[PATCH 2/4] ARM: opcodes: Make opcode byteswapping macros assembly-compatible

[Dave Martin]

Most of the existing macros don't work with assembler, due to the
use of type casts and C functions from <linux/swab.h>.

This patch abstracts out those operations and provides simple
explicit versions for use in assembly code.

__opcode_is_thumb32() and __opcode_is_thumb16() are also converted
to do bitmask-based testing to avoid confusion if these are used in
assembly code (the assembler typically treats all arithmetic values
as signed).

Signed-off-by: Dave Martin <dave.martin at linaro.org>
---
 arch/arm/include/asm/opcodes.h |   97 +++++++++++++++++++++++++++++++++------
 1 files changed, 82 insertions(+), 15 deletions(-)

diff --git a/arch/arm/include/asm/opcodes.h b/arch/arm/include/asm/opcodes.h
index cf877c8..32730a8 100644
--- a/arch/arm/include/asm/opcodes.h
+++ b/arch/arm/include/asm/opcodes.h
@@ -19,6 +19,33 @@ extern asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr);
 
 
 /*
+ * Assembler opcode byteswap helpers.
+ * These are only intended for use by this header: don't use them directly,
+ * because they will be suboptimal in most cases.
+ */
+#define ___asm_opcode_swab32(x) (	\
+	  (((x) << 24) & 0xFF000000)	\
+	| (((x) <<  8) & 0x00FF0000)	\
+	| (((x) >>  8) & 0x0000FF00)	\
+	| (((x) >> 24) & 0x000000FF)	\
+)
+#define ___asm_opcode_swab16(x) (	\
+	  (((x) << 8) & 0xFF00)		\
+	| (((x) >> 8) & 0x00FF)		\
+)
+#define ___asm_opcode_swahb32(x) (	\
+	  (((x) << 8) & 0xFF00FF00)	\
+	| (((x) >> 8) & 0x00FF00FF)	\
+)
+#define ___asm_opcode_swahw32(x) (	\
+	  (((x) << 16) & 0xFFFF0000)	\
+	| (((x) >> 16) & 0x0000FFFF)	\
+)
+#define ___asm_opcode_identity32(x) ((x) & 0xFFFFFFFF)
+#define ___asm_opcode_identity16(x) ((x) & 0xFFFF)
+
+
+/*
  * Opcode byteswap helpers
  *
  * These macros help with converting instructions between a canonical integer
@@ -41,30 +68,58 @@ extern asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr);
  * Note that values in the range 0x0000E800..0xE7FFFFFF intentionally do not
  * represent any valid Thumb-2 instruction.  For this range,
  * __opcode_is_thumb32() and __opcode_is_thumb16() will both be false.
+ *
+ * The ___asm variants are intended only for use by this header, in situations
+ * involving inline assembler.  For .S files, the normal __opcode_*() macros
+ * should do the right thing.
  */
+#ifdef __ASSEMBLY__
 
-#ifndef __ASSEMBLY__
+#define ___opcode_swab32(x) ___asm_opcode_swab32(x)
+#define ___opcode_swab16(x) ___asm_opcode_swab16(x)
+#define ___opcode_swahb32(x) ___asm_opcode_swahb32(x)
+#define ___opcode_swahw32(x) ___asm_opcode_swahw32(x)
+#define ___opcode_identity32(x) ___asm_opcode_identity32(x)
+#define ___opcode_identity16(x) ___asm_opcode_identity16(x)
+
+#else /* ! __ASSEMBLY__ */
 
 #include <linux/types.h>
 #include <linux/swab.h>
 
+#define ___opcode_swab32(x) swab32(x)
+#define ___opcode_swab16(x) swab16(x)
+#define ___opcode_swahb32(x) swahb32(x)
+#define ___opcode_swahw32(x) swahw32(x)
+#define ___opcode_identity32(x) ((u32)(x))
+#define ___opcode_identity16(x) ((u16)(x))
+
+#endif /* ! __ASSEMBLY__ */
+
+
 #ifdef CONFIG_CPU_ENDIAN_BE8
 
-#define __opcode_to_mem_arm(x) swab32(x)
-#define __opcode_to_mem_thumb16(x) swab16(x)
-#define __opcode_to_mem_thumb32(x) swahb32(x)
+#define __opcode_to_mem_arm(x) ___opcode_swab32(x)
+#define __opcode_to_mem_thumb16(x) ___opcode_swab16(x)
+#define __opcode_to_mem_thumb32(x) ___opcode_swahb32(x)
+#define ___asm_opcode_to_mem_arm(x) ___asm_opcode_swab32(x)
+#define ___asm_opcode_to_mem_thumb16(x) ___asm_opcode_swab16(x)
+#define ___asm_opcode_to_mem_thumb32(x) ___asm_opcode_swahb32(x)
 
 #else /* ! CONFIG_CPU_ENDIAN_BE8 */
 
-#define __opcode_to_mem_arm(x) ((u32)(x))
-#define __opcode_to_mem_thumb16(x) ((u16)(x))
+#define __opcode_to_mem_arm(x) ___opcode_identity32(x)
+#define __opcode_to_mem_thumb16(x) ___opcode_identity16(x)
+#define ___asm_opcode_to_mem_arm(x) ___asm_opcode_identity32(x)
+#define ___asm_opcode_to_mem_thumb16(x) ___asm_opcode_identity16(x)
 #ifndef CONFIG_CPU_ENDIAN_BE32
 /*
  * On BE32 systems, using 32-bit accesses to store Thumb instructions will not
  * work in all cases, due to alignment constraints.  For now, a correct
  * version is not proivided for BE32.
  */
-#define __opcode_to_mem_thumb32(x) swahw32(x)
+#define __opcode_to_mem_thumb32(x) ___opcode_swahw32(x)
+#define ___asm_opcode_to_mem_thumb32(x) ___asm_opcode_swahw32(x)
 #endif
 
 #endif /* ! CONFIG_CPU_ENDIAN_BE8 */
@@ -78,15 +133,27 @@ extern asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr);
 /* Operations specific to Thumb opcodes */
 
 /* Instruction size checks: */
-#define __opcode_is_thumb32(x) ((u32)(x) >= 0xE8000000UL)
-#define __opcode_is_thumb16(x) ((u32)(x) < 0xE800UL)
+#define __opcode_is_thumb32(x) (		\
+	   ((x) & 0xF8000000) == 0xE8000000	\
+	|| ((x) & 0xF0000000) == 0xF0000000	\
+)
+#define __opcode_is_thumb16(x) (					\
+	   ((x) & 0xFFFF0000) == 0					\
+	&& !(((x) & 0xF800) == 0xE800 || ((x) & 0xF000) == 0xF000)	\
+)
 
 /* Operations to construct or split 32-bit Thumb instructions: */
-#define __opcode_thumb32_first(x) ((u16)((x) >> 16))
-#define __opcode_thumb32_second(x) ((u16)(x))
-#define __opcode_thumb32_compose(first, second) \
-	(((u32)(u16)(first) << 16) | (u32)(u16)(second))
-
-#endif /* __ASSEMBLY__ */
+#define __opcode_thumb32_first(x) (___opcode_identity16((x) >> 16))
+#define __opcode_thumb32_second(x) (___opcode_identity16(x))
+#define __opcode_thumb32_compose(first, second) (			\
+	  (___opcode_identity32(___opcode_identity16(first)) << 16)	\
+	| ___opcode_identity32(___opcode_identity16(second))		\
+)
+#define ___asm_opcode_thumb32_first(x) (___asm_opcode_identity16((x) >> 16))
+#define ___asm_opcode_thumb32_second(x) (___asm_opcode_identity16(x))
+#define ___asm_opcode_thumb32_compose(first, second) (			    \
+	  (___asm_opcode_identity32(___asm_opcode_identity16(first)) << 16) \
+	| ___asm_opcode_identity32(___asm_opcode_identity16(second))	    \
+)
 
 #endif /* __ASM_ARM_OPCODES_H */
-- 
1.7.4.1