[PATCH v13 01/10] arm64: smccc: add support for SMCCCv1.2 x0-x17 registers

Abdellatif El Khlifi
2023-06-16T15:28:50Z

add support for x0-x17 registers used by the SMC calls

In SMCCC v1.2 [1] arguments are passed in registers x1-x17.
Results are returned in x0-x17.

This work is inspired from the following kernel commit:

arm64: smccc: Add support for SMCCCv1.2 extended input/output registers

[1]: https://documentation-service.arm.com/static/5f8edaeff86e16515cdbe4c6?token=

Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>

---

Changelog:
===============

v9:

* update the copyright string

v7:

* improve indentation of ARM_SMCCC_1_2_REGS_Xn_OFFS

v4:

* rename the commit title and improve description
new commit title: the current

v3:

* port x0-x17 registers support from linux kernel as defined by SMCCCv1.2
commit title:
arm64: smccc: add Xn registers support used by SMC calls

arch/arm/cpu/armv8/smccc-call.S | 57 ++++++++++++++++++++++++++++++++-
arch/arm/lib/asm-offsets.c | 16 +++++++++
include/linux/arm-smccc.h | 45 ++++++++++++++++++++++++++
3 files changed, 117 insertions(+), 1 deletion(-)

diff --git a/arch/arm/cpu/armv8/smccc-call.S b/arch/arm/cpu/armv8/smccc-call.S
index dc92b28777..93f66d3366 100644
--- a/arch/arm/cpu/armv8/smccc-call.S
+++ b/arch/arm/cpu/armv8/smccc-call.S
@@ -1,7 +1,11 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2015, Linaro Limited
- */
+ * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+ *
+ * Authors:
+ * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
+*/
#include <linux/linkage.h>
#include <linux/arm-smccc.h>
#include <generated/asm-offsets.h>
@@ -45,3 +49,54 @@ 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 6de0ce9152..181a8ac4c2 100644
--- a/arch/arm/lib/asm-offsets.c
+++ b/arch/arm/lib/asm-offsets.c
@@ -9,6 +9,11 @@
* generate asm statements containing #defines,
* compile this file to assembler, and then extract the
* #defines from the assembly-language output.
+ *
+ * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+ *
+ * Authors:
+ * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
*/

#include <common.h>
@@ -90,6 +95,17 @@ 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..f44e9e8f93 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -1,6 +1,10 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2015, Linaro Limited
+ * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+ *
+ * Authors:
+ * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
*/
#ifndef __LINUX_ARM_SMCCC_H
#define __LINUX_ARM_SMCCC_H
@@ -70,6 +74,47 @@ 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
--
2.25.1