From mboxrd@z Thu Jan  1 00:00:00 1970
From: Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH 26/33] x86/kvm: Add stack frame dependency to test_cc()
 inline asm
Date: Fri, 22 Jan 2016 10:02:45 -0600
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Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
	linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
	Michal Marek <mmarek@suse.cz>,
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	Andy Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andi Kleen <andi@firstfloor.org>,
	Pedro Alves <palves@redhat.com>,
	Namhyung Kim <namhyung@gmail.com>,
	Bernd Petrovitsch <bernd@petrovitsch.priv.at>,
	Chris J Arges <chris.j.arges@canonical.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Gleb Natapov <gleb@kernel.org>, kvm@vger.kernel.org
To: Paolo Bonzini <pbonzini@redhat.com>
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On Fri, Jan 22, 2016 at 11:05:06AM +0100, Paolo Bonzini wrote:
> 
> 
> On 21/01/2016 23:49, Josh Poimboeuf wrote:
> > With some configs, gcc doesn't inline test_cc().  When that happens, it
> > doesn't create a stack frame before inserting the call instruction.
> > This breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled
> > and can result in a bad stack trace.
> > 
> > Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by
> > listing the stack pointer as an output operand for the inline asm
> > statement.
> 
> If an __always_inline allocation works, that would be better.

Yeah, that seems to work.  I'll update the patch.

-- 
Josh