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