ARM: Fix up vfp exception location in thumb mode

The exception handler in entry-armv.S checks for thumb mode and
correctly determines the exception location and instruction,
but VFP_bounce uses the uncorrected location off the stack.
If the VFP exception occured in Thumb mode, fix up the
exception location on the stack to match the value that would
be returned in ARM mode.

Fixes segfaults in userspace applications running in Thumb mode
caused by a handled VFP exception returning to the middle of the
instruction that triggered the exception.

Change-Id: I02be4c5b546561d9a967a02c1e9eb1de876cff07
Original-author: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 2b46fea..b3ec6f9 100644 (file)
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -491,7 +491,8 @@ __und_usr:
        blo     __und_usr_unknown
 3:     ldrht   r0, [r4]
        add     r2, r2, #2                      @ r2 is PC + 2, make it PC + 4
-       orr     r0, r0, r5, lsl #16
+       str     r2, [sp, #S_PC]                 @ it's a 2x16bit instr, update
+       orr     r0, r0, r5, lsl #16             @  regs->ARM_pc
 #else
        b       __und_usr_unknown
 #endif