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- /*
- * Code for replacing ftrace calls with jumps.
- *
- * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
- *
- * Thanks goes to Ingo Molnar, for suggesting the idea.
- * Mathieu Desnoyers, for suggesting postponing the modifications.
- * Arjan van de Ven, for keeping me straight, and explaining to me
- * the dangers of modifying code on the run.
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/spinlock.h>
- #include <linux/hardirq.h>
- #include <linux/uaccess.h>
- #include <linux/ftrace.h>
- #include <linux/percpu.h>
- #include <linux/sched.h>
- #include <linux/slab.h>
- #include <linux/init.h>
- #include <linux/list.h>
- #include <linux/module.h>
- #include <trace/syscall.h>
- #include <asm/cacheflush.h>
- #include <asm/kprobes.h>
- #include <asm/ftrace.h>
- #include <asm/nops.h>
- #ifdef CONFIG_DYNAMIC_FTRACE
- int ftrace_arch_code_modify_prepare(void)
- {
- set_kernel_text_rw();
- set_all_modules_text_rw();
- return 0;
- }
- int ftrace_arch_code_modify_post_process(void)
- {
- set_all_modules_text_ro();
- set_kernel_text_ro();
- return 0;
- }
- union ftrace_code_union {
- char code[MCOUNT_INSN_SIZE];
- struct {
- unsigned char e8;
- int offset;
- } __attribute__((packed));
- };
- static int ftrace_calc_offset(long ip, long addr)
- {
- return (int)(addr - ip);
- }
- static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
- {
- static union ftrace_code_union calc;
- calc.e8 = 0xe8;
- calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
- /*
- * No locking needed, this must be called via kstop_machine
- * which in essence is like running on a uniprocessor machine.
- */
- return calc.code;
- }
- static inline int
- within(unsigned long addr, unsigned long start, unsigned long end)
- {
- return addr >= start && addr < end;
- }
- static unsigned long text_ip_addr(unsigned long ip)
- {
- /*
- * On x86_64, kernel text mappings are mapped read-only with
- * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
- * of the kernel text mapping to modify the kernel text.
- *
- * For 32bit kernels, these mappings are same and we can use
- * kernel identity mapping to modify code.
- */
- if (within(ip, (unsigned long)_text, (unsigned long)_etext))
- ip = (unsigned long)__va(__pa_symbol(ip));
- return ip;
- }
- static const unsigned char *ftrace_nop_replace(void)
- {
- return ideal_nops[NOP_ATOMIC5];
- }
- static int
- ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code)
- {
- unsigned char replaced[MCOUNT_INSN_SIZE];
- /*
- * Note: Due to modules and __init, code can
- * disappear and change, we need to protect against faulting
- * as well as code changing. We do this by using the
- * probe_kernel_* functions.
- *
- * No real locking needed, this code is run through
- * kstop_machine, or before SMP starts.
- */
- /* read the text we want to modify */
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
- /* Make sure it is what we expect it to be */
- if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
- ip = text_ip_addr(ip);
- /* replace the text with the new text */
- if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
- return -EPERM;
- sync_core();
- return 0;
- }
- int ftrace_make_nop(struct module *mod,
- struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned const char *new, *old;
- unsigned long ip = rec->ip;
- old = ftrace_call_replace(ip, addr);
- new = ftrace_nop_replace();
- /*
- * On boot up, and when modules are loaded, the MCOUNT_ADDR
- * is converted to a nop, and will never become MCOUNT_ADDR
- * again. This code is either running before SMP (on boot up)
- * or before the code will ever be executed (module load).
- * We do not want to use the breakpoint version in this case,
- * just modify the code directly.
- */
- if (addr == MCOUNT_ADDR)
- return ftrace_modify_code_direct(rec->ip, old, new);
- /* Normal cases use add_brk_on_nop */
- WARN_ONCE(1, "invalid use of ftrace_make_nop");
- return -EINVAL;
- }
- int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned const char *new, *old;
- unsigned long ip = rec->ip;
- old = ftrace_nop_replace();
- new = ftrace_call_replace(ip, addr);
- /* Should only be called when module is loaded */
- return ftrace_modify_code_direct(rec->ip, old, new);
- }
- /*
- * The modifying_ftrace_code is used to tell the breakpoint
- * handler to call ftrace_int3_handler(). If it fails to
- * call this handler for a breakpoint added by ftrace, then
- * the kernel may crash.
- *
- * As atomic_writes on x86 do not need a barrier, we do not
- * need to add smp_mb()s for this to work. It is also considered
- * that we can not read the modifying_ftrace_code before
- * executing the breakpoint. That would be quite remarkable if
- * it could do that. Here's the flow that is required:
- *
- * CPU-0 CPU-1
- *
- * atomic_inc(mfc);
- * write int3s
- * <trap-int3> // implicit (r)mb
- * if (atomic_read(mfc))
- * call ftrace_int3_handler()
- *
- * Then when we are finished:
- *
- * atomic_dec(mfc);
- *
- * If we hit a breakpoint that was not set by ftrace, it does not
- * matter if ftrace_int3_handler() is called or not. It will
- * simply be ignored. But it is crucial that a ftrace nop/caller
- * breakpoint is handled. No other user should ever place a
- * breakpoint on an ftrace nop/caller location. It must only
- * be done by this code.
- */
- atomic_t modifying_ftrace_code __read_mostly;
- static int
- ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code);
- /*
- * Should never be called:
- * As it is only called by __ftrace_replace_code() which is called by
- * ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
- * which is called to turn mcount into nops or nops into function calls
- * but not to convert a function from not using regs to one that uses
- * regs, which ftrace_modify_call() is for.
- */
- int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
- unsigned long addr)
- {
- WARN_ON(1);
- return -EINVAL;
- }
- static unsigned long ftrace_update_func;
- static int update_ftrace_func(unsigned long ip, void *new)
- {
- unsigned char old[MCOUNT_INSN_SIZE];
- int ret;
- memcpy(old, (void *)ip, MCOUNT_INSN_SIZE);
- ftrace_update_func = ip;
- /* Make sure the breakpoints see the ftrace_update_func update */
- smp_wmb();
- /* See comment above by declaration of modifying_ftrace_code */
- atomic_inc(&modifying_ftrace_code);
- ret = ftrace_modify_code(ip, old, new);
- atomic_dec(&modifying_ftrace_code);
- return ret;
- }
- int ftrace_update_ftrace_func(ftrace_func_t func)
- {
- unsigned long ip = (unsigned long)(&ftrace_call);
- unsigned char *new;
- int ret;
- new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
- /* Also update the regs callback function */
- if (!ret) {
- ip = (unsigned long)(&ftrace_regs_call);
- new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
- }
- return ret;
- }
- static int is_ftrace_caller(unsigned long ip)
- {
- if (ip == ftrace_update_func)
- return 1;
- return 0;
- }
- /*
- * A breakpoint was added to the code address we are about to
- * modify, and this is the handle that will just skip over it.
- * We are either changing a nop into a trace call, or a trace
- * call to a nop. While the change is taking place, we treat
- * it just like it was a nop.
- */
- int ftrace_int3_handler(struct pt_regs *regs)
- {
- unsigned long ip;
- if (WARN_ON_ONCE(!regs))
- return 0;
- ip = regs->ip - 1;
- if (!ftrace_location(ip) && !is_ftrace_caller(ip))
- return 0;
- regs->ip += MCOUNT_INSN_SIZE - 1;
- return 1;
- }
- static int ftrace_write(unsigned long ip, const char *val, int size)
- {
- ip = text_ip_addr(ip);
- if (probe_kernel_write((void *)ip, val, size))
- return -EPERM;
- return 0;
- }
- static int add_break(unsigned long ip, const char *old)
- {
- unsigned char replaced[MCOUNT_INSN_SIZE];
- unsigned char brk = BREAKPOINT_INSTRUCTION;
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
- /* Make sure it is what we expect it to be */
- if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
- return ftrace_write(ip, &brk, 1);
- }
- static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned const char *old;
- unsigned long ip = rec->ip;
- old = ftrace_call_replace(ip, addr);
- return add_break(rec->ip, old);
- }
- static int add_brk_on_nop(struct dyn_ftrace *rec)
- {
- unsigned const char *old;
- old = ftrace_nop_replace();
- return add_break(rec->ip, old);
- }
- static int add_breakpoints(struct dyn_ftrace *rec, int enable)
- {
- unsigned long ftrace_addr;
- int ret;
- ftrace_addr = ftrace_get_addr_curr(rec);
- ret = ftrace_test_record(rec, enable);
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return add_brk_on_nop(rec);
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return add_brk_on_call(rec, ftrace_addr);
- }
- return 0;
- }
- /*
- * On error, we need to remove breakpoints. This needs to
- * be done caefully. If the address does not currently have a
- * breakpoint, we know we are done. Otherwise, we look at the
- * remaining 4 bytes of the instruction. If it matches a nop
- * we replace the breakpoint with the nop. Otherwise we replace
- * it with the call instruction.
- */
- static int remove_breakpoint(struct dyn_ftrace *rec)
- {
- unsigned char ins[MCOUNT_INSN_SIZE];
- unsigned char brk = BREAKPOINT_INSTRUCTION;
- const unsigned char *nop;
- unsigned long ftrace_addr;
- unsigned long ip = rec->ip;
- /* If we fail the read, just give up */
- if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
- /* If this does not have a breakpoint, we are done */
- if (ins[0] != brk)
- return 0;
- nop = ftrace_nop_replace();
- /*
- * If the last 4 bytes of the instruction do not match
- * a nop, then we assume that this is a call to ftrace_addr.
- */
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) {
- /*
- * For extra paranoidism, we check if the breakpoint is on
- * a call that would actually jump to the ftrace_addr.
- * If not, don't touch the breakpoint, we make just create
- * a disaster.
- */
- ftrace_addr = ftrace_get_addr_new(rec);
- nop = ftrace_call_replace(ip, ftrace_addr);
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
- goto update;
- /* Check both ftrace_addr and ftrace_old_addr */
- ftrace_addr = ftrace_get_addr_curr(rec);
- nop = ftrace_call_replace(ip, ftrace_addr);
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
- return -EINVAL;
- }
- update:
- return ftrace_write(ip, nop, 1);
- }
- static int add_update_code(unsigned long ip, unsigned const char *new)
- {
- /* skip breakpoint */
- ip++;
- new++;
- return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1);
- }
- static int add_update_call(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned long ip = rec->ip;
- unsigned const char *new;
- new = ftrace_call_replace(ip, addr);
- return add_update_code(ip, new);
- }
- static int add_update_nop(struct dyn_ftrace *rec)
- {
- unsigned long ip = rec->ip;
- unsigned const char *new;
- new = ftrace_nop_replace();
- return add_update_code(ip, new);
- }
- static int add_update(struct dyn_ftrace *rec, int enable)
- {
- unsigned long ftrace_addr;
- int ret;
- ret = ftrace_test_record(rec, enable);
- ftrace_addr = ftrace_get_addr_new(rec);
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return add_update_call(rec, ftrace_addr);
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return add_update_nop(rec);
- }
- return 0;
- }
- static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned long ip = rec->ip;
- unsigned const char *new;
- new = ftrace_call_replace(ip, addr);
- return ftrace_write(ip, new, 1);
- }
- static int finish_update_nop(struct dyn_ftrace *rec)
- {
- unsigned long ip = rec->ip;
- unsigned const char *new;
- new = ftrace_nop_replace();
- return ftrace_write(ip, new, 1);
- }
- static int finish_update(struct dyn_ftrace *rec, int enable)
- {
- unsigned long ftrace_addr;
- int ret;
- ret = ftrace_update_record(rec, enable);
- ftrace_addr = ftrace_get_addr_new(rec);
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return finish_update_call(rec, ftrace_addr);
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return finish_update_nop(rec);
- }
- return 0;
- }
- static void do_sync_core(void *data)
- {
- sync_core();
- }
- static void run_sync(void)
- {
- int enable_irqs = irqs_disabled();
- /* We may be called with interrupts disbled (on bootup). */
- if (enable_irqs)
- local_irq_enable();
- on_each_cpu(do_sync_core, NULL, 1);
- if (enable_irqs)
- local_irq_disable();
- }
- void ftrace_replace_code(int enable)
- {
- struct ftrace_rec_iter *iter;
- struct dyn_ftrace *rec;
- const char *report = "adding breakpoints";
- int count = 0;
- int ret;
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
- ret = add_breakpoints(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
- run_sync();
- report = "updating code";
- count = 0;
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
- ret = add_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
- run_sync();
- report = "removing breakpoints";
- count = 0;
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
- ret = finish_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
- run_sync();
- return;
- remove_breakpoints:
- pr_warn("Failed on %s (%d):\n", report, count);
- ftrace_bug(ret, rec);
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
- /*
- * Breakpoints are handled only when this function is in
- * progress. The system could not work with them.
- */
- if (remove_breakpoint(rec))
- BUG();
- }
- run_sync();
- }
- static int
- ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code)
- {
- int ret;
- ret = add_break(ip, old_code);
- if (ret)
- goto out;
- run_sync();
- ret = add_update_code(ip, new_code);
- if (ret)
- goto fail_update;
- run_sync();
- ret = ftrace_write(ip, new_code, 1);
- /*
- * The breakpoint is handled only when this function is in progress.
- * The system could not work if we could not remove it.
- */
- BUG_ON(ret);
- out:
- run_sync();
- return ret;
- fail_update:
- /* Also here the system could not work with the breakpoint */
- if (ftrace_write(ip, old_code, 1))
- BUG();
- goto out;
- }
- void arch_ftrace_update_code(int command)
- {
- /* See comment above by declaration of modifying_ftrace_code */
- atomic_inc(&modifying_ftrace_code);
- ftrace_modify_all_code(command);
- atomic_dec(&modifying_ftrace_code);
- }
- int __init ftrace_dyn_arch_init(void)
- {
- return 0;
- }
- #if defined(CONFIG_X86_64) || defined(CONFIG_FUNCTION_GRAPH_TRACER)
- static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
- {
- static union ftrace_code_union calc;
- /* Jmp not a call (ignore the .e8) */
- calc.e8 = 0xe9;
- calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
- /*
- * ftrace external locks synchronize the access to the static variable.
- */
- return calc.code;
- }
- #endif
- /* Currently only x86_64 supports dynamic trampolines */
- #ifdef CONFIG_X86_64
- #ifdef CONFIG_MODULES
- #include <linux/moduleloader.h>
- /* Module allocation simplifies allocating memory for code */
- static inline void *alloc_tramp(unsigned long size)
- {
- return module_alloc(size);
- }
- static inline void tramp_free(void *tramp)
- {
- module_memfree(tramp);
- }
- #else
- /* Trampolines can only be created if modules are supported */
- static inline void *alloc_tramp(unsigned long size)
- {
- return NULL;
- }
- static inline void tramp_free(void *tramp) { }
- #endif
- /* Defined as markers to the end of the ftrace default trampolines */
- extern void ftrace_caller_end(void);
- extern void ftrace_regs_caller_end(void);
- extern void ftrace_return(void);
- extern void ftrace_caller_op_ptr(void);
- extern void ftrace_regs_caller_op_ptr(void);
- /* movq function_trace_op(%rip), %rdx */
- /* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */
- #define OP_REF_SIZE 7
- /*
- * The ftrace_ops is passed to the function callback. Since the
- * trampoline only services a single ftrace_ops, we can pass in
- * that ops directly.
- *
- * The ftrace_op_code_union is used to create a pointer to the
- * ftrace_ops that will be passed to the callback function.
- */
- union ftrace_op_code_union {
- char code[OP_REF_SIZE];
- struct {
- char op[3];
- int offset;
- } __attribute__((packed));
- };
- static unsigned long
- create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
- {
- unsigned const char *jmp;
- unsigned long start_offset;
- unsigned long end_offset;
- unsigned long op_offset;
- unsigned long offset;
- unsigned long size;
- unsigned long ip;
- unsigned long *ptr;
- void *trampoline;
- /* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */
- unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 };
- union ftrace_op_code_union op_ptr;
- int ret;
- if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
- start_offset = (unsigned long)ftrace_regs_caller;
- end_offset = (unsigned long)ftrace_regs_caller_end;
- op_offset = (unsigned long)ftrace_regs_caller_op_ptr;
- } else {
- start_offset = (unsigned long)ftrace_caller;
- end_offset = (unsigned long)ftrace_caller_end;
- op_offset = (unsigned long)ftrace_caller_op_ptr;
- }
- size = end_offset - start_offset;
- /*
- * Allocate enough size to store the ftrace_caller code,
- * the jmp to ftrace_return, as well as the address of
- * the ftrace_ops this trampoline is used for.
- */
- trampoline = alloc_tramp(size + MCOUNT_INSN_SIZE + sizeof(void *));
- if (!trampoline)
- return 0;
- *tramp_size = size + MCOUNT_INSN_SIZE + sizeof(void *);
- /* Copy ftrace_caller onto the trampoline memory */
- ret = probe_kernel_read(trampoline, (void *)start_offset, size);
- if (WARN_ON(ret < 0)) {
- tramp_free(trampoline);
- return 0;
- }
- ip = (unsigned long)trampoline + size;
- /* The trampoline ends with a jmp to ftrace_return */
- jmp = ftrace_jmp_replace(ip, (unsigned long)ftrace_return);
- memcpy(trampoline + size, jmp, MCOUNT_INSN_SIZE);
- /*
- * The address of the ftrace_ops that is used for this trampoline
- * is stored at the end of the trampoline. This will be used to
- * load the third parameter for the callback. Basically, that
- * location at the end of the trampoline takes the place of
- * the global function_trace_op variable.
- */
- ptr = (unsigned long *)(trampoline + size + MCOUNT_INSN_SIZE);
- *ptr = (unsigned long)ops;
- op_offset -= start_offset;
- memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE);
- /* Are we pointing to the reference? */
- if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) {
- tramp_free(trampoline);
- return 0;
- }
- /* Load the contents of ptr into the callback parameter */
- offset = (unsigned long)ptr;
- offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE;
- op_ptr.offset = offset;
- /* put in the new offset to the ftrace_ops */
- memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE);
- /* ALLOC_TRAMP flags lets us know we created it */
- ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
- return (unsigned long)trampoline;
- }
- static unsigned long calc_trampoline_call_offset(bool save_regs)
- {
- unsigned long start_offset;
- unsigned long call_offset;
- if (save_regs) {
- start_offset = (unsigned long)ftrace_regs_caller;
- call_offset = (unsigned long)ftrace_regs_call;
- } else {
- start_offset = (unsigned long)ftrace_caller;
- call_offset = (unsigned long)ftrace_call;
- }
- return call_offset - start_offset;
- }
- void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
- {
- ftrace_func_t func;
- unsigned char *new;
- unsigned long offset;
- unsigned long ip;
- unsigned int size;
- int ret;
- if (ops->trampoline) {
- /*
- * The ftrace_ops caller may set up its own trampoline.
- * In such a case, this code must not modify it.
- */
- if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
- return;
- } else {
- ops->trampoline = create_trampoline(ops, &size);
- if (!ops->trampoline)
- return;
- ops->trampoline_size = size;
- }
- offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
- ip = ops->trampoline + offset;
- func = ftrace_ops_get_func(ops);
- /* Do a safe modify in case the trampoline is executing */
- new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
- /* The update should never fail */
- WARN_ON(ret);
- }
- /* Return the address of the function the trampoline calls */
- static void *addr_from_call(void *ptr)
- {
- union ftrace_code_union calc;
- int ret;
- ret = probe_kernel_read(&calc, ptr, MCOUNT_INSN_SIZE);
- if (WARN_ON_ONCE(ret < 0))
- return NULL;
- /* Make sure this is a call */
- if (WARN_ON_ONCE(calc.e8 != 0xe8)) {
- pr_warn("Expected e8, got %x\n", calc.e8);
- return NULL;
- }
- return ptr + MCOUNT_INSN_SIZE + calc.offset;
- }
- void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
- unsigned long frame_pointer);
- /*
- * If the ops->trampoline was not allocated, then it probably
- * has a static trampoline func, or is the ftrace caller itself.
- */
- static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
- {
- unsigned long offset;
- bool save_regs = rec->flags & FTRACE_FL_REGS_EN;
- void *ptr;
- if (ops && ops->trampoline) {
- #ifdef CONFIG_FUNCTION_GRAPH_TRACER
- /*
- * We only know about function graph tracer setting as static
- * trampoline.
- */
- if (ops->trampoline == FTRACE_GRAPH_ADDR)
- return (void *)prepare_ftrace_return;
- #endif
- return NULL;
- }
- offset = calc_trampoline_call_offset(save_regs);
- if (save_regs)
- ptr = (void *)FTRACE_REGS_ADDR + offset;
- else
- ptr = (void *)FTRACE_ADDR + offset;
- return addr_from_call(ptr);
- }
- void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
- {
- unsigned long offset;
- /* If we didn't allocate this trampoline, consider it static */
- if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
- return static_tramp_func(ops, rec);
- offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
- return addr_from_call((void *)ops->trampoline + offset);
- }
- void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
- {
- if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
- return;
- tramp_free((void *)ops->trampoline);
- ops->trampoline = 0;
- }
- #endif /* CONFIG_X86_64 */
- #endif /* CONFIG_DYNAMIC_FTRACE */
- #ifdef CONFIG_FUNCTION_GRAPH_TRACER
- #ifdef CONFIG_DYNAMIC_FTRACE
- extern void ftrace_graph_call(void);
- static int ftrace_mod_jmp(unsigned long ip, void *func)
- {
- unsigned char *new;
- new = ftrace_jmp_replace(ip, (unsigned long)func);
- return update_ftrace_func(ip, new);
- }
- int ftrace_enable_ftrace_graph_caller(void)
- {
- unsigned long ip = (unsigned long)(&ftrace_graph_call);
- return ftrace_mod_jmp(ip, &ftrace_graph_caller);
- }
- int ftrace_disable_ftrace_graph_caller(void)
- {
- unsigned long ip = (unsigned long)(&ftrace_graph_call);
- return ftrace_mod_jmp(ip, &ftrace_stub);
- }
- #endif /* !CONFIG_DYNAMIC_FTRACE */
- /*
- * Hook the return address and push it in the stack of return addrs
- * in current thread info.
- */
- void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
- unsigned long frame_pointer)
- {
- unsigned long old;
- int faulted;
- struct ftrace_graph_ent trace;
- unsigned long return_hooker = (unsigned long)
- &return_to_handler;
- /*
- * When resuming from suspend-to-ram, this function can be indirectly
- * called from early CPU startup code while the CPU is in real mode,
- * which would fail miserably. Make sure the stack pointer is a
- * virtual address.
- *
- * This check isn't as accurate as virt_addr_valid(), but it should be
- * good enough for this purpose, and it's fast.
- */
- if (unlikely((long)__builtin_frame_address(0) >= 0))
- return;
- if (unlikely(ftrace_graph_is_dead()))
- return;
- if (unlikely(atomic_read(¤t->tracing_graph_pause)))
- return;
- /*
- * Protect against fault, even if it shouldn't
- * happen. This tool is too much intrusive to
- * ignore such a protection.
- */
- asm volatile(
- "1: " _ASM_MOV " (%[parent]), %[old]\n"
- "2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
- " movl $0, %[faulted]\n"
- "3:\n"
- ".section .fixup, \"ax\"\n"
- "4: movl $1, %[faulted]\n"
- " jmp 3b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 4b)
- _ASM_EXTABLE(2b, 4b)
- : [old] "=&r" (old), [faulted] "=r" (faulted)
- : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
- : "memory"
- );
- if (unlikely(faulted)) {
- ftrace_graph_stop();
- WARN_ON(1);
- return;
- }
- trace.func = self_addr;
- trace.depth = current->curr_ret_stack + 1;
- /* Only trace if the calling function expects to */
- if (!ftrace_graph_entry(&trace)) {
- *parent = old;
- return;
- }
- if (ftrace_push_return_trace(old, self_addr, &trace.depth,
- frame_pointer) == -EBUSY) {
- *parent = old;
- return;
- }
- }
- #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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