1/* 2 * 3 * Copyright (C) 2008 Advanced Micro Devices, Inc. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29/* calling syntax: i386_do_exec(long addr, int argc, char **argv, int *ret) */ 30 31/* This implements the payload API detailed here: 32 * https://www.coreboot.org/Payload_API 33 */ 34 35.align 4 36.text 37 38.global i386_do_exec 39 .type i386_do_exec,@function 40 41i386_do_exec: 42 pushl %ebp 43 movl %esp, %ebp 44 45 /* Save the remaining callee preserved registers */ 46 pushl %ebx 47 pushl %esi 48 pushl %edi 49 50 /* Push argc and argv on to the stack. 51 * 52 * We need to put a dummy value inbetween, as argc should be at offset 53 * 0x10, according to the payload API. 54 */ 55 pushl 12(%ebp) 56 pushl $0 57 pushl 16(%ebp) 58 59 /* Push a "magic" number on the stack - the other payload will use this 60 * as a clue that the argc and argv values on the stack are sane. 61 */ 62 pushl $0x12345678 63 64 /* Jump to the code */ 65 call *8(%ebp) 66 /* %eax has the return value */ 67 68 /* Skip over the argc/argv stuff still on the stack. 69 * Don't assume %ebp is sane, here. Restore it from the stack. 70 */ 71 addl $0x10, %esp 72 73 /* Restore the saved registers */ 74 popl %edi 75 popl %esi 76 popl %ebx 77 popl %ebp 78 79 /* Get pointer to return value and save the return value in it. */ 80 movl 16(%esp), %ecx 81 movl %eax, (%ecx) 82 83 ret 84