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(&current->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