ARM: 7895/1: signal: fix armv7-m build issue in sigreturn_codes.S

After "ARM: signal: sigreturn_codes should be endian neutral to
work in BE8" commit, thumb only platforms, like armv7m, fails to
compile sigreturn_codes.S. The reason is that for such arch
values '.arm' directive and arm opcodes are not allowed.

Fix conditionally enables arm opcodes only if no CONFIG_CPU_THUMBONLY
defined and it uses .org instructions to keep sigreturn_codes
layout.

Suggested-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 31 insertions, 9 deletions

diff --git a/arch/arm/kernel/sigreturn_codes.S b/arch/arm/kernel/sigreturn_codes.S
index 3c5d0f2170fd..b84d0cb13682 100644
--- a/arch/arm/kernel/sigreturn_codes.S
+++ b/arch/arm/kernel/sigreturn_codes.S
@@ -30,6 +30,27 @@
  * snippets.
  */
 
+/*
+ * In CPU_THUMBONLY case kernel arm opcodes are not allowed.
+ * Note in this case codes skips those instructions but it uses .org
+ * directive to keep correct layout of sigreturn_codes array.
+ */
+#ifndef CONFIG_CPU_THUMBONLY
+#define ARM_OK(code...) code
+#else
+#define ARM_OK(code...)
+#endif
+
+        .macro arm_slot n
+        .org    sigreturn_codes + 12 * (\n)
+ARM_OK( .arm    )
+        .endm
+
+        .macro thumb_slot n
+        .org    sigreturn_codes + 12 * (\n) + 8
+        .thumb
+        .endm
+
 #if __LINUX_ARM_ARCH__ <= 4
         /*
          * Note we manually set minimally required arch that supports
@@ -45,26 +66,27 @@
         .global sigreturn_codes
         .type   sigreturn_codes, #object
 
-        .arm
+        .align
 
 sigreturn_codes:
 
         /* ARM sigreturn syscall code snippet */
-        mov     r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)
-        swi     #(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)
+        arm_slot 0
+ARM_OK( mov     r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)       )
+ARM_OK( swi     #(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)      )
 
         /* Thumb sigreturn syscall code snippet */
-        .thumb
+        thumb_slot 0
         movs    r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)
         swi     #0
 
         /* ARM sigreturn_rt syscall code snippet */
-        .arm
-        mov     r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)
-        swi     #(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)
+        arm_slot 1
+ARM_OK( mov     r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)    )
+ARM_OK( swi     #(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)   )
 
         /* Thumb sigreturn_rt syscall code snippet */
-        .thumb
+        thumb_slot 1
         movs    r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)
         swi     #0
 
@@ -74,7 +96,7 @@ sigreturn_codes:
          * it is thumb case or not, so we need additional
          * word after real last entry.
          */
-        .arm
+        arm_slot 2
         .space  4
 
         .size   sigreturn_codes, . - sigreturn_codes