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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/asm-prototypes.h>
26 #include <asm/cacheflush.h>
27 #include <asm/code-patching.h>
28 #include <asm/ftrace.h>
29 #include <asm/syscall.h>
30 #include <asm/inst.h>
31 
32 
33 #ifdef CONFIG_DYNAMIC_FTRACE
34 
35 /*
36  * We generally only have a single long_branch tramp and at most 2 or 3 plt
37  * tramps generated. But, we don't use the plt tramps currently. We also allot
38  * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
39  * tramps in total. Set aside 8 just to be sure.
40  */
41 #define	NUM_FTRACE_TRAMPS	8
42 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
43 
44 static struct ppc_inst
ftrace_call_replace(unsigned long ip,unsigned long addr,int link)45 ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
46 {
47 	struct ppc_inst op;
48 
49 	addr = ppc_function_entry((void *)addr);
50 
51 	/* if (link) set op to 'bl' else 'b' */
52 	create_branch(&op, (struct ppc_inst *)ip, addr, link ? 1 : 0);
53 
54 	return op;
55 }
56 
57 static int
ftrace_modify_code(unsigned long ip,struct ppc_inst old,struct ppc_inst new)58 ftrace_modify_code(unsigned long ip, struct ppc_inst old, struct ppc_inst new)
59 {
60 	struct ppc_inst replaced;
61 
62 	/*
63 	 * Note:
64 	 * We are paranoid about modifying text, as if a bug was to happen, it
65 	 * could cause us to read or write to someplace that could cause harm.
66 	 * Carefully read and modify the code with probe_kernel_*(), and make
67 	 * sure what we read is what we expected it to be before modifying it.
68 	 */
69 
70 	/* read the text we want to modify */
71 	if (probe_kernel_read_inst(&replaced, (void *)ip))
72 		return -EFAULT;
73 
74 	/* Make sure it is what we expect it to be */
75 	if (!ppc_inst_equal(replaced, old)) {
76 		pr_err("%p: replaced (%s) != old (%s)",
77 		(void *)ip, ppc_inst_as_str(replaced), ppc_inst_as_str(old));
78 		return -EINVAL;
79 	}
80 
81 	/* replace the text with the new text */
82 	if (patch_instruction((struct ppc_inst *)ip, new))
83 		return -EPERM;
84 
85 	return 0;
86 }
87 
88 /*
89  * Helper functions that are the same for both PPC64 and PPC32.
90  */
test_24bit_addr(unsigned long ip,unsigned long addr)91 static int test_24bit_addr(unsigned long ip, unsigned long addr)
92 {
93 	struct ppc_inst op;
94 	addr = ppc_function_entry((void *)addr);
95 
96 	/* use the create_branch to verify that this offset can be branched */
97 	return create_branch(&op, (struct ppc_inst *)ip, addr, 0) == 0;
98 }
99 
is_bl_op(struct ppc_inst op)100 static int is_bl_op(struct ppc_inst op)
101 {
102 	return (ppc_inst_val(op) & 0xfc000003) == 0x48000001;
103 }
104 
is_b_op(struct ppc_inst op)105 static int is_b_op(struct ppc_inst op)
106 {
107 	return (ppc_inst_val(op) & 0xfc000003) == 0x48000000;
108 }
109 
find_bl_target(unsigned long ip,struct ppc_inst op)110 static unsigned long find_bl_target(unsigned long ip, struct ppc_inst op)
111 {
112 	int offset;
113 
114 	offset = (ppc_inst_val(op) & 0x03fffffc);
115 	/* make it signed */
116 	if (offset & 0x02000000)
117 		offset |= 0xfe000000;
118 
119 	return ip + (long)offset;
120 }
121 
122 #ifdef CONFIG_MODULES
123 #ifdef CONFIG_PPC64
124 static int
__ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)125 __ftrace_make_nop(struct module *mod,
126 		  struct dyn_ftrace *rec, unsigned long addr)
127 {
128 	unsigned long entry, ptr, tramp;
129 	unsigned long ip = rec->ip;
130 	struct ppc_inst op, pop;
131 
132 	/* read where this goes */
133 	if (probe_kernel_read_inst(&op, (void *)ip)) {
134 		pr_err("Fetching opcode failed.\n");
135 		return -EFAULT;
136 	}
137 
138 	/* Make sure that that this is still a 24bit jump */
139 	if (!is_bl_op(op)) {
140 		pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
141 		return -EINVAL;
142 	}
143 
144 	/* lets find where the pointer goes */
145 	tramp = find_bl_target(ip, op);
146 
147 	pr_devel("ip:%lx jumps to %lx", ip, tramp);
148 
149 	if (module_trampoline_target(mod, tramp, &ptr)) {
150 		pr_err("Failed to get trampoline target\n");
151 		return -EFAULT;
152 	}
153 
154 	pr_devel("trampoline target %lx", ptr);
155 
156 	entry = ppc_global_function_entry((void *)addr);
157 	/* This should match what was called */
158 	if (ptr != entry) {
159 		pr_err("addr %lx does not match expected %lx\n", ptr, entry);
160 		return -EINVAL;
161 	}
162 
163 #ifdef CONFIG_MPROFILE_KERNEL
164 	/* When using -mkernel_profile there is no load to jump over */
165 	pop = ppc_inst(PPC_INST_NOP);
166 
167 	if (probe_kernel_read_inst(&op, (void *)(ip - 4))) {
168 		pr_err("Fetching instruction at %lx failed.\n", ip - 4);
169 		return -EFAULT;
170 	}
171 
172 	/* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
173 	if (!ppc_inst_equal(op, ppc_inst(PPC_INST_MFLR)) &&
174 	    !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
175 		pr_err("Unexpected instruction %s around bl _mcount\n",
176 		       ppc_inst_as_str(op));
177 		return -EINVAL;
178 	}
179 #else
180 	/*
181 	 * Our original call site looks like:
182 	 *
183 	 * bl <tramp>
184 	 * ld r2,XX(r1)
185 	 *
186 	 * Milton Miller pointed out that we can not simply nop the branch.
187 	 * If a task was preempted when calling a trace function, the nops
188 	 * will remove the way to restore the TOC in r2 and the r2 TOC will
189 	 * get corrupted.
190 	 *
191 	 * Use a b +8 to jump over the load.
192 	 */
193 
194 	pop = ppc_inst(PPC_INST_BRANCH | 8);	/* b +8 */
195 
196 	/*
197 	 * Check what is in the next instruction. We can see ld r2,40(r1), but
198 	 * on first pass after boot we will see mflr r0.
199 	 */
200 	if (probe_kernel_read_inst(&op, (void *)(ip + 4))) {
201 		pr_err("Fetching op failed.\n");
202 		return -EFAULT;
203 	}
204 
205 	if (!ppc_inst_equal(op,  ppc_inst(PPC_INST_LD_TOC))) {
206 		pr_err("Expected %08x found %s\n", PPC_INST_LD_TOC, ppc_inst_as_str(op));
207 		return -EINVAL;
208 	}
209 #endif /* CONFIG_MPROFILE_KERNEL */
210 
211 	if (patch_instruction((struct ppc_inst *)ip, pop)) {
212 		pr_err("Patching NOP failed.\n");
213 		return -EPERM;
214 	}
215 
216 	return 0;
217 }
218 
219 #else /* !PPC64 */
220 static int
__ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)221 __ftrace_make_nop(struct module *mod,
222 		  struct dyn_ftrace *rec, unsigned long addr)
223 {
224 	struct ppc_inst op;
225 	unsigned int jmp[4];
226 	unsigned long ip = rec->ip;
227 	unsigned long tramp;
228 
229 	if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
230 		return -EFAULT;
231 
232 	/* Make sure that that this is still a 24bit jump */
233 	if (!is_bl_op(op)) {
234 		pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
235 		return -EINVAL;
236 	}
237 
238 	/* lets find where the pointer goes */
239 	tramp = find_bl_target(ip, op);
240 
241 	/*
242 	 * On PPC32 the trampoline looks like:
243 	 *  0x3d, 0x80, 0x00, 0x00  lis r12,sym@ha
244 	 *  0x39, 0x8c, 0x00, 0x00  addi r12,r12,sym@l
245 	 *  0x7d, 0x89, 0x03, 0xa6  mtctr r12
246 	 *  0x4e, 0x80, 0x04, 0x20  bctr
247 	 */
248 
249 	pr_devel("ip:%lx jumps to %lx", ip, tramp);
250 
251 	/* Find where the trampoline jumps to */
252 	if (copy_from_kernel_nofault(jmp, (void *)tramp, sizeof(jmp))) {
253 		pr_err("Failed to read %lx\n", tramp);
254 		return -EFAULT;
255 	}
256 
257 	pr_devel(" %08x %08x ", jmp[0], jmp[1]);
258 
259 	/* verify that this is what we expect it to be */
260 	if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
261 	    ((jmp[1] & 0xffff0000) != 0x398c0000) ||
262 	    (jmp[2] != 0x7d8903a6) ||
263 	    (jmp[3] != 0x4e800420)) {
264 		pr_err("Not a trampoline\n");
265 		return -EINVAL;
266 	}
267 
268 	tramp = (jmp[1] & 0xffff) |
269 		((jmp[0] & 0xffff) << 16);
270 	if (tramp & 0x8000)
271 		tramp -= 0x10000;
272 
273 	pr_devel(" %lx ", tramp);
274 
275 	if (tramp != addr) {
276 		pr_err("Trampoline location %08lx does not match addr\n",
277 		       tramp);
278 		return -EINVAL;
279 	}
280 
281 	op = ppc_inst(PPC_INST_NOP);
282 
283 	if (patch_instruction((struct ppc_inst *)ip, op))
284 		return -EPERM;
285 
286 	return 0;
287 }
288 #endif /* PPC64 */
289 #endif /* CONFIG_MODULES */
290 
find_ftrace_tramp(unsigned long ip)291 static unsigned long find_ftrace_tramp(unsigned long ip)
292 {
293 	int i;
294 	struct ppc_inst instr;
295 
296 	/*
297 	 * We have the compiler generated long_branch tramps at the end
298 	 * and we prefer those
299 	 */
300 	for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
301 		if (!ftrace_tramps[i])
302 			continue;
303 		else if (create_branch(&instr, (void *)ip,
304 				       ftrace_tramps[i], 0) == 0)
305 			return ftrace_tramps[i];
306 
307 	return 0;
308 }
309 
add_ftrace_tramp(unsigned long tramp)310 static int add_ftrace_tramp(unsigned long tramp)
311 {
312 	int i;
313 
314 	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
315 		if (!ftrace_tramps[i]) {
316 			ftrace_tramps[i] = tramp;
317 			return 0;
318 		}
319 
320 	return -1;
321 }
322 
323 /*
324  * If this is a compiler generated long_branch trampoline (essentially, a
325  * trampoline that has a branch to _mcount()), we re-write the branch to
326  * instead go to ftrace_[regs_]caller() and note down the location of this
327  * trampoline.
328  */
setup_mcount_compiler_tramp(unsigned long tramp)329 static int setup_mcount_compiler_tramp(unsigned long tramp)
330 {
331 	int i;
332 	struct ppc_inst op;
333 	unsigned long ptr;
334 	struct ppc_inst instr;
335 	static unsigned long ftrace_plt_tramps[NUM_FTRACE_TRAMPS];
336 
337 	/* Is this a known long jump tramp? */
338 	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
339 		if (ftrace_tramps[i] == tramp)
340 			return 0;
341 
342 	/* Is this a known plt tramp? */
343 	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
344 		if (!ftrace_plt_tramps[i])
345 			break;
346 		else if (ftrace_plt_tramps[i] == tramp)
347 			return -1;
348 
349 	/* New trampoline -- read where this goes */
350 	if (probe_kernel_read_inst(&op, (void *)tramp)) {
351 		pr_debug("Fetching opcode failed.\n");
352 		return -1;
353 	}
354 
355 	/* Is this a 24 bit branch? */
356 	if (!is_b_op(op)) {
357 		pr_debug("Trampoline is not a long branch tramp.\n");
358 		return -1;
359 	}
360 
361 	/* lets find where the pointer goes */
362 	ptr = find_bl_target(tramp, op);
363 
364 	if (ptr != ppc_global_function_entry((void *)_mcount)) {
365 		pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
366 		return -1;
367 	}
368 
369 	/* Let's re-write the tramp to go to ftrace_[regs_]caller */
370 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
371 	ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
372 #else
373 	ptr = ppc_global_function_entry((void *)ftrace_caller);
374 #endif
375 	if (create_branch(&instr, (void *)tramp, ptr, 0)) {
376 		pr_debug("%ps is not reachable from existing mcount tramp\n",
377 				(void *)ptr);
378 		return -1;
379 	}
380 
381 	if (patch_branch((struct ppc_inst *)tramp, ptr, 0)) {
382 		pr_debug("REL24 out of range!\n");
383 		return -1;
384 	}
385 
386 	if (add_ftrace_tramp(tramp)) {
387 		pr_debug("No tramp locations left\n");
388 		return -1;
389 	}
390 
391 	return 0;
392 }
393 
__ftrace_make_nop_kernel(struct dyn_ftrace * rec,unsigned long addr)394 static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
395 {
396 	unsigned long tramp, ip = rec->ip;
397 	struct ppc_inst op;
398 
399 	/* Read where this goes */
400 	if (probe_kernel_read_inst(&op, (void *)ip)) {
401 		pr_err("Fetching opcode failed.\n");
402 		return -EFAULT;
403 	}
404 
405 	/* Make sure that that this is still a 24bit jump */
406 	if (!is_bl_op(op)) {
407 		pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
408 		return -EINVAL;
409 	}
410 
411 	/* Let's find where the pointer goes */
412 	tramp = find_bl_target(ip, op);
413 
414 	pr_devel("ip:%lx jumps to %lx", ip, tramp);
415 
416 	if (setup_mcount_compiler_tramp(tramp)) {
417 		/* Are other trampolines reachable? */
418 		if (!find_ftrace_tramp(ip)) {
419 			pr_err("No ftrace trampolines reachable from %ps\n",
420 					(void *)ip);
421 			return -EINVAL;
422 		}
423 	}
424 
425 	if (patch_instruction((struct ppc_inst *)ip, ppc_inst(PPC_INST_NOP))) {
426 		pr_err("Patching NOP failed.\n");
427 		return -EPERM;
428 	}
429 
430 	return 0;
431 }
432 
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)433 int ftrace_make_nop(struct module *mod,
434 		    struct dyn_ftrace *rec, unsigned long addr)
435 {
436 	unsigned long ip = rec->ip;
437 	struct ppc_inst old, new;
438 
439 	/*
440 	 * If the calling address is more that 24 bits away,
441 	 * then we had to use a trampoline to make the call.
442 	 * Otherwise just update the call site.
443 	 */
444 	if (test_24bit_addr(ip, addr)) {
445 		/* within range */
446 		old = ftrace_call_replace(ip, addr, 1);
447 		new = ppc_inst(PPC_INST_NOP);
448 		return ftrace_modify_code(ip, old, new);
449 	} else if (core_kernel_text(ip))
450 		return __ftrace_make_nop_kernel(rec, addr);
451 
452 #ifdef CONFIG_MODULES
453 	/*
454 	 * Out of range jumps are called from modules.
455 	 * We should either already have a pointer to the module
456 	 * or it has been passed in.
457 	 */
458 	if (!rec->arch.mod) {
459 		if (!mod) {
460 			pr_err("No module loaded addr=%lx\n", addr);
461 			return -EFAULT;
462 		}
463 		rec->arch.mod = mod;
464 	} else if (mod) {
465 		if (mod != rec->arch.mod) {
466 			pr_err("Record mod %p not equal to passed in mod %p\n",
467 			       rec->arch.mod, mod);
468 			return -EINVAL;
469 		}
470 		/* nothing to do if mod == rec->arch.mod */
471 	} else
472 		mod = rec->arch.mod;
473 
474 	return __ftrace_make_nop(mod, rec, addr);
475 #else
476 	/* We should not get here without modules */
477 	return -EINVAL;
478 #endif /* CONFIG_MODULES */
479 }
480 
481 #ifdef CONFIG_MODULES
482 #ifdef CONFIG_PPC64
483 /*
484  * Examine the existing instructions for __ftrace_make_call.
485  * They should effectively be a NOP, and follow formal constraints,
486  * depending on the ABI. Return false if they don't.
487  */
488 #ifndef CONFIG_MPROFILE_KERNEL
489 static int
expected_nop_sequence(void * ip,struct ppc_inst op0,struct ppc_inst op1)490 expected_nop_sequence(void *ip, struct ppc_inst op0, struct ppc_inst op1)
491 {
492 	/*
493 	 * We expect to see:
494 	 *
495 	 * b +8
496 	 * ld r2,XX(r1)
497 	 *
498 	 * The load offset is different depending on the ABI. For simplicity
499 	 * just mask it out when doing the compare.
500 	 */
501 	if (!ppc_inst_equal(op0, ppc_inst(0x48000008)) ||
502 	    (ppc_inst_val(op1) & 0xffff0000) != 0xe8410000)
503 		return 0;
504 	return 1;
505 }
506 #else
507 static int
expected_nop_sequence(void * ip,struct ppc_inst op0,struct ppc_inst op1)508 expected_nop_sequence(void *ip, struct ppc_inst op0, struct ppc_inst op1)
509 {
510 	/* look for patched "NOP" on ppc64 with -mprofile-kernel */
511 	if (!ppc_inst_equal(op0, ppc_inst(PPC_INST_NOP)))
512 		return 0;
513 	return 1;
514 }
515 #endif
516 
517 static int
__ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)518 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
519 {
520 	struct ppc_inst op[2];
521 	struct ppc_inst instr;
522 	void *ip = (void *)rec->ip;
523 	unsigned long entry, ptr, tramp;
524 	struct module *mod = rec->arch.mod;
525 
526 	/* read where this goes */
527 	if (probe_kernel_read_inst(op, ip))
528 		return -EFAULT;
529 
530 	if (probe_kernel_read_inst(op + 1, ip + 4))
531 		return -EFAULT;
532 
533 	if (!expected_nop_sequence(ip, op[0], op[1])) {
534 		pr_err("Unexpected call sequence at %p: %s %s\n",
535 		ip, ppc_inst_as_str(op[0]), ppc_inst_as_str(op[1]));
536 		return -EINVAL;
537 	}
538 
539 	/* If we never set up ftrace trampoline(s), then bail */
540 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
541 	if (!mod->arch.tramp || !mod->arch.tramp_regs) {
542 #else
543 	if (!mod->arch.tramp) {
544 #endif
545 		pr_err("No ftrace trampoline\n");
546 		return -EINVAL;
547 	}
548 
549 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
550 	if (rec->flags & FTRACE_FL_REGS)
551 		tramp = mod->arch.tramp_regs;
552 	else
553 #endif
554 		tramp = mod->arch.tramp;
555 
556 	if (module_trampoline_target(mod, tramp, &ptr)) {
557 		pr_err("Failed to get trampoline target\n");
558 		return -EFAULT;
559 	}
560 
561 	pr_devel("trampoline target %lx", ptr);
562 
563 	entry = ppc_global_function_entry((void *)addr);
564 	/* This should match what was called */
565 	if (ptr != entry) {
566 		pr_err("addr %lx does not match expected %lx\n", ptr, entry);
567 		return -EINVAL;
568 	}
569 
570 	/* Ensure branch is within 24 bits */
571 	if (create_branch(&instr, ip, tramp, BRANCH_SET_LINK)) {
572 		pr_err("Branch out of range\n");
573 		return -EINVAL;
574 	}
575 
576 	if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
577 		pr_err("REL24 out of range!\n");
578 		return -EINVAL;
579 	}
580 
581 	return 0;
582 }
583 
584 #else  /* !CONFIG_PPC64: */
585 static int
586 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
587 {
588 	int err;
589 	struct ppc_inst op;
590 	unsigned long ip = rec->ip;
591 
592 	/* read where this goes */
593 	if (probe_kernel_read_inst(&op, (void *)ip))
594 		return -EFAULT;
595 
596 	/* It should be pointing to a nop */
597 	if (!ppc_inst_equal(op,  ppc_inst(PPC_INST_NOP))) {
598 		pr_err("Expected NOP but have %s\n", ppc_inst_as_str(op));
599 		return -EINVAL;
600 	}
601 
602 	/* If we never set up a trampoline to ftrace_caller, then bail */
603 	if (!rec->arch.mod->arch.tramp) {
604 		pr_err("No ftrace trampoline\n");
605 		return -EINVAL;
606 	}
607 
608 	/* create the branch to the trampoline */
609 	err = create_branch(&op, (struct ppc_inst *)ip,
610 			    rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
611 	if (err) {
612 		pr_err("REL24 out of range!\n");
613 		return -EINVAL;
614 	}
615 
616 	pr_devel("write to %lx\n", rec->ip);
617 
618 	if (patch_instruction((struct ppc_inst *)ip, op))
619 		return -EPERM;
620 
621 	return 0;
622 }
623 #endif /* CONFIG_PPC64 */
624 #endif /* CONFIG_MODULES */
625 
626 static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
627 {
628 	struct ppc_inst op;
629 	void *ip = (void *)rec->ip;
630 	unsigned long tramp, entry, ptr;
631 
632 	/* Make sure we're being asked to patch branch to a known ftrace addr */
633 	entry = ppc_global_function_entry((void *)ftrace_caller);
634 	ptr = ppc_global_function_entry((void *)addr);
635 
636 	if (ptr != entry) {
637 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
638 		entry = ppc_global_function_entry((void *)ftrace_regs_caller);
639 		if (ptr != entry) {
640 #endif
641 			pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
642 			return -EINVAL;
643 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
644 		}
645 #endif
646 	}
647 
648 	/* Make sure we have a nop */
649 	if (probe_kernel_read_inst(&op, ip)) {
650 		pr_err("Unable to read ftrace location %p\n", ip);
651 		return -EFAULT;
652 	}
653 
654 	if (!ppc_inst_equal(op, ppc_inst(PPC_INST_NOP))) {
655 		pr_err("Unexpected call sequence at %p: %s\n", ip, ppc_inst_as_str(op));
656 		return -EINVAL;
657 	}
658 
659 	tramp = find_ftrace_tramp((unsigned long)ip);
660 	if (!tramp) {
661 		pr_err("No ftrace trampolines reachable from %ps\n", ip);
662 		return -EINVAL;
663 	}
664 
665 	if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
666 		pr_err("Error patching branch to ftrace tramp!\n");
667 		return -EINVAL;
668 	}
669 
670 	return 0;
671 }
672 
673 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
674 {
675 	unsigned long ip = rec->ip;
676 	struct ppc_inst old, new;
677 
678 	/*
679 	 * If the calling address is more that 24 bits away,
680 	 * then we had to use a trampoline to make the call.
681 	 * Otherwise just update the call site.
682 	 */
683 	if (test_24bit_addr(ip, addr)) {
684 		/* within range */
685 		old = ppc_inst(PPC_INST_NOP);
686 		new = ftrace_call_replace(ip, addr, 1);
687 		return ftrace_modify_code(ip, old, new);
688 	} else if (core_kernel_text(ip))
689 		return __ftrace_make_call_kernel(rec, addr);
690 
691 #ifdef CONFIG_MODULES
692 	/*
693 	 * Out of range jumps are called from modules.
694 	 * Being that we are converting from nop, it had better
695 	 * already have a module defined.
696 	 */
697 	if (!rec->arch.mod) {
698 		pr_err("No module loaded\n");
699 		return -EINVAL;
700 	}
701 
702 	return __ftrace_make_call(rec, addr);
703 #else
704 	/* We should not get here without modules */
705 	return -EINVAL;
706 #endif /* CONFIG_MODULES */
707 }
708 
709 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
710 #ifdef CONFIG_MODULES
711 static int
712 __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
713 					unsigned long addr)
714 {
715 	struct ppc_inst op;
716 	unsigned long ip = rec->ip;
717 	unsigned long entry, ptr, tramp;
718 	struct module *mod = rec->arch.mod;
719 
720 	/* If we never set up ftrace trampolines, then bail */
721 	if (!mod->arch.tramp || !mod->arch.tramp_regs) {
722 		pr_err("No ftrace trampoline\n");
723 		return -EINVAL;
724 	}
725 
726 	/* read where this goes */
727 	if (probe_kernel_read_inst(&op, (void *)ip)) {
728 		pr_err("Fetching opcode failed.\n");
729 		return -EFAULT;
730 	}
731 
732 	/* Make sure that that this is still a 24bit jump */
733 	if (!is_bl_op(op)) {
734 		pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
735 		return -EINVAL;
736 	}
737 
738 	/* lets find where the pointer goes */
739 	tramp = find_bl_target(ip, op);
740 	entry = ppc_global_function_entry((void *)old_addr);
741 
742 	pr_devel("ip:%lx jumps to %lx", ip, tramp);
743 
744 	if (tramp != entry) {
745 		/* old_addr is not within range, so we must have used a trampoline */
746 		if (module_trampoline_target(mod, tramp, &ptr)) {
747 			pr_err("Failed to get trampoline target\n");
748 			return -EFAULT;
749 		}
750 
751 		pr_devel("trampoline target %lx", ptr);
752 
753 		/* This should match what was called */
754 		if (ptr != entry) {
755 			pr_err("addr %lx does not match expected %lx\n", ptr, entry);
756 			return -EINVAL;
757 		}
758 	}
759 
760 	/* The new target may be within range */
761 	if (test_24bit_addr(ip, addr)) {
762 		/* within range */
763 		if (patch_branch((struct ppc_inst *)ip, addr, BRANCH_SET_LINK)) {
764 			pr_err("REL24 out of range!\n");
765 			return -EINVAL;
766 		}
767 
768 		return 0;
769 	}
770 
771 	if (rec->flags & FTRACE_FL_REGS)
772 		tramp = mod->arch.tramp_regs;
773 	else
774 		tramp = mod->arch.tramp;
775 
776 	if (module_trampoline_target(mod, tramp, &ptr)) {
777 		pr_err("Failed to get trampoline target\n");
778 		return -EFAULT;
779 	}
780 
781 	pr_devel("trampoline target %lx", ptr);
782 
783 	entry = ppc_global_function_entry((void *)addr);
784 	/* This should match what was called */
785 	if (ptr != entry) {
786 		pr_err("addr %lx does not match expected %lx\n", ptr, entry);
787 		return -EINVAL;
788 	}
789 
790 	/* Ensure branch is within 24 bits */
791 	if (create_branch(&op, (struct ppc_inst *)ip, tramp, BRANCH_SET_LINK)) {
792 		pr_err("Branch out of range\n");
793 		return -EINVAL;
794 	}
795 
796 	if (patch_branch((struct ppc_inst *)ip, tramp, BRANCH_SET_LINK)) {
797 		pr_err("REL24 out of range!\n");
798 		return -EINVAL;
799 	}
800 
801 	return 0;
802 }
803 #endif
804 
805 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
806 			unsigned long addr)
807 {
808 	unsigned long ip = rec->ip;
809 	struct ppc_inst old, new;
810 
811 	/*
812 	 * If the calling address is more that 24 bits away,
813 	 * then we had to use a trampoline to make the call.
814 	 * Otherwise just update the call site.
815 	 */
816 	if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
817 		/* within range */
818 		old = ftrace_call_replace(ip, old_addr, 1);
819 		new = ftrace_call_replace(ip, addr, 1);
820 		return ftrace_modify_code(ip, old, new);
821 	} else if (core_kernel_text(ip)) {
822 		/*
823 		 * We always patch out of range locations to go to the regs
824 		 * variant, so there is nothing to do here
825 		 */
826 		return 0;
827 	}
828 
829 #ifdef CONFIG_MODULES
830 	/*
831 	 * Out of range jumps are called from modules.
832 	 */
833 	if (!rec->arch.mod) {
834 		pr_err("No module loaded\n");
835 		return -EINVAL;
836 	}
837 
838 	return __ftrace_modify_call(rec, old_addr, addr);
839 #else
840 	/* We should not get here without modules */
841 	return -EINVAL;
842 #endif /* CONFIG_MODULES */
843 }
844 #endif
845 
846 int ftrace_update_ftrace_func(ftrace_func_t func)
847 {
848 	unsigned long ip = (unsigned long)(&ftrace_call);
849 	struct ppc_inst old, new;
850 	int ret;
851 
852 	old = ppc_inst_read((struct ppc_inst *)&ftrace_call);
853 	new = ftrace_call_replace(ip, (unsigned long)func, 1);
854 	ret = ftrace_modify_code(ip, old, new);
855 
856 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
857 	/* Also update the regs callback function */
858 	if (!ret) {
859 		ip = (unsigned long)(&ftrace_regs_call);
860 		old = ppc_inst_read((struct ppc_inst *)&ftrace_regs_call);
861 		new = ftrace_call_replace(ip, (unsigned long)func, 1);
862 		ret = ftrace_modify_code(ip, old, new);
863 	}
864 #endif
865 
866 	return ret;
867 }
868 
869 /*
870  * Use the default ftrace_modify_all_code, but without
871  * stop_machine().
872  */
873 void arch_ftrace_update_code(int command)
874 {
875 	ftrace_modify_all_code(command);
876 }
877 
878 #ifdef CONFIG_PPC64
879 #define PACATOC offsetof(struct paca_struct, kernel_toc)
880 
881 extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
882 
883 void ftrace_free_init_tramp(void)
884 {
885 	int i;
886 
887 	for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
888 		if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
889 			ftrace_tramps[i] = 0;
890 			return;
891 		}
892 }
893 
894 int __init ftrace_dyn_arch_init(void)
895 {
896 	int i;
897 	unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
898 	u32 stub_insns[] = {
899 		0xe98d0000 | PACATOC,	/* ld      r12,PACATOC(r13)	*/
900 		0x3d8c0000,		/* addis   r12,r12,<high>	*/
901 		0x398c0000,		/* addi    r12,r12,<low>	*/
902 		0x7d8903a6,		/* mtctr   r12			*/
903 		0x4e800420,		/* bctr				*/
904 	};
905 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
906 	unsigned long addr = ppc_global_function_entry((void *)ftrace_regs_caller);
907 #else
908 	unsigned long addr = ppc_global_function_entry((void *)ftrace_caller);
909 #endif
910 	long reladdr = addr - kernel_toc_addr();
911 
912 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
913 		pr_err("Address of %ps out of range of kernel_toc.\n",
914 				(void *)addr);
915 		return -1;
916 	}
917 
918 	for (i = 0; i < 2; i++) {
919 		memcpy(tramp[i], stub_insns, sizeof(stub_insns));
920 		tramp[i][1] |= PPC_HA(reladdr);
921 		tramp[i][2] |= PPC_LO(reladdr);
922 		add_ftrace_tramp((unsigned long)tramp[i]);
923 	}
924 
925 	return 0;
926 }
927 #else
928 int __init ftrace_dyn_arch_init(void)
929 {
930 	return 0;
931 }
932 #endif
933 #endif /* CONFIG_DYNAMIC_FTRACE */
934 
935 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
936 
937 extern void ftrace_graph_call(void);
938 extern void ftrace_graph_stub(void);
939 
940 int ftrace_enable_ftrace_graph_caller(void)
941 {
942 	unsigned long ip = (unsigned long)(&ftrace_graph_call);
943 	unsigned long addr = (unsigned long)(&ftrace_graph_caller);
944 	unsigned long stub = (unsigned long)(&ftrace_graph_stub);
945 	struct ppc_inst old, new;
946 
947 	old = ftrace_call_replace(ip, stub, 0);
948 	new = ftrace_call_replace(ip, addr, 0);
949 
950 	return ftrace_modify_code(ip, old, new);
951 }
952 
953 int ftrace_disable_ftrace_graph_caller(void)
954 {
955 	unsigned long ip = (unsigned long)(&ftrace_graph_call);
956 	unsigned long addr = (unsigned long)(&ftrace_graph_caller);
957 	unsigned long stub = (unsigned long)(&ftrace_graph_stub);
958 	struct ppc_inst old, new;
959 
960 	old = ftrace_call_replace(ip, addr, 0);
961 	new = ftrace_call_replace(ip, stub, 0);
962 
963 	return ftrace_modify_code(ip, old, new);
964 }
965 
966 /*
967  * Hook the return address and push it in the stack of return addrs
968  * in current thread info. Return the address we want to divert to.
969  */
970 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
971 						unsigned long sp)
972 {
973 	unsigned long return_hooker;
974 
975 	if (unlikely(ftrace_graph_is_dead()))
976 		goto out;
977 
978 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
979 		goto out;
980 
981 	return_hooker = ppc_function_entry(return_to_handler);
982 
983 	if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
984 		parent = return_hooker;
985 out:
986 	return parent;
987 }
988 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
989 
990 #ifdef PPC64_ELF_ABI_v1
991 char *arch_ftrace_match_adjust(char *str, const char *search)
992 {
993 	if (str[0] == '.' && search[0] != '.')
994 		return str + 1;
995 	else
996 		return str;
997 }
998 #endif /* PPC64_ELF_ABI_v1 */
999