Re: [RFC PATCH v1.9 07/14] x86/stacktrace: add function for detecting reliable stack traces

[Miroslav Benes]

On Fri, 25 Mar 2016, Josh Poimboeuf wrote:

> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 2dc18605..76274b8 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -138,6 +138,7 @@ config X86
>  	select HAVE_PERF_REGS
>  	select HAVE_PERF_USER_STACK_DUMP
>  	select HAVE_REGS_AND_STACK_ACCESS_API
> +	select HAVE_RELIABLE_STACKTRACE		if X86_64 && FRAME_POINTER

I understand we have to rely on frame pointer for now. Do you plan to 
switch to dwarf unwinder one day in the future? IOW is there a plan to 
implement dwarf stuff generation in objtool and then to have a dwarf-based 
stack unwinder upstream and to use it for live patching? 

We have FRAME_POINTER unset in SLES for performance reasons (there was 
some 5 percent slowdown measured in the past. However we should redo the 
experiments.) and one day we'd really like to switch to upstream from 
kgraft :). So I'm just asking.

Miroslav