/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

        .file   "syscall.s"

#include "SYS.h"
#include <sys/trap.h>

        ANSI_PRAGMA_WEAK(syscall,function)

/*
 * See sparc/sys/syscall.s to understand why _syscall6() exists.
 * On x86, the implementation of the two are the same, the only
 * difference being that _syscall6 is not an exported symbol.
 */
        ENTRY2(syscall,_syscall6)
        popl    %edx            / return address
        popl    %eax            / system call number
        pushl   %edx
#if defined(_SYSC_INSN)
        .byte   0xf, 0x5        /* syscall */
#elif defined(_SEP_INSN)
        call    8f
8:      popl    %edx
        movl    %esp, %ecx
        addl    $[9f - 8b], %edx
        sysenter
9:
#else
        int     $T_SYSCALLINT
#endif
        movl    0(%esp), %edx
        pushl   %edx            / restore the return address
        SYSCERROR
        ret
        SET_SIZE(syscall)
        SET_SIZE(_syscall6)

/*
 * See sparc/sys/syscall.s to understand why __systemcall6() exists.
 * On x86, the implementation of the two are the same, the only
 * difference being that __systemcall6 is not an exported symbol.
 *
 * WARNING WARNING WARNING:
 * The int $T_SYSCALL instruction below is needed by /proc when it scans a
 * controlled process's text for a syscall instruction.  It must be present in
 * all libc variants because /proc cannot use an optimized syscall instruction
 * to enter the kernel; optimized syscalls could be disabled by private LDT use.
 * We must leave at least one int $T_SYSCALLINT in the text for /proc to find
 * (see the Pscantext() routine).
 */
        ENTRY2(__systemcall,__systemcall6)
        popl    %edx            / return address
        popl    %ecx            / structure return address
        popl    %eax            / system call number
        pushl   %edx
        int     $T_SYSCALLINT
        jae     1f
        / error; clear syscall return values in the structure
        movl    $-1, 0(%ecx)    / sys_rval1
        movl    $-1, 4(%ecx)    / sys_rval2
        jmp     2f              / %eax contains the error number
1:
        / no error; copy syscall return values to the structure
        movl    %eax, 0(%ecx)   / sys_rval1
        movl    %edx, 4(%ecx)   / sys_rval2
        xorl    %eax, %eax      / no error, set %eax to zero
2:
        movl    0(%esp), %edx   / Restore the stack frame to original size
        pushl   %ecx
        pushl   %edx            / restore the return address
        ret
        SET_SIZE(__systemcall)
        SET_SIZE(__systemcall6)