linux-kernel - Re: [PATCH v15 21/25] x86/asm: Create stack frames in rwsem functions

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Date:	Tue, 12 Jan 2016 13:41:58 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Josh Poimboeuf <jpoimboe@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
	Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Pedro Alves <palves@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
	Chris J Arges <chris.j.arges@...onical.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH v15 21/25] x86/asm: Create stack frames in rwsem functions

On Fri, Dec 18, 2015 at 06:39:35AM -0600, Josh Poimboeuf wrote:
> rwsem.S has several callable non-leaf functions which don't honor
> CONFIG_FRAME_POINTER, which can result in bad stack traces.
> 
> Create stack frames for them when CONFIG_FRAME_POINTER is enabled.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> ---
>  arch/x86/lib/rwsem.S | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S
> index 40027db..be110ef 100644
> --- a/arch/x86/lib/rwsem.S
> +++ b/arch/x86/lib/rwsem.S
> @@ -15,6 +15,7 @@
>  
>  #include <linux/linkage.h>
>  #include <asm/alternative-asm.h>
> +#include <asm/frame.h>
>  
>  #define __ASM_HALF_REG(reg)	__ASM_SEL(reg, e##reg)
>  #define __ASM_HALF_SIZE(inst)	__ASM_SEL(inst##w, inst##l)
> @@ -84,24 +85,29 @@
>  
>  /* Fix up special calling conventions */
>  ENTRY(call_rwsem_down_read_failed)
> +	FRAME_BEGIN

Remind me again, please, why aren't we hiding those
FRAME_BEGIN/FRAME_END macros in the ENTRY/ENDPROC ones?

>  	save_common_regs
>  	__ASM_SIZE(push,) %__ASM_REG(dx)
>  	movq %rax,%rdi
>  	call rwsem_down_read_failed
>  	__ASM_SIZE(pop,) %__ASM_REG(dx)
>  	restore_common_regs
> +	FRAME_END
>  	ret
>  ENDPROC(call_rwsem_down_read_failed)

Thanks!

-- 
Regards/Gruss,
    Boris.

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