linux-kernel - [PATCH v16.1 26/33] x86/kvm: Make test

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Message-ID: <20160122161612.GE20502@treble.redhat.com>
Date:	Fri, 22 Jan 2016 10:16:12 -0600
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Paolo Bonzini <pbonzini@...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>,
	Borislav Petkov <bp@...en8.de>,
	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>,
	Gleb Natapov <gleb@...nel.org>, kvm@...r.kernel.org
Subject: [PATCH v16.1 26/33] x86/kvm: Make test_cc() always inline

With some configs (including allyesconfig), gcc doesn't inline
test_cc().  When that happens, test_cc() doesn't create a stack frame
before inserting the inline asm call instruction.  This breaks frame
pointer convention if CONFIG_FRAME_POINTER is enabled and can result in
a bad stack trace.

Force it to always be inlined so that its containing function's stack
frame can be used.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Gleb Natapov <gleb@...nel.org>
Cc: kvm@...r.kernel.org
---
 arch/x86/kvm/emulate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index aa4d726..80363eb 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -969,7 +969,7 @@ static int em_bsr_c(struct x86_emulate_ctxt *ctxt)
 	return fastop(ctxt, em_bsr);
 }
 
-static u8 test_cc(unsigned int condition, unsigned long flags)
+static __always_inline u8 test_cc(unsigned int condition, unsigned long flags)
 {
 	u8 rc;
 	void (*fop)(void) = (void *)em_setcc + 4 * (condition & 0xf);
-- 
2.4.3