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>

3 files changed, 15 insertions, 15 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 3b1dd29..7231a70 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -30,6 +30,7 @@
 #include <asm/ppc_asm.h>
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
+#include <asm/ftrace.h>
 
 #undef SHOW_SYSCALLS
 #undef SHOW_SYSCALLS_TASK
@@ -1053,6 +1054,7 @@ _GLOBAL(_mcount)
 	stw	r10,40(r1)
 	stw	r3, 44(r1)
 	stw	r5, 8(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
 	.globl mcount_call
 mcount_call:
 	bl	ftrace_stub
@@ -1090,6 +1092,7 @@ _GLOBAL(ftrace_caller)
 	stw	r10,40(r1)
 	stw	r3, 44(r1)
 	stw	r5, 8(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
 .globl ftrace_call
 ftrace_call:
 	bl	ftrace_stub
@@ -1128,6 +1131,7 @@ _GLOBAL(_mcount)
 	stw	r3, 44(r1)
 	stw	r5, 8(r1)
 
+	subi	r3, r3, MCOUNT_INSN_SIZE
 	LOAD_REG_ADDR(r5, ftrace_trace_function)
 	lwz	r5,0(r5)
 
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 2c4d9e0..2f511a9 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -31,6 +31,7 @@
 #include <asm/bug.h>
 #include <asm/ptrace.h>
 #include <asm/irqflags.h>
+#include <asm/ftrace.h>
 
 /*
  * System calls.
@@ -879,6 +880,7 @@ _GLOBAL(_mcount)
 	mflr	r3
 	stdu	r1, -112(r1)
 	std	r3, 128(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
 	.globl mcount_call
 mcount_call:
 	bl	ftrace_stub
@@ -895,6 +897,7 @@ _GLOBAL(ftrace_caller)
 	stdu	r1, -112(r1)
 	std	r3, 128(r1)
 	ld	r4, 16(r11)
+	subi	r3, r3, MCOUNT_INSN_SIZE
 .globl ftrace_call
 ftrace_call:
 	bl	ftrace_stub
@@ -916,7 +919,7 @@ _GLOBAL(_mcount)
 	std	r3, 128(r1)
 	ld	r4, 16(r11)
 
-
+	subi	r3, r3, MCOUNT_INSN_SIZE
 	LOAD_REG_ADDR(r5,ftrace_trace_function)
 	ld	r5,0(r5)
 	ld	r5,0(r5)
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index e12c593..3855ceb 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -15,8 +15,8 @@
 #include <linux/list.h>
 
 #include <asm/cacheflush.h>
+#include <asm/ftrace.h>
 
-#define CALL_BACK		4
 
 static unsigned int ftrace_nop = 0x60000000;
 
@@ -27,9 +27,10 @@ static unsigned int ftrace_nop = 0x60000000;
 # define GET_ADDR(addr) *(unsigned long *)addr
 #endif
 
+
 static unsigned int notrace ftrace_calc_offset(long ip, long addr)
 {
-	return (int)((addr + CALL_BACK) - ip);
+	return (int)(addr - ip);
 }
 
 notrace unsigned char *ftrace_nop_replace(void)
@@ -76,9 +77,6 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 	unsigned new = *(unsigned *)new_code;
 	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
@@ -118,12 +116,10 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 notrace int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	unsigned long ip = (unsigned long)(&ftrace_call);
-	unsigned char old[4], *new;
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
 	int ret;
 
-	ip += CALL_BACK;
-
-	memcpy(old, &ftrace_call, 4);
+	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
 	new = ftrace_call_replace(ip, (unsigned long)func);
 	ret = ftrace_modify_code(ip, old, new);
 
@@ -134,16 +130,13 @@ notrace int ftrace_mcount_set(unsigned long *data)
 {
 	unsigned long ip = (long)(&mcount_call);
 	unsigned long *addr = data;
-	unsigned char old[4], *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, 4);
+	memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
 	new = ftrace_call_replace(ip, *addr);
 	*addr = ftrace_modify_code(ip, old, new);