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