On Wed, Mar 17, 2021 at 08:17:59AM +0100, Jens Wiklander wrote:

On Fri, Feb 12, 2021 at 03:46:09PM +0000, Sudeep Holla wrote:

quoted

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 <redacted>
---
 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 301784463587..89b444591575 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c

@@ -129,6 +129,10 @@ 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 */

It would be nice to have this TODO resolved.

Agreed, but I don't have a complete stack to test this and bit nervous to push
untested code out or even merge it. We can push/get that merged when there
is need for it. It is definitely in my TODO list.

Thanks for all the review and testing. Sorry for the delay in response.
I was off until yesterday.

-- 
Regards,
Sudeep