From 3d44d51bd339766f0178f0cf2e8d048b4a4872aa Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@kernel.org>
Date: Wed, 24 Feb 2016 12:18:49 -0800
Subject: [PATCH] x86/entry/compat: Add missing CLAC to entry_INT80_32
This doesn't seem to fix a regression -- I don't think the CLAC was
ever there.
I double-checked in a debugger: entries through the int80 gate do
not automatically clear AC.
Stable maintainers: I can provide a backport to 4.3 and earlier if
needed. This needs to be backported all the way to 3.10.
Reported-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org> # v3.10 and later
Fixes: 63bcff2a307b ("x86, smap: Add STAC and CLAC instructions to control user space access")
Link: http://lkml.kernel.org/r/b02b7e71ae54074be01fc171cbd4b72517055c0e.1456345086.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/entry/entry_64_compat.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index ff1c6d61f332..3c990eeee40b 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -261,6 +261,7 @@ ENTRY(entry_INT80_compat)
* Interrupts are off on entry.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
+ ASM_CLAC /* Do this early to minimize exposure */
SWAPGS
/*
--
2.5.0