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>

5 files changed, 19 insertions, 19 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 04ea83c..95e6bbe 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -51,6 +51,7 @@
 #include <asm/percpu.h>
 #include <asm/dwarf2.h>
 #include <asm/processor-flags.h>
+#include <asm/ftrace.h>
 #include "irq_vectors.h"
 
 /*
@@ -1118,6 +1119,7 @@ ENTRY(mcount)
 	pushl %ecx
 	pushl %edx
 	movl 0xc(%esp), %eax
+	subl $MCOUNT_INSN_SIZE, %eax
 
 .globl mcount_call
 mcount_call:
@@ -1136,6 +1138,7 @@ ENTRY(ftrace_caller)
 	pushl %edx
 	movl 0xc(%esp), %eax
 	movl 0x4(%ebp), %edx
+	subl $MCOUNT_INSN_SIZE, %eax
 
 .globl ftrace_call
 ftrace_call:
@@ -1166,6 +1169,7 @@ trace:
 	pushl %edx
 	movl 0xc(%esp), %eax
 	movl 0x4(%ebp), %edx
+	subl $MCOUNT_INSN_SIZE, %eax
 
 	call *ftrace_trace_function
 
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index fe25e5f..b0f7308 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -51,6 +51,7 @@
 #include <asm/page.h>
 #include <asm/irqflags.h>
 #include <asm/paravirt.h>
+#include <asm/ftrace.h>
 
 	.code64
 
@@ -68,6 +69,7 @@ ENTRY(mcount)
 	movq %r9, 48(%rsp)
 
 	movq 0x38(%rsp), %rdi
+	subq $MCOUNT_INSN_SIZE, %rdi
 
 .globl mcount_call
 mcount_call:
@@ -99,6 +101,7 @@ ENTRY(ftrace_caller)
 
 	movq 0x38(%rsp), %rdi
 	movq 8(%rbp), %rsi
+	subq $MCOUNT_INSN_SIZE, %rdi
 
 .globl ftrace_call
 ftrace_call:
@@ -139,6 +142,7 @@ trace:
 
 	movq 0x38(%rsp), %rdi
 	movq 8(%rbp), %rsi
+	subq $MCOUNT_INSN_SIZE, %rdi
 
 	call   *ftrace_trace_function
 
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 @@ notrace 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, 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 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 	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 @@ 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[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 @@ notrace int ftrace_mcount_set(unsigned long *data)
 {
 	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 @@ int __init ftrace_dyn_arch_init(void *data)
 
 	ftrace_mcount_set(data);
 
-	ftrace_nop = (unsigned long *)noptable[CALL_BACK];
+	ftrace_nop = (unsigned long *)noptable[MCOUNT_INSN_SIZE];
 
 	return 0;
 }
-
diff --git a/arch/x86/kernel/i386_ksyms_32.c b/arch/x86/kernel/i386_ksyms_32.c
index 29999db..dd7ebee 100644
--- a/arch/x86/kernel/i386_ksyms_32.c
+++ b/arch/x86/kernel/i386_ksyms_32.c
@@ -1,9 +1,9 @@
-#include <linux/ftrace.h>
 #include <linux/module.h>
 
 #include <asm/checksum.h>
 #include <asm/pgtable.h>
 #include <asm/desc.h>
+#include <asm/ftrace.h>
 
 #ifdef CONFIG_FTRACE
 /* mcount is defined in assembly */
diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
index 122885b..16ff4bf 100644
--- a/arch/x86/kernel/x8664_ksyms_64.c
+++ b/arch/x86/kernel/x8664_ksyms_64.c
@@ -1,7 +1,6 @@
 /* Exports for assembly files.
    All C exports should go in the respective C files. */
 
-#include <linux/ftrace.h>
 #include <linux/module.h>
 #include <linux/smp.h>
 
@@ -11,6 +10,7 @@
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/desc.h>
+#include <asm/ftrace.h>
 
 #ifdef CONFIG_FTRACE
 /* mcount is defined in assembly */