1 files changed, 36 insertions, 0 deletions
diff --git a/roms/edk2/ArmPkg/Library/ArmSvcLib/Arm/ArmSvc.S b/roms/edk2/ArmPkg/Library/ArmSvcLib/Arm/ArmSvc.S
new file mode 100644
index 000000000..e81eb88f2
--- /dev/null
+++ b/roms/edk2/ArmPkg/Library/ArmSvcLib/Arm/ArmSvc.S
@@ -0,0 +1,36 @@
+//
+//  Copyright (c) 2016 - 2020, ARM Limited. All rights reserved.
+//
+//  SPDX-License-Identifier: BSD-2-Clause-Patent
+//
+//
+
+.text
+.align 3
+
+GCC_ASM_EXPORT(ArmCallSvc)
+
+ASM_PFX(ArmCallSvc):
+    // r0 will be popped just after the SVC call
+    push    {r0, r4-r8}
+
+    // Load the SVC arguments values into the appropriate registers
+    ldm     r0, {r0-r7}
+
+    svc     #0
+    // Prevent speculative execution beyond svc instruction
+    dsb     nsh
+    isb
+
+    // Load the ARM_SVC_ARGS structure address from the stack into r8
+    ldr     r8, [sp]
+
+    // Load the SVC returned values into the appropriate registers
+    // A SVC call can return up to 4 values - we do not need to store back r4-r7.
+    stm     r8, {r0-r3}
+
+    mov     r0, r8
+
+    // Restore the registers r4-r8
+    pop     {r1, r4-r8}
+    bx      lr