diff options
authorSteven Rostedt <srostedt@redhat.com>2009-03-25 14:30:04 -0400
committerIngo Molnar <mingo@elte.hu>2009-04-10 12:50:58 +0200
commite71e99c294058a61b7a8b9bb6da2f745ac51aa4f (patch)
parent2062501ae6505dbc5bff3a792246c2661d114050 (diff)
x86, function-graph: only save return values on x86_64
Impact: speed up The return to handler portion of the function graph tracer should only need to save the return values. The caller already saved off the registers that the callee can modify. The returning function already saved the registers it modified. When we call our own trace function it too will save the registers that the callee must restore. There's no reason to save off anything more that the registers used to return the values. Note, I did a complete kernel build with this modification and the function graph tracer running on x86_64. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
1 files changed, 3 insertions, 16 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index a331ec38af9e..1ac99865591c 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -147,27 +147,14 @@ END(ftrace_graph_caller)
subq $80, %rsp
+ /* Save the return values */
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 %r10, 56(%rsp)
- movq %r11, 64(%rsp)
+ movq %rdx, 8(%rsp)
call ftrace_return_to_handler
movq %rax, 72(%rsp)
- movq 64(%rsp), %r11
- movq 56(%rsp), %r10
- 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 8(%rsp), %rdx
movq (%rsp), %rax
addq $72, %rsp

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