[PATCH v3 2/7] arm64: smccc: Add support for SMCCCv1.2 input/output registers

[Sudeep Holla]

SMCCC v1.2 allows x8-x17 to be used as parameter registers and x4—x17
to be used as result registers in SMC64/HVC64. Arm Firmware Framework
for Armv8-A specification makes use of x0-x7 as parameter and result
registers.

Current SMCCC interface in the kernel just use x0-x7 as parameter and
x0-x3 as result registers. Let us add new interface to support x0-x7
as parameter and result registers. This can be extended to include
x8-x17 when there are users for the same.

Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
---
 arch/arm64/kernel/asm-offsets.c |  4 +++
 arch/arm64/kernel/smccc-call.S  | 22 +++++++++++++++
 include/linux/arm-smccc.h       | 50 +++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)

diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 7d32fc959b1a..32bcc25337ce 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -122,6 +122,10 @@ int main(void)
   DEFINE(ARM_SMCCC_RES_X2_OFFS,		offsetof(struct arm_smccc_res, a2));
   DEFINE(ARM_SMCCC_QUIRK_ID_OFFS,	offsetof(struct arm_smccc_quirk, id));
   DEFINE(ARM_SMCCC_QUIRK_STATE_OFFS,	offsetof(struct arm_smccc_quirk, state));
+  DEFINE(ARM_SMCCC_V1_2_RES_X0_OFFS,	offsetof(struct arm_smccc_v1_2_res, a0));
+  DEFINE(ARM_SMCCC_V1_2_RES_X2_OFFS,	offsetof(struct arm_smccc_v1_2_res, a2));
+  DEFINE(ARM_SMCCC_V1_2_RES_X4_OFFS,	offsetof(struct arm_smccc_v1_2_res, a4));
+  DEFINE(ARM_SMCCC_V1_2_RES_X6_OFFS,	offsetof(struct arm_smccc_v1_2_res, a6));
   BLANK();
   DEFINE(HIBERN_PBE_ORIG,	offsetof(struct pbe, orig_address));
   DEFINE(HIBERN_PBE_ADDR,	offsetof(struct pbe, address));
diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index d62447964ed9..0ea15c1742f3 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -43,3 +43,25 @@ SYM_FUNC_START(__arm_smccc_hvc)
 	SMCCC	hvc
 SYM_FUNC_END(__arm_smccc_hvc)
 EXPORT_SYMBOL(__arm_smccc_hvc)
+
+	.macro SMCCC_v1_2 instr
+	.cfi_startproc
+	\instr #0
+	ldr x8, [sp]
+	stp x0, x1, [x8, #ARM_SMCCC_V1_2_RES_X0_OFFS]
+	stp x2, x3, [x8, #ARM_SMCCC_V1_2_RES_X2_OFFS]
+	stp x4, x5, [x8, #ARM_SMCCC_V1_2_RES_X4_OFFS]
+	stp x6, x7, [x8, #ARM_SMCCC_V1_2_RES_X6_OFFS]
+	ret
+	.cfi_endproc
+.endm
+
+SYM_FUNC_START(arm_smccc_v1_2_hvc)
+	SMCCC_v1_2 hvc
+SYM_FUNC_END(arm_smccc_v1_2_hvc)
+EXPORT_SYMBOL(arm_smccc_v1_2_hvc)
+
+SYM_FUNC_START(arm_smccc_v1_2_smc)
+	SMCCC_v1_2 smc
+SYM_FUNC_END(arm_smccc_v1_2_smc)
+EXPORT_SYMBOL(arm_smccc_v1_2_smc)
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index f860645f6512..66fd3d582c7f 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -155,6 +155,56 @@ struct arm_smccc_res {
 	unsigned long a3;
 };
 
+#ifdef CONFIG_ARM64
+/* TODO Need to implement for ARM too */
+/**
+ * struct arm_smccc_v1_2_res - Result from SMC/HVC call
+ * @a0-a7 result values from registers 0 to 7
+ */
+struct arm_smccc_v1_2_res {
+	unsigned long a0;
+	unsigned long a1;
+	unsigned long a2;
+	unsigned long a3;
+	unsigned long a4;
+	unsigned long a5;
+	unsigned long a6;
+	unsigned long a7;
+};
+
+/**
+ * arm_smccc_v1_2_hvc() - make HVC calls
+ * @a0-a7: arguments passed in registers 0 to 7
+ * @res: result values from registers 0 to 7
+ *
+ * This function is used to make HVC calls following SMC Calling Convention
+ * v1.2 or above. 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 7 on return from the HVC instruction.
+ */
+asmlinkage
+void arm_smccc_v1_2_hvc(unsigned long a0, unsigned long a1, unsigned long a2,
+			unsigned long a3, unsigned long a4, unsigned long a5,
+			unsigned long a6, unsigned long a7,
+			struct arm_smccc_v1_2_res  *res);
+
+/**
+ * arm_smccc_v1_2_smc() - make SMC calls
+ * @a0-a7: arguments passed in registers 0 to 7
+ * @res: result values from registers 0 to 7
+ *
+ * This function is used to make SMC calls following SMC Calling Convention
+ * v1.2 or above. 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 7 on return from the SMC instruction.
+ */
+asmlinkage
+void arm_smccc_v1_2_smc(unsigned long a0, unsigned long a1, unsigned long a2,
+			unsigned long a3, unsigned long a4, unsigned long a5,
+			unsigned long a6, unsigned long a7,
+			struct arm_smccc_v1_2_res  *res);
+#endif
+
 /**
  * struct arm_smccc_quirk - Contains quirk information
  * @id: quirk identification
-- 
2.25.1