Messages in this thread | | | Date | Fri, 15 Jun 2012 12:02:58 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC][PATCH 03/13 v2] ftrace: Return pt_regs to function trace callback |
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(2012/06/13 7:43), Steven Rostedt wrote: > From: Steven Rostedt <srostedt@redhat.com> > > Return as the 4th paramater to the function tracer callback the pt_regs. > > Currently x86_64 just passes NULL as the regs arguement. Later patches > that implement regs passing will require having the ftrace_ops set the > SAVE_REGS flag, which will tell the arch to take the time to pass a > full set of pt_regs to the ftrace_ops callback function. If the arch > does not support it then it should pass NULL.
Hmm, I think the x86-64 part of this patch would be better to be separated with x86-64 part of [5/13], so that I can easily review the change... Another reason is that this patch doesn't define ARCH_SUPPORTS_FTRACE_SAVE_REGS on x86_64 too...
> A ftrace_ops call back can either check if the macro ARCH_SUPPORTS_FTRACE_SAVE_REGS > is defined, or it can check if regs is NULL. As it will be NULL if > it is not supported by the arch even if the SAVE_REGS flag is set. > > If an arch can pass full regs, then it should define: > ARCH_SUPPORTS_FTRACE_SAVE_REGS to 1 > > Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [...] > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index 2b4f94c..83d8ae0 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -80,7 +80,11 @@ ENTRY(ftrace_caller) > MCOUNT_SAVE_FRAME > > leaq function_trace_op, %rdx > - movq 0x38(%rsp), %rdi > + > + /* regs go into 4th parameter (but make it NULL) */ > + movq $0, %rcx
There is no ARCH_SUPPORTS_FTRACE_SAVE_REGS, so I think you don't need to clear rcx at least this time.
Another generic ftrace part of this patch is good to me :)
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thank you,
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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