[PATCH 3/9] arm64: smccc: Add support for SMCCCv1.2 input/output registers

Sudeep Holla
2020-08-29T17:11:29Z

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@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 1f93809528a4..70e3749b44cf 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -45,3 +45,25 @@ 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 15c706fb0a37..b64552076b7e 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -152,6 +152,56 @@ 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-a3 result values from registers 0 to 3
+ */
+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 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_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
--
2.17.1