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

From	Miroslav Benes <mbenes@suse.cz>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH v1.9 07/14] x86/stacktrace: add function for detecting reliable stack traces
Date	2016-03-31 15:10 +0200
Message-ID	<riKwi-5yc-31@gated-at.bofh.it> (permalink)
References	<rgFKp-6zA-3@gated-at.bofh.it> <rgFKr-6zA-59@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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

Thread

[RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  [RFC PATCH v1.9 03/14] x86/asm/head: standardize the bottom of the stack for idle tasks Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  [RFC PATCH v1.9 09/14] livepatch: remove unnecessary object loaded check Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  [RFC PATCH v1.9 11/14] livepatch: store function sizes Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  [RFC PATCH v1.9 13/14] livepatch: add /proc/<pid>/patch_status Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
    Re: [RFC PATCH v1.9 13/14] livepatch: add /proc/<pid>/patch_status Jiri Slaby <jslaby@suse.cz> - 2016-03-31 11:40 +0200
      Re: [RFC PATCH v1.9 13/14] livepatch: add /proc/<pid>/patch_status Jiri Slaby <jslaby@suse.cz> - 2016-03-31 11:50 +0200
  [RFC PATCH v1.9 02/14] x86/asm/head: use a common function for starting CPUs Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  [RFC PATCH v1.9 07/14] x86/stacktrace: add function for detecting reliable stack traces Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
    Re: [RFC PATCH v1.9 07/14] x86/stacktrace: add function for detecting  reliable stack traces Miroslav Benes <mbenes@suse.cz> - 2016-03-31 15:10 +0200
  [RFC PATCH v1.9 12/14] livepatch: create per-task consistency model Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
    Re: [RFC PATCH v1.9 12/14] livepatch: create per-task consistency  model Miroslav Benes <mbenes@suse.cz> - 2016-03-31 15:20 +0200
  [RFC PATCH v1.9 08/14] livepatch: separate enabled and patched states Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  [RFC PATCH v1.9 04/14] x86: move _stext marker before head code Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-25 20:40 +0100
  Re: [RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Miroslav Benes <mbenes@suse.cz> - 2016-03-31 15:00 +0200
  Re: [RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Petr Mladek <pmladek@suse.com> - 2016-04-01 15:40 +0200
    Re: [RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Petr Mladek <pmladek@suse.com> - 2016-04-01 17:40 +0200
  Re: [RFC PATCH v1.9 00/14] livepatch: hybrid consistency model Miroslav Benes <mbenes@suse.cz> - 2016-04-01 15:40 +0200

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