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authorSteven Rostedt <rostedt@goodmis.org>2008-08-14 15:45:12 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-14 10:34:58 +0200
commit0a37605c2261a06d8cafc62dee11374ad676c8c4 (patch)
tree0867723688dbdb824a5a15f91551f88bd47c6936 /arch
parente4b2b8866121bd06d5f3d9de0f79a04339ffa252 (diff)
ftrace: x86 mcount stub
x86 now sets up the mcount locations through the build and no longer needs to record the ip when the function is executed. This patch changes the initial mcount to simply return. There's no need to do any other work. If the ftrace start up test fails, the original mcount will be what everything will use, so having this as fast as possible is a good thing. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/entry_32.S14
-rw-r--r--arch/x86/kernel/entry_64.S26
-rw-r--r--arch/x86/kernel/ftrace.c14
3 files changed, 2 insertions, 52 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index b21fbfaffe3..4e4269c73bb 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1153,20 +1153,6 @@ ENDPROC(xen_failsafe_callback)
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
- pushl %eax
- pushl %ecx
- pushl %edx
- movl 0xc(%esp), %eax
- subl $MCOUNT_INSN_SIZE, %eax
-
-.globl mcount_call
-mcount_call:
- call ftrace_stub
-
- popl %edx
- popl %ecx
- popl %eax
-
ret
END(mcount)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1db6ce4314e..09e7145484c 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -64,32 +64,6 @@
#ifdef CONFIG_FTRACE
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
-
- subq $0x38, %rsp
- movq %rax, (%rsp)
- movq %rcx, 8(%rsp)
- movq %rdx, 16(%rsp)
- movq %rsi, 24(%rsp)
- movq %rdi, 32(%rsp)
- movq %r8, 40(%rsp)
- movq %r9, 48(%rsp)
-
- movq 0x38(%rsp), %rdi
- subq $MCOUNT_INSN_SIZE, %rdi
-
-.globl mcount_call
-mcount_call:
- call ftrace_stub
-
- movq 48(%rsp), %r9
- movq 40(%rsp), %r8
- movq 32(%rsp), %rdi
- movq 24(%rsp), %rsi
- movq 16(%rsp), %rdx
- movq 8(%rsp), %rcx
- movq (%rsp), %rax
- addq $0x38, %rsp
-
retq
END(mcount)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ab115cd15fd..96aadbfedcc 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -112,18 +112,8 @@ notrace int ftrace_update_ftrace_func(ftrace_func_t func)
notrace int ftrace_mcount_set(unsigned long *data)
{
- unsigned long ip = (long)(&mcount_call);
- unsigned long *addr = data;
- unsigned char old[MCOUNT_INSN_SIZE], *new;
-
- /*
- * Replace the mcount stub with a pointer to the
- * ip recorder function.
- */
- memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
- new = ftrace_call_replace(ip, *addr);
- *addr = ftrace_modify_code(ip, old, new);
-
+ /* mcount is initialized as a nop */
+ *data = 0;
return 0;
}