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
38 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
39 
40 unsigned long ftrace_call_adjust(unsigned long addr)
41 {
42 	return addr;
43 }
44 
45 static ppc_inst_t
46 ftrace_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 
58 static inline int
59 ftrace_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  */
89 static 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 
96 static int is_bl_op(ppc_inst_t op)
97 {
98 	return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
99 }
100 
101 static int is_b_op(ppc_inst_t op)
102 {
103 	return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
104 }
105 
106 static 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
119 static 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
216 static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
217 {
218 	return 0;
219 }
220 #endif /* CONFIG_MODULES */
221 
222 static 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 
239 static 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  */
258 static 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 
308 static 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 
347 int 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  */
399 static 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 
408 static 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
464 static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
465 {
466 	return 0;
467 }
468 #endif /* CONFIG_MODULES */
469 
470 static 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 
514 int 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
551 static 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
638 static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
639 {
640 	return 0;
641 }
642 #endif
643 
644 int 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 
683 int 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  */
708 void 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 
716 extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
717 
718 void 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 
729 int __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 
769 extern void ftrace_graph_call(void);
770 extern void ftrace_graph_stub(void);
771 
772 static 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 
788 int ftrace_enable_ftrace_graph_caller(void)
789 {
790 	return ftrace_modify_ftrace_graph_caller(true);
791 }
792 
793 int 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  */
802 static 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(&current->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);
824 out:
825 	return parent;
826 }
827 
828 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
829 void 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
835 unsigned 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
844 char *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 */
852