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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/asm_linkage.h>
.file "mach-crt1.s"
.ident ""
.global _start_crt
/*
* The SVR4/amd64 ABI (pages 3-29) says that when the entry
* point runs registers' %rbp, %rsp, %rdx values are specified
* the following:
*
* %rbp The content of this register is unspecified at
* process initialization time, but the user code should mark
* the deepest stack frame by setting the frame pointer to zero.
* No other frame's %ebp should have a zero value.
*
* %rsp Performing its usual job, the stack pointer holds the address
* of the bottom of the stack, which is guaranteed to be
* quadword aligned.
*
* The stack contains the arguments and environment:
* ...
* envp[0] (16+(8*argc))(%rsp)
* NULL (8+(8*argc))(%rsp)
* ...
* argv[0] 8(%rsp)
* argc 0(%rsp)
*
* %rdx In a conforming program, this register contains a function
* pointer that the application should register with atexit(BA_OS).
* This function is used for shared object termination code
* [see Dynamic Linking in Chapter 5 of the System V ABI].
*
*/
ENTRY_NP(_start)
/*
* Allocate a NULL return address and a NULL previous %rbp as if
* there was a genuine call to _start.
*/
pushq $0
pushq $0
movq %rsp,%rbp /* The first stack frame */
/*
* The stack now is
*
* envp[0] (32+(8*argc))(%rsp) - (A)
* NULL (24+(8*argc))(%rsp)
* ...
* argv[0] 24(%rbp) - (B)
* argc 16(%rbp)
* 0 8(%rbp)
* 0 0(%rbp)
*/
andq $-16,%rsp /* align the stack */
movq 16(%rbp),%rdi /* argc */
leaq 24(%rbp),%rsi /* argv */
/* NB: rt_do_exit, if applicable, is already in %rdx */
call _start_crt
hlt
SET_SIZE(_start)
/*
* The following is here in case any object module compiled with cc -p
* was linked into this module.
*/
ENTRY_NP(_mcount)
.weak _mcount
ret
SET_SIZE(_mcount)
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