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/* Copyright (C) 1992, 1993, 1995 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
/* In the Linux/ELF world, C symbols are asm symbols. */
#define NO_UNDERSCORES
/* There is some commonality. */
#include <sysdeps/unix/i386/sysdep.h>
#ifdef ASSEMBLER
/* Linux uses a negative return value to indicate syscall errors, unlike
most Unices, which use the condition codes' carry flag. */
#undef PSEUDO
#define PSEUDO(name, syscall_name, args) \
.text; \
.globl __syscall_error; \
ENTRY (name) \
movl $SYS_##syscall_name, %eax; \
DO_CALL (args) \
testl %eax, %eax; \
jl JUMPTARGET(__syscall_error)
/* Linux takes system call arguments in registers:
syscall number %eax call-clobbered
arg 1 %ebx call-saved
arg 2 %ecx call-clobbered
arg 3 %edx call-clobbered
arg 4 %esi call-saved
arg 5 %edi call-saved
The stack layout upon entering the function is:
24(%esp) Arg# 5
20(%esp) Arg# 4
16(%esp) Arg# 3
12(%esp) Arg# 2
8(%esp) Arg# 1
4(%esp) Return address
(%esp)
(Of course a function with e.g. 3 argumentS does not have entries for
arguments 4 and 5.)
We put the arguments into registers from the stack, and save the
call-saved registers, by using the 386 `xchg' instruction to swap the
values in both directions. */
#undef DO_CALL
#define DO_CALL(args) \
DOARGS_##args \
int $0x80; \
UNDOARGS_##args \
#define DOARGS_0 /* No arguments to frob. */
#define UNDOARGS_0 /* No arguments to unfrob. */
#define DOARGS_1 xchg 8(%esp), %ebx; DOARGS_0 /* Save %ebx on stack. */
#define UNDOARGS_1 xchg 8(%esp), %ebx; UNDOARGS_0 /* Restore %ebx */
#define DOARGS_2 movel 12(%esp), %ecx; DOARGS_1
#define UNDOARGS_2 UNDOARGS_1 /* %ecx is clobbered. */
#define DOARGS_3 movel 16(%esp), %edx; DOARGS_2
#define UNDOARGS_3 UNDOARGS_2 /* %edx is clobbered. */
#define DOARGS_4 xchg 20(%esp), %esi; DOARGS_3 /* Save %esi on stack. */
#define UNDOARGS_4 xchg 20(%esp), %esi; UNDOARGS_3 /* Restore %esi. */
#define DOARGS_5 xchg 24(%esp), %edi; DOARGS_3 /* Save %edi on stack. */
#define UNDOARGS_5 xchg 24(%esp), %edi; UNDOARGS_3 /* Restore %edi. */
#endif /* ASSEMBLER */
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