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110 lines
3.6 KiB
C
110 lines
3.6 KiB
C
/* Copyright (C) 1992, 93, 95, 96, 97, 98 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper, <drepper@gnu.ai.mit.edu>, August 1995.
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ARM changes by Philip Blundell, <pjb27@cam.ac.uk>, May 1997.
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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 not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#ifndef _LINUX_ARM_SYSDEP_H
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#define _LINUX_ARM_SYSDEP_H 1
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/* There is some commonality. */
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#include <sysdeps/unix/arm/sysdep.h>
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/* For Linux we can use the system call table in the header file
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/usr/include/asm/unistd.h
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of the kernel. But these symbols do not follow the SYS_* syntax
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so we have to redefine the `SYS_ify' macro here. */
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#undef SYS_ify
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#define SWI_BASE (0x900000)
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#define SYS_ify(syscall_name) (__NR_##syscall_name)
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#ifdef ASSEMBLER
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/* Linux uses a negative return value to indicate syscall errors,
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unlike most Unices, which use the condition codes' carry flag.
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Since version 2.1 the return value of a system call might be
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negative even if the call succeeded. E.g., the `lseek' system call
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might return a large offset. Therefore we must not anymore test
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for < 0, but test for a real error by making sure the value in R0
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is a real error number. Linus said he will make sure the no syscall
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returns a value in -1 .. -4095 as a valid result so we can savely
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test with -4095. */
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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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.type syscall_error,%function ; \
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ENTRY (name) \
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DO_CALL (args, syscall_name); \
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cmn r0, $4096; \
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bhs PLTJMP(C_SYMBOL_NAME(__syscall_error));
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#undef PSEUDO_END
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#define PSEUDO_END(name) \
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SYSCALL_ERROR_HANDLER \
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END (name)
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#define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
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/* Linux takes system call args in registers:
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syscall number in the SWI instruction
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arg 1 r0
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arg 2 r1
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arg 3 r2
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arg 4 r3
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arg 5 r4 (this is different from the APCS convention)
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The compiler is going to form a call by coming here, through PSEUDO, with
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arguments
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syscall number in the DO_CALL macro
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arg 1 r0
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arg 2 r1
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arg 3 r2
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arg 4 r3
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arg 5 [sp]
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We need to shuffle values between R4 and the stack so that the caller's
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R4 is not corrupted, and the kernel sees the right argument there.
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*/
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#undef DO_CALL
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#define DO_CALL(args, syscall_name) \
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DOARGS_##args \
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swi SYS_ify (syscall_name); \
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UNDOARGS_##args
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#define DOARGS_0 /* nothing */
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#define DOARGS_1 /* nothing */
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#define DOARGS_2 /* nothing */
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#define DOARGS_3 /* nothing */
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#define DOARGS_4 /* nothing */
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#define DOARGS_5 ldr ip, [sp]; str r4, [sp]; mov r4, ip;
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#define UNDOARGS_0 /* nothing */
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#define UNDOARGS_1 /* nothing */
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#define UNDOARGS_2 /* nothing */
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#define UNDOARGS_3 /* nothing */
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#define UNDOARGS_4 /* nothing */
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#define UNDOARGS_5 ldr r4, [sp];
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#endif /* ASSEMBLER */
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#endif /* linux/arm/sysdep.h */
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