[3.13.y.z extended stable] Patch "ARM: 8165/1: alignment: don't break misaligned NEON load/store" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Thu Oct 9 20:51:48 UTC 2014

This is a note to let you know that I have just added a patch titled

    ARM: 8165/1: alignment: don't break misaligned NEON load/store

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From d45c0cd2d664f8c0a0bb0096cf8ebca62c78cf3b Mon Sep 17 00:00:00 2001
From: Robin Murphy <robin.murphy at arm.com>
Date: Thu, 25 Sep 2014 11:56:19 +0100
Subject: ARM: 8165/1: alignment: don't break misaligned NEON load/store

commit 5ca918e5e3f9df4634077c06585c42bc6a8d699a upstream.

The alignment fixup incorrectly decodes faulting ARM VLDn/VSTn
instructions (where the optional alignment hint is given but incorrect)
as LDR/STR, leading to register corruption. Detect these and correctly
treat them as unhandled, so that userspace gets the fault it expects.

Reported-by: Simon Hosie <simon.hosie at arm.com>
Signed-off-by: Robin Murphy <robin.murphy at arm.com>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 arch/arm/mm/alignment.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 9240364..d301662 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -40,6 +40,7 @@
  * This code is not portable to processors with late data abort handling.
 #define CODING_BITS(i)	(i & 0x0e000000)
+#define COND_BITS(i)	(i & 0xf0000000)

 #define LDST_I_BIT(i)	(i & (1 << 26))		/* Immediate constant	*/
 #define LDST_P_BIT(i)	(i & (1 << 24))		/* Preindex		*/
@@ -817,6 +818,8 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)

 	case 0x04000000:	/* ldr or str immediate */
+		if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */
+			goto bad;
 		offset.un = OFFSET_BITS(instr);
 		handler = do_alignment_ldrstr;

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