4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me
know.
---8<------------------------------------------------------------
From: Andy Lutomirski <l...@kernel.org>
commit 3d44d51bd339766f0178f0cf2e8d048b4a4872aa upstream.
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 <brge...@gmail.com>
Signed-off-by: Andy Lutomirski <l...@kernel.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Denys Vlasenko <dvlas...@redhat.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Fixes: 63bcff2a307b ("x86, smap: Add STAC and CLAC instructions to control user
space access")
Link:
http://lkml.kernel.org/r/b02b7e71ae54074be01fc171cbd4b72517055c0e.1456345086.git.l...@kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
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 a7e257d..1adeb50 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -468,6 +468,7 @@ ENTRY(entry_INT80_compat)
* it is too small to ever cause noticeable irq latency.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
+ ASM_CLAC /* Do this early to minimize exposure */
SWAPGS
ENABLE_INTERRUPTS(CLBR_NONE)
--
2.7.0
