1 // SPDX-License-Identifier: GPL-2.0
3 * Code for replacing ftrace calls with jumps.
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
7 * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
9 * Added function graph tracer code, taken from x86 that was written
10 * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
14 #define pr_fmt(fmt) "ftrace-powerpc: " fmt
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>
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>
32 #ifdef CONFIG_DYNAMIC_FTRACE
34 ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
38 addr = ppc_function_entry((void *)addr);
40 /* if (link) set op to 'bl' else 'b' */
41 op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
47 ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
49 unsigned int replaced;
53 * We are paranoid about modifying text, as if a bug was to happen, it
54 * could cause us to read or write to someplace that could cause harm.
55 * Carefully read and modify the code with probe_kernel_*(), and make
56 * sure what we read is what we expected it to be before modifying it.
59 /* read the text we want to modify */
60 if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
63 /* Make sure it is what we expect it to be */
64 if (replaced != old) {
65 pr_err("%p: replaced (%#x) != old (%#x)",
66 (void *)ip, replaced, old);
70 /* replace the text with the new text */
71 if (patch_instruction((unsigned int *)ip, new))
78 * Helper functions that are the same for both PPC64 and PPC32.
80 static int test_24bit_addr(unsigned long ip, unsigned long addr)
82 addr = ppc_function_entry((void *)addr);
84 /* use the create_branch to verify that this offset can be branched */
85 return create_branch((unsigned int *)ip, addr, 0);
90 static int is_bl_op(unsigned int op)
92 return (op & 0xfc000003) == 0x48000001;
95 static unsigned long find_bl_target(unsigned long ip, unsigned int op)
99 offset = (op & 0x03fffffc);
101 if (offset & 0x02000000)
102 offset |= 0xfe000000;
104 return ip + (long)offset;
109 __ftrace_make_nop(struct module *mod,
110 struct dyn_ftrace *rec, unsigned long addr)
112 unsigned long entry, ptr, tramp;
113 unsigned long ip = rec->ip;
114 unsigned int op, pop;
116 /* read where this goes */
117 if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
118 pr_err("Fetching opcode failed.\n");
122 /* Make sure that that this is still a 24bit jump */
124 pr_err("Not expected bl: opcode is %x\n", op);
128 /* lets find where the pointer goes */
129 tramp = find_bl_target(ip, op);
131 pr_devel("ip:%lx jumps to %lx", ip, tramp);
133 if (module_trampoline_target(mod, tramp, &ptr)) {
134 pr_err("Failed to get trampoline target\n");
138 pr_devel("trampoline target %lx", ptr);
140 entry = ppc_global_function_entry((void *)addr);
141 /* This should match what was called */
143 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
147 #ifdef CONFIG_MPROFILE_KERNEL
148 /* When using -mkernel_profile there is no load to jump over */
151 if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {
152 pr_err("Fetching instruction at %lx failed.\n", ip - 4);
156 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
157 if (op != PPC_INST_MFLR && op != PPC_INST_STD_LR) {
158 pr_err("Unexpected instruction %08x around bl _mcount\n", op);
163 * Our original call site looks like:
168 * Milton Miller pointed out that we can not simply nop the branch.
169 * If a task was preempted when calling a trace function, the nops
170 * will remove the way to restore the TOC in r2 and the r2 TOC will
173 * Use a b +8 to jump over the load.
176 pop = PPC_INST_BRANCH | 8; /* b +8 */
179 * Check what is in the next instruction. We can see ld r2,40(r1), but
180 * on first pass after boot we will see mflr r0.
182 if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {
183 pr_err("Fetching op failed.\n");
187 if (op != PPC_INST_LD_TOC) {
188 pr_err("Expected %08x found %08x\n", PPC_INST_LD_TOC, op);
191 #endif /* CONFIG_MPROFILE_KERNEL */
193 if (patch_instruction((unsigned int *)ip, pop)) {
194 pr_err("Patching NOP failed.\n");
203 __ftrace_make_nop(struct module *mod,
204 struct dyn_ftrace *rec, unsigned long addr)
208 unsigned long ip = rec->ip;
211 if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
214 /* Make sure that that this is still a 24bit jump */
216 pr_err("Not expected bl: opcode is %x\n", op);
220 /* lets find where the pointer goes */
221 tramp = find_bl_target(ip, op);
224 * On PPC32 the trampoline looks like:
225 * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
226 * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
227 * 0x7d, 0x89, 0x03, 0xa6 mtctr r12
228 * 0x4e, 0x80, 0x04, 0x20 bctr
231 pr_devel("ip:%lx jumps to %lx", ip, tramp);
233 /* Find where the trampoline jumps to */
234 if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
235 pr_err("Failed to read %lx\n", tramp);
239 pr_devel(" %08x %08x ", jmp[0], jmp[1]);
241 /* verify that this is what we expect it to be */
242 if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
243 ((jmp[1] & 0xffff0000) != 0x398c0000) ||
244 (jmp[2] != 0x7d8903a6) ||
245 (jmp[3] != 0x4e800420)) {
246 pr_err("Not a trampoline\n");
250 tramp = (jmp[1] & 0xffff) |
251 ((jmp[0] & 0xffff) << 16);
255 pr_devel(" %lx ", tramp);
258 pr_err("Trampoline location %08lx does not match addr\n",
265 if (patch_instruction((unsigned int *)ip, op))
271 #endif /* CONFIG_MODULES */
273 int ftrace_make_nop(struct module *mod,
274 struct dyn_ftrace *rec, unsigned long addr)
276 unsigned long ip = rec->ip;
277 unsigned int old, new;
280 * If the calling address is more that 24 bits away,
281 * then we had to use a trampoline to make the call.
282 * Otherwise just update the call site.
284 if (test_24bit_addr(ip, addr)) {
286 old = ftrace_call_replace(ip, addr, 1);
288 return ftrace_modify_code(ip, old, new);
291 #ifdef CONFIG_MODULES
293 * Out of range jumps are called from modules.
294 * We should either already have a pointer to the module
295 * or it has been passed in.
297 if (!rec->arch.mod) {
299 pr_err("No module loaded addr=%lx\n", addr);
304 if (mod != rec->arch.mod) {
305 pr_err("Record mod %p not equal to passed in mod %p\n",
309 /* nothing to do if mod == rec->arch.mod */
313 return __ftrace_make_nop(mod, rec, addr);
315 /* We should not get here without modules */
317 #endif /* CONFIG_MODULES */
320 #ifdef CONFIG_MODULES
323 * Examine the existing instructions for __ftrace_make_call.
324 * They should effectively be a NOP, and follow formal constraints,
325 * depending on the ABI. Return false if they don't.
327 #ifndef CONFIG_MPROFILE_KERNEL
329 expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1)
337 * The load offset is different depending on the ABI. For simplicity
338 * just mask it out when doing the compare.
340 if ((op0 != 0x48000008) || ((op1 & 0xffff0000) != 0xe8410000))
346 expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1)
348 /* look for patched "NOP" on ppc64 with -mprofile-kernel */
349 if (op0 != PPC_INST_NOP)
356 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
359 void *ip = (void *)rec->ip;
360 unsigned long entry, ptr, tramp;
361 struct module *mod = rec->arch.mod;
363 /* read where this goes */
364 if (probe_kernel_read(op, ip, sizeof(op)))
367 if (!expected_nop_sequence(ip, op[0], op[1])) {
368 pr_err("Unexpected call sequence at %p: %x %x\n",
373 /* If we never set up ftrace trampoline(s), then bail */
374 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
375 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
377 if (!mod->arch.tramp) {
379 pr_err("No ftrace trampoline\n");
383 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
384 if (rec->flags & FTRACE_FL_REGS)
385 tramp = mod->arch.tramp_regs;
388 tramp = mod->arch.tramp;
390 if (module_trampoline_target(mod, tramp, &ptr)) {
391 pr_err("Failed to get trampoline target\n");
395 pr_devel("trampoline target %lx", ptr);
397 entry = ppc_global_function_entry((void *)addr);
398 /* This should match what was called */
400 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
404 /* Ensure branch is within 24 bits */
405 if (!create_branch(ip, tramp, BRANCH_SET_LINK)) {
406 pr_err("Branch out of range\n");
410 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
411 pr_err("REL24 out of range!\n");
418 #else /* !CONFIG_PPC64: */
420 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
423 unsigned long ip = rec->ip;
425 /* read where this goes */
426 if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
429 /* It should be pointing to a nop */
430 if (op != PPC_INST_NOP) {
431 pr_err("Expected NOP but have %x\n", op);
435 /* If we never set up a trampoline to ftrace_caller, then bail */
436 if (!rec->arch.mod->arch.tramp) {
437 pr_err("No ftrace trampoline\n");
441 /* create the branch to the trampoline */
442 op = create_branch((unsigned int *)ip,
443 rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
445 pr_err("REL24 out of range!\n");
449 pr_devel("write to %lx\n", rec->ip);
451 if (patch_instruction((unsigned int *)ip, op))
456 #endif /* CONFIG_PPC64 */
457 #endif /* CONFIG_MODULES */
459 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
461 unsigned long ip = rec->ip;
462 unsigned int old, new;
465 * If the calling address is more that 24 bits away,
466 * then we had to use a trampoline to make the call.
467 * Otherwise just update the call site.
469 if (test_24bit_addr(ip, addr)) {
472 new = ftrace_call_replace(ip, addr, 1);
473 return ftrace_modify_code(ip, old, new);
476 #ifdef CONFIG_MODULES
478 * Out of range jumps are called from modules.
479 * Being that we are converting from nop, it had better
480 * already have a module defined.
482 if (!rec->arch.mod) {
483 pr_err("No module loaded\n");
487 return __ftrace_make_call(rec, addr);
489 /* We should not get here without modules */
491 #endif /* CONFIG_MODULES */
494 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
495 #ifdef CONFIG_MODULES
497 __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
501 unsigned long ip = rec->ip;
502 unsigned long entry, ptr, tramp;
503 struct module *mod = rec->arch.mod;
505 /* If we never set up ftrace trampolines, then bail */
506 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
507 pr_err("No ftrace trampoline\n");
511 /* read where this goes */
512 if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
513 pr_err("Fetching opcode failed.\n");
517 /* Make sure that that this is still a 24bit jump */
519 pr_err("Not expected bl: opcode is %x\n", op);
523 /* lets find where the pointer goes */
524 tramp = find_bl_target(ip, op);
525 entry = ppc_global_function_entry((void *)old_addr);
527 pr_devel("ip:%lx jumps to %lx", ip, tramp);
529 if (tramp != entry) {
530 /* old_addr is not within range, so we must have used a trampoline */
531 if (module_trampoline_target(mod, tramp, &ptr)) {
532 pr_err("Failed to get trampoline target\n");
536 pr_devel("trampoline target %lx", ptr);
538 /* This should match what was called */
540 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
545 /* The new target may be within range */
546 if (test_24bit_addr(ip, addr)) {
548 if (patch_branch((unsigned int *)ip, addr, BRANCH_SET_LINK)) {
549 pr_err("REL24 out of range!\n");
556 if (rec->flags & FTRACE_FL_REGS)
557 tramp = mod->arch.tramp_regs;
559 tramp = mod->arch.tramp;
561 if (module_trampoline_target(mod, tramp, &ptr)) {
562 pr_err("Failed to get trampoline target\n");
566 pr_devel("trampoline target %lx", ptr);
568 entry = ppc_global_function_entry((void *)addr);
569 /* This should match what was called */
571 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
575 /* Ensure branch is within 24 bits */
576 if (!create_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) {
577 pr_err("Branch out of range\n");
581 if (patch_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) {
582 pr_err("REL24 out of range!\n");
590 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
593 unsigned long ip = rec->ip;
594 unsigned int old, new;
597 * If the calling address is more that 24 bits away,
598 * then we had to use a trampoline to make the call.
599 * Otherwise just update the call site.
601 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
603 old = ftrace_call_replace(ip, old_addr, 1);
604 new = ftrace_call_replace(ip, addr, 1);
605 return ftrace_modify_code(ip, old, new);
608 #ifdef CONFIG_MODULES
610 * Out of range jumps are called from modules.
612 if (!rec->arch.mod) {
613 pr_err("No module loaded\n");
617 return __ftrace_modify_call(rec, old_addr, addr);
619 /* We should not get here without modules */
621 #endif /* CONFIG_MODULES */
625 int ftrace_update_ftrace_func(ftrace_func_t func)
627 unsigned long ip = (unsigned long)(&ftrace_call);
628 unsigned int old, new;
631 old = *(unsigned int *)&ftrace_call;
632 new = ftrace_call_replace(ip, (unsigned long)func, 1);
633 ret = ftrace_modify_code(ip, old, new);
635 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
636 /* Also update the regs callback function */
638 ip = (unsigned long)(&ftrace_regs_call);
639 old = *(unsigned int *)&ftrace_regs_call;
640 new = ftrace_call_replace(ip, (unsigned long)func, 1);
641 ret = ftrace_modify_code(ip, old, new);
649 * Use the default ftrace_modify_all_code, but without
652 void arch_ftrace_update_code(int command)
654 ftrace_modify_all_code(command);
657 int __init ftrace_dyn_arch_init(void)
661 #endif /* CONFIG_DYNAMIC_FTRACE */
663 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
665 extern void ftrace_graph_call(void);
666 extern void ftrace_graph_stub(void);
668 int ftrace_enable_ftrace_graph_caller(void)
670 unsigned long ip = (unsigned long)(&ftrace_graph_call);
671 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
672 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
673 unsigned int old, new;
675 old = ftrace_call_replace(ip, stub, 0);
676 new = ftrace_call_replace(ip, addr, 0);
678 return ftrace_modify_code(ip, old, new);
681 int ftrace_disable_ftrace_graph_caller(void)
683 unsigned long ip = (unsigned long)(&ftrace_graph_call);
684 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
685 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
686 unsigned int old, new;
688 old = ftrace_call_replace(ip, addr, 0);
689 new = ftrace_call_replace(ip, stub, 0);
691 return ftrace_modify_code(ip, old, new);
695 * Hook the return address and push it in the stack of return addrs
696 * in current thread info. Return the address we want to divert to.
698 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
700 unsigned long return_hooker;
702 if (unlikely(ftrace_graph_is_dead()))
705 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
708 return_hooker = ppc_function_entry(return_to_handler);
710 if (!function_graph_enter(parent, ip, 0, NULL))
711 parent = return_hooker;
715 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
717 #if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64)
718 unsigned long __init arch_syscall_addr(int nr)
720 return sys_call_table[nr*2];
722 #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 */
724 #ifdef PPC64_ELF_ABI_v1
725 char *arch_ftrace_match_adjust(char *str, const char *search)
727 if (str[0] == '.' && search[0] != '.')
732 #endif /* PPC64_ELF_ABI_v1 */