[ARM] 3746/2: Userspace helpers must be Thumb mode interworkable
Patch from Nicolas Pitre
The userspace helpers in clean/arch/arm/kernel/entry-armv.S are called
directly in/from userspace. They need to cope with being called from
Thumb code.
Patch below uses the bx interworking instruction when
CONFIG_ARM_THUMB=y.
Based on an earlier patch from Paul Brook <paul@codesourcery.com>
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 7ea5f01..de4e331 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -634,6 +634,14 @@
* purpose.
*/
+ .macro usr_ret, reg
+#ifdef CONFIG_ARM_THUMB
+ bx \reg
+#else
+ mov pc, \reg
+#endif
+ .endm
+
.align 5
.globl __kuser_helper_start
__kuser_helper_start:
@@ -675,7 +683,7 @@
#if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_SMP)
mcr p15, 0, r0, c7, c10, 5 @ dmb
#endif
- mov pc, lr
+ usr_ret lr
.align 5
@@ -778,7 +786,7 @@
mov r0, #-1
adds r0, r0, #0
#endif
- mov pc, lr
+ usr_ret lr
#else
@@ -792,7 +800,7 @@
#ifdef CONFIG_SMP
mcr p15, 0, r0, c7, c10, 5 @ dmb
#endif
- mov pc, lr
+ usr_ret lr
#endif
@@ -834,16 +842,11 @@
__kuser_get_tls: @ 0xffff0fe0
#if !defined(CONFIG_HAS_TLS_REG) && !defined(CONFIG_TLS_REG_EMUL)
-
ldr r0, [pc, #(16 - 8)] @ TLS stored at 0xffff0ff0
- mov pc, lr
-
#else
-
mrc p15, 0, r0, c13, c0, 3 @ read TLS register
- mov pc, lr
-
#endif
+ usr_ret lr
.rep 5
.word 0 @ pad up to __kuser_helper_version