linux-kernel - Re: [PATCH v5 06/10] x86/asm/efi: Fix asmvalidate warnings for efi_stub

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Date:	Thu, 11 Jun 2015 14:14:39 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Josh Poimboeuf <jpoimboe@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
	Matt Fleming <matt.fleming@...el.com>,
	linux-efi@...r.kernel.org
Subject: Re: [PATCH v5 06/10] x86/asm/efi: Fix asmvalidate warnings for
 efi_stub_64.S

On Wed, 10 Jun, at 07:06:14AM, Josh Poimboeuf wrote:
> Fix the following asmvalidate warnings:
> 
>    asmvalidate: arch/x86/platform/efi/efi_stub_64.o: efi_call(): missing FP_SAVE/RESTORE macros
>    asmvalidate: arch/x86/boot/compressed/efi_stub_64.o: efi_call(): missing FP_SAVE/RESTORE macros
> 
> efi_call() is a non-leaf callable function, so save/restore the frame
> pointer with FP_SAVE/RESTORE.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> Cc: Matt Fleming <matt.fleming@...el.com>
> Cc: linux-efi@...r.kernel.org
> ---
>  arch/x86/platform/efi/efi_stub_64.S | 3 +++
>  1 file changed, 3 insertions(+)

Yeah, fair enough. Though it's worth noting that because we're calling
firmware functions, which use the Microsoft ABI, %rbp will be saved by
the callee function if used. Anyway,

Acked-by: Matt Fleming <matt.fleming@...el.com>

And since I know Boris in particular has poked around in this area, an
ACK from him would be worth alot.

-- 
Matt Fleming, Intel Open Source Technology Center
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