[ARM] Fix byte order macros for Thumb

The byte order functions are visible to userspace. Unfortunately, __arch_swab32() contains an assembly instruction which is invalid when compiling for Thumb. This reverts to the C version when compiling for Thumb. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

[ARM] Fix byte order macros for Thumb
The byte order functions are visible to userspace. Unfortunately, __arch_swab32() contains an assembly instruction which is invalid when compiling for Thumb. This reverts to the C version when compiling for Thumb. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
H. Peter Anvin · Russell King
1 parent 5e64238717
Showing 1 changed file with 6 additions and 4 deletions Side-by-side Diff
include/asm-arm/byteorder.h
@@ -22,16 +22,18 @@
 {
 	__u32 t;
  
-	if (__builtin_constant_p(x)) {
-		t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */
-	} else {
+#ifndef __thumb__
+	if (!__builtin_constant_p(x)) {
 		/*
 		 * The compiler needs a bit of a hint here to always do the
 		 * right thing and not screw it up to different degrees
 		 * depending on the gcc version.
 		 */
 		asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
-	}
+	} else
+#endif
+		t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */
+
 	x = (x << 24) | (x >> 8);		/* mov r0,r0,ror #8      */
 	t &= ~0x00FF0000;			/* bic r1,r1,#0x00FF0000 */
 	x ^= (t >> 8);				/* eor r0,r0,r1,lsr #8   */
...	...	@@ -22,16 +22,18 @@
22	22	{
23	23	__u32 t;
24	24
25		- if (__builtin_constant_p(x)) {
26		- t = x ^ ((x << 16) \| (x >> 16)); /* eor r1,r0,r0,ror #16 */
27		- } else {
	25	+#ifndef __thumb__
	26	+ if (!__builtin_constant_p(x)) {
28	27	/*
29	28	* The compiler needs a bit of a hint here to always do the
30	29	* right thing and not screw it up to different degrees
31	30	* depending on the gcc version.
32	31	*/
33	32	asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
34		- }
	33	+ } else
	34	+#endif
	35	+ t = x ^ ((x << 16) \| (x >> 16)); /* eor r1,r0,r0,ror #16 */
	36	+
35	37	x = (x << 24) \| (x >> 8); /* mov r0,r0,ror #8 */
36	38	t &= ~0x00FF0000; /* bic r1,r1,#0x00FF0000 */
37	39	x ^= (t >> 8); /* eor r0,r0,r1,lsr #8 */