Fix unified syntax in ARM inline assembly

GCC 4.9 always emits assembly with divided syntax. Setting unified
syntax in inline assembly causes the assembler to complain about
GCC's generated code, because the directive extends past the scope
of the inline asm. Fix this by setting divided mode at the end of
the inline assembly block.

The assembler directives are hidden behind macros because later
versions of GCC won't need this workaround: they can be told to
use the unified syntax with -masm-syntax-unified.

Change-Id: Ic09e729e5bbb6fd44d08dac348daf6f55c75d7d8

1 files changed, 2 insertions, 1 deletions

diff --git a/firmware/asm/arm/thread.c b/firmware/asm/arm/thread.c
index bd9f950616..30df56e0d9 100644
--- a/firmware/asm/arm/thread.c
+++ b/firmware/asm/arm/thread.c
@@ -73,7 +73,7 @@ static inline void store_context(void* addr)
 static inline void load_context(const void* addr)
 {
     asm volatile(
-        ".syntax unified                \n"
+        BEGIN_ARM_ASM_SYNTAX_UNIFIED
         "ldr     r0, [%0, #40]          \n" /* Load start pointer */
         "cmp     r0, #0                 \n" /* Check for NULL */
 
@@ -86,6 +86,7 @@ static inline void load_context(const void* addr)
 #endif
 
         "ldmia   %0, { r4-r11, sp, lr } \n" /* Load regs r4 to r14 from context */
+        END_ARM_ASM_SYNTAX_UNIFIED
         : : "r" (addr) : "r0" /* only! */
     );
 }