linux-kernel - [04/18] x86: Use u32 instead of long to set reset vector back to 0

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Message-Id: <20110305010352.218066009@clark.kroah.org>
Date:	Fri, 04 Mar 2011 17:02:58 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Don Zickus <dzickus@...hat.com>,
	Matthew Garrett <mjg@...hat.com>, Ingo Molnar <mingo@...e.hu>
Subject: [04/18] x86: Use u32 instead of long to set reset vector back to 0

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Don Zickus <dzickus@...hat.com>

commit 299c56966a72b9109d47c71a6db52097098703dd upstream.

A customer of ours, complained that when setting the reset
vector back to 0, it trashed other data and hung their box.
They noticed when only 4 bytes were set to 0 instead of 8,
everything worked correctly.

Mathew pointed out:

 |
 | We're supposed to be resetting trampoline_phys_low and
 | trampoline_phys_high here, which are two 16-bit values.
 | Writing 64 bits is definitely going to overwrite space
 | that we're not supposed to be touching.
 |

So limit the area modified to u32.

Signed-off-by: Don Zickus <dzickus@...hat.com>
Acked-by: Matthew Garrett <mjg@...hat.com>
LKML-Reference: <1297139100-424-1-git-send-email-dzickus@...hat.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/include/asm/smpboot_hooks.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/smpboot_hooks.h
+++ b/arch/x86/include/asm/smpboot_hooks.h
@@ -34,7 +34,7 @@ static inline void smpboot_restore_warm_
 	 */
 	CMOS_WRITE(0, 0xf);
 
-	*((volatile long *)phys_to_virt(apic->trampoline_phys_low)) = 0;
+	*((volatile u32 *)phys_to_virt(apic->trampoline_phys_low)) = 0;
 }
 
 static inline void __init smpboot_setup_io_apic(void)


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