From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Fri, 20 Oct 2017 11:21:35 -0500
Subject: [PATCH] x86/asm: Don't use the confusing '.ifeq' directive
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CVE-2017-5754

I find the '.ifeq <expression>' directive to be confusing.  Reading it
quickly seems to suggest its opposite meaning, or that it's missing an
argument.

Improve readability by replacing all of its x86 uses with
'.if <expression> == 0'.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrei Vagin <avagin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/757da028e802c7e98d23fbab8d234b1063e161cf.1508516398.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 82c62fa0c49aa305104013cee4468772799bb391)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
(cherry picked from commit 981dedac1061fb47d0b04e07f6752be195d7e41a)
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
 arch/x86/entry/entry_64.S | 2 +-
 arch/x86/kernel/head_32.S | 2 +-
 arch/x86/kernel/head_64.S | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 2e4fc6425f47..34adfe0221d2 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -830,7 +830,7 @@ ENTRY(\sym)
 
 	ASM_CLAC
 
-	.ifeq \has_error_code
+	.if \has_error_code == 0
 	pushq	$-1				/* ORIG_RAX: no syscall to restart */
 	.endif
 
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 1f85ee8f9439..337a65377baf 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -435,7 +435,7 @@ ENTRY(early_idt_handler_array)
 	# 24(%rsp) error code
 	i = 0
 	.rept NUM_EXCEPTION_VECTORS
-	.ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
+	.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
 	pushl $0		# Dummy error code, to make stack frame uniform
 	.endif
 	pushl $i		# 20(%esp) Vector number
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 12daaa0b187f..a2d8541b1da4 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -258,7 +258,7 @@ ENDPROC(start_cpu0)
 ENTRY(early_idt_handler_array)
 	i = 0
 	.rept NUM_EXCEPTION_VECTORS
-	.ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
+	.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
 		UNWIND_HINT_IRET_REGS
 		pushq $0	# Dummy error code, to make stack frame uniform
 	.else
-- 
2.14.2

