[Xen-devel] [PATCH 3/6] xen/arm: add SMC wrapper that is compatible with SMCCC v1.0

[Julien Grall <julien.grall@xxxxxxx>]

From: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>

Existing SMC wrapper call_smc() allows only 4 parameters and
returns only one value. This is enough for existing
use in PSCI code, but TEE mediator will need a call that is
fully compatible with ARM SMCCC v1.0.

This patch adds a wrapper for both arm32 and arm64. In the case of
arm32, the wrapper is just an alias to the ARM SMCCC v1.1 as the
convention is the same.

CC: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxxx>
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
[julien: Rework the wrapper to make it closer to SMCC 1.1 wrapper]
Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/arm64/Makefile      |  1 +
 xen/arch/arm/arm64/asm-offsets.c |  5 ++++
 xen/arch/arm/arm64/smc.S         | 32 +++++++++++++++++++++++++
 xen/include/asm-arm/smccc.h      | 51 +++++++++++++++++++++++++++++++++++++++-
 4 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 xen/arch/arm/arm64/smc.S

diff --git a/xen/arch/arm/arm64/Makefile b/xen/arch/arm/arm64/Makefile
index bb5c610b2a..c4f3a28a0d 100644
--- a/xen/arch/arm/arm64/Makefile
+++ b/xen/arch/arm/arm64/Makefile
@@ -8,6 +8,7 @@ obj-y += domain.o
 obj-y += entry.o
 obj-y += insn.o
 obj-$(CONFIG_LIVEPATCH) += livepatch.o
+obj-y += smc.o
 obj-y += smpboot.o
 obj-y += traps.o
 obj-y += vfp.o
diff --git a/xen/arch/arm/arm64/asm-offsets.c b/xen/arch/arm/arm64/asm-offsets.c
index 62833d8c8b..280ddb55bf 100644
--- a/xen/arch/arm/arm64/asm-offsets.c
+++ b/xen/arch/arm/arm64/asm-offsets.c
@@ -10,6 +10,7 @@
 #include <xen/bitops.h>
 #include <public/xen.h>
 #include <asm/current.h>
+#include <asm/smccc.h>
 
 #define DEFINE(_sym, _val)                                                 \
     asm volatile ("\n.ascii\"==>#define " #_sym " %0 /* " #_val " */<==\"" \
@@ -51,6 +52,10 @@ void __dummy__(void)
 
    BLANK();
    OFFSET(INITINFO_stack, struct init_info, stack);
+
+   BLANK();
+   OFFSET(SMCCC_RES_a0, struct arm_smccc_res, a0);
+   OFFSET(SMCCC_RES_a2, struct arm_smccc_res, a2);
 }
 
 /*
diff --git a/xen/arch/arm/arm64/smc.S b/xen/arch/arm/arm64/smc.S
new file mode 100644
index 0000000000..b0752be57e
--- /dev/null
+++ b/xen/arch/arm/arm64/smc.S
@@ -0,0 +1,32 @@
+/*
+ * xen/arch/arm/arm64/smc.S
+ *
+ * Wrapper for Secure Monitors Calls
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <asm/asm_defns.h>
+#include <asm/macros.h>
+
+/*
+ * void __arm_smccc_1_0_smc(register_t a0, register_t a1, register_t a2,
+ *                          register_t a3, register_t a4, register_t a5,
+ *                          register_t a6, register_t a7,
+ *                          struct arm_smccc_res *res)
+ */
+ENTRY(__arm_smccc_1_0_smc)
+        smc     #0
+        ldr     x4, [sp]
+        cbz     x4, 1f          /* No need to store the result */
+        stp     x0, x1, [x4, #SMCCC_RES_a0]
+        stp     x2, x3, [x4, #SMCCC_RES_a2]
+1:
+        ret
diff --git a/xen/include/asm-arm/smccc.h b/xen/include/asm-arm/smccc.h
index 648bef28bd..1ed6cbaa48 100644
--- a/xen/include/asm-arm/smccc.h
+++ b/xen/include/asm-arm/smccc.h
@@ -207,7 +207,56 @@ struct arm_smccc_res {
         *___res = (typeof(*___res)){r0, r1, r2, r3};            \
     } while ( 0 )
 
-#endif
+/*
+ * The calling convention for arm32 is the same for both SMCCC v1.0 and
+ * v1.1.
+ */
+#ifdef CONFIG_ARM_32
+#define arm_smccc_1_0_smc(...) arm_smccc_1_1_smc(__VA_ARGS__)
+#else
+
+void __arm_smccc_1_0_smc(register_t a0, register_t a1, register_t a2,
+                         register_t a3, register_t a4, register_t a5,
+                         register_t a6, register_t a7,
+                         struct arm_smccc_res *res);
+
+/* Macros to handle variadic parameter for SMCCC v1.0 helper */
+#define __arm_smccc_1_0_smc_7(a0, a1, a2, a3, a4, a5, a6, a7, res)  \
+    __arm_smccc_1_0_smc(a0, a1, a2, a3, a4, a5, a6, a7, res)
+
+#define __arm_smccc_1_0_smc_6(a0, a1, a2, a3, a4, a5, a6, res)  \
+    __arm_smccc_1_0_smc_7(a0, a1, a2, a3, a4, a5, a6, 0, res)
+
+#define __arm_smccc_1_0_smc_5(a0, a1, a2, a3, a4, a5, res)  \
+    __arm_smccc_1_0_smc_6(a0, a1, a2, a3, a4, a5, 0, res)
+
+#define __arm_smccc_1_0_smc_4(a0, a1, a2, a3, a4, res)  \
+    __arm_smccc_1_0_smc_5(a0, a1, a2, a3, a4, 0, res)
+
+#define __arm_smccc_1_0_smc_3(a0, a1, a2, a3, res)  \
+    __arm_smccc_1_0_smc_4(a0, a1, a2, a3, 0, res)
+
+#define __arm_smccc_1_0_smc_2(a0, a1, a2, res)  \
+    __arm_smccc_1_0_smc_3(a0, a1, a2, 0, res)
+
+#define __arm_smccc_1_0_smc_1(a0, a1, res)  \
+    __arm_smccc_1_0_smc_2(a0, a1, 0, res)
+
+#define __arm_smccc_1_0_smc_0(a0, res)  \
+    __arm_smccc_1_0_smc_1(a0, 0, res)
+
+#define ___arm_smccc_1_0_smc_count(count, ...)    \
+    __arm_smccc_1_0_smc_ ## count(__VA_ARGS__)
+
+#define __arm_smccc_1_0_smc_count(count, ...)   \
+    ___arm_smccc_1_0_smc_count(count, __VA_ARGS__)
+
+#define arm_smccc_1_0_smc(...)                                              \
+        __arm_smccc_1_0_smc_count(__count_args(__VA_ARGS__), __VA_ARGS__)
+
+#endif /* CONFIG_ARM_64 */
+
+#endif /* __ASSEMBLY__ */
 
 /*
  * Construct function identifier from call type (fast or standard),
-- 
2.11.0


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