ARM: 5757/1: Thumb-2: Correct "mov.w pc, lr" instruction which is unpredictable

The 32-bit wide variant of "mov pc, reg" in Thumb-2 is unpredictable
causing improper handling of the undefined instructions not caught by
the kernel. This patch adds a movw_pc macro for such situations
(currently only used in call_fpe).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index ac34c0d9384b..7e9ed1eea40a 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -110,6 +110,13 @@
         mov     \rd, sp, lsr #13
         mov     \rd, \rd, lsl #13
         .endm
+
+        @
+        @ 32-bit wide "mov pc, reg"
+        @
+        .macro  movw_pc, reg
+        mov     pc, \reg
+        .endm
 #else   /* CONFIG_THUMB2_KERNEL */
         .macro  svc_exit, rpsr
         clrex                                   @ clear the exclusive monitor
@@ -146,6 +153,14 @@
         lsr     \rd, \rd, #13
         mov     \rd, \rd, lsl #13
         .endm
+
+        @
+        @ 32-bit wide "mov pc, reg"
+        @
+        .macro  movw_pc, reg
+        mov     pc, \reg
+        nop
+        .endm
 #endif  /* !CONFIG_THUMB2_KERNEL */
 
 /*