linux-kernel - [PATCH 1/1] x86: ensure we correctly advertise 32 bit processes in a 64 bit kernel

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Message-Id: <1284480057-18120-2-git-send-email-apw@canonical.com>
Date:	Tue, 14 Sep 2010 17:00:57 +0100
From:	Andy Whitcroft <apw@...onical.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Christoph Hellwig <hch@....de>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Andy Whitcroft <apw@...onical.com>
Subject: [PATCH 1/1] x86: ensure we correctly advertise 32 bit processes in a 64 bit kernel

A number of generic system calls modify their behaviour for 32 bit
processes when executed on a 64 bit kernel.  For example the uname
family return i686 for 32 bit processes but x86_64 for 64 bit processes.
These calls determine which return to use based on the personality,
specifically they check for PER_LINUX32.  x86 does not currently set this
personality type, using an x86 specific thread bit to distinguish.

Ensure we use personality PER_LINUX32 for 32 bit processes.

Signed-off-by: Andy Whitcroft <apw@...onical.com>
---
 arch/x86/kernel/process_64.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3d9ea53..3793a6a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -518,7 +518,7 @@ void set_personality_ia32(void)
 
 	/* Make sure to be in 32bit mode */
 	set_thread_flag(TIF_IA32);
-	current->personality |= force_personality32;
+	current->personality |= force_personality32 | PER_LINUX32;
 
 	/* Prepare the first "return" to user space */
 	current_thread_info()->status |= TS_COMPAT;
-- 
1.7.0.4

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