[Xen-changelog] [xen staging] xen/arm: Workaround clang/armclang support for register allocation

[patchbot@xxxxxxx]

commit 0c35d446047aa632ec3a03221814ad5a6a37af97
Author:     Julien Grall <julien@xxxxxxx>
AuthorDate: Mon Feb 17 22:20:34 2020 +0000
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Tue Mar 3 18:04:34 2020 -0800

    xen/arm: Workaround clang/armclang support for register allocation
    
    Clang 8.0 (see [1]) and by extent some of the version of armclang does
    not support register allocation using the syntax rN.
    
    Thankfully, both GCC [2] and clang are able to support the xN syntax for
    Arm64. Introduce a new macro ASM_REG() and use in common code for
    register allocation.
    
    [1] https://reviews.llvm.org/rL328829
    [2] https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html
    
    Cc: Andrii Anisov <andrii_anisov@xxxxxxxx>
    Signed-off-by: Julien Grall <julien@xxxxxxx>
    Tested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/include/asm-arm/asm_defns.h |  8 ++++-
 xen/include/asm-arm/smccc.h     | 74 ++++++++++++++++++++---------------------
 2 files changed, 44 insertions(+), 38 deletions(-)

diff --git a/xen/include/asm-arm/asm_defns.h b/xen/include/asm-arm/asm_defns.h
index b4fbcdae1d..29a9dbb002 100644
--- a/xen/include/asm-arm/asm_defns.h
+++ b/xen/include/asm-arm/asm_defns.h
@@ -7,11 +7,17 @@
 #endif
 #include <asm/processor.h>
 
-/* For generic assembly code: use macros to define operand sizes. */
+/* Macros for generic assembly code */
 #if defined(CONFIG_ARM_32)
 # define __OP32
+# define ASM_REG(index) asm("r" # index)
 #elif defined(CONFIG_ARM_64)
 # define __OP32 "w"
+/*
+ * Clang < 8.0 doesn't support register alllocation using the syntax rN.
+ * See https://reviews.llvm.org/rL328829.
+ */
+# define ASM_REG(index) asm("x" # index)
 #else
 # error "unknown ARM variant"
 #endif
diff --git a/xen/include/asm-arm/smccc.h b/xen/include/asm-arm/smccc.h
index 126399dd70..9d94beb3df 100644
--- a/xen/include/asm-arm/smccc.h
+++ b/xen/include/asm-arm/smccc.h
@@ -120,59 +120,59 @@ struct arm_smccc_res {
 #define __constraint_read_6 __constraint_read_5, "r" (r6)
 #define __constraint_read_7 __constraint_read_6, "r" (r7)
 
-#define __declare_arg_0(a0, res)                        \
-    struct arm_smccc_res    *___res = res;              \
-    register unsigned long  r0 asm("r0") = (uint32_t)a0;\
-    register unsigned long  r1 asm("r1");               \
-    register unsigned long  r2 asm("r2");               \
-    register unsigned long  r3 asm("r3")
-
-#define __declare_arg_1(a0, a1, res)                    \
-    typeof(a1) __a1 = a1;                               \
-    struct arm_smccc_res    *___res = res;              \
-    register unsigned long  r0 asm("r0") = (uint32_t)a0;\
-    register unsigned long  r1 asm("r1") = __a1;        \
-    register unsigned long  r2 asm("r2");               \
-    register unsigned long  r3 asm("r3")
-
-#define __declare_arg_2(a0, a1, a2, res)                \
-    typeof(a1) __a1 = a1;                               \
-    typeof(a2) __a2 = a2;                               \
-    struct arm_smccc_res    *___res = res;                             \
-    register unsigned long  r0 asm("r0") = (uint32_t)a0;\
-    register unsigned long  r1 asm("r1") = __a1;        \
-    register unsigned long  r2 asm("r2") = __a2;        \
-    register unsigned long  r3 asm("r3")
-
-#define __declare_arg_3(a0, a1, a2, a3, res)            \
-    typeof(a1) __a1 = a1;                               \
-    typeof(a2) __a2 = a2;                               \
-    typeof(a3) __a3 = a3;                               \
-    struct arm_smccc_res    *___res = res;              \
-    register unsigned long  r0 asm("r0") = (uint32_t)a0;\
-    register unsigned long  r1 asm("r1") = __a1;        \
-    register unsigned long  r2 asm("r2") = __a2;        \
-    register unsigned long  r3 asm("r3") = __a3
+#define __declare_arg_0(a0, res)                            \
+    struct arm_smccc_res    *___res = res;                  \
+    register unsigned long  r0 ASM_REG(0) = (uint32_t)a0;   \
+    register unsigned long  r1 ASM_REG(1);                  \
+    register unsigned long  r2 ASM_REG(2);                  \
+    register unsigned long  r3 ASM_REG(3)
+
+#define __declare_arg_1(a0, a1, res)                        \
+    typeof(a1) __a1 = a1;                                   \
+    struct arm_smccc_res    *___res = res;                  \
+    register unsigned long  r0 ASM_REG(0) = (uint32_t)a0;   \
+    register unsigned long  r1 ASM_REG(1) = __a1;           \
+    register unsigned long  r2 ASM_REG(2);                  \
+    register unsigned long  r3 ASM_REG(3)
+
+#define __declare_arg_2(a0, a1, a2, res)                    \
+    typeof(a1) __a1 = a1;                                   \
+    typeof(a2) __a2 = a2;                                   \
+    struct arm_smccc_res    *___res = res;                                 \
+    register unsigned long  r0 ASM_REG(0) = (uint32_t)a0;   \
+    register unsigned long  r1 ASM_REG(1) = __a1;           \
+    register unsigned long  r2 ASM_REG(2) = __a2;           \
+    register unsigned long  r3 ASM_REG(3)
+
+#define __declare_arg_3(a0, a1, a2, a3, res)                \
+    typeof(a1) __a1 = a1;                                   \
+    typeof(a2) __a2 = a2;                                   \
+    typeof(a3) __a3 = a3;                                   \
+    struct arm_smccc_res    *___res = res;                  \
+    register unsigned long  r0 ASM_REG(0) = (uint32_t)a0;   \
+    register unsigned long  r1 ASM_REG(1) = __a1;           \
+    register unsigned long  r2 ASM_REG(2) = __a2;           \
+    register unsigned long  r3 ASM_REG(3) = __a3
 
 #define __declare_arg_4(a0, a1, a2, a3, a4, res)        \
     typeof(a4) __a4 = a4;                               \
     __declare_arg_3(a0, a1, a2, a3, res);               \
-    register unsigned long r4 asm("r4") = __a4
+    register unsigned long r4 ASM_REG(4) = __a4
 
 #define __declare_arg_5(a0, a1, a2, a3, a4, a5, res)    \
     typeof(a5) __a5 = a5;                               \
     __declare_arg_4(a0, a1, a2, a3, a4, res);           \
-    register typeof(a5) r5 asm("r5") = __a5
+    register typeof(a5) r5 ASM_REG(5) = __a5
 
 #define __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res)    \
     typeof(a6) __a6 = a6;                                   \
     __declare_arg_5(a0, a1, a2, a3, a4, a5, res);           \
-    register typeof(a6) r6 asm("r6") = __a6
+    register typeof(a6) r6 ASM_REG(6) = __a6
 
 #define __declare_arg_7(a0, a1, a2, a3, a4, a5, a6, a7, res)    \
     typeof(a7) __a7 = a7;                                       \
     __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res);           \
-    register typeof(a7) r7 asm("r7") = __a7
+    register typeof(a7) r7 ASM_REG(7) = __a7
 
 #define ___declare_args(count, ...) __declare_arg_ ## count(__VA_ARGS__)
 #define __declare_args(count, ...)  ___declare_args(count, __VA_ARGS__)
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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