arm/arm64: smccc: Implement SMCCC v1.1 inline primitive

One of the major improvement of SMCCC v1.1 is that it only clobbers
the first 4 registers, both on 32 and 64bit. This means that it
becomes very easy to provide an inline version of the SMC call
primitive, and avoid performing a function call to stash the
registers that would otherwise be clobbered by SMCCC v1.0.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 141 insertions, 0 deletions

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index dd44d8458c04..a031897fca76 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -150,5 +150,146 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
 
 #define arm_smccc_hvc_quirk(...) __arm_smccc_hvc(__VA_ARGS__)
 
+/* SMCCC v1.1 implementation madness follows */
+#ifdef CONFIG_ARM64
+
+#define SMCCC_SMC_INST  "smc    #0"
+#define SMCCC_HVC_INST  "hvc    #0"
+
+#elif defined(CONFIG_ARM)
+#include <asm/opcodes-sec.h>
+#include <asm/opcodes-virt.h>
+
+#define SMCCC_SMC_INST  __SMC(0)
+#define SMCCC_HVC_INST  __HVC(0)
+
+#endif
+
+#define ___count_args(_0, _1, _2, _3, _4, _5, _6, _7, _8, x, ...) x
+
+#define __count_args(...)                                               \
+        ___count_args(__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0)
+
+#define __constraint_write_0                                            \
+        "+r" (r0), "=&r" (r1), "=&r" (r2), "=&r" (r3)
+#define __constraint_write_1                                            \
+        "+r" (r0), "+r" (r1), "=&r" (r2), "=&r" (r3)
+#define __constraint_write_2                                            \
+        "+r" (r0), "+r" (r1), "+r" (r2), "=&r" (r3)
+#define __constraint_write_3                                            \
+        "+r" (r0), "+r" (r1), "+r" (r2), "+r" (r3)
+#define __constraint_write_4    __constraint_write_3
+#define __constraint_write_5    __constraint_write_4
+#define __constraint_write_6    __constraint_write_5
+#define __constraint_write_7    __constraint_write_6
+
+#define __constraint_read_0
+#define __constraint_read_1
+#define __constraint_read_2
+#define __constraint_read_3
+#define __constraint_read_4     "r" (r4)
+#define __constraint_read_5     __constraint_read_4, "r" (r5)
+#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 u32           r0 asm("r0") = 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)                                    \
+        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")
+
+#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")
+
+#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
+
+#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
+
+#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
+
+#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
+
+#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
+
+#define ___declare_args(count, ...) __declare_arg_ ## count(__VA_ARGS__)
+#define __declare_args(count, ...)  ___declare_args(count, __VA_ARGS__)
+
+#define ___constraints(count)                                           \
+        : __constraint_write_ ## count                                  \
+        : __constraint_read_ ## count                                   \
+        : "memory"
+#define __constraints(count)    ___constraints(count)
+
+/*
+ * We have an output list that is not necessarily used, and GCC feels
+ * entitled to optimise the whole sequence away. "volatile" is what
+ * makes it stick.
+ */
+#define __arm_smccc_1_1(inst, ...)                                      \
+        do {                                                            \
+                __declare_args(__count_args(__VA_ARGS__), __VA_ARGS__); \
+                asm volatile(inst "\n"                                  \
+                             __constraints(__count_args(__VA_ARGS__))); \
+                if (___res)                                             \
+                        *___res = (typeof(*___res)){r0, r1, r2, r3};    \
+        } while (0)
+
+/*
+ * arm_smccc_1_1_smc() - make an SMCCC v1.1 compliant SMC call
+ *
+ * This is a variadic macro taking one to eight source arguments, and
+ * an optional return structure.
+ *
+ * @a0-a7: arguments passed in registers 0 to 7
+ * @res: result values from registers 0 to 3
+ *
+ * This macro is used to make SMC calls following SMC Calling Convention v1.1.
+ * The content of the supplied param are copied to registers 0 to 7 prior
+ * to the SMC instruction. The return values are updated with the content
+ * from register 0 to 3 on return from the SMC instruction if not NULL.
+ */
+#define arm_smccc_1_1_smc(...)  __arm_smccc_1_1(SMCCC_SMC_INST, __VA_ARGS__)
+
+/*
+ * arm_smccc_1_1_hvc() - make an SMCCC v1.1 compliant HVC call
+ *
+ * This is a variadic macro taking one to eight source arguments, and
+ * an optional return structure.
+ *
+ * @a0-a7: arguments passed in registers 0 to 7
+ * @res: result values from registers 0 to 3
+ *
+ * This macro is used to make HVC calls following SMC Calling Convention v1.1.
+ * The content of the supplied param are copied to registers 0 to 7 prior
+ * to the HVC instruction. The return values are updated with the content
+ * from register 0 to 3 on return from the HVC instruction if not NULL.
+ */
+#define arm_smccc_1_1_hvc(...)  __arm_smccc_1_1(SMCCC_HVC_INST, __VA_ARGS__)
+
 #endif /*__ASSEMBLY__*/
 #endif /*__LINUX_ARM_SMCCC_H*/