linux-kernel - Re: [PATCH] [RFC] cross-arch: don't corrupt personality flags upon exec()

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Date:	Tue, 28 Aug 2012 12:53:00 -0400
From:	Chris Metcalf <cmetcalf@...era.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Kosina <jkosina@...e.cz>,
	Haavard Skinnemoen <hskinnemoen@...il.com>,
	Hans-Christian Egtvedt <egtvedt@...fundet.no>,
	Mike Frysinger <vapier@...too.org>,
	Mark Salter <msalter@...hat.com>,
	Mikael Starvik <starvik@...s.com>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	David Howells <dhowells@...hat.com>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>,
	Richard Kuo <rkuo@...eaurora.org>,
	Hirokazu Takata <takata@...ux-m32r.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Michal Simek <monstr@...str.eu>,
	Koichi Yasutake <yasutake.koichi@...panasonic.com>,
	Jonas Bonn <jonas@...thpole.se>,
	Chen Liqin <liqin.chen@...plusct.com>,
	Lennox Wu <lennox.wu@...il.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	"David S. Miller" <davem@...emloft.net>,
	Chris Zankel <chris@...kel.net>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [RFC] cross-arch: don't corrupt personality flags upon
 exec()

On 8/22/2012 3:27 PM, Arnd Bergmann wrote:
> On tile, the PER_LINUX_32BIT is always set for 32 bit compat tasks in a
> 64 bit kernel, which is harmless but wrong anyway. Also this, tile never
> calls set_personality, which is also harmless because it just means that
> exec_domain switching on tile is broken, but the only non-bogus
> exec_domain besides the default one is an experimental support for Acorn
> RISC OS binaries that was last updated in 2002 for for linux-2.5.49.

Arnd, thanks for the drive-by code review.  Is this change the correct fix
for your observation?

diff --git a/arch/tile/include/asm/elf.h b/arch/tile/include/asm/elf.h
index d16d006..fd31920 100644
--- a/arch/tile/include/asm/elf.h
+++ b/arch/tile/include/asm/elf.h
@@ -156,12 +156,12 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
 #undef SET_PERSONALITY
 #define SET_PERSONALITY(ex) \
 do { \
-       current->personality = PER_LINUX; \
+       set_personality(PER_LINUX);                  \
        current_thread_info()->status &= ~TS_COMPAT; \
 } while (0)
 #define COMPAT_SET_PERSONALITY(ex) \
 do { \
-       current->personality = PER_LINUX_32BIT; \
+       set_personality(PER_LINUX);                 \
        current_thread_info()->status |= TS_COMPAT; \
 } while (0)

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com

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