1/* 2 * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are met: 6 * 7 * Redistributions of source code must retain the above copyright notice, this 8 * list of conditions and the following disclaimer. 9 * 10 * Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 14 * Neither the name of ARM nor the names of its contributors may be used 15 * to endorse or promote products derived from this software without specific 16 * prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#include <asm_macros.S> 32#include "tlkd_private.h" 33 34 .global tlkd_enter_sp 35 .global tlkd_exit_sp 36 37 /* --------------------------------------------- 38 * This function is called with SP_EL0 as stack. 39 * Here we stash our EL3 callee-saved registers 40 * on to the stack as a part of saving the C 41 * runtime and enter the secure payload. 42 * 'x0' contains a pointer to the memory where 43 * the address of the C runtime context is to be 44 * saved. 45 * --------------------------------------------- 46 */ 47func tlkd_enter_sp 48 /* Make space for the registers that we're going to save */ 49 mov x3, sp 50 str x3, [x0, #0] 51 sub sp, sp, #TLKD_C_RT_CTX_SIZE 52 53 /* Save callee-saved registers on to the stack */ 54 stp x19, x20, [sp, #TLKD_C_RT_CTX_X19] 55 stp x21, x22, [sp, #TLKD_C_RT_CTX_X21] 56 stp x23, x24, [sp, #TLKD_C_RT_CTX_X23] 57 stp x25, x26, [sp, #TLKD_C_RT_CTX_X25] 58 stp x27, x28, [sp, #TLKD_C_RT_CTX_X27] 59 stp x29, x30, [sp, #TLKD_C_RT_CTX_X29] 60 61 /* ---------------------------------------------- 62 * Everything is setup now. el3_exit() will 63 * use the secure context to restore to the 64 * general purpose and EL3 system registers to 65 * ERET into the secure payload. 66 * ---------------------------------------------- 67 */ 68 b el3_exit 69endfunc tlkd_enter_sp 70 71 /* ---------------------------------------------- 72 * This function is called with 'x0' pointing to 73 * a C runtime context saved in tlkd_enter_sp(). 74 * It restores the saved registers and jumps to 75 * that runtime with 'x0' as the new sp. This 76 * destroys the C runtime context that had been 77 * built on the stack below the saved context by 78 * the caller. Later the second parameter 'x1' 79 * is passed as return value to the caller 80 * ---------------------------------------------- 81 */ 82func tlkd_exit_sp 83 /* Restore the previous stack */ 84 mov sp, x0 85 86 /* Restore callee-saved registers on to the stack */ 87 ldp x19, x20, [x0, #(TLKD_C_RT_CTX_X19 - TLKD_C_RT_CTX_SIZE)] 88 ldp x21, x22, [x0, #(TLKD_C_RT_CTX_X21 - TLKD_C_RT_CTX_SIZE)] 89 ldp x23, x24, [x0, #(TLKD_C_RT_CTX_X23 - TLKD_C_RT_CTX_SIZE)] 90 ldp x25, x26, [x0, #(TLKD_C_RT_CTX_X25 - TLKD_C_RT_CTX_SIZE)] 91 ldp x27, x28, [x0, #(TLKD_C_RT_CTX_X27 - TLKD_C_RT_CTX_SIZE)] 92 ldp x29, x30, [x0, #(TLKD_C_RT_CTX_X29 - TLKD_C_RT_CTX_SIZE)] 93 94 /* ------------------------------------------------ 95 * This should take us back to the instruction 96 * after the call to the last tlkd_enter_sp(). 97 * Place the second parameter to x0 so that the 98 * caller will see it as a return value from the 99 * original entry call 100 * ------------------------------------------------ 101 */ 102 mov x0, x1 103 ret 104endfunc tlkd_exit_sp 105