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37 lines
855 B
ArmAsm
37 lines
855 B
ArmAsm
//
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// Copyright (c) 2016 - 2020, ARM Limited. All rights reserved.
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//
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// SPDX-License-Identifier: BSD-2-Clause-Patent
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//
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//
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.text
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.align 3
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GCC_ASM_EXPORT(ArmCallSvc)
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ASM_PFX(ArmCallSvc):
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// r0 will be popped just after the SVC call
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push {r0, r4-r8}
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// Load the SVC arguments values into the appropriate registers
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ldm r0, {r0-r7}
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svc #0
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// Prevent speculative execution beyond svc instruction
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dsb nsh
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isb
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// Load the ARM_SVC_ARGS structure address from the stack into r8
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ldr r8, [sp]
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// Load the SVC returned values into the appropriate registers
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// A SVC call can return up to 4 values - we do not need to store back r4-r7.
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stm r8, {r0-r3}
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mov r0, r8
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// Restore the registers r4-r8
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pop {r1, r4-r8}
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bx lr
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