp, entry, ptr;
477
478 /* Make sure we're being asked to patch branch to a known ftrace addr */
479 entry = ppc_global_function_entry((void *)ftrace_caller);
480 ptr = ppc_global_function_entry((void *)addr);
481
482 if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
483 entry = ppc_global_function_entry((void *)ftrace_regs_caller);
484
485 if (ptr != entry) {
486 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
487 return -EINVAL;
488 }
489
490 /* Make sure we have a nop */
491 if (copy_inst_from_kernel_nofault(&op, ip)) {
492 pr_err("Unable to read ftrace location %p\n", ip);
493 return -EFAULT;
494 }
495
496 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
497 pr_err("Unexpected call sequence at %p: %08lx\n",
498 ip, ppc_inst_as_ulong(op));
499 return -EINVAL;
500 }
501
502 tramp = find_ftrace_tramp((unsigned long)ip);
503 if (!tramp) {
504 pr_err("No ftrace trampolines reachable from %ps\n", ip);
505 return -EINVAL;
506 }
507
508 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
509 pr_err("Error patching branch to ftrace tramp!\n");
510 return -EINVAL;
511 }
512
513 return 0;
514}
515
516int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
517{
518 unsigned long ip = rec->ip;
519 ppc_inst_t old, new;
520
521 /*
522 * If the calling address is more that 24 bits away,
523 * then we had to use a trampoline to make the call.
524 * Otherwise just update the call site.
525 */
526 if (test_24bit_addr(ip, addr)) {
527 /* within range */
528 old = ppc_inst(PPC_RAW_NOP());
529 new = ftrace_call_replace(ip, addr, 1);
530 return ftrace_modify_code(ip, old, new);
531 } else if (core_kernel_text(ip)) {
532 return __ftrace_make_call_kernel(rec, addr);
533 } else if (!IS_ENABLED(CONFIG_MODULES)) {
534 /* We should not get here without modules */
535 return -EINVAL;
536 }
537
538 return __ftrace_make_call(rec, addr);
539}
540
541#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
542#ifdef CONFIG_MODULES
543static int
544__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
545 unsigned long addr)
546{
547 ppc_inst_t op;
548 unsigned long ip = rec->ip;
549 unsigned long entry, ptr, tramp;
550 struct module *mod = ftrace_lookup_module(rec);
551
552 if (!mod)
553 return -EINVAL;
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 return __ftrace_modify_call(rec, old_addr, addr);
667}
668#endif
669
670int ftrace_update_ftrace_func(ftrace_func_t func)
671{
672 unsigned long ip = (unsigned long)(&ftrace_call);
673 ppc_inst_t old, new;
674 int ret;
675
676 old = ppc_inst_read((u32 *)&ftrace_call);
677 new = ftrace_call_replace(ip, (unsigned long)func, 1);
678 ret = ftrace_modify_code(ip, old, new);
679
680 /* Also update the regs callback function */
681 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
682 ip = (unsigned long)(&ftrace_regs_call);
683 old = ppc_inst_read((u32 *)&ftrace_regs_call);
684 new = ftrace_call_replace(ip, (unsigned long)func, 1);
685 ret = ftrace_modify_code(ip, old, new);
686 }
687
688 return ret;
689}
690
691/*
692 * Use the default ftrace_modify_all_code, but without
693 * stop_machine().
694 */
695void arch_ftrace_update_code(int command)
696{
697 ftrace_modify_all_code(command);
698}
699
700#ifdef CONFIG_PPC64
701#define PACATOC offsetof(struct paca_struct, kernel_toc)
702
703extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
704
705void ftrace_free_init_tramp(void)
706{
707 int i;
708
709 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
710 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
711 ftrace_tramps[i] = 0;
712 return;
713 }
714}
715
716int __init ftrace_dyn_arch_init(void)
717{
718 int i;
719 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
720 u32 stub_insns[] = {
721 PPC_RAW_LD(_R12, _R13, PACATOC),
722 PPC_RAW_ADDIS(_R12, _R12, 0),
723 PPC_RAW_ADDI(_R12, _R12, 0),
724 PPC_RAW_MTCTR(_R12),
725 PPC_RAW_BCTR()
726 };
727 unsigned long addr;
728 long reladdr;
729
730 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
731 addr = ppc_global_function_entry((void *)ftrace_regs_caller);
732 else
733 addr = ppc_global_function_entry((void *)ftrace_caller);
734
735 reladdr = addr - kernel_toc_addr();
736
737 if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {
738 pr_err("Address of %ps out of range of kernel_toc.\n",
739 (void *)addr);
740 return -1;
741 }
742
743 for (i = 0; i < 2; i++) {
744 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
745 tramp[i][1] |= PPC_HA(reladdr);
746 tramp[i][2] |= PPC_LO(reladdr);
747 add_ftrace_tramp((unsigned long)tramp[i]);
748 }
749
750 return 0;
751}
752#endif
753
754#ifdef CONFIG_FUNCTION_GRAPH_TRACER
755
756extern void ftrace_graph_call(void);
757extern void ftrace_graph_stub(void);
758
759static int ftrace_modify_ftrace_graph_caller(bool enable)
760{
761 unsigned long ip = (unsigned long)(&ftrace_graph_call);
762 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
763 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
764 ppc_inst_t old, new;
765
766 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
767 return 0;
768
769 old = ftrace_call_replace(ip, enable ? stub : addr, 0);
770 new = ftrace_call_replace(ip, enable ? addr : stub, 0);
771
772 return ftrace_modify_code(ip, old, new);
773}
774
775int ftrace_enable_ftrace_graph_caller(void)
776{
777 return ftrace_modify_ftrace_graph_caller(true);
778}
779
780int ftrace_disable_ftrace_graph_caller(void)
781{
782 return ftrace_modify_ftrace_graph_caller(false);
783}
784
785/*
786 * Hook the return address and push it in the stack of return addrs
787 * in current thread info. Return the address we want to divert to.
788 */
789static unsigned long
790__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
791{
792 unsigned long return_hooker;
793 int bit;
794
795 if (unlikely(ftrace_graph_is_dead()))
796 goto out;
797
798 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
799 goto out;
800
801 bit = ftrace_test_recursion_trylock(ip, parent);
802 if (bit < 0)
803 goto out;
804
805 return_hooker = ppc_function_entry(return_to_handler);
806
807 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
808 parent = return_hooker;
809
810 ftrace_test_recursion_unlock(bit);
811out:
812 return parent;
813}
814
815#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
816void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
817 struct ftrace_ops *op, struct ftrace_regs *fregs)
818{
819 arch_ftrace_regs(fregs)->regs.link = __prepare_ftrace_return(parent_ip, ip, arch_ftrace_regs(fregs)->regs.gpr[1]);
820}
821#else
822unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
823 unsigned long sp)
824{
825 return __prepare_ftrace_return(parent, ip, sp);
826}
827#endif
828#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
829
830#ifdef CONFIG_PPC64_ELF_ABI_V1
831char *arch_ftrace_match_adjust(char *str, const char *search)
832{
833 if (str[0] == '.' && search[0] != '.')
834 return str + 1;
835 else
836 return str;
837}
838#endif /* CONFIG_PPC64_ELF_ABI_V1 */