[PATCH v2] arm/arm64: smccc: Fix CLANG compilation for arm64

[PATCH v2] arm/arm64: smccc: Fix CLANG compilation for arm64

[Isaac J. Manjarres]

When CLANG compiles inline assembly for 64 bit ARM
architectures, it is unable to map register names,
such as "r0" to the correct alias, such as "x0" for 64
bit accesses, and "w0" for 32 bit accesses. While GCC
can perform this mapping, CLANG can not, which results in
compilation failures when building the kernel. Allow for
differentiation of which register names to use, based on
ARM architecture, to compile the kernel with CLANG.

Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
---
 include/linux/arm-smccc.h | 43 +++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index a031897..0f2846e 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -155,6 +155,8 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
 
 #define SMCCC_SMC_INST	"smc	#0"
 #define SMCCC_HVC_INST	"hvc	#0"
+#define SMCCC_REG(n)	"x" #n
+
 
 #elif defined(CONFIG_ARM)
 #include <asm/opcodes-sec.h>
@@ -162,6 +164,7 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
 
 #define SMCCC_SMC_INST	__SMC(0)
 #define SMCCC_HVC_INST	__HVC(0)
+#define SMCCC_REG(n)	"r" #n
 
 #endif
 
@@ -194,47 +197,47 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
 
 #define __declare_arg_0(a0, res)					\
 	struct arm_smccc_res   *___res = res;				\
-	register u32           r0 asm("r0") = a0;			\
-	register unsigned long r1 asm("r1");				\
-	register unsigned long r2 asm("r2");				\
-	register unsigned long r3 asm("r3")
+	register u32           r0 asm(SMCCC_REG(0)) = a0;		\
+	register unsigned long r1 asm(SMCCC_REG(1));			\
+	register unsigned long r2 asm(SMCCC_REG(2));			\
+	register unsigned long r3 asm(SMCCC_REG(3))
 
 #define __declare_arg_1(a0, a1, res)					\
 	struct arm_smccc_res   *___res = res;				\
-	register u32           r0 asm("r0") = a0;			\
-	register typeof(a1)    r1 asm("r1") = a1;			\
-	register unsigned long r2 asm("r2");				\
-	register unsigned long r3 asm("r3")
+	register u32           r0 asm(SMCCC_REG(0)) = a0;		\
+	register typeof(a1)    r1 asm(SMCCC_REG(1)) = a1;		\
+	register unsigned long r2 asm(SMCCC_REG(2));			\
+	register unsigned long r3 asm(SMCCC_REG(3))
 
 #define __declare_arg_2(a0, a1, a2, res)				\
 	struct arm_smccc_res   *___res = res;				\
-	register u32           r0 asm("r0") = a0;			\
-	register typeof(a1)    r1 asm("r1") = a1;			\
-	register typeof(a2)    r2 asm("r2") = a2;			\
-	register unsigned long r3 asm("r3")
+	register u32           r0 asm(SMCCC_REG(0)) = a0;		\
+	register typeof(a1)    r1 asm(SMCCC_REG(1)) = a1;		\
+	register typeof(a2)    r2 asm(SMCCC_REG(2)) = a2;		\
+	register unsigned long r3 asm(SMCCC_REG(3))
 
 #define __declare_arg_3(a0, a1, a2, a3, res)				\
 	struct arm_smccc_res   *___res = res;				\
-	register u32           r0 asm("r0") = a0;			\
-	register typeof(a1)    r1 asm("r1") = a1;			\
-	register typeof(a2)    r2 asm("r2") = a2;			\
-	register typeof(a3)    r3 asm("r3") = a3
+	register u32           r0 asm(SMCCC_REG(0)) = a0;		\
+	register typeof(a1)    r1 asm(SMCCC_REG(1)) = a1;		\
+	register typeof(a2)    r2 asm(SMCCC_REG(2)) = a2;		\
+	register typeof(a3)    r3 asm(SMCCC_REG(3)) = a3
 
 #define __declare_arg_4(a0, a1, a2, a3, a4, res)			\
 	__declare_arg_3(a0, a1, a2, a3, res);				\
-	register typeof(a4) r4 asm("r4") = a4
+	register typeof(a4) r4 asm(SMCCC_REG(4)) = a4
 
 #define __declare_arg_5(a0, a1, a2, a3, a4, a5, res)			\
 	__declare_arg_4(a0, a1, a2, a3, a4, res);			\
-	register typeof(a5) r5 asm("r5") = a5
+	register typeof(a5) r5 asm(SMCCC_REG(5)) = a5
 
 #define __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res)		\
 	__declare_arg_5(a0, a1, a2, a3, a4, a5, res);			\
-	register typeof(a6) r6 asm("r6") = a6
+	register typeof(a6) r6 asm(SMCCC_REG(6)) = a6
 
 #define __declare_arg_7(a0, a1, a2, a3, a4, a5, a6, a7, res)		\
 	__declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res);		\
-	register typeof(a7) r7 asm("r7") = a7
+	register typeof(a7) r7 asm(SMCCC_REG(7)) = a7
 
 #define ___declare_args(count, ...) __declare_arg_ ## count(__VA_ARGS__)
 #define __declare_args(count, ...)  ___declare_args(count, __VA_ARGS__)
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v2] arm/arm64: smccc: Fix CLANG compilation for arm64

[Marc Zyngier]

On 22/03/18 20:50, Isaac J. Manjarres wrote:
> When CLANG compiles inline assembly for 64 bit ARM
> architectures, it is unable to map register names,
> such as "r0" to the correct alias, such as "x0" for 64
> bit accesses, and "w0" for 32 bit accesses. While GCC
> can perform this mapping, CLANG can not, which results in
> compilation failures when building the kernel. Allow for
> differentiation of which register names to use, based on
> ARM architecture, to compile the kernel with CLANG.
> 
> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Please see the other 2 threads on the list. There is a fix under way for
Clang, so I don't think there is a need for this hack.

If you're using Clang to compile the kernel, you're already carrying a
number of extra patches, so adding this one shouldn't be a big deal.
Once Clang gains feature parity with GCC, you'll be able to drop it.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...