linux-kernel - [PATCH 1/6] x86: fix duplicated X86

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Date:	Thu, 30 Jun 2016 17:12:10 -0700
From:	Dave Hansen <dave@...1.net>
To:	linux-kernel@...r.kernel.org
Cc:	x86@...nel.org, linux-mm@...ck.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, bp@...en8.de, ak@...ux.intel.com,
	mhocko@...e.com, Dave Hansen <dave@...1.net>,
	dave.hansen@...ux.intel.com, luto@...nel.org,
	stable@...r.kernel.org
Subject: [PATCH 1/6] x86: fix duplicated X86_BUG(9) macro


From: Dave Hansen <dave.hansen@...ux.intel.com>

epufeatures.h currently defines X86_BUG(9) twice on 32-bit:

	#define X86_BUG_NULL_SEG        X86_BUG(9) /* Nulling a selector preserves the base */
	...
	#ifdef CONFIG_X86_32
	#define X86_BUG_ESPFIX          X86_BUG(9) /* "" IRET to 16-bit SS corrupts ESP/RSP high bits */
	#endif

I think what happened was that this added the X86_BUG_ESPFIX, but
in an #ifdef below most of the bugs:

	[58a5aac5] x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled

Then this came along and added X86_BUG_NULL_SEG, but collided
with the earlier one that did the bug below the main block
defining all the X86_BUG()s.

	[7a5d6704] x86/cpu: Probe the behavior of nulling out a segment at boot time

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Acked-by: Andy Lutomirski <luto@...nel.org>
Cc: stable@...r.kernel.org
---

 b/arch/x86/include/asm/cpufeatures.h |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff -puN arch/x86/include/asm/cpufeatures.h~knl-leak-10-fix-x86-bugs-macros arch/x86/include/asm/cpufeatures.h
--- a/arch/x86/include/asm/cpufeatures.h~knl-leak-10-fix-x86-bugs-macros	2016-06-30 17:10:41.215185869 -0700
+++ b/arch/x86/include/asm/cpufeatures.h	2016-06-30 17:10:41.218186005 -0700
@@ -301,10 +301,6 @@
 #define X86_BUG_FXSAVE_LEAK	X86_BUG(6) /* FXSAVE leaks FOP/FIP/FOP */
 #define X86_BUG_CLFLUSH_MONITOR	X86_BUG(7) /* AAI65, CLFLUSH required before MONITOR */
 #define X86_BUG_SYSRET_SS_ATTRS	X86_BUG(8) /* SYSRET doesn't fix up SS attrs */
-#define X86_BUG_NULL_SEG	X86_BUG(9) /* Nulling a selector preserves the base */
-#define X86_BUG_SWAPGS_FENCE	X86_BUG(10) /* SWAPGS without input dep on GS */
-
-
 #ifdef CONFIG_X86_32
 /*
  * 64-bit kernels don't use X86_BUG_ESPFIX.  Make the define conditional
@@ -312,5 +308,7 @@
  */
 #define X86_BUG_ESPFIX		X86_BUG(9) /* "" IRET to 16-bit SS corrupts ESP/RSP high bits */
 #endif
+#define X86_BUG_NULL_SEG	X86_BUG(10) /* Nulling a selector preserves the base */
+#define X86_BUG_SWAPGS_FENCE	X86_BUG(11) /* SWAPGS without input dep on GS */
 
 #endif /* _ASM_X86_CPUFEATURES_H */
_