74 lines
2.8 KiB
ArmAsm
74 lines
2.8 KiB
ArmAsm
/*
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* Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "../rmmd_private.h"
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#include <asm_macros.S>
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.global rmmd_rmm_enter
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.global rmmd_rmm_exit
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/* ---------------------------------------------------------------------
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* This function is called with SP_EL0 as stack. Here we stash our EL3
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* callee-saved registers on to the stack as a part of saving the C
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* runtime and enter the secure payload.
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* 'x0' contains a pointer to the memory where the address of the C
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* runtime context is to be saved.
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* ---------------------------------------------------------------------
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*/
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func rmmd_rmm_enter
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/* Make space for the registers that we're going to save */
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mov x3, sp
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str x3, [x0, #0]
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sub sp, sp, #RMMD_C_RT_CTX_SIZE
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/* Save callee-saved registers on to the stack */
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stp x19, x20, [sp, #RMMD_C_RT_CTX_X19]
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stp x21, x22, [sp, #RMMD_C_RT_CTX_X21]
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stp x23, x24, [sp, #RMMD_C_RT_CTX_X23]
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stp x25, x26, [sp, #RMMD_C_RT_CTX_X25]
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stp x27, x28, [sp, #RMMD_C_RT_CTX_X27]
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stp x29, x30, [sp, #RMMD_C_RT_CTX_X29]
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/* ---------------------------------------------------------------------
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* Everything is setup now. el3_exit() will use the secure context to
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* restore to the general purpose and EL3 system registers to ERET
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* into the secure payload.
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* ---------------------------------------------------------------------
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*/
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b el3_exit
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endfunc rmmd_rmm_enter
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/* ---------------------------------------------------------------------
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* This function is called with 'x0' pointing to a C runtime context.
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* It restores the saved registers and jumps to that runtime with 'x0'
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* as the new SP register. This destroys the C runtime context that had
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* been built on the stack below the saved context by the caller. Later
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* the second parameter 'x1' is passed as a return value to the caller.
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* ---------------------------------------------------------------------
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*/
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func rmmd_rmm_exit
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/* Restore the previous stack */
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mov sp, x0
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/* Restore callee-saved registers on to the stack */
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ldp x19, x20, [x0, #(RMMD_C_RT_CTX_X19 - RMMD_C_RT_CTX_SIZE)]
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ldp x21, x22, [x0, #(RMMD_C_RT_CTX_X21 - RMMD_C_RT_CTX_SIZE)]
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ldp x23, x24, [x0, #(RMMD_C_RT_CTX_X23 - RMMD_C_RT_CTX_SIZE)]
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ldp x25, x26, [x0, #(RMMD_C_RT_CTX_X25 - RMMD_C_RT_CTX_SIZE)]
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ldp x27, x28, [x0, #(RMMD_C_RT_CTX_X27 - RMMD_C_RT_CTX_SIZE)]
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ldp x29, x30, [x0, #(RMMD_C_RT_CTX_X29 - RMMD_C_RT_CTX_SIZE)]
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/* ---------------------------------------------------------------------
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* This should take us back to the instruction after the call to the
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* last rmmd_rmm_enter().* Place the second parameter to x0
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* so that the caller will see it as a return value from the original
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* entry call.
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* ---------------------------------------------------------------------
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*/
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mov x0, x1
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ret
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endfunc rmmd_rmm_exit
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