[PATCH 3.2 070/102] ARM: 8165/1: alignment: don't break misaligned NEON load/store

[Ben Hutchings]

3.2.64-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Robin Murphy <robin.murphy@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/arm/mm/alignment.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -38,6 +38,7 @@
  * 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		*/
@@ -812,6 +813,8 @@ do_alignment(unsigned long addr, unsigne
 		break;
 
 	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;
 		break;

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