1 // SPDX-License-Identifier: GPL-2.0
3 * Dynamic function tracing support.
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
7 * Thanks goes to Ingo Molnar, for suggesting the idea.
8 * Mathieu Desnoyers, for suggesting postponing the modifications.
9 * Arjan van de Ven, for keeping me straight, and explaining to me
10 * the dangers of modifying code on the run.
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/spinlock.h>
16 #include <linux/hardirq.h>
17 #include <linux/uaccess.h>
18 #include <linux/ftrace.h>
19 #include <linux/percpu.h>
20 #include <linux/sched.h>
21 #include <linux/slab.h>
22 #include <linux/init.h>
23 #include <linux/list.h>
24 #include <linux/module.h>
25 #include <linux/memory.h>
27 #include <trace/syscall.h>
29 #include <asm/set_memory.h>
30 #include <asm/kprobes.h>
31 #include <asm/ftrace.h>
33 #include <asm/text-patching.h>
35 #ifdef CONFIG_DYNAMIC_FTRACE
37 int ftrace_arch_code_modify_prepare(void)
38 __acquires(&text_mutex)
40 mutex_lock(&text_mutex);
42 set_all_modules_text_rw();
46 int ftrace_arch_code_modify_post_process(void)
47 __releases(&text_mutex)
49 set_all_modules_text_ro();
51 mutex_unlock(&text_mutex);
55 union ftrace_code_union {
56 char code[MCOUNT_INSN_SIZE];
60 } __attribute__((packed));
63 static int ftrace_calc_offset(long ip, long addr)
65 return (int)(addr - ip);
68 static unsigned char *
69 ftrace_text_replace(unsigned char op, unsigned long ip, unsigned long addr)
71 static union ftrace_code_union calc;
74 calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
79 static unsigned char *
80 ftrace_call_replace(unsigned long ip, unsigned long addr)
82 return ftrace_text_replace(0xe8, ip, addr);
86 within(unsigned long addr, unsigned long start, unsigned long end)
88 return addr >= start && addr < end;
91 static unsigned long text_ip_addr(unsigned long ip)
94 * On x86_64, kernel text mappings are mapped read-only, so we use
95 * the kernel identity mapping instead of the kernel text mapping
96 * to modify the kernel text.
98 * For 32bit kernels, these mappings are same and we can use
99 * kernel identity mapping to modify code.
101 if (within(ip, (unsigned long)_text, (unsigned long)_etext))
102 ip = (unsigned long)__va(__pa_symbol(ip));
107 static const unsigned char *ftrace_nop_replace(void)
109 return ideal_nops[NOP_ATOMIC5];
113 ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
114 unsigned const char *new_code)
116 unsigned char replaced[MCOUNT_INSN_SIZE];
118 ftrace_expected = old_code;
122 * We are paranoid about modifying text, as if a bug was to happen, it
123 * could cause us to read or write to someplace that could cause harm.
124 * Carefully read and modify the code with probe_kernel_*(), and make
125 * sure what we read is what we expected it to be before modifying it.
128 /* read the text we want to modify */
129 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
132 /* Make sure it is what we expect it to be */
133 if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
136 ip = text_ip_addr(ip);
138 /* replace the text with the new text */
139 if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
147 int ftrace_make_nop(struct module *mod,
148 struct dyn_ftrace *rec, unsigned long addr)
150 unsigned const char *new, *old;
151 unsigned long ip = rec->ip;
153 old = ftrace_call_replace(ip, addr);
154 new = ftrace_nop_replace();
157 * On boot up, and when modules are loaded, the MCOUNT_ADDR
158 * is converted to a nop, and will never become MCOUNT_ADDR
159 * again. This code is either running before SMP (on boot up)
160 * or before the code will ever be executed (module load).
161 * We do not want to use the breakpoint version in this case,
162 * just modify the code directly.
164 if (addr == MCOUNT_ADDR)
165 return ftrace_modify_code_direct(rec->ip, old, new);
167 ftrace_expected = NULL;
169 /* Normal cases use add_brk_on_nop */
170 WARN_ONCE(1, "invalid use of ftrace_make_nop");
174 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
176 unsigned const char *new, *old;
177 unsigned long ip = rec->ip;
179 old = ftrace_nop_replace();
180 new = ftrace_call_replace(ip, addr);
182 /* Should only be called when module is loaded */
183 return ftrace_modify_code_direct(rec->ip, old, new);
187 * The modifying_ftrace_code is used to tell the breakpoint
188 * handler to call ftrace_int3_handler(). If it fails to
189 * call this handler for a breakpoint added by ftrace, then
190 * the kernel may crash.
192 * As atomic_writes on x86 do not need a barrier, we do not
193 * need to add smp_mb()s for this to work. It is also considered
194 * that we can not read the modifying_ftrace_code before
195 * executing the breakpoint. That would be quite remarkable if
196 * it could do that. Here's the flow that is required:
202 * <trap-int3> // implicit (r)mb
203 * if (atomic_read(mfc))
204 * call ftrace_int3_handler()
206 * Then when we are finished:
210 * If we hit a breakpoint that was not set by ftrace, it does not
211 * matter if ftrace_int3_handler() is called or not. It will
212 * simply be ignored. But it is crucial that a ftrace nop/caller
213 * breakpoint is handled. No other user should ever place a
214 * breakpoint on an ftrace nop/caller location. It must only
215 * be done by this code.
217 atomic_t modifying_ftrace_code __read_mostly;
220 ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
221 unsigned const char *new_code);
224 * Should never be called:
225 * As it is only called by __ftrace_replace_code() which is called by
226 * ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
227 * which is called to turn mcount into nops or nops into function calls
228 * but not to convert a function from not using regs to one that uses
229 * regs, which ftrace_modify_call() is for.
231 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
235 ftrace_expected = NULL;
239 static unsigned long ftrace_update_func;
240 static unsigned long ftrace_update_func_call;
242 static int update_ftrace_func(unsigned long ip, void *new)
244 unsigned char old[MCOUNT_INSN_SIZE];
247 memcpy(old, (void *)ip, MCOUNT_INSN_SIZE);
249 ftrace_update_func = ip;
250 /* Make sure the breakpoints see the ftrace_update_func update */
253 /* See comment above by declaration of modifying_ftrace_code */
254 atomic_inc(&modifying_ftrace_code);
256 ret = ftrace_modify_code(ip, old, new);
258 atomic_dec(&modifying_ftrace_code);
263 int ftrace_update_ftrace_func(ftrace_func_t func)
265 unsigned long ip = (unsigned long)(&ftrace_call);
269 ftrace_update_func_call = (unsigned long)func;
271 new = ftrace_call_replace(ip, (unsigned long)func);
272 ret = update_ftrace_func(ip, new);
274 /* Also update the regs callback function */
276 ip = (unsigned long)(&ftrace_regs_call);
277 new = ftrace_call_replace(ip, (unsigned long)func);
278 ret = update_ftrace_func(ip, new);
284 static int is_ftrace_caller(unsigned long ip)
286 if (ip == ftrace_update_func)
293 * A breakpoint was added to the code address we are about to
294 * modify, and this is the handle that will just skip over it.
295 * We are either changing a nop into a trace call, or a trace
296 * call to a nop. While the change is taking place, we treat
297 * it just like it was a nop.
299 int ftrace_int3_handler(struct pt_regs *regs)
303 if (WARN_ON_ONCE(!regs))
306 ip = regs->ip - INT3_INSN_SIZE;
309 if (ftrace_location(ip)) {
310 int3_emulate_call(regs, (unsigned long)ftrace_regs_caller);
312 } else if (is_ftrace_caller(ip)) {
313 if (!ftrace_update_func_call) {
314 int3_emulate_jmp(regs, ip + CALL_INSN_SIZE);
317 int3_emulate_call(regs, ftrace_update_func_call);
321 if (ftrace_location(ip) || is_ftrace_caller(ip)) {
322 int3_emulate_jmp(regs, ip + CALL_INSN_SIZE);
330 static int ftrace_write(unsigned long ip, const char *val, int size)
332 ip = text_ip_addr(ip);
334 if (probe_kernel_write((void *)ip, val, size))
340 static int add_break(unsigned long ip, const char *old)
342 unsigned char replaced[MCOUNT_INSN_SIZE];
343 unsigned char brk = BREAKPOINT_INSTRUCTION;
345 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
348 ftrace_expected = old;
350 /* Make sure it is what we expect it to be */
351 if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0)
354 return ftrace_write(ip, &brk, 1);
357 static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr)
359 unsigned const char *old;
360 unsigned long ip = rec->ip;
362 old = ftrace_call_replace(ip, addr);
364 return add_break(rec->ip, old);
368 static int add_brk_on_nop(struct dyn_ftrace *rec)
370 unsigned const char *old;
372 old = ftrace_nop_replace();
374 return add_break(rec->ip, old);
377 static int add_breakpoints(struct dyn_ftrace *rec, int enable)
379 unsigned long ftrace_addr;
382 ftrace_addr = ftrace_get_addr_curr(rec);
384 ret = ftrace_test_record(rec, enable);
387 case FTRACE_UPDATE_IGNORE:
390 case FTRACE_UPDATE_MAKE_CALL:
391 /* converting nop to call */
392 return add_brk_on_nop(rec);
394 case FTRACE_UPDATE_MODIFY_CALL:
395 case FTRACE_UPDATE_MAKE_NOP:
396 /* converting a call to a nop */
397 return add_brk_on_call(rec, ftrace_addr);
403 * On error, we need to remove breakpoints. This needs to
404 * be done caefully. If the address does not currently have a
405 * breakpoint, we know we are done. Otherwise, we look at the
406 * remaining 4 bytes of the instruction. If it matches a nop
407 * we replace the breakpoint with the nop. Otherwise we replace
408 * it with the call instruction.
410 static int remove_breakpoint(struct dyn_ftrace *rec)
412 unsigned char ins[MCOUNT_INSN_SIZE];
413 unsigned char brk = BREAKPOINT_INSTRUCTION;
414 const unsigned char *nop;
415 unsigned long ftrace_addr;
416 unsigned long ip = rec->ip;
418 /* If we fail the read, just give up */
419 if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE))
422 /* If this does not have a breakpoint, we are done */
426 nop = ftrace_nop_replace();
429 * If the last 4 bytes of the instruction do not match
430 * a nop, then we assume that this is a call to ftrace_addr.
432 if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) {
434 * For extra paranoidism, we check if the breakpoint is on
435 * a call that would actually jump to the ftrace_addr.
436 * If not, don't touch the breakpoint, we make just create
439 ftrace_addr = ftrace_get_addr_new(rec);
440 nop = ftrace_call_replace(ip, ftrace_addr);
442 if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
445 /* Check both ftrace_addr and ftrace_old_addr */
446 ftrace_addr = ftrace_get_addr_curr(rec);
447 nop = ftrace_call_replace(ip, ftrace_addr);
449 ftrace_expected = nop;
451 if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
456 return ftrace_write(ip, nop, 1);
459 static int add_update_code(unsigned long ip, unsigned const char *new)
461 /* skip breakpoint */
464 return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1);
467 static int add_update_call(struct dyn_ftrace *rec, unsigned long addr)
469 unsigned long ip = rec->ip;
470 unsigned const char *new;
472 new = ftrace_call_replace(ip, addr);
473 return add_update_code(ip, new);
476 static int add_update_nop(struct dyn_ftrace *rec)
478 unsigned long ip = rec->ip;
479 unsigned const char *new;
481 new = ftrace_nop_replace();
482 return add_update_code(ip, new);
485 static int add_update(struct dyn_ftrace *rec, int enable)
487 unsigned long ftrace_addr;
490 ret = ftrace_test_record(rec, enable);
492 ftrace_addr = ftrace_get_addr_new(rec);
495 case FTRACE_UPDATE_IGNORE:
498 case FTRACE_UPDATE_MODIFY_CALL:
499 case FTRACE_UPDATE_MAKE_CALL:
500 /* converting nop to call */
501 return add_update_call(rec, ftrace_addr);
503 case FTRACE_UPDATE_MAKE_NOP:
504 /* converting a call to a nop */
505 return add_update_nop(rec);
511 static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr)
513 unsigned long ip = rec->ip;
514 unsigned const char *new;
516 new = ftrace_call_replace(ip, addr);
518 return ftrace_write(ip, new, 1);
521 static int finish_update_nop(struct dyn_ftrace *rec)
523 unsigned long ip = rec->ip;
524 unsigned const char *new;
526 new = ftrace_nop_replace();
528 return ftrace_write(ip, new, 1);
531 static int finish_update(struct dyn_ftrace *rec, int enable)
533 unsigned long ftrace_addr;
536 ret = ftrace_update_record(rec, enable);
538 ftrace_addr = ftrace_get_addr_new(rec);
541 case FTRACE_UPDATE_IGNORE:
544 case FTRACE_UPDATE_MODIFY_CALL:
545 case FTRACE_UPDATE_MAKE_CALL:
546 /* converting nop to call */
547 return finish_update_call(rec, ftrace_addr);
549 case FTRACE_UPDATE_MAKE_NOP:
550 /* converting a call to a nop */
551 return finish_update_nop(rec);
557 static void do_sync_core(void *data)
562 static void run_sync(void)
566 /* No need to sync if there's only one CPU */
567 if (num_online_cpus() == 1)
570 enable_irqs = irqs_disabled();
572 /* We may be called with interrupts disabled (on bootup). */
575 on_each_cpu(do_sync_core, NULL, 1);
580 void ftrace_replace_code(int enable)
582 struct ftrace_rec_iter *iter;
583 struct dyn_ftrace *rec;
584 const char *report = "adding breakpoints";
588 for_ftrace_rec_iter(iter) {
589 rec = ftrace_rec_iter_record(iter);
591 ret = add_breakpoints(rec, enable);
593 goto remove_breakpoints;
599 report = "updating code";
602 for_ftrace_rec_iter(iter) {
603 rec = ftrace_rec_iter_record(iter);
605 ret = add_update(rec, enable);
607 goto remove_breakpoints;
613 report = "removing breakpoints";
616 for_ftrace_rec_iter(iter) {
617 rec = ftrace_rec_iter_record(iter);
619 ret = finish_update(rec, enable);
621 goto remove_breakpoints;
630 pr_warn("Failed on %s (%d):\n", report, count);
631 ftrace_bug(ret, rec);
632 for_ftrace_rec_iter(iter) {
633 rec = ftrace_rec_iter_record(iter);
635 * Breakpoints are handled only when this function is in
636 * progress. The system could not work with them.
638 if (remove_breakpoint(rec))
645 ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
646 unsigned const char *new_code)
650 ret = add_break(ip, old_code);
656 ret = add_update_code(ip, new_code);
662 ret = ftrace_write(ip, new_code, 1);
664 * The breakpoint is handled only when this function is in progress.
665 * The system could not work if we could not remove it.
673 /* Also here the system could not work with the breakpoint */
674 if (ftrace_write(ip, old_code, 1))
679 void arch_ftrace_update_code(int command)
681 /* See comment above by declaration of modifying_ftrace_code */
682 atomic_inc(&modifying_ftrace_code);
684 ftrace_modify_all_code(command);
686 atomic_dec(&modifying_ftrace_code);
689 int __init ftrace_dyn_arch_init(void)
694 /* Currently only x86_64 supports dynamic trampolines */
697 #ifdef CONFIG_MODULES
698 #include <linux/moduleloader.h>
699 /* Module allocation simplifies allocating memory for code */
700 static inline void *alloc_tramp(unsigned long size)
702 return module_alloc(size);
704 static inline void tramp_free(void *tramp, int size)
706 int npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
708 set_memory_nx((unsigned long)tramp, npages);
709 set_memory_rw((unsigned long)tramp, npages);
710 module_memfree(tramp);
713 /* Trampolines can only be created if modules are supported */
714 static inline void *alloc_tramp(unsigned long size)
718 static inline void tramp_free(void *tramp, int size) { }
721 /* Defined as markers to the end of the ftrace default trampolines */
722 extern void ftrace_regs_caller_end(void);
723 extern void ftrace_epilogue(void);
724 extern void ftrace_caller_op_ptr(void);
725 extern void ftrace_regs_caller_op_ptr(void);
727 /* movq function_trace_op(%rip), %rdx */
728 /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */
729 #define OP_REF_SIZE 7
732 * The ftrace_ops is passed to the function callback. Since the
733 * trampoline only services a single ftrace_ops, we can pass in
736 * The ftrace_op_code_union is used to create a pointer to the
737 * ftrace_ops that will be passed to the callback function.
739 union ftrace_op_code_union {
740 char code[OP_REF_SIZE];
744 } __attribute__((packed));
750 create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
752 unsigned long start_offset;
753 unsigned long end_offset;
754 unsigned long op_offset;
755 unsigned long offset;
756 unsigned long npages;
762 /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */
763 unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 };
764 union ftrace_op_code_union op_ptr;
767 if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
768 start_offset = (unsigned long)ftrace_regs_caller;
769 end_offset = (unsigned long)ftrace_regs_caller_end;
770 op_offset = (unsigned long)ftrace_regs_caller_op_ptr;
772 start_offset = (unsigned long)ftrace_caller;
773 end_offset = (unsigned long)ftrace_epilogue;
774 op_offset = (unsigned long)ftrace_caller_op_ptr;
777 size = end_offset - start_offset;
780 * Allocate enough size to store the ftrace_caller code,
781 * the iret , as well as the address of the ftrace_ops this
782 * trampoline is used for.
784 trampoline = alloc_tramp(size + RET_SIZE + sizeof(void *));
788 *tramp_size = size + RET_SIZE + sizeof(void *);
789 npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE);
791 /* Copy ftrace_caller onto the trampoline memory */
792 ret = probe_kernel_read(trampoline, (void *)start_offset, size);
793 if (WARN_ON(ret < 0))
796 ip = trampoline + size;
798 /* The trampoline ends with ret(q) */
799 retq = (unsigned long)ftrace_stub;
800 ret = probe_kernel_read(ip, (void *)retq, RET_SIZE);
801 if (WARN_ON(ret < 0))
805 * The address of the ftrace_ops that is used for this trampoline
806 * is stored at the end of the trampoline. This will be used to
807 * load the third parameter for the callback. Basically, that
808 * location at the end of the trampoline takes the place of
809 * the global function_trace_op variable.
812 ptr = (unsigned long *)(trampoline + size + RET_SIZE);
813 *ptr = (unsigned long)ops;
815 op_offset -= start_offset;
816 memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE);
818 /* Are we pointing to the reference? */
819 if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0))
822 /* Load the contents of ptr into the callback parameter */
823 offset = (unsigned long)ptr;
824 offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE;
826 op_ptr.offset = offset;
828 /* put in the new offset to the ftrace_ops */
829 memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE);
831 /* ALLOC_TRAMP flags lets us know we created it */
832 ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
835 * Module allocation needs to be completed by making the page
836 * executable. The page is still writable, which is a security hazard,
837 * but anyhow ftrace breaks W^X completely.
839 set_memory_x((unsigned long)trampoline, npages);
840 return (unsigned long)trampoline;
842 tramp_free(trampoline, *tramp_size);
846 static unsigned long calc_trampoline_call_offset(bool save_regs)
848 unsigned long start_offset;
849 unsigned long call_offset;
852 start_offset = (unsigned long)ftrace_regs_caller;
853 call_offset = (unsigned long)ftrace_regs_call;
855 start_offset = (unsigned long)ftrace_caller;
856 call_offset = (unsigned long)ftrace_call;
859 return call_offset - start_offset;
862 void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
866 unsigned long offset;
871 if (ops->trampoline) {
873 * The ftrace_ops caller may set up its own trampoline.
874 * In such a case, this code must not modify it.
876 if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
878 npages = PAGE_ALIGN(ops->trampoline_size) >> PAGE_SHIFT;
879 set_memory_rw(ops->trampoline, npages);
881 ops->trampoline = create_trampoline(ops, &size);
882 if (!ops->trampoline)
884 ops->trampoline_size = size;
885 npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
888 offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
889 ip = ops->trampoline + offset;
891 func = ftrace_ops_get_func(ops);
893 ftrace_update_func_call = (unsigned long)func;
895 /* Do a safe modify in case the trampoline is executing */
896 new = ftrace_call_replace(ip, (unsigned long)func);
897 ret = update_ftrace_func(ip, new);
898 set_memory_ro(ops->trampoline, npages);
900 /* The update should never fail */
904 /* Return the address of the function the trampoline calls */
905 static void *addr_from_call(void *ptr)
907 union ftrace_code_union calc;
910 ret = probe_kernel_read(&calc, ptr, MCOUNT_INSN_SIZE);
911 if (WARN_ON_ONCE(ret < 0))
914 /* Make sure this is a call */
915 if (WARN_ON_ONCE(calc.op != 0xe8)) {
916 pr_warn("Expected e8, got %x\n", calc.op);
920 return ptr + MCOUNT_INSN_SIZE + calc.offset;
923 void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
924 unsigned long frame_pointer);
927 * If the ops->trampoline was not allocated, then it probably
928 * has a static trampoline func, or is the ftrace caller itself.
930 static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
932 unsigned long offset;
933 bool save_regs = rec->flags & FTRACE_FL_REGS_EN;
936 if (ops && ops->trampoline) {
937 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
939 * We only know about function graph tracer setting as static
942 if (ops->trampoline == FTRACE_GRAPH_ADDR)
943 return (void *)prepare_ftrace_return;
948 offset = calc_trampoline_call_offset(save_regs);
951 ptr = (void *)FTRACE_REGS_ADDR + offset;
953 ptr = (void *)FTRACE_ADDR + offset;
955 return addr_from_call(ptr);
958 void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
960 unsigned long offset;
962 /* If we didn't allocate this trampoline, consider it static */
963 if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
964 return static_tramp_func(ops, rec);
966 offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
967 return addr_from_call((void *)ops->trampoline + offset);
970 void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
972 if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
975 tramp_free((void *)ops->trampoline, ops->trampoline_size);
979 #endif /* CONFIG_X86_64 */
980 #endif /* CONFIG_DYNAMIC_FTRACE */
982 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
984 #ifdef CONFIG_DYNAMIC_FTRACE
985 extern void ftrace_graph_call(void);
987 static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
989 return ftrace_text_replace(0xe9, ip, addr);
992 static int ftrace_mod_jmp(unsigned long ip, void *func)
996 ftrace_update_func_call = 0UL;
997 new = ftrace_jmp_replace(ip, (unsigned long)func);
999 return update_ftrace_func(ip, new);
1002 int ftrace_enable_ftrace_graph_caller(void)
1004 unsigned long ip = (unsigned long)(&ftrace_graph_call);
1006 return ftrace_mod_jmp(ip, &ftrace_graph_caller);
1009 int ftrace_disable_ftrace_graph_caller(void)
1011 unsigned long ip = (unsigned long)(&ftrace_graph_call);
1013 return ftrace_mod_jmp(ip, &ftrace_stub);
1016 #endif /* !CONFIG_DYNAMIC_FTRACE */
1019 * Hook the return address and push it in the stack of return addrs
1020 * in current thread info.
1022 void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
1023 unsigned long frame_pointer)
1027 unsigned long return_hooker = (unsigned long)
1031 * When resuming from suspend-to-ram, this function can be indirectly
1032 * called from early CPU startup code while the CPU is in real mode,
1033 * which would fail miserably. Make sure the stack pointer is a
1036 * This check isn't as accurate as virt_addr_valid(), but it should be
1037 * good enough for this purpose, and it's fast.
1039 if (unlikely((long)__builtin_frame_address(0) >= 0))
1042 if (unlikely(ftrace_graph_is_dead()))
1045 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
1049 * Protect against fault, even if it shouldn't
1050 * happen. This tool is too much intrusive to
1051 * ignore such a protection.
1054 "1: " _ASM_MOV " (%[parent]), %[old]\n"
1055 "2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
1056 " movl $0, %[faulted]\n"
1059 ".section .fixup, \"ax\"\n"
1060 "4: movl $1, %[faulted]\n"
1064 _ASM_EXTABLE(1b, 4b)
1065 _ASM_EXTABLE(2b, 4b)
1067 : [old] "=&r" (old), [faulted] "=r" (faulted)
1068 : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
1072 if (unlikely(faulted)) {
1073 ftrace_graph_stop();
1078 if (function_graph_enter(old, self_addr, frame_pointer, parent))
1081 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */