1/* 2 * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7#include <asm_macros.S> 8#include "tspd_private.h" 9 10 .global tspd_enter_sp 11 /* --------------------------------------------- 12 * This function is called with SP_EL0 as stack. 13 * Here we stash our EL3 callee-saved registers 14 * on to the stack as a part of saving the C 15 * runtime and enter the secure payload. 16 * 'x0' contains a pointer to the memory where 17 * the address of the C runtime context is to be 18 * saved. 19 * --------------------------------------------- 20 */ 21func tspd_enter_sp 22 /* Make space for the registers that we're going to save */ 23 mov x3, sp 24 str x3, [x0, #0] 25 sub sp, sp, #TSPD_C_RT_CTX_SIZE 26 27 /* Save callee-saved registers on to the stack */ 28 stp x19, x20, [sp, #TSPD_C_RT_CTX_X19] 29 stp x21, x22, [sp, #TSPD_C_RT_CTX_X21] 30 stp x23, x24, [sp, #TSPD_C_RT_CTX_X23] 31 stp x25, x26, [sp, #TSPD_C_RT_CTX_X25] 32 stp x27, x28, [sp, #TSPD_C_RT_CTX_X27] 33 stp x29, x30, [sp, #TSPD_C_RT_CTX_X29] 34 35 /* --------------------------------------------- 36 * Everything is setup now. el3_exit() will 37 * use the secure context to restore to the 38 * general purpose and EL3 system registers to 39 * ERET into the secure payload. 40 * --------------------------------------------- 41 */ 42 b el3_exit 43endfunc tspd_enter_sp 44 45 /* --------------------------------------------- 46 * This function is called 'x0' pointing to a C 47 * runtime context saved in tspd_enter_sp(). It 48 * restores the saved registers and jumps to 49 * that runtime with 'x0' as the new sp. This 50 * destroys the C runtime context that had been 51 * built on the stack below the saved context by 52 * the caller. Later the second parameter 'x1' 53 * is passed as return value to the caller 54 * --------------------------------------------- 55 */ 56 .global tspd_exit_sp 57func tspd_exit_sp 58 /* Restore the previous stack */ 59 mov sp, x0 60 61 /* Restore callee-saved registers on to the stack */ 62 ldp x19, x20, [x0, #(TSPD_C_RT_CTX_X19 - TSPD_C_RT_CTX_SIZE)] 63 ldp x21, x22, [x0, #(TSPD_C_RT_CTX_X21 - TSPD_C_RT_CTX_SIZE)] 64 ldp x23, x24, [x0, #(TSPD_C_RT_CTX_X23 - TSPD_C_RT_CTX_SIZE)] 65 ldp x25, x26, [x0, #(TSPD_C_RT_CTX_X25 - TSPD_C_RT_CTX_SIZE)] 66 ldp x27, x28, [x0, #(TSPD_C_RT_CTX_X27 - TSPD_C_RT_CTX_SIZE)] 67 ldp x29, x30, [x0, #(TSPD_C_RT_CTX_X29 - TSPD_C_RT_CTX_SIZE)] 68 69 /* --------------------------------------------- 70 * This should take us back to the instruction 71 * after the call to the last tspd_enter_sp(). 72 * Place the second parameter to x0 so that the 73 * caller will see it as a return value from the 74 * original entry call 75 * --------------------------------------------- 76 */ 77 mov x0, x1 78 ret 79endfunc tspd_exit_sp 80