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From: tip-bot for Andy Lutomirski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: luto@kernel.org, bp@alien8.de, luto@amacapital.net,
	torvalds@linux-foundation.org, brgerst@gmail.com,
	tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com,
	dvlasenk@redhat.com, linux-kernel@vger.kernel.org,
	peterz@infradead.org
Subject: [tip:x86/urgent] x86/entry/compat: Add missing CLAC to entry_INT80_32
Date: Wed, 24 Feb 2016 23:47:05 -0800	[thread overview]
Message-ID: <tip-3d44d51bd339766f0178f0cf2e8d048b4a4872aa@git.kernel.org> (raw)
In-Reply-To: <b02b7e71ae54074be01fc171cbd4b72517055c0e.1456345086.git.luto@kernel.org>

Commit-ID:  3d44d51bd339766f0178f0cf2e8d048b4a4872aa
Gitweb:     http://git.kernel.org/tip/3d44d51bd339766f0178f0cf2e8d048b4a4872aa
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Wed, 24 Feb 2016 12:18:49 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 25 Feb 2016 08:31:20 +0100

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 ff1c6d6..3c990ee 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
 
 	/*

      reply	other threads:[~2016-02-25  7:48 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-24 20:18 [PATCH] " Andy Lutomirski
2016-02-25  7:47 ` tip-bot for Andy Lutomirski [this message]

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