Re: [RFC][PATCH] objtool,ftrace: Implement UNWIND_HINT_RET_OFFSET

[Josh Poimboeuf]

On Tue, Mar 31, 2020 at 09:58:41PM +0200, Peter Zijlstra wrote:
> On Tue, Mar 31, 2020 at 11:31:36AM -0400, Steven Rostedt wrote:
> 
> > Can you send this change as a separate patch as it has nothing to do with
> > this current change, and is a clean up patch that stands on its own.
> 
> I also found this.. should I write it up?
> 
> ---
> diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
> index 369e61faacfe..0f108096f278 100644
> --- a/arch/x86/kernel/ftrace_64.S
> +++ b/arch/x86/kernel/ftrace_64.S
> @@ -23,7 +23,7 @@
>  #endif /* CONFIG_FRAME_POINTER */
> 
>  /* Size of stack used to save mcount regs in save_mcount_regs */
> -#define MCOUNT_REG_SIZE		(SS+8 + MCOUNT_FRAME_SIZE)
> +#define MCOUNT_REG_SIZE		(SIZEOF_PTREGS + MCOUNT_FRAME_SIZE)
> 
>  /*
>   * gcc -pg option adds a call to 'mcount' in most functions.
> @@ -77,7 +77,7 @@
>  	/*
>  	 * We add enough stack to save all regs.
>  	 */
> -	subq $(MCOUNT_REG_SIZE - MCOUNT_FRAME_SIZE), %rsp
> +	subq $(SIZEOF_PTREGS), %rsp
>  	movq %rax, RAX(%rsp)
>  	movq %rcx, RCX(%rsp)
>  	movq %rdx, RDX(%rsp)

I was going to suggest the same thing :-)

Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

-- 
Josh