sysdeps/unix/sysv/linux/m68k/sysdep.h

   1 /* Copyright (C) 1996, 1997, 1998, 2000 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Written by Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>,
   4    December 1995.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <sysdeps/unix/sysdep.h>
  22 #include <sysdeps/m68k/sysdep.h>
  23
  24 /* For Linux we can use the system call table in the header file
  25         /usr/include/asm/unistd.h
  26    of the kernel.  But these symbols do not follow the SYS_* syntax
  27    so we have to redefine the `SYS_ify' macro here.  */
  28 #undef SYS_ify
  29 #ifdef __STDC__
  30 # define SYS_ify(syscall_name)  __NR_##syscall_name
  31 #else
  32 # define SYS_ify(syscall_name)  __NR_/**/syscall_name
  33 #endif
  34
  35 #ifdef __ASSEMBLER__
  36
  37 /* Linux uses a negative return value to indicate syscall errors, unlike
  38    most Unices, which use the condition codes' carry flag.
  39
  40    Since version 2.1 the return value of a system call might be negative
  41    even if the call succeeded.  E.g., the `lseek' system call might return
  42    a large offset.  Therefore we must not anymore test for < 0, but test
  43    for a real error by making sure the value in %d0 is a real error
  44    number.  Linus said he will make sure the no syscall returns a value
  45    in -1 .. -4095 as a valid result so we can savely test with -4095.  */
  46
  47 /* We don't want the label for the error handler to be visible in the symbol
  48    table when we define it here.  */
  49 #ifdef PIC
  50 #define SYSCALL_ERROR_LABEL .Lsyscall_error
  51 #else
  52 #define SYSCALL_ERROR_LABEL __syscall_error
  53 #endif
  54
  55 #undef PSEUDO
  56 #define PSEUDO(name, syscall_name, args)                                      \
  57   .text;                                                                      \
  58   ENTRY (name)                                                                \
  59     DO_CALL (syscall_name, args);                                             \
  60     cmp.l &-4095, %d0;                                                        \
  61     jcc SYSCALL_ERROR_LABEL
  62
  63 #undef PSEUDO_END
  64 #define PSEUDO_END(name)                                                      \
  65   SYSCALL_ERROR_HANDLER;                                                      \
  66   END (name)
  67
  68 #ifdef PIC
  69 /* Store (- %d0) into errno through the GOT.  */
  70 #ifdef _LIBC_REENTRANT
  71 #define SYSCALL_ERROR_HANDLER                                                 \
  72 SYSCALL_ERROR_LABEL:                                                          \
  73     neg.l %d0;                                                                \
  74     move.l %d0, -(%sp);                                                       \
  75     jbsr __errno_location@PLTPC;                                              \
  76     move.l (%sp)+, (%a0);                                                     \
  77     move.l &-1, %d0;                                                          \
  78     /* Copy return value to %a0 for syscalls that are declared to return      \
  79        a pointer (e.g., mmap).  */                                            \
  80     move.l %d0, %a0;                                                          \
  81     rts;
  82 #else /* !_LIBC_REENTRANT */
  83 #define SYSCALL_ERROR_HANDLER                                                 \
  84 SYSCALL_ERROR_LABEL:                                                          \
  85     move.l (errno@GOTPC, %pc), %a0;                                           \
  86     neg.l %d0;                                                                \
  87     move.l %d0, (%a0);                                                        \
  88     move.l &-1, %d0;                                                          \
  89     /* Copy return value to %a0 for syscalls that are declared to return      \
  90        a pointer (e.g., mmap).  */                                            \
  91     move.l %d0, %a0;                                                          \
  92     rts;
  93 #endif /* _LIBC_REENTRANT */
  94 #else
  95 #define SYSCALL_ERROR_HANDLER   /* Nothing here; code in sysdep.S is used.  */
  96 #endif /* PIC */
  97
  98 /* Linux takes system call arguments in registers:
  99
 100         syscall number  %d0          call-clobbered
 101         arg 1           %d1          call-clobbered
 102         arg 2           %d2          call-saved
 103         arg 3           %d3          call-saved
 104         arg 4           %d4          call-saved
 105         arg 5           %d5          call-saved
 106
 107    The stack layout upon entering the function is:
 108
 109         20(%sp)         Arg# 5
 110         16(%sp)         Arg# 4
 111         12(%sp)         Arg# 3
 112          8(%sp)         Arg# 2
 113          4(%sp)         Arg# 1
 114           (%sp)         Return address
 115
 116    (Of course a function with say 3 arguments does not have entries for
 117    arguments 4 and 5.)
 118
 119    Separate move's are faster than movem, but need more space.  Since
 120    speed is more important, we don't use movem.  Since %a0 and %a1 are
 121    scratch registers, we can use them for saving as well.  */
 122
 123 #define DO_CALL(syscall_name, args)                                           \
 124     move.l &SYS_ify(syscall_name), %d0;                                       \
 125     DOARGS_##args                                                             \
 126     trap &0;                                                                  \
 127     UNDOARGS_##args
 128
 129 #define DOARGS_0        /* No arguments to frob.  */
 130 #define UNDOARGS_0      /* No arguments to unfrob.  */
 131 #define _DOARGS_0(n)    /* No arguments to frob.  */
 132
 133 #define DOARGS_1        _DOARGS_1 (4)
 134 #define _DOARGS_1(n)    move.l n(%sp), %d1; _DOARGS_0 (n)
 135 #define UNDOARGS_1      UNDOARGS_0
 136
 137 #define DOARGS_2        _DOARGS_2 (8)
 138 #define _DOARGS_2(n)    move.l %d2, %a0; move.l n(%sp), %d2; _DOARGS_1 (n-4)
 139 #define UNDOARGS_2      UNDOARGS_1; move.l %a0, %d2
 140
 141 #define DOARGS_3        _DOARGS_3 (12)
 142 #define _DOARGS_3(n)    move.l %d3, %a1; move.l n(%sp), %d3; _DOARGS_2 (n-4)
 143 #define UNDOARGS_3      UNDOARGS_2; move.l %a1, %d3
 144
 145 #define DOARGS_4        _DOARGS_4 (16)
 146 #define _DOARGS_4(n)    move.l %d4, -(%sp); move.l n+4(%sp), %d4; _DOARGS_3 (n)
 147 #define UNDOARGS_4      UNDOARGS_3; move.l (%sp)+, %d4
 148
 149 #define DOARGS_5        _DOARGS_5 (20)
 150 #define _DOARGS_5(n)    move.l %d5, -(%sp); move.l n+4(%sp), %d5; _DOARGS_4 (n)
 151 #define UNDOARGS_5      UNDOARGS_4; move.l (%sp)+, %d5
 152
 153
 154 #define ret     rts
 155 #if 0 /* Not used by Linux */
 156 #define r0      %d0
 157 #define r1      %d1
 158 #define MOVE(x,y)       movel x , y
 159 #endif
 160
 161 #else /* not __ASSEMBLER__ */
 162
 163 /* Define a macro which expands into the inline wrapper code for a system
 164    call.  */
 165 #undef INLINE_SYSCALL
 166 #define INLINE_SYSCALL(name, nr, args...)               \
 167   ({ unsigned int _sys_result;                          \
 168      {                                                  \
 169        LOAD_ARGS_##nr (args)                            \
 170        register int _d0 asm ("%d0") = __NR_##name;      \
 171        asm volatile ("trap #0"                          \
 172                      : "=d" (_d0)                       \
 173                      : "0" (_d0) ASM_ARGS_##nr          \
 174                      : "d0", "memory");                 \
 175        _sys_result = _d0;                               \
 176      }                                                  \
 177      if (_sys_result >= (unsigned int) -4095)           \
 178        {                                                \
 179          __set_errno (-_sys_result);                    \
 180          _sys_result = (unsigned int) -1;               \
 181        }                                                \
 182      (int) _sys_result; })
 183
 184 #define LOAD_ARGS_0()
 185 #define ASM_ARGS_0
 186 #define LOAD_ARGS_1(a1)                         \
 187   register int _d1 asm ("d1") = (int) (a1);     \
 188   LOAD_ARGS_0 ()
 189 #define ASM_ARGS_1      ASM_ARGS_0, "d" (_d1)
 190 #define LOAD_ARGS_2(a1, a2)                     \
 191   register int _d2 asm ("d2") = (int) (a2);     \
 192   LOAD_ARGS_1 (a1)
 193 #define ASM_ARGS_2      ASM_ARGS_1, "d" (_d2)
 194 #define LOAD_ARGS_3(a1, a2, a3)                 \
 195   register int _d3 asm ("d3") = (int) (a3);     \
 196   LOAD_ARGS_2 (a1, a2)
 197 #define ASM_ARGS_3      ASM_ARGS_2, "d" (_d3)
 198 #define LOAD_ARGS_4(a1, a2, a3, a4)             \
 199   register int _d4 asm ("d4") = (int) (a4);     \
 200   LOAD_ARGS_3 (a1, a2, a3)
 201 #define ASM_ARGS_4      ASM_ARGS_3, "d" (_d4)
 202 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)         \
 203   register int _d5 asm ("d5") = (int) (a5);     \
 204   LOAD_ARGS_4 (a1, a2, a3, a4)
 205 #define ASM_ARGS_5      ASM_ARGS_4, "d" (_d5)
 206
 207 #endif /* not __ASSEMBLER__ */