ftrace: store mcount address in rec->ip
Record the address of the mcount call-site. Currently all archs except sparc64
record the address of the instruction following the mcount call-site. Some
general cleanups are entailed. Storing mcount addresses in rec->ip enables
looking them up in the kprobe hash table later on to check if they're kprobe'd.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: davem@davemloft.net
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 5582814..ab115cd 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -17,20 +17,21 @@
#include <linux/list.h>
#include <asm/alternative.h>
+#include <asm/ftrace.h>
-#define CALL_BACK 5
/* Long is fine, even if it is only 4 bytes ;-) */
static long *ftrace_nop;
union ftrace_code_union {
- char code[5];
+ char code[MCOUNT_INSN_SIZE];
struct {
char e8;
int offset;
} __attribute__((packed));
};
+
static int notrace ftrace_calc_offset(long ip, long addr)
{
return (int)(addr - ip);
@@ -46,7 +47,7 @@
static union ftrace_code_union calc;
calc.e8 = 0xe8;
- calc.offset = ftrace_calc_offset(ip, addr);
+ calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
/*
* No locking needed, this must be called via kstop_machine
@@ -65,9 +66,6 @@
unsigned char newch = new_code[4];
int faulted = 0;
- /* move the IP back to the start of the call */
- ip -= CALL_BACK;
-
/*
* Note: Due to modules and __init, code can
* disappear and change, we need to protect against faulting
@@ -102,12 +100,10 @@
notrace int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
- unsigned char old[5], *new;
+ unsigned char old[MCOUNT_INSN_SIZE], *new;
int ret;
- ip += CALL_BACK;
-
- memcpy(old, &ftrace_call, 5);
+ memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(ip, (unsigned long)func);
ret = ftrace_modify_code(ip, old, new);
@@ -118,16 +114,13 @@
{
unsigned long ip = (long)(&mcount_call);
unsigned long *addr = data;
- unsigned char old[5], *new;
-
- /* ip is at the location, but modify code will subtact this */
- ip += CALL_BACK;
+ unsigned char old[MCOUNT_INSN_SIZE], *new;
/*
* Replace the mcount stub with a pointer to the
* ip recorder function.
*/
- memcpy(old, &mcount_call, 5);
+ memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(ip, *addr);
*addr = ftrace_modify_code(ip, old, new);
@@ -142,8 +135,7 @@
ftrace_mcount_set(data);
- ftrace_nop = (unsigned long *)noptable[CALL_BACK];
+ ftrace_nop = (unsigned long *)noptable[MCOUNT_INSN_SIZE];
return 0;
}
-