275 lines
6 KiB
C
275 lines
6 KiB
C
/*
|
|
* Dynamic function tracing support.
|
|
*
|
|
* Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
|
|
* Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
|
|
*
|
|
* For licencing details, see COPYING.
|
|
*
|
|
* Defines low-level handling of mcount calls when the kernel
|
|
* is compiled with the -pg flag. When using dynamic ftrace, the
|
|
* mcount call-sites get patched with NOP till they are enabled.
|
|
* All code mutation routines here are called under stop_machine().
|
|
*/
|
|
|
|
#include <linux/ftrace.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/module.h>
|
|
#include <linux/stop_machine.h>
|
|
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/opcodes.h>
|
|
#include <asm/ftrace.h>
|
|
|
|
#include "insn.h"
|
|
|
|
#ifdef CONFIG_THUMB2_KERNEL
|
|
#define NOP 0xf85deb04 /* pop.w {lr} */
|
|
#else
|
|
#define NOP 0xe8bd4000 /* pop {lr} */
|
|
#endif
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
#define OLD_MCOUNT_ADDR ((unsigned long) mcount)
|
|
#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
|
|
|
|
#define OLD_NOP 0xe1a00000 /* mov r0, r0 */
|
|
|
|
static int __ftrace_modify_code(void *data)
|
|
{
|
|
int *command = data;
|
|
|
|
set_kernel_text_rw();
|
|
ftrace_modify_all_code(*command);
|
|
set_kernel_text_ro();
|
|
|
|
return 0;
|
|
}
|
|
|
|
void arch_ftrace_update_code(int command)
|
|
{
|
|
stop_machine(__ftrace_modify_code, &command, NULL);
|
|
}
|
|
|
|
static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
|
|
{
|
|
return rec->arch.old_mcount ? OLD_NOP : NOP;
|
|
}
|
|
|
|
static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
if (!rec->arch.old_mcount)
|
|
return addr;
|
|
|
|
if (addr == MCOUNT_ADDR)
|
|
addr = OLD_MCOUNT_ADDR;
|
|
else if (addr == FTRACE_ADDR)
|
|
addr = OLD_FTRACE_ADDR;
|
|
|
|
return addr;
|
|
}
|
|
#else
|
|
static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
|
|
{
|
|
return NOP;
|
|
}
|
|
|
|
static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
return addr;
|
|
}
|
|
#endif
|
|
|
|
int ftrace_arch_code_modify_prepare(void)
|
|
{
|
|
set_all_modules_text_rw();
|
|
return 0;
|
|
}
|
|
|
|
int ftrace_arch_code_modify_post_process(void)
|
|
{
|
|
set_all_modules_text_ro();
|
|
/* Make sure any TLB misses during machine stop are cleared. */
|
|
flush_tlb_all();
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
|
|
{
|
|
return arm_gen_branch_link(pc, addr);
|
|
}
|
|
|
|
static int ftrace_modify_code(unsigned long pc, unsigned long old,
|
|
unsigned long new, bool validate)
|
|
{
|
|
unsigned long replaced;
|
|
|
|
if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
|
|
old = __opcode_to_mem_thumb32(old);
|
|
new = __opcode_to_mem_thumb32(new);
|
|
} else {
|
|
old = __opcode_to_mem_arm(old);
|
|
new = __opcode_to_mem_arm(new);
|
|
}
|
|
|
|
if (validate) {
|
|
if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
|
|
return -EFAULT;
|
|
|
|
if (replaced != old)
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
|
|
return -EPERM;
|
|
|
|
flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int ftrace_update_ftrace_func(ftrace_func_t func)
|
|
{
|
|
unsigned long pc;
|
|
unsigned long new;
|
|
int ret;
|
|
|
|
pc = (unsigned long)&ftrace_call;
|
|
new = ftrace_call_replace(pc, (unsigned long)func);
|
|
|
|
ret = ftrace_modify_code(pc, 0, new, false);
|
|
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
if (!ret) {
|
|
pc = (unsigned long)&ftrace_call_old;
|
|
new = ftrace_call_replace(pc, (unsigned long)func);
|
|
|
|
ret = ftrace_modify_code(pc, 0, new, false);
|
|
}
|
|
#endif
|
|
|
|
return ret;
|
|
}
|
|
|
|
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long new, old;
|
|
unsigned long ip = rec->ip;
|
|
|
|
old = ftrace_nop_replace(rec);
|
|
new = ftrace_call_replace(ip, adjust_address(rec, addr));
|
|
|
|
return ftrace_modify_code(rec->ip, old, new, true);
|
|
}
|
|
|
|
int ftrace_make_nop(struct module *mod,
|
|
struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long ip = rec->ip;
|
|
unsigned long old;
|
|
unsigned long new;
|
|
int ret;
|
|
|
|
old = ftrace_call_replace(ip, adjust_address(rec, addr));
|
|
new = ftrace_nop_replace(rec);
|
|
ret = ftrace_modify_code(ip, old, new, true);
|
|
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
if (ret == -EINVAL && addr == MCOUNT_ADDR) {
|
|
rec->arch.old_mcount = true;
|
|
|
|
old = ftrace_call_replace(ip, adjust_address(rec, addr));
|
|
new = ftrace_nop_replace(rec);
|
|
ret = ftrace_modify_code(ip, old, new, true);
|
|
}
|
|
#endif
|
|
|
|
return ret;
|
|
}
|
|
|
|
int __init ftrace_dyn_arch_init(void)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
|
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
|
|
unsigned long frame_pointer)
|
|
{
|
|
unsigned long return_hooker = (unsigned long) &return_to_handler;
|
|
struct ftrace_graph_ent trace;
|
|
unsigned long old;
|
|
int err;
|
|
|
|
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
|
|
return;
|
|
|
|
old = *parent;
|
|
*parent = return_hooker;
|
|
|
|
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;
|
|
}
|
|
|
|
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
|
|
frame_pointer);
|
|
if (err == -EBUSY) {
|
|
*parent = old;
|
|
return;
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
extern unsigned long ftrace_graph_call;
|
|
extern unsigned long ftrace_graph_call_old;
|
|
extern void ftrace_graph_caller_old(void);
|
|
|
|
static int __ftrace_modify_caller(unsigned long *callsite,
|
|
void (*func) (void), bool enable)
|
|
{
|
|
unsigned long caller_fn = (unsigned long) func;
|
|
unsigned long pc = (unsigned long) callsite;
|
|
unsigned long branch = arm_gen_branch(pc, caller_fn);
|
|
unsigned long nop = 0xe1a00000; /* mov r0, r0 */
|
|
unsigned long old = enable ? nop : branch;
|
|
unsigned long new = enable ? branch : nop;
|
|
|
|
return ftrace_modify_code(pc, old, new, true);
|
|
}
|
|
|
|
static int ftrace_modify_graph_caller(bool enable)
|
|
{
|
|
int ret;
|
|
|
|
ret = __ftrace_modify_caller(&ftrace_graph_call,
|
|
ftrace_graph_caller,
|
|
enable);
|
|
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
if (!ret)
|
|
ret = __ftrace_modify_caller(&ftrace_graph_call_old,
|
|
ftrace_graph_caller_old,
|
|
enable);
|
|
#endif
|
|
|
|
return ret;
|
|
}
|
|
|
|
int ftrace_enable_ftrace_graph_caller(void)
|
|
{
|
|
return ftrace_modify_graph_caller(true);
|
|
}
|
|
|
|
int ftrace_disable_ftrace_graph_caller(void)
|
|
{
|
|
return ftrace_modify_graph_caller(false);
|
|
}
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|