The Realm Service Interface (RSI) commands use registers between
X1-X10 as parameters and between X0-X8 as return values for SMC
calls.
According to the SMCCC Section 2.6 SMC32/HVC32 argument passing
When an SMC32/HVC32 call is made from AArch32:
- Arguments are passed in registers R1-R7.
- Results are returned in R0-R7.
When an SMC32/HVC32 call is made from AArch64:
- Arguments are passed in registers W1-W7.
- Results are returned in W0-W7.
According to SMCCC Section 2.7 SMC64/HVC64 argument passing
When an SMC64/HVC64 call is made from AArch64:
- Arguments are passed in registers X1-X17.
- Results are returned in X0-X17.
This means SMC calls can take up to 7/17 arguments and return up
to 7/17 return values.
However, for the current use-case(s):
- SMC32/HVC32 calls made from AArch32/AArch64 require up to 7
arguments and 4 return values.
- SMC64/HVC64 calls made from AArch64 require up to 10 arguments
and 9 return values.
Therefore, for SMC32/HVC32 calls made from AArch32/AArch64 there is
no update required. However, for AMC64/HVC64 calls made from AArch64,
extend the ArmCallSmc () to use registers X1-X11 as parameters and
return values for SMC call.
Signed-off-by: Sami Mujawar <sami.muja...@arm.com>
---
ArmPkg/Include/Library/ArmSmcLib.h | 50 ++++++++++++++++++--
ArmPkg/Library/ArmSmcLib/AArch64/ArmSmc.S | 22 ++++++---
2 files changed, 62 insertions(+), 10 deletions(-)
diff --git a/ArmPkg/Include/Library/ArmSmcLib.h
b/ArmPkg/Include/Library/ArmSmcLib.h
index
beef0175c35ce86aac9e465f9062bf8052b08dfb..e80b74671a6424723323bab95917fb3909771759
100644
--- a/ArmPkg/Include/Library/ArmSmcLib.h
+++ b/ArmPkg/Include/Library/ArmSmcLib.h
@@ -1,10 +1,13 @@
/** @file
*
* Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
-* Copyright (c) 2012-2014, ARM Limited. All rights reserved.
+* Copyright (c) 2012-2023, Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: BSD-2-Clause-Patent
*
+* @par Reference(s):
+* - SMC Calling Convention (SMCCC), ARM DEN 0028E, EAC0, 1.4
+* (https://developer.arm.com/documentation/den0028/e/)
**/
#ifndef ARM_SMC_LIB_H_
@@ -13,6 +16,18 @@
/**
* The size of the SMC arguments are different between AArch64 and AArch32.
* The native size is used for the arguments.
+ * According to the SMCCC Section 2.6 SMC32/HVC32 argument passing
+ * When an SMC32/HVC32 call is made from AArch32:
+ * - Arguments are passed in registers R1-R7.
+ * - Results are returned in R0-R7.
+ * When an SMC32/HVC32 call is made from AArch64:
+ * - Arguments are passed in registers W1-W7.
+ * - Results are returned in W0-W7.
+ *
+ * According to SMCCC Section 2.7 SMC64/HVC64 argument passing
+ * When an SMC64/HVC64 call is made from AArch64:
+ * - Arguments are passed in registers X1-X17.
+ * - Results are returned in X0-X17.
*/
typedef struct {
UINTN Arg0;
@@ -23,13 +38,42 @@ typedef struct {
UINTN Arg5;
UINTN Arg6;
UINTN Arg7;
+ #ifdef MDE_CPU_AARCH64
+ UINTN Arg8;
+ UINTN Arg9;
+ UINTN Arg10;
+ UINTN Arg11;
+ #endif
} ARM_SMC_ARGS;
/**
Trigger an SMC call
- SMC calls can take up to 7 arguments and return up to 4 return values.
- Therefore, the 4 first fields in the ARM_SMC_ARGS structure are used
+ According to the SMCCC Section 2.6 SMC32/HVC32 argument passing
+ When an SMC32/HVC32 call is made from AArch32:
+ - Arguments are passed in registers R1-R7.
+ - Results are returned in R0-R7.
+ When an SMC32/HVC32 call is made from AArch64:
+ - Arguments are passed in registers W1-W7.
+ - Results are returned in W0-W7.
+
+ According to SMCCC Section 2.7 SMC64/HVC64 argument passing
+ When an SMC64/HVC64 call is made from AArch64:
+ - Arguments are passed in registers X1-X17.
+ - Results are returned in X0-X17.
+
+ This means SMC calls can take up to 7/17 arguments and return up
+ to 7/17 return values.
+
+ However, the current use-case:
+ - For SMC32/HVC32 calls made from AArch32/AArch64 up to 7 arguments
+ and 4 return values are required. Therefore, limit the maximum
+ arguments to 7 and return values to 4.
+ - For AMC64/HVC64 calls made from AArch64 up to 11 arguments and
+ return values are required. Therefore, limit the maximum arguments
+ and return values to 11.
+
+ The fields in the ARM_SMC_ARGS structure are used
for both input and output values.
**/
diff --git a/ArmPkg/Library/ArmSmcLib/AArch64/ArmSmc.S
b/ArmPkg/Library/ArmSmcLib/AArch64/ArmSmc.S
index
4a8c2a8f59eab3e5b66dda2515d5bbced131af13..299d612dc5e1ebfeaf69a356b400c511905d72fe
100644
--- a/ArmPkg/Library/ArmSmcLib/AArch64/ArmSmc.S
+++ b/ArmPkg/Library/ArmSmcLib/AArch64/ArmSmc.S
@@ -1,8 +1,11 @@
//
-// Copyright (c) 2012-2014, ARM Limited. All rights reserved.
+// Copyright (c) 2012-2023, Arm Limited. All rights reserved.
//
// SPDX-License-Identifier: BSD-2-Clause-Patent
//
+// @par Reference(s):
+// - SMC Calling Convention (SMCCC), ARM DEN 0028E, EAC0, 1.4
+// (https://developer.arm.com/documentation/den0028/e/)
//
#include <AsmMacroIoLibV8.h>
@@ -12,6 +15,8 @@ ASM_FUNC(ArmCallSmc)
str x0, [sp, #-16]!
// Load the SMC arguments values into the appropriate registers
+ ldp x10, x11, [x0, #80]
+ ldp x8, x9, [x0, #64]
ldp x6, x7, [x0, #48]
ldp x4, x5, [x0, #32]
ldp x2, x3, [x0, #16]
@@ -19,14 +24,17 @@ ASM_FUNC(ArmCallSmc)
smc #0
- // Pop the ARM_SMC_ARGS structure address from the stack into x9
- ldr x9, [sp], #16
+ // Pop the ARM_SMC_ARGS structure address from the stack into x13
+ ldr x13, [sp], #16
// Store the SMC returned values into the ARM_SMC_ARGS structure.
- // A SMC call can return up to 4 values - we do not need to store back x4-x7.
- stp x2, x3, [x9, #16]
- stp x0, x1, [x9, #0]
+ stp x10, x11, [x13, #80]
+ stp x8, x9, [x13, #64]
+ stp x6, x7, [x13, #48]
+ stp x4, x5, [x13, #32]
+ stp x2, x3, [x13, #16]
+ stp x0, x1, [x13, #0]
- mov x0, x9
+ mov x0, x13
ret
--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
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