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
33 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
34
ftrace_call_adjust(unsigned long addr)35 unsigned 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
ftrace_create_branch_inst(unsigned long ip,unsigned long addr,int link)50 static 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
ftrace_read_inst(unsigned long ip,ppc_inst_t * op)60 static 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
ftrace_validate_inst(unsigned long ip,ppc_inst_t inst)70 static 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
ftrace_modify_code(unsigned long ip,ppc_inst_t old,ppc_inst_t new)85 static 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
is_bl_op(ppc_inst_t op)95 static int is_bl_op(ppc_inst_t op)
96 {
97 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
98 }
99
find_ftrace_tramp(unsigned long ip)100 static 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
ftrace_lookup_module_stub(unsigned long ip,unsigned long addr)114 static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long addr)
115 {
116 struct module *mod = NULL;
117
118 scoped_guard(rcu)
119 mod = __module_text_address(ip);
120 if (!mod)
121 pr_err("No module loaded at addr=%lx\n", ip);
122
123 return (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs);
124 }
125 #else
ftrace_lookup_module_stub(unsigned long ip,unsigned long addr)126 static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long addr)
127 {
128 return 0;
129 }
130 #endif
131
ftrace_get_ool_stub(struct dyn_ftrace * rec)132 static unsigned long ftrace_get_ool_stub(struct dyn_ftrace *rec)
133 {
134 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
135 return rec->arch.ool_stub;
136 #else
137 BUILD_BUG();
138 #endif
139 }
140
ftrace_get_call_inst(struct dyn_ftrace * rec,unsigned long addr,ppc_inst_t * call_inst)141 static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
142 {
143 unsigned long ip;
144 unsigned long stub;
145
146 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
147 ip = ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE; /* second instruction in stub */
148 else
149 ip = rec->ip;
150
151 if (!is_offset_in_branch_range(addr - ip) && addr != FTRACE_ADDR &&
152 addr != FTRACE_REGS_ADDR) {
153 /* This can only happen with ftrace direct */
154 if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS)) {
155 pr_err("0x%lx (0x%lx): Unexpected target address 0x%lx\n",
156 ip, rec->ip, addr);
157 return -EINVAL;
158 }
159 addr = FTRACE_ADDR;
160 }
161
162 if (is_offset_in_branch_range(addr - ip))
163 /* Within range */
164 stub = addr;
165 else if (core_kernel_text(ip))
166 /* We would be branching to one of our ftrace stubs */
167 stub = find_ftrace_tramp(ip);
168 else
169 stub = ftrace_lookup_module_stub(ip, addr);
170
171 if (!stub) {
172 pr_err("0x%lx (0x%lx): No ftrace stubs reachable\n", ip, rec->ip);
173 return -EINVAL;
174 }
175
176 *call_inst = ftrace_create_branch_inst(ip, stub, 1);
177 return 0;
178 }
179
ftrace_init_ool_stub(struct module * mod,struct dyn_ftrace * rec)180 static int ftrace_init_ool_stub(struct module *mod, struct dyn_ftrace *rec)
181 {
182 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
183 static int ool_stub_text_index, ool_stub_text_end_index, ool_stub_inittext_index;
184 int ret = 0, ool_stub_count, *ool_stub_index;
185 ppc_inst_t inst;
186 /*
187 * See ftrace_entry.S if changing the below instruction sequence, as we rely on
188 * decoding the last branch instruction here to recover the correct function ip.
189 */
190 struct ftrace_ool_stub *ool_stub, ool_stub_template = {
191 .insn = {
192 PPC_RAW_MFLR(_R0),
193 PPC_RAW_NOP(), /* bl ftrace_caller */
194 PPC_RAW_MTLR(_R0),
195 PPC_RAW_NOP() /* b rec->ip + 4 */
196 }
197 };
198
199 WARN_ON(rec->arch.ool_stub);
200
201 if (is_kernel_inittext(rec->ip)) {
202 ool_stub = ftrace_ool_stub_inittext;
203 ool_stub_index = &ool_stub_inittext_index;
204 ool_stub_count = ftrace_ool_stub_inittext_count;
205 } else if (is_kernel_text(rec->ip)) {
206 /*
207 * ftrace records are sorted, so we first use up the stub area within .text
208 * (ftrace_ool_stub_text) before using the area at the end of .text
209 * (ftrace_ool_stub_text_end), unless the stub is out of range of the record.
210 */
211 if (ool_stub_text_index >= ftrace_ool_stub_text_count ||
212 !is_offset_in_branch_range((long)rec->ip -
213 (long)&ftrace_ool_stub_text[ool_stub_text_index])) {
214 ool_stub = ftrace_ool_stub_text_end;
215 ool_stub_index = &ool_stub_text_end_index;
216 ool_stub_count = ftrace_ool_stub_text_end_count;
217 } else {
218 ool_stub = ftrace_ool_stub_text;
219 ool_stub_index = &ool_stub_text_index;
220 ool_stub_count = ftrace_ool_stub_text_count;
221 }
222 #ifdef CONFIG_MODULES
223 } else if (mod) {
224 ool_stub = mod->arch.ool_stubs;
225 ool_stub_index = &mod->arch.ool_stub_index;
226 ool_stub_count = mod->arch.ool_stub_count;
227 #endif
228 } else {
229 return -EINVAL;
230 }
231
232 ool_stub += (*ool_stub_index)++;
233
234 if (WARN_ON(*ool_stub_index > ool_stub_count))
235 return -EINVAL;
236
237 if (!is_offset_in_branch_range((long)rec->ip - (long)&ool_stub->insn[0]) ||
238 !is_offset_in_branch_range((long)(rec->ip + MCOUNT_INSN_SIZE) -
239 (long)&ool_stub->insn[3])) {
240 pr_err("%s: ftrace ool stub out of range (%p -> %p).\n",
241 __func__, (void *)rec->ip, (void *)&ool_stub->insn[0]);
242 return -EINVAL;
243 }
244
245 rec->arch.ool_stub = (unsigned long)&ool_stub->insn[0];
246
247 /* bl ftrace_caller */
248 if (!mod)
249 ret = ftrace_get_call_inst(rec, (unsigned long)ftrace_caller, &inst);
250 #ifdef CONFIG_MODULES
251 else
252 /*
253 * We can't use ftrace_get_call_inst() since that uses
254 * __module_text_address(rec->ip) to look up the module.
255 * But, since the module is not fully formed at this stage,
256 * the lookup fails. We know the target though, so generate
257 * the branch inst directly.
258 */
259 inst = ftrace_create_branch_inst(ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE,
260 mod->arch.tramp, 1);
261 #endif
262 ool_stub_template.insn[1] = ppc_inst_val(inst);
263
264 /* b rec->ip + 4 */
265 if (!ret && create_branch(&inst, &ool_stub->insn[3], rec->ip + MCOUNT_INSN_SIZE, 0))
266 return -EINVAL;
267 ool_stub_template.insn[3] = ppc_inst_val(inst);
268
269 if (!ret)
270 ret = patch_instructions((u32 *)ool_stub, (u32 *)&ool_stub_template,
271 sizeof(ool_stub_template), false);
272
273 return ret;
274 #else /* !CONFIG_PPC_FTRACE_OUT_OF_LINE */
275 BUILD_BUG();
276 #endif
277 }
278
279 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
powerpc_rec_get_ops(struct dyn_ftrace * rec)280 static const struct ftrace_ops *powerpc_rec_get_ops(struct dyn_ftrace *rec)
281 {
282 const struct ftrace_ops *ops = NULL;
283
284 if (rec->flags & FTRACE_FL_CALL_OPS_EN) {
285 ops = ftrace_find_unique_ops(rec);
286 WARN_ON_ONCE(!ops);
287 }
288
289 if (!ops)
290 ops = &ftrace_list_ops;
291
292 return ops;
293 }
294
ftrace_rec_set_ops(struct dyn_ftrace * rec,const struct ftrace_ops * ops)295 static int ftrace_rec_set_ops(struct dyn_ftrace *rec, const struct ftrace_ops *ops)
296 {
297 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
298 return patch_ulong((void *)(ftrace_get_ool_stub(rec) - sizeof(unsigned long)),
299 (unsigned long)ops);
300 else
301 return patch_ulong((void *)(rec->ip - MCOUNT_INSN_SIZE - sizeof(unsigned long)),
302 (unsigned long)ops);
303 }
304
ftrace_rec_set_nop_ops(struct dyn_ftrace * rec)305 static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec)
306 {
307 return ftrace_rec_set_ops(rec, &ftrace_nop_ops);
308 }
309
ftrace_rec_update_ops(struct dyn_ftrace * rec)310 static int ftrace_rec_update_ops(struct dyn_ftrace *rec)
311 {
312 return ftrace_rec_set_ops(rec, powerpc_rec_get_ops(rec));
313 }
314 #else
ftrace_rec_set_nop_ops(struct dyn_ftrace * rec)315 static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) { return 0; }
ftrace_rec_update_ops(struct dyn_ftrace * rec)316 static int ftrace_rec_update_ops(struct dyn_ftrace *rec) { return 0; }
317 #endif
318
319 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
ftrace_modify_call(struct dyn_ftrace * rec,unsigned long old_addr,unsigned long addr)320 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
321 {
322 /* This should never be called since we override ftrace_replace_code() */
323 WARN_ON(1);
324 return -EINVAL;
325 }
326 #endif
327
ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)328 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
329 {
330 ppc_inst_t old, new;
331 unsigned long ip = rec->ip;
332 int ret = 0;
333
334 /* This can only ever be called during module load */
335 if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(ip)))
336 return -EINVAL;
337
338 old = ppc_inst(PPC_RAW_NOP());
339 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) {
340 ip = ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE; /* second instruction in stub */
341 ret = ftrace_get_call_inst(rec, (unsigned long)ftrace_caller, &old);
342 }
343
344 ret |= ftrace_get_call_inst(rec, addr, &new);
345
346 if (!ret)
347 ret = ftrace_modify_code(ip, old, new);
348
349 ret = ftrace_rec_update_ops(rec);
350 if (ret)
351 return ret;
352
353 if (!ret && IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
354 ret = ftrace_modify_code(rec->ip, ppc_inst(PPC_RAW_NOP()),
355 ppc_inst(PPC_RAW_BRANCH((long)ftrace_get_ool_stub(rec) - (long)rec->ip)));
356
357 return ret;
358 }
359
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)360 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
361 {
362 /*
363 * This should never be called since we override ftrace_replace_code(),
364 * as well as ftrace_init_nop()
365 */
366 WARN_ON(1);
367 return -EINVAL;
368 }
369
ftrace_replace_code(int enable)370 void ftrace_replace_code(int enable)
371 {
372 ppc_inst_t old, new, call_inst, new_call_inst;
373 ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
374 unsigned long ip, new_addr, addr;
375 struct ftrace_rec_iter *iter;
376 struct dyn_ftrace *rec;
377 int ret = 0, update;
378
379 for_ftrace_rec_iter(iter) {
380 rec = ftrace_rec_iter_record(iter);
381 ip = rec->ip;
382
383 if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
384 continue;
385
386 addr = ftrace_get_addr_curr(rec);
387 new_addr = ftrace_get_addr_new(rec);
388 update = ftrace_update_record(rec, enable);
389
390 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) && update != FTRACE_UPDATE_IGNORE) {
391 ip = ftrace_get_ool_stub(rec) + MCOUNT_INSN_SIZE;
392 ret = ftrace_get_call_inst(rec, (unsigned long)ftrace_caller, &nop_inst);
393 if (ret)
394 goto out;
395 }
396
397 switch (update) {
398 case FTRACE_UPDATE_IGNORE:
399 default:
400 continue;
401 case FTRACE_UPDATE_MODIFY_CALL:
402 ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
403 ret |= ftrace_get_call_inst(rec, addr, &call_inst);
404 ret |= ftrace_rec_update_ops(rec);
405 old = call_inst;
406 new = new_call_inst;
407 break;
408 case FTRACE_UPDATE_MAKE_NOP:
409 ret = ftrace_get_call_inst(rec, addr, &call_inst);
410 ret |= ftrace_rec_set_nop_ops(rec);
411 old = call_inst;
412 new = nop_inst;
413 break;
414 case FTRACE_UPDATE_MAKE_CALL:
415 ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
416 ret |= ftrace_rec_update_ops(rec);
417 old = nop_inst;
418 new = call_inst;
419 break;
420 }
421
422 if (!ret)
423 ret = ftrace_modify_code(ip, old, new);
424
425 if (!ret && IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) &&
426 (update == FTRACE_UPDATE_MAKE_NOP || update == FTRACE_UPDATE_MAKE_CALL)) {
427 /* Update the actual ftrace location */
428 call_inst = ppc_inst(PPC_RAW_BRANCH((long)ftrace_get_ool_stub(rec) -
429 (long)rec->ip));
430 nop_inst = ppc_inst(PPC_RAW_NOP());
431 ip = rec->ip;
432
433 if (update == FTRACE_UPDATE_MAKE_NOP)
434 ret = ftrace_modify_code(ip, call_inst, nop_inst);
435 else
436 ret = ftrace_modify_code(ip, nop_inst, call_inst);
437
438 if (ret)
439 goto out;
440 }
441
442 if (ret)
443 goto out;
444 }
445
446 out:
447 if (ret)
448 ftrace_bug(ret, rec);
449 return;
450 }
451
ftrace_init_nop(struct module * mod,struct dyn_ftrace * rec)452 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
453 {
454 unsigned long addr, ip = rec->ip;
455 ppc_inst_t old, new;
456 int ret = 0;
457
458 /* Verify instructions surrounding the ftrace location */
459 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
460 /* Expect nops */
461 if (!IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
462 ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
463 if (!ret)
464 ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
465 } else if (IS_ENABLED(CONFIG_PPC32)) {
466 /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
467 ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
468 if (ret)
469 return ret;
470 ret = ftrace_modify_code(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)),
471 ppc_inst(PPC_RAW_NOP()));
472 } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
473 /* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */
474 ret = ftrace_read_inst(ip - 4, &old);
475 if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) {
476 /* Gcc v5.x emit the additional 'std' instruction, gcc v6.x don't */
477 ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
478 if (ret)
479 return ret;
480 ret = ftrace_modify_code(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16)),
481 ppc_inst(PPC_RAW_NOP()));
482 }
483 } else {
484 return -EINVAL;
485 }
486
487 if (ret)
488 return ret;
489
490 /* Set up out-of-line stub */
491 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE))
492 return ftrace_init_ool_stub(mod, rec);
493
494 /* Nop-out the ftrace location */
495 new = ppc_inst(PPC_RAW_NOP());
496 addr = MCOUNT_ADDR;
497 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
498 /* we instead patch-in the 'mflr r0' */
499 old = ppc_inst(PPC_RAW_NOP());
500 new = ppc_inst(PPC_RAW_MFLR(_R0));
501 ret = ftrace_modify_code(ip - 4, old, new);
502 } else if (is_offset_in_branch_range(addr - ip)) {
503 /* Within range */
504 old = ftrace_create_branch_inst(ip, addr, 1);
505 ret = ftrace_modify_code(ip, old, new);
506 } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
507 /*
508 * We would be branching to a linker-generated stub, or to the module _mcount
509 * stub. Let's just confirm we have a 'bl' here.
510 */
511 ret = ftrace_read_inst(ip, &old);
512 if (ret)
513 return ret;
514 if (!is_bl_op(old)) {
515 pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
516 return -EINVAL;
517 }
518 ret = patch_instruction((u32 *)ip, new);
519 } else {
520 return -EINVAL;
521 }
522
523 return ret;
524 }
525
ftrace_update_ftrace_func(ftrace_func_t func)526 int ftrace_update_ftrace_func(ftrace_func_t func)
527 {
528 unsigned long ip = (unsigned long)(&ftrace_call);
529 ppc_inst_t old, new;
530 int ret;
531
532 /*
533 * When using CALL_OPS, the function to call is associated with the
534 * call site, and we don't have a global function pointer to update.
535 */
536 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS))
537 return 0;
538
539 old = ppc_inst_read((u32 *)&ftrace_call);
540 new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
541 ret = ftrace_modify_code(ip, old, new);
542
543 /* Also update the regs callback function */
544 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
545 ip = (unsigned long)(&ftrace_regs_call);
546 old = ppc_inst_read((u32 *)&ftrace_regs_call);
547 new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
548 ret = ftrace_modify_code(ip, old, new);
549 }
550
551 return ret;
552 }
553
554 /*
555 * Use the default ftrace_modify_all_code, but without
556 * stop_machine().
557 */
arch_ftrace_update_code(int command)558 void arch_ftrace_update_code(int command)
559 {
560 ftrace_modify_all_code(command);
561 }
562
ftrace_free_init_tramp(void)563 void ftrace_free_init_tramp(void)
564 {
565 int i;
566
567 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
568 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
569 ftrace_tramps[i] = 0;
570 return;
571 }
572 }
573
add_ftrace_tramp(unsigned long tramp)574 static void __init add_ftrace_tramp(unsigned long tramp)
575 {
576 int i;
577
578 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
579 if (!ftrace_tramps[i]) {
580 ftrace_tramps[i] = tramp;
581 return;
582 }
583 }
584
ftrace_dyn_arch_init(void)585 int __init ftrace_dyn_arch_init(void)
586 {
587 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
588 unsigned long addr = FTRACE_REGS_ADDR;
589 long reladdr;
590 int i;
591 u32 stub_insns[] = {
592 #ifdef CONFIG_PPC_KERNEL_PCREL
593 /* pla r12,addr */
594 PPC_PREFIX_MLS | __PPC_PRFX_R(1),
595 PPC_INST_PADDI | ___PPC_RT(_R12),
596 PPC_RAW_MTCTR(_R12),
597 PPC_RAW_BCTR()
598 #elif defined(CONFIG_PPC64)
599 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
600 PPC_RAW_ADDIS(_R12, _R12, 0),
601 PPC_RAW_ADDI(_R12, _R12, 0),
602 PPC_RAW_MTCTR(_R12),
603 PPC_RAW_BCTR()
604 #else
605 PPC_RAW_LIS(_R12, 0),
606 PPC_RAW_ADDI(_R12, _R12, 0),
607 PPC_RAW_MTCTR(_R12),
608 PPC_RAW_BCTR()
609 #endif
610 };
611
612 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
613 for (i = 0; i < 2; i++) {
614 reladdr = addr - (unsigned long)tramp[i];
615
616 if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
617 pr_err("Address of %ps out of range of pcrel address.\n",
618 (void *)addr);
619 return -1;
620 }
621
622 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
623 tramp[i][0] |= IMM_H18(reladdr);
624 tramp[i][1] |= IMM_L(reladdr);
625 add_ftrace_tramp((unsigned long)tramp[i]);
626 }
627 } else if (IS_ENABLED(CONFIG_PPC64)) {
628 reladdr = addr - kernel_toc_addr();
629
630 if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
631 pr_err("Address of %ps out of range of kernel_toc.\n",
632 (void *)addr);
633 return -1;
634 }
635
636 for (i = 0; i < 2; i++) {
637 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
638 tramp[i][1] |= PPC_HA(reladdr);
639 tramp[i][2] |= PPC_LO(reladdr);
640 add_ftrace_tramp((unsigned long)tramp[i]);
641 }
642 } else {
643 for (i = 0; i < 2; i++) {
644 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
645 tramp[i][0] |= PPC_HA(addr);
646 tramp[i][1] |= PPC_LO(addr);
647 add_ftrace_tramp((unsigned long)tramp[i]);
648 }
649 }
650
651 return 0;
652 }
653
654 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
ftrace_graph_func(unsigned long ip,unsigned long parent_ip,struct ftrace_ops * op,struct ftrace_regs * fregs)655 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
656 struct ftrace_ops *op, struct ftrace_regs *fregs)
657 {
658 unsigned long sp = arch_ftrace_regs(fregs)->regs.gpr[1];
659
660 if (unlikely(ftrace_graph_is_dead()))
661 goto out;
662
663 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
664 goto out;
665
666 if (!function_graph_enter_regs(parent_ip, ip, 0, (unsigned long *)sp, fregs))
667 parent_ip = ppc_function_entry(return_to_handler);
668
669 out:
670 arch_ftrace_regs(fregs)->regs.link = parent_ip;
671 }
672 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
673