linux-kernel - [tip: x86/urgent] x86/entry/32: Fix IRET exception

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Message-ID: <157436726565.21853.619431994754383289.tip-bot2@tip-bot2>
Date:   Thu, 21 Nov 2019 20:14:25 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>, stable@...nel.org,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/urgent] x86/entry/32: Fix IRET exception

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     40ad2199580e248dce2a2ebb722854180c334b9e
Gitweb:        https://git.kernel.org/tip/40ad2199580e248dce2a2ebb722854180c334b9e
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Wed, 20 Nov 2019 13:05:06 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 21 Nov 2019 19:37:43 +01:00

x86/entry/32: Fix IRET exception

As reported by Lai, the commit 3c88c692c287 ("x86/stackframe/32:
Provide consistent pt_regs") wrecked the IRET EXTABLE entry by making
.Lirq_return not point at IRET.

Fix this by placing IRET_FRAME in RESTORE_REGS, to mirror how
FIXUP_FRAME is part of SAVE_ALL.

Fixes: 3c88c692c287 ("x86/stackframe/32: Provide consistent pt_regs")
Reported-by: Lai Jiangshan <laijs@...ux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Andy Lutomirski <luto@...nel.org>
Cc: stable@...nel.org
---
 arch/x86/entry/entry_32.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 019dbac..f4335ac 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -357,6 +357,7 @@
 2:	popl	%es
 3:	popl	%fs
 	POP_GS \pop
+	IRET_FRAME
 .pushsection .fixup, "ax"
 4:	movl	$0, (%esp)
 	jmp	1b
@@ -1075,7 +1076,6 @@ restore_all:
 	/* Restore user state */
 	RESTORE_REGS pop=4			# skip orig_eax/error_code
 .Lirq_return:
-	IRET_FRAME
 	/*
 	 * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on IRET core serialization
 	 * when returning from IPI handler and when returning from