1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22/* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27#include <sys/asm_linkage.h> 28 29 .file "mach-crt1.s" 30 31 .global _start_crt 32 33/* 34 * The SVR4/amd64 ABI (pages 3-29) says that when the entry 35 * point runs registers' %rbp, %rsp, %rdx values are specified 36 * the following: 37 * 38 * %rbp The content of this register is unspecified at 39 * process initialization time, but the user code should mark 40 * the deepest stack frame by setting the frame pointer to zero. 41 * No other frame's %ebp should have a zero value. 42 * 43 * %rsp Performing its usual job, the stack pointer holds the address 44 * of the bottom of the stack, which is guaranteed to be 45 * quadword aligned. 46 * 47 * The stack contains the arguments and environment: 48 * ... 49 * envp[0] (16+(8*argc))(%rsp) 50 * NULL (8+(8*argc))(%rsp) 51 * ... 52 * argv[0] 8(%rsp) 53 * argc 0(%rsp) 54 * 55 * %rdx In a conforming program, this register contains a function 56 * pointer that the application should register with atexit(BA_OS). 57 * This function is used for shared object termination code 58 * [see Dynamic Linking in Chapter 5 of the System V ABI]. 59 * 60 */ 61 62ENTRY_NP(_start) 63/* 64 * Allocate a NULL return address and a NULL previous %rbp as if 65 * there was a genuine call to _start. 66 */ 67 pushq $0 68 pushq $0 69 movq %rsp,%rbp /* The first stack frame */ 70 71/* 72 * The stack now is 73 * 74 * envp[0] (32+(8*argc))(%rsp) - (A) 75 * NULL (24+(8*argc))(%rsp) 76 * ... 77 * argv[0] 24(%rbp) - (B) 78 * argc 16(%rbp) 79 * 0 8(%rbp) 80 * 0 0(%rbp) 81 */ 82 83 andq $-16,%rsp /* align the stack */ 84 movq 16(%rbp),%rdi /* argc */ 85 leaq 24(%rbp),%rsi /* argv */ 86 /* NB: rt_do_exit, if applicable, is already in %rdx */ 87 call _start_crt 88 hlt 89SET_SIZE(_start) 90 91/* 92 * The following is here in case any object module compiled with cc -p 93 * was linked into this module. 94 */ 95ENTRY_NP(_mcount) 96 .weak _mcount 97 ret 98SET_SIZE(_mcount) 99