On Thu, 2012-08-09 at 09:46 -0400, Steven Rostedt wrote:
> Peter and Masami
>
> During my final tests, I found that this change breaks the
> !DYNAMIC_FTRACE config. That is, when we don't do the run-time updates
> of mcount calls to nops, the compiler will use fentry but the code still
> uses mcount.
>
> I fixed this in the patch below. But as you two have acked and reviewed
> it, I can't add your tags if I have changed the code. Can you ack/review
> it again.
>
> Thanks!
>
This is the changes that were made against the original patch:
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 2add3bb..a698521 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -68,18 +68,19 @@
.section .entry.text, "ax"
#ifdef CONFIG_FUNCTION_TRACER
-#ifdef CONFIG_DYNAMIC_FTRACE
#ifdef CC_USING_FENTRY
-ENTRY(__fentry__)
- retq
-END(__fentry__)
+# define function_hook __fentry__
#else
-ENTRY(mcount)
- retq
-END(mcount)
+# define function_hook mcount
#endif
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+ENTRY(function_hook)
+ retq
+END(function_hook)
+
/* skip is set if stack has been adjusted */
.macro ftrace_caller_setup skip=0
MCOUNT_SAVE_FRAME \skip
@@ -188,7 +189,8 @@ END(ftrace_regs_caller)
#else /* ! CONFIG_DYNAMIC_FTRACE */
-ENTRY(mcount)
+
+ENTRY(function_hook)
cmpl $0, function_trace_stop
jne ftrace_stub
@@ -210,7 +212,11 @@ trace:
MCOUNT_SAVE_FRAME
movq RIP(%rsp), %rdi
+#ifdef CC_USING_FENTRY
+ movq SS+16(%rsp), %rsi
+#else
movq 8(%rbp), %rsi
+#endif
subq $MCOUNT_INSN_SIZE, %rdi
call *ftrace_trace_function
@@ -218,7 +224,7 @@ trace:
MCOUNT_RESTORE_FRAME
jmp ftrace_stub
-END(mcount)
+END(function_hook)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_TRACER */
--
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