linux-kernel - [34-longterm 033/209] um: remove PAGE_SIZE alignment in linker script causing kernel segfault.

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Message-Id: <1302803039-9400-34-git-send-email-paul.gortmaker@windriver.com>
Date:	Thu, 14 Apr 2011 13:41:03 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Richard Weinberger <richard@....at>,
	Tim Abbott <tabbott@...lice.com>,
	Jeff Dike <jdike@...toit.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 033/209] um: remove PAGE_SIZE alignment in linker script causing kernel segfault.

From: Richard Weinberger <richard@....at>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 6915e04f8847bea16d0890f559694ad8eedd026c upstream.

The linker script cleanup that I did in commit 5d150a97f93 ("um: Clean up
linker script using standard macros.") (2.6.32) accidentally introduced an
ALIGN(PAGE_SIZE) when converting to use INIT_TEXT_SECTION; Richard
Weinberger reported that this causes the kernel to segfault with
CONFIG_STATIC_LINK=y.

I'm not certain why this extra alignment is a problem, but it seems likely
it is because previously

__init_begin = _stext = _text = _sinittext

and with the extra ALIGN(PAGE_SIZE), _sinittext becomes different from the
rest.  So there is likely a bug here where something is assuming that
_sinittext is the same as one of those other symbols.  But reverting the
accidental change fixes the regression, so it seems worth committing that
now.

Signed-off-by: Tim Abbott <tabbott@...lice.com>
Reported-by: Richard Weinberger <richard@....at>
Cc: Jeff Dike <jdike@...toit.com>
Tested by: Antoine Martin <antoine@...afix.co.uk>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 arch/um/kernel/uml.lds.S |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index e7a6cca..664f942 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -22,7 +22,7 @@ SECTIONS
   _text = .;
   _stext = .;
   __init_begin = .;
-  INIT_TEXT_SECTION(PAGE_SIZE)
+  INIT_TEXT_SECTION(0)
   . = ALIGN(PAGE_SIZE);

   .text      :
-- 
1.7.4.4

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