[PATCH v3 1/4] arm64: smccc: add Xn registers support used by SMC calls

[Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>]

use x0-x17 registers in the SMC32/SMC64 calls according to SMCCCv1.2

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jens Wiklander <jens.wiklander@linaro.org>
---
 arch/arm/cpu/armv8/smccc-call.S | 53 +++++++++++++++++++++++++++++++++
 arch/arm/lib/asm-offsets.c      | 13 ++++++++
 include/linux/arm-smccc.h       | 43 ++++++++++++++++++++++++++
 3 files changed, 109 insertions(+)

diff --git a/arch/arm/cpu/armv8/smccc-call.S b/arch/arm/cpu/armv8/smccc-call.S
index dc92b28777..ec6f299bc9 100644
--- a/arch/arm/cpu/armv8/smccc-call.S
+++ b/arch/arm/cpu/armv8/smccc-call.S
@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (c) 2015, Linaro Limited
+ * (C) Copyright 2022 ARM Limited
+ * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
  */
 #include <linux/linkage.h>
 #include <linux/arm-smccc.h>
@@ -45,3 +47,54 @@ ENDPROC(__arm_smccc_smc)
 ENTRY(__arm_smccc_hvc)
 	SMCCC	hvc
 ENDPROC(__arm_smccc_hvc)
+
+#ifdef CONFIG_ARM64
+
+	.macro SMCCC_1_2 instr
+	/* Save `res` and free a GPR that won't be clobbered */
+	stp     x1, x19, [sp, #-16]!
+
+	/* Ensure `args` won't be clobbered while loading regs in next step */
+	mov	x19, x0
+
+	/* Load the registers x0 - x17 from the struct arm_smccc_1_2_regs */
+	ldp	x0, x1, [x19, #ARM_SMCCC_1_2_REGS_X0_OFFS]
+	ldp	x2, x3, [x19, #ARM_SMCCC_1_2_REGS_X2_OFFS]
+	ldp	x4, x5, [x19, #ARM_SMCCC_1_2_REGS_X4_OFFS]
+	ldp	x6, x7, [x19, #ARM_SMCCC_1_2_REGS_X6_OFFS]
+	ldp	x8, x9, [x19, #ARM_SMCCC_1_2_REGS_X8_OFFS]
+	ldp	x10, x11, [x19, #ARM_SMCCC_1_2_REGS_X10_OFFS]
+	ldp	x12, x13, [x19, #ARM_SMCCC_1_2_REGS_X12_OFFS]
+	ldp	x14, x15, [x19, #ARM_SMCCC_1_2_REGS_X14_OFFS]
+	ldp	x16, x17, [x19, #ARM_SMCCC_1_2_REGS_X16_OFFS]
+
+	\instr #0
+
+	/* Load the `res` from the stack */
+	ldr	x19, [sp]
+
+	/* Store the registers x0 - x17 into the result structure */
+	stp	x0, x1, [x19, #ARM_SMCCC_1_2_REGS_X0_OFFS]
+	stp	x2, x3, [x19, #ARM_SMCCC_1_2_REGS_X2_OFFS]
+	stp	x4, x5, [x19, #ARM_SMCCC_1_2_REGS_X4_OFFS]
+	stp	x6, x7, [x19, #ARM_SMCCC_1_2_REGS_X6_OFFS]
+	stp	x8, x9, [x19, #ARM_SMCCC_1_2_REGS_X8_OFFS]
+	stp	x10, x11, [x19, #ARM_SMCCC_1_2_REGS_X10_OFFS]
+	stp	x12, x13, [x19, #ARM_SMCCC_1_2_REGS_X12_OFFS]
+	stp	x14, x15, [x19, #ARM_SMCCC_1_2_REGS_X14_OFFS]
+	stp	x16, x17, [x19, #ARM_SMCCC_1_2_REGS_X16_OFFS]
+
+	/* Restore original x19 */
+	ldp     xzr, x19, [sp], #16
+	ret
+	.endm
+
+/*
+ * void arm_smccc_1_2_smc(const struct arm_smccc_1_2_regs *args,
+ *			  struct arm_smccc_1_2_regs *res);
+ */
+ENTRY(arm_smccc_1_2_smc)
+	SMCCC_1_2 smc
+ENDPROC(arm_smccc_1_2_smc)
+
+#endif
diff --git a/arch/arm/lib/asm-offsets.c b/arch/arm/lib/asm-offsets.c
index 22fd541f9a..b6bd1b32b0 100644
--- a/arch/arm/lib/asm-offsets.c
+++ b/arch/arm/lib/asm-offsets.c
@@ -9,6 +9,8 @@
  * generate asm statements containing #defines,
  * compile this file to assembler, and then extract the
  * #defines from the assembly-language output.
+ *
+ * (C) Copyright 2022 ARM Limited
  */
 
 #include <common.h>
@@ -117,6 +119,17 @@ 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));
+	#ifdef CONFIG_ARM64
+		DEFINE(ARM_SMCCC_1_2_REGS_X0_OFFS,	offsetof(struct arm_smccc_1_2_regs, a0));
+		DEFINE(ARM_SMCCC_1_2_REGS_X2_OFFS,	offsetof(struct arm_smccc_1_2_regs, a2));
+		DEFINE(ARM_SMCCC_1_2_REGS_X4_OFFS,	offsetof(struct arm_smccc_1_2_regs, a4));
+		DEFINE(ARM_SMCCC_1_2_REGS_X6_OFFS,	offsetof(struct arm_smccc_1_2_regs, a6));
+		DEFINE(ARM_SMCCC_1_2_REGS_X8_OFFS,	offsetof(struct arm_smccc_1_2_regs, a8));
+		DEFINE(ARM_SMCCC_1_2_REGS_X10_OFFS,	offsetof(struct arm_smccc_1_2_regs, a10));
+		DEFINE(ARM_SMCCC_1_2_REGS_X12_OFFS,	offsetof(struct arm_smccc_1_2_regs, a12));
+		DEFINE(ARM_SMCCC_1_2_REGS_X14_OFFS,	offsetof(struct arm_smccc_1_2_regs, a14));
+		DEFINE(ARM_SMCCC_1_2_REGS_X16_OFFS,	offsetof(struct arm_smccc_1_2_regs, a16));
+	#endif
 #endif
 
 	return 0;
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index e1d09884a1..9105031d55 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (c) 2015, Linaro Limited
+ * (C) Copyright 2022 ARM Limited
+ * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
  */
 #ifndef __LINUX_ARM_SMCCC_H
 #define __LINUX_ARM_SMCCC_H
@@ -70,6 +72,47 @@ struct arm_smccc_res {
 	unsigned long a3;
 };
 
+#ifdef CONFIG_ARM64
+/**
+ * struct arm_smccc_1_2_regs - Arguments for or Results from SMC call
+ * @a0-a17 argument values from registers 0 to 17
+ */
+struct arm_smccc_1_2_regs {
+	unsigned long a0;
+	unsigned long a1;
+	unsigned long a2;
+	unsigned long a3;
+	unsigned long a4;
+	unsigned long a5;
+	unsigned long a6;
+	unsigned long a7;
+	unsigned long a8;
+	unsigned long a9;
+	unsigned long a10;
+	unsigned long a11;
+	unsigned long a12;
+	unsigned long a13;
+	unsigned long a14;
+	unsigned long a15;
+	unsigned long a16;
+	unsigned long a17;
+};
+
+/**
+ * arm_smccc_1_2_smc() - make SMC calls
+ * @args: arguments passed via struct arm_smccc_1_2_regs
+ * @res: result values via struct arm_smccc_1_2_regs
+ *
+ * This function is used to make SMC calls following SMC Calling Convention
+ * v1.2 or above. The content of the supplied param are copied from the
+ * structure to registers prior to the SMC instruction. The return values
+ * are updated with the content from registers on return from the SMC
+ * instruction.
+ */
+asmlinkage void arm_smccc_1_2_smc(const struct arm_smccc_1_2_regs *args,
+				  struct arm_smccc_1_2_regs *res);
+#endif
+
 /**
  * struct arm_smccc_quirk - Contains quirk information
  * @id: quirk identification
-- 
2.17.1