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187 lines
6.2 KiB
C
187 lines
6.2 KiB
C
/* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Written by Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>,
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December 1995.
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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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#include <sysdeps/unix/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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#ifdef __STDC__
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# define SYS_ify(syscall_name) __NR_##syscall_name
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#else
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# define SYS_ify(syscall_name) __NR_/**/syscall_name
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#endif
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#ifdef ASSEMBLER
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/* Define an entry point visible from C. */
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#define ENTRY(name) \
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.globl name; \
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.type name, @function; \
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.align 4; \
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C_LABEL(name) \
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CALL_MCOUNT
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#undef END
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#define END(name) .size name, . - name
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/* If compiled for profiling, call `_mcount' at the start of each function. */
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#ifdef PROF
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/* The mcount code relies on a normal frame pointer being on the stack
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to locate our caller, so push one just for its benefit. */
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#define CALL_MCOUNT \
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move.l %fp, -(%sp); move.l %sp, %fp; \
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jbsr JUMPTARGET (_mcount); \
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move.l (%sp)+, %fp;
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#else
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#define CALL_MCOUNT /* Do nothing. */
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#endif
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#ifdef PIC
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#define JUMPTARGET(name) name##@PLTPC
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#else
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#define JUMPTARGET(name) name
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#endif
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/* Since C identifiers are not normally prefixed with an underscore
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on this system, the asm identifier `syscall_error' intrudes on the
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C name space. Make sure we use an innocuous name. */
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#define syscall_error __syscall_error
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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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Since version 2.1 the return value of a system call might be negative
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even if the call succeeded. E.g., the `lseek' system call might return
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a large offset. Therefore we must not anymore test for < 0, but test
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for a real error by making sure the value in %d0 is a real error
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number. Linus said he will make sure the no syscall returns a value
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in -1 .. -4095 as a valid result so we can savely test with -4095. */
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#define PSEUDO(name, syscall_name, args) \
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.text; \
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ENTRY (name) \
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DO_CALL (&SYS_ify (syscall_name), args); \
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cmp.l &-4095, %d0; \
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jcc 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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#ifdef PIC
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/* Store (- %d0) into errno through the GOT. */
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#ifdef _LIBC_REENTRANT
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#define SYSCALL_ERROR_HANDLER \
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syscall_error: \
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move.l (errno@GOTPC, %pc), %a0; \
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neg.l %d0; \
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move.l %d0, (%a0); \
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move.l %d0, -(%sp); \
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jbsr __errno_location@PLTPC; \
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move.l (%sp)+, (%a0); \
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move.l &-1, %d0; \
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/* Copy return value to %a0 for syscalls that are declared to return \
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a pointer (e.g., mmap). */ \
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move.l %d0, %a0; \
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rts;
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#else
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#define SYSCALL_ERROR_HANDLER \
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syscall_error: \
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move.l (errno@GOTPC, %pc), %a0; \
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neg.l %d0; \
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move.l %d0, (%a0); \
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move.l &-1, %d0; \
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/* Copy return value to %a0 for syscalls that are declared to return \
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a pointer (e.g., mmap). */ \
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move.l %d0, %a0; \
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rts;
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#endif /* _LIBC_REENTRANT */
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#else
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#define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
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#endif /* PIC */
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/* Linux takes system call arguments in registers:
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syscall number %d0 call-clobbered
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arg 1 %d1 call-clobbered
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arg 2 %d2 call-saved
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arg 3 %d3 call-saved
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arg 4 %d4 call-saved
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arg 5 %d5 call-saved
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The stack layout upon entering the function is:
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20(%sp) Arg# 5
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16(%sp) Arg# 4
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12(%sp) Arg# 3
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8(%sp) Arg# 2
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4(%sp) Arg# 1
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(%sp) Return address
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(Of course a function with say 3 arguments does not have entries for
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arguments 4 and 5.)
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Separate move's are faster than movem, but need more space. Since
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speed is more important, we don't use movem. Since %a0 and %a1 are
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scratch registers, we can use them for saving as well. */
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#define DO_CALL(syscall, args) \
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move.l syscall, %d0; \
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DOARGS_##args \
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trap &0; \
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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_0(n) /* No arguments to frob. */
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#define DOARGS_1 _DOARGS_1 (4)
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#define _DOARGS_1(n) move.l n(%sp), %d1; _DOARGS_0 (n)
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#define UNDOARGS_1 UNDOARGS_0
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#define DOARGS_2 _DOARGS_2 (8)
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#define _DOARGS_2(n) move.l %d2, %a0; move.l n(%sp), %d2; _DOARGS_1 (n-4)
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#define UNDOARGS_2 UNDOARGS_1; move.l %a0, %d2
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#define DOARGS_3 _DOARGS_3 (12)
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#define _DOARGS_3(n) move.l %d3, %a1; move.l n(%sp), %d3; _DOARGS_2 (n-4)
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#define UNDOARGS_3 UNDOARGS_2; move.l %a1, %d3
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#define DOARGS_4 _DOARGS_4 (16)
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#define _DOARGS_4(n) move.l %d4, -(%sp); move.l n+4(%sp), %d4; _DOARGS_3 (n)
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#define UNDOARGS_4 UNDOARGS_3; move.l (%sp)+, %d4
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#define DOARGS_5 _DOARGS_5 (20)
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#define _DOARGS_5(n) move.l %d5, -(%sp); move.l n+4(%sp), %d5; _DOARGS_4 (n)
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#define UNDOARGS_5 UNDOARGS_4; move.l (%sp)+, %d5
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#define ret rts
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#if 0 /* Not used by Linux */
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#define r0 %d0
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#define r1 %d1
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#define MOVE(x,y) movel x , y
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#endif
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#endif /* ASSEMBLER */
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