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

   1 /* Copyright (C) 1996-2014 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <tls.h>
  21
  22 /* Defines RTLD_PRIVATE_ERRNO.  */
  23 #include <dl-sysdep.h>
  24
  25 /* For Linux we can use the system call table in the header file
  26         /usr/include/asm/unistd.h
  27    of the kernel.  But these symbols do not follow the SYS_* syntax
  28    so we have to redefine the `SYS_ify' macro here.  */
  29 #undef SYS_ify
  30 #define SYS_ify(syscall_name)   __NR_##syscall_name
  31
  32 #ifdef __ASSEMBLER__
  33
  34 /* Linux uses a negative return value to indicate syscall errors, unlike
  35    most Unices, which use the condition codes' carry flag.
  36
  37    Since version 2.1 the return value of a system call might be negative
  38    even if the call succeeded.  E.g., the `lseek' system call might return
  39    a large offset.  Therefore we must not anymore test for < 0, but test
  40    for a real error by making sure the value in %d0 is a real error
  41    number.  Linus said he will make sure the no syscall returns a value
  42    in -1 .. -4095 as a valid result so we can savely test with -4095.  */
  43
  44 /* We don't want the label for the error handler to be visible in the symbol
  45    table when we define it here.  */
  46 #ifdef PIC
  47 #define SYSCALL_ERROR_LABEL .Lsyscall_error
  48 #else
  49 #define SYSCALL_ERROR_LABEL __syscall_error
  50 #endif
  51
  52 #undef PSEUDO
  53 #define PSEUDO(name, syscall_name, args)                                      \
  54   .text;                                                                      \
  55   ENTRY (name)                                                                \
  56     DO_CALL (syscall_name, args);                                             \
  57     cmp.l &-4095, %d0;                                                        \
  58     jcc SYSCALL_ERROR_LABEL
  59
  60 #undef PSEUDO_END
  61 #define PSEUDO_END(name)                                                      \
  62   SYSCALL_ERROR_HANDLER;                                                      \
  63   END (name)
  64
  65 #undef PSEUDO_NOERRNO
  66 #define PSEUDO_NOERRNO(name, syscall_name, args)                              \
  67   .text;                                                                      \
  68   ENTRY (name)                                                                \
  69     DO_CALL (syscall_name, args)
  70
  71 #undef PSEUDO_END_NOERRNO
  72 #define PSEUDO_END_NOERRNO(name)                                              \
  73   END (name)
  74
  75 #define ret_NOERRNO rts
  76
  77 /* The function has to return the error code.  */
  78 #undef  PSEUDO_ERRVAL
  79 #define PSEUDO_ERRVAL(name, syscall_name, args) \
  80   .text;                                                                      \
  81   ENTRY (name)                                                                \
  82     DO_CALL (syscall_name, args);                                             \
  83     negl %d0
  84
  85 #undef  PSEUDO_END_ERRVAL
  86 #define PSEUDO_END_ERRVAL(name) \
  87   END (name)
  88
  89 #define ret_ERRVAL rts
  90
  91 #ifdef PIC
  92 # if RTLD_PRIVATE_ERRNO
  93 #  define SYSCALL_ERROR_HANDLER                                               \
  94 SYSCALL_ERROR_LABEL:                                                          \
  95     PCREL_OP (lea, rtld_errno, %a0, %a0);                                     \
  96     neg.l %d0;                                                                \
  97     move.l %d0, (%a0);                                                        \
  98     move.l &-1, %d0;                                                          \
  99     /* Copy return value to %a0 for syscalls that are declared to return      \
 100        a pointer (e.g., mmap).  */                                            \
 101     move.l %d0, %a0;                                                          \
 102     rts;
 103 # elif defined _LIBC_REENTRANT
 104 #  ifndef NOT_IN_libc
 105 #   define SYSCALL_ERROR_ERRNO __libc_errno
 106 #  else
 107 #   define SYSCALL_ERROR_ERRNO errno
 108 #  endif
 109 #  define SYSCALL_ERROR_HANDLER                                               \
 110 SYSCALL_ERROR_LABEL:                                                          \
 111     neg.l %d0;                                                                \
 112     move.l %d0, -(%sp);                                                       \
 113     cfi_adjust_cfa_offset (4);                                                \
 114     jbsr __m68k_read_tp@PLTPC;                                                \
 115     SYSCALL_ERROR_LOAD_GOT (%a1);                                             \
 116     add.l (SYSCALL_ERROR_ERRNO@TLSIE, %a1), %a0;                              \
 117     move.l (%sp)+, (%a0);                                                     \
 118     cfi_adjust_cfa_offset (-4);                                               \
 119     move.l &-1, %d0;                                                          \
 120     /* Copy return value to %a0 for syscalls that are declared to return      \
 121        a pointer (e.g., mmap).  */                                            \
 122     move.l %d0, %a0;                                                          \
 123     rts;
 124 # else /* !_LIBC_REENTRANT */
 125 /* Store (- %d0) into errno through the GOT.  */
 126 #  define SYSCALL_ERROR_HANDLER                                               \
 127 SYSCALL_ERROR_LABEL:                                                          \
 128     move.l (errno@GOTPC, %pc), %a0;                                           \
 129     neg.l %d0;                                                                \
 130     move.l %d0, (%a0);                                                        \
 131     move.l &-1, %d0;                                                          \
 132     /* Copy return value to %a0 for syscalls that are declared to return      \
 133        a pointer (e.g., mmap).  */                                            \
 134     move.l %d0, %a0;                                                          \
 135     rts;
 136 # endif /* _LIBC_REENTRANT */
 137 #else
 138 # define SYSCALL_ERROR_HANDLER  /* Nothing here; code in sysdep.S is used.  */
 139 #endif /* PIC */
 140
 141 /* Linux takes system call arguments in registers:
 142
 143         syscall number  %d0          call-clobbered
 144         arg 1           %d1          call-clobbered
 145         arg 2           %d2          call-saved
 146         arg 3           %d3          call-saved
 147         arg 4           %d4          call-saved
 148         arg 5           %d5          call-saved
 149         arg 6           %a0          call-clobbered
 150
 151    The stack layout upon entering the function is:
 152
 153         24(%sp)         Arg# 6
 154         20(%sp)         Arg# 5
 155         16(%sp)         Arg# 4
 156         12(%sp)         Arg# 3
 157          8(%sp)         Arg# 2
 158          4(%sp)         Arg# 1
 159           (%sp)         Return address
 160
 161    (Of course a function with say 3 arguments does not have entries for
 162    arguments 4 and 5.)
 163
 164    Separate move's are faster than movem, but need more space.  Since
 165    speed is more important, we don't use movem.  Since %a0 and %a1 are
 166    scratch registers, we can use them for saving as well.  */
 167
 168 #define DO_CALL(syscall_name, args)                                           \
 169     move.l &SYS_ify(syscall_name), %d0;                                       \
 170     DOARGS_##args                                                             \
 171     trap &0;                                                                  \
 172     UNDOARGS_##args
 173
 174 #define DOARGS_0        /* No arguments to frob.  */
 175 #define UNDOARGS_0      /* No arguments to unfrob.  */
 176 #define _DOARGS_0(n)    /* No arguments to frob.  */
 177
 178 #define DOARGS_1        _DOARGS_1 (4)
 179 #define _DOARGS_1(n)    move.l n(%sp), %d1; _DOARGS_0 (n)
 180 #define UNDOARGS_1      UNDOARGS_0
 181
 182 #define DOARGS_2        _DOARGS_2 (8)
 183 #define _DOARGS_2(n)    move.l %d2, %a0; cfi_register (%d2, %a0);             \
 184                         move.l n(%sp), %d2; _DOARGS_1 (n-4)
 185 #define UNDOARGS_2      UNDOARGS_1; move.l %a0, %d2; cfi_restore (%d2)
 186
 187 #define DOARGS_3        _DOARGS_3 (12)
 188 #define _DOARGS_3(n)    move.l %d3, %a1; cfi_register (%d3, %a1);             \
 189                         move.l n(%sp), %d3; _DOARGS_2 (n-4)
 190 #define UNDOARGS_3      UNDOARGS_2; move.l %a1, %d3; cfi_restore (%d3)
 191
 192 #define DOARGS_4        _DOARGS_4 (16)
 193 #define _DOARGS_4(n)    move.l %d4, -(%sp);                                   \
 194                         cfi_adjust_cfa_offset (4); cfi_rel_offset (%d4, 0);   \
 195                         move.l n+4(%sp), %d4; _DOARGS_3 (n)
 196 #define UNDOARGS_4      UNDOARGS_3; move.l (%sp)+, %d4;                       \
 197                         cfi_adjust_cfa_offset (-4); cfi_restore (%d4)
 198
 199 #define DOARGS_5        _DOARGS_5 (20)
 200 #define _DOARGS_5(n)    move.l %d5, -(%sp);                                   \
 201                         cfi_adjust_cfa_offset (4); cfi_rel_offset (%d5, 0);   \
 202                         move.l n+4(%sp), %d5; _DOARGS_4 (n)
 203 #define UNDOARGS_5      UNDOARGS_4; move.l (%sp)+, %d5;                       \
 204                         cfi_adjust_cfa_offset (-4); cfi_restore (%d5)
 205
 206 #define DOARGS_6        _DOARGS_6 (24)
 207 #define _DOARGS_6(n)    _DOARGS_5 (n-4); move.l %a0, -(%sp);                  \
 208                         cfi_adjust_cfa_offset (4);                            \
 209                         move.l n+12(%sp), %a0;
 210 #define UNDOARGS_6      move.l (%sp)+, %a0; cfi_adjust_cfa_offset (-4);       \
 211                         UNDOARGS_5
 212
 213
 214 #define ret     rts
 215 #if 0 /* Not used by Linux */
 216 #define r0      %d0
 217 #define r1      %d1
 218 #define MOVE(x,y)       movel x , y
 219 #endif
 220
 221 #else /* not __ASSEMBLER__ */
 222
 223 /* Define a macro which expands into the inline wrapper code for a system
 224    call.  */
 225 #undef INLINE_SYSCALL
 226 #define INLINE_SYSCALL(name, nr, args...)                               \
 227   ({ unsigned int _sys_result = INTERNAL_SYSCALL (name, , nr, args);    \
 228      if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (_sys_result, ), 0))\
 229        {                                                                \
 230          __set_errno (INTERNAL_SYSCALL_ERRNO (_sys_result, ));          \
 231          _sys_result = (unsigned int) -1;                               \
 232        }                                                                \
 233      (int) _sys_result; })
 234
 235 #undef INTERNAL_SYSCALL_DECL
 236 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 237
 238 /* Define a macro which expands inline into the wrapper code for a system
 239    call.  This use is for internal calls that do not need to handle errors
 240    normally.  It will never touch errno.  This returns just what the kernel
 241    gave back.  */
 242 #undef INTERNAL_SYSCALL
 243 #define INTERNAL_SYSCALL_NCS(name, err, nr, args...)    \
 244   ({ unsigned int _sys_result;                          \
 245      {                                                  \
 246        /* Load argument values in temporary variables
 247           to perform side effects like function calls
 248           before the call used registers are set.  */   \
 249        LOAD_ARGS_##nr (args)                            \
 250        LOAD_REGS_##nr                                   \
 251        register int _d0 asm ("%d0") = name;             \
 252        asm volatile ("trap #0"                          \
 253                      : "=d" (_d0)                       \
 254                      : "0" (_d0) ASM_ARGS_##nr          \
 255                      : "memory");                       \
 256        _sys_result = _d0;                               \
 257      }                                                  \
 258      (int) _sys_result; })
 259 #define INTERNAL_SYSCALL(name, err, nr, args...)        \
 260   INTERNAL_SYSCALL_NCS (__NR_##name, err, nr, ##args)
 261
 262 #undef INTERNAL_SYSCALL_ERROR_P
 263 #define INTERNAL_SYSCALL_ERROR_P(val, err)              \
 264   ((unsigned int) (val) >= -4095U)
 265
 266 #undef INTERNAL_SYSCALL_ERRNO
 267 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 268
 269 #define LOAD_ARGS_0()
 270 #define LOAD_REGS_0
 271 #define ASM_ARGS_0
 272 #define LOAD_ARGS_1(a1)                         \
 273   LOAD_ARGS_0 ()                                \
 274   int __arg1 = (int) (a1);
 275 #define LOAD_REGS_1                             \
 276   register int _d1 asm ("d1") = __arg1;         \
 277   LOAD_REGS_0
 278 #define ASM_ARGS_1      ASM_ARGS_0, "d" (_d1)
 279 #define LOAD_ARGS_2(a1, a2)                     \
 280   LOAD_ARGS_1 (a1)                              \
 281   int __arg2 = (int) (a2);
 282 #define LOAD_REGS_2                             \
 283   register int _d2 asm ("d2") = __arg2;         \
 284   LOAD_REGS_1
 285 #define ASM_ARGS_2      ASM_ARGS_1, "d" (_d2)
 286 #define LOAD_ARGS_3(a1, a2, a3)                 \
 287   LOAD_ARGS_2 (a1, a2)                          \
 288   int __arg3 = (int) (a3);
 289 #define LOAD_REGS_3                             \
 290   register int _d3 asm ("d3") = __arg3;         \
 291   LOAD_REGS_2
 292 #define ASM_ARGS_3      ASM_ARGS_2, "d" (_d3)
 293 #define LOAD_ARGS_4(a1, a2, a3, a4)             \
 294   LOAD_ARGS_3 (a1, a2, a3)                      \
 295   int __arg4 = (int) (a4);
 296 #define LOAD_REGS_4                             \
 297   register int _d4 asm ("d4") = __arg4;         \
 298   LOAD_REGS_3
 299 #define ASM_ARGS_4      ASM_ARGS_3, "d" (_d4)
 300 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)         \
 301   LOAD_ARGS_4 (a1, a2, a3, a4)                  \
 302   int __arg5 = (int) (a5);
 303 #define LOAD_REGS_5                             \
 304   register int _d5 asm ("d5") = __arg5;         \
 305   LOAD_REGS_4
 306 #define ASM_ARGS_5      ASM_ARGS_4, "d" (_d5)
 307 #define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6)     \
 308   LOAD_ARGS_5 (a1, a2, a3, a4, a5)              \
 309   int __arg6 = (int) (a6);
 310 #define LOAD_REGS_6                             \
 311   register int _a0 asm ("a0") = __arg6;         \
 312   LOAD_REGS_5
 313 #define ASM_ARGS_6      ASM_ARGS_5, "a" (_a0)
 314
 315 #endif /* not __ASSEMBLER__ */
 316
 317 /* Pointer mangling is not yet supported for M68K.  */
 318 #define PTR_MANGLE(var) (void) (var)
 319 #define PTR_DEMANGLE(var) (void) (var)
 320
 321 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 322 /* M68K needs system-supplied DSO to access TLS helpers
 323    even when statically linked.  */
 324 # define NEED_STATIC_SYSINFO_DSO 1
 325 #endif