sysdeps/unix/sysv/linux/arm/sysdep.h

   1 /* Copyright (C) 1992, 93, 95, 96, 97 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper, <drepper@gnu.ai.mit.edu>, August 1995.
   4    ARM changes by Philip Blundell, <pjb27@cam.ac.uk>, May 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #ifndef _LINUX_ARM_SYSDEP_H
  22 #define _LINUX_ARM_SYSDEP_H 1
  23
  24 /* There is some commonality.  */
  25 #include <sysdeps/unix/arm/sysdep.h>
  26
  27 /* For Linux we can use the system call table in the header file
  28         /usr/include/asm/unistd.h
  29    of the kernel.  But these symbols do not follow the SYS_* syntax
  30    so we have to redefine the `SYS_ify' macro here.  */
  31 #undef SYS_ify
  32 #define SWI_BASE  (9 << 20)
  33 #define SYS_ify(syscall_name)   (SWI_BASE + __NR_##syscall_name)
  34
  35
  36 #ifdef ASSEMBLER
  37
  38 /* Linux uses a negative return value to indicate syscall errors,
  39    unlike most Unices, which use the condition codes' carry flag.
  40
  41    Since version 2.1 the return value of a system call might be
  42    negative even if the call succeeded.  E.g., the `lseek' system call
  43    might return a large offset.  Therefore we must not anymore test
  44    for < 0, but test for a real error by making sure the value in %eax
  45    is a real error number.  Linus said he will make sure the no syscall
  46    returns a value in -1 .. -4095 as a valid result so we can savely
  47    test with -4095.  */
  48 #undef  PSEUDO
  49 #define PSEUDO(name, syscall_name, args)                                      \
  50   .text;                                                                      \
  51   ENTRY (name)                                                                \
  52     DO_CALL (args, syscall_name);                                             \
  53     cmn r0, $4096;                                                            \
  54     bge syscall_error;
  55
  56 #undef  PSEUDO_END
  57 #define PSEUDO_END(name)                                                      \
  58   SYSCALL_ERROR_HANDLER                                                       \
  59   END (name)
  60
  61 #ifndef PIC
  62 #define SYSCALL_ERROR_HANDLER   /* Nothing here; code in sysdep.S is used.  */
  63 #else
  64 #error Aiee
  65 #endif  /* PIC */
  66
  67 #undef  DO_CALL
  68 #define DO_CALL(args, syscall_name)                                           \
  69     swi SYS_ify (syscall_name);
  70
  71 #endif  /* ASSEMBLER */
  72
  73 #endif /* linux/arm/sysdep.h */