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

   1 /* Copyright (C) 1992-2013 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 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 #ifndef _LINUX_ARM_SYSDEP_H
  21 #define _LINUX_ARM_SYSDEP_H 1
  22
  23 /* There is some commonality.  */
  24 #include <sysdeps/unix/arm/sysdep.h>
  25
  26 /* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO.  */
  27 #include <dl-sysdep.h>
  28
  29 #include <tls.h>
  30
  31 /* In order to get __set_errno() definition in INLINE_SYSCALL.  */
  32 #ifndef __ASSEMBLER__
  33 #include <errno.h>
  34 #endif
  35
  36 /* For Linux we can use the system call table in the header file
  37         /usr/include/asm/unistd.h
  38    of the kernel.  But these symbols do not follow the SYS_* syntax
  39    so we have to redefine the `SYS_ify' macro here.  */
  40 #undef SYS_ify
  41 #define SYS_ify(syscall_name)   (__NR_##syscall_name)
  42
  43 #define _SYS_AUXV_H 1
  44 #include <bits/hwcap.h>
  45
  46 #ifdef __ASSEMBLER__
  47
  48 /* Linux uses a negative return value to indicate syscall errors,
  49    unlike most Unices, which use the condition codes' carry flag.
  50
  51    Since version 2.1 the return value of a system call might be
  52    negative even if the call succeeded.  E.g., the `lseek' system call
  53    might return a large offset.  Therefore we must not anymore test
  54    for < 0, but test for a real error by making sure the value in R0
  55    is a real error number.  Linus said he will make sure the no syscall
  56    returns a value in -1 .. -4095 as a valid result so we can safely
  57    test with -4095.  */
  58
  59 #undef  PSEUDO
  60 #define PSEUDO(name, syscall_name, args)                \
  61         .text;                                          \
  62   ENTRY (name);                                         \
  63         DO_CALL (syscall_name, args);                   \
  64         cmn     r0, $4096;
  65
  66 #define PSEUDO_RET                                      \
  67         RETINSTR(cc, lr);                               \
  68         b       PLTJMP(SYSCALL_ERROR)
  69 #undef ret
  70 #define ret PSEUDO_RET
  71
  72 #undef  PSEUDO_END
  73 #define PSEUDO_END(name)                                \
  74         SYSCALL_ERROR_HANDLER;                          \
  75   END (name)
  76
  77 #undef  PSEUDO_NOERRNO
  78 #define PSEUDO_NOERRNO(name, syscall_name, args)        \
  79         .text;                                          \
  80   ENTRY (name);                                         \
  81         DO_CALL (syscall_name, args);
  82
  83 #define PSEUDO_RET_NOERRNO                              \
  84         DO_RET (lr);
  85
  86 #undef ret_NOERRNO
  87 #define ret_NOERRNO PSEUDO_RET_NOERRNO
  88
  89 #undef  PSEUDO_END_NOERRNO
  90 #define PSEUDO_END_NOERRNO(name)                        \
  91   END (name)
  92
  93 /* The function has to return the error code.  */
  94 #undef  PSEUDO_ERRVAL
  95 #define PSEUDO_ERRVAL(name, syscall_name, args)         \
  96         .text;                                          \
  97   ENTRY (name)                                          \
  98         DO_CALL (syscall_name, args);                   \
  99         rsb     r0, r0, #0
 100
 101 #undef  PSEUDO_END_ERRVAL
 102 #define PSEUDO_END_ERRVAL(name)                         \
 103   END (name)
 104
 105 #define ret_ERRVAL PSEUDO_RET_NOERRNO
 106
 107 #if NOT_IN_libc
 108 # define SYSCALL_ERROR __local_syscall_error
 109 # if RTLD_PRIVATE_ERRNO
 110 #  define SYSCALL_ERROR_HANDLER                                 \
 111 __local_syscall_error:                                          \
 112        ldr     r1, 1f;                                          \
 113        rsb     r0, r0, #0;                                      \
 114 0:     str     r0, [pc, r1];                                    \
 115        mvn     r0, #0;                                          \
 116        DO_RET(lr);                                              \
 117 1:     .word C_SYMBOL_NAME(rtld_errno) - 0b - 8;
 118 # else
 119 #  if defined(__ARM_ARCH_4T__) && defined(__THUMB_INTERWORK__)
 120 #   define POP_PC \
 121   ldr lr, [sp], #4; \
 122   cfi_adjust_cfa_offset (-4); \
 123   cfi_restore (lr); \
 124   bx lr
 125 #  else
 126 #   define POP_PC  \
 127   ldr pc, [sp], #4
 128 #  endif
 129 #  define SYSCALL_ERROR_HANDLER                                 \
 130 __local_syscall_error:                                          \
 131         str     lr, [sp, #-4]!;                                 \
 132         cfi_adjust_cfa_offset (4);                              \
 133         cfi_rel_offset (lr, 0);                                 \
 134         str     r0, [sp, #-4]!;                                 \
 135         cfi_adjust_cfa_offset (4);                              \
 136         bl      PLTJMP(C_SYMBOL_NAME(__errno_location));        \
 137         ldr     r1, [sp], #4;                                   \
 138         cfi_adjust_cfa_offset (-4);                             \
 139         rsb     r1, r1, #0;                                     \
 140         str     r1, [r0];                                       \
 141         mvn     r0, #0;                                         \
 142         POP_PC;
 143 # endif
 144 #else
 145 # define SYSCALL_ERROR_HANDLER  /* Nothing here; code in sysdep.S is used.  */
 146 # define SYSCALL_ERROR __syscall_error
 147 #endif
 148
 149 /* The ARM EABI user interface passes the syscall number in r7, instead
 150    of in the swi.  This is more efficient, because the kernel does not need
 151    to fetch the swi from memory to find out the number; which can be painful
 152    with separate I-cache and D-cache.  Make sure to use 0 for the SWI
 153    argument; otherwise the (optional) compatibility code for APCS binaries
 154    may be invoked.  */
 155
 156 /* Linux takes system call args in registers:
 157         arg 1           r0
 158         arg 2           r1
 159         arg 3           r2
 160         arg 4           r3
 161         arg 5           r4      (this is different from the APCS convention)
 162         arg 6           r5
 163         arg 7           r6
 164
 165    The compiler is going to form a call by coming here, through PSEUDO, with
 166    arguments
 167         syscall number  in the DO_CALL macro
 168         arg 1           r0
 169         arg 2           r1
 170         arg 3           r2
 171         arg 4           r3
 172         arg 5           [sp]
 173         arg 6           [sp+4]
 174         arg 7           [sp+8]
 175
 176    We need to shuffle values between R4..R6 and the stack so that the
 177    caller's v1..v3 and stack frame are not corrupted, and the kernel
 178    sees the right arguments.
 179
 180 */
 181
 182 /* We must save and restore r7 (call-saved) for the syscall number.
 183    We never make function calls from inside here (only potentially
 184    signal handlers), so we do not bother with doubleword alignment.
 185
 186    Just like the APCS syscall convention, the EABI syscall convention uses
 187    r0 through r6 for up to seven syscall arguments.  None are ever passed to
 188    the kernel on the stack, although incoming arguments are on the stack for
 189    syscalls with five or more arguments.
 190
 191    The assembler will convert the literal pool load to a move for most
 192    syscalls.  */
 193
 194 #undef  DO_CALL
 195 #define DO_CALL(syscall_name, args)                     \
 196         DOARGS_##args;                                  \
 197         ldr     r7, =SYS_ify (syscall_name);            \
 198         swi     0x0;                                    \
 199         UNDOARGS_##args
 200
 201 #undef  DOARGS_0
 202 #define DOARGS_0                                        \
 203         .fnstart;                                       \
 204         str r7, [sp, #-4]!;                             \
 205         cfi_adjust_cfa_offset (4);                      \
 206         cfi_rel_offset (r7, 0);                         \
 207         .save   { r7 }
 208 #undef  DOARGS_1
 209 #define DOARGS_1 DOARGS_0
 210 #undef  DOARGS_2
 211 #define DOARGS_2 DOARGS_0
 212 #undef  DOARGS_3
 213 #define DOARGS_3 DOARGS_0
 214 #undef  DOARGS_4
 215 #define DOARGS_4 DOARGS_0
 216 #undef  DOARGS_5
 217 #define DOARGS_5                                        \
 218         .fnstart;                                       \
 219         stmfd   sp!, {r4, r7};                          \
 220         cfi_adjust_cfa_offset (8);                      \
 221         cfi_rel_offset (r4, 0);                         \
 222         cfi_rel_offset (r7, 4);                         \
 223         .save   { r4, r7 };                             \
 224         ldr     r4, [sp, #8]
 225 #undef  DOARGS_6
 226 #define DOARGS_6                                        \
 227         .fnstart;                                       \
 228         mov     ip, sp;                                 \
 229         stmfd   sp!, {r4, r5, r7};                      \
 230         cfi_adjust_cfa_offset (12);                     \
 231         cfi_rel_offset (r4, 0);                         \
 232         cfi_rel_offset (r5, 4);                         \
 233         cfi_rel_offset (r7, 8);                         \
 234         .save   { r4, r5, r7 };                         \
 235         ldmia   ip, {r4, r5}
 236 #undef  DOARGS_7
 237 #define DOARGS_7                                        \
 238         .fnstart;                                       \
 239         mov     ip, sp;                                 \
 240         stmfd   sp!, {r4, r5, r6, r7};                  \
 241         cfi_adjust_cfa_offset (16);                     \
 242         cfi_rel_offset (r4, 0);                         \
 243         cfi_rel_offset (r5, 4);                         \
 244         cfi_rel_offset (r6, 8);                         \
 245         cfi_rel_offset (r7, 12);                        \
 246         .save   { r4, r5, r6, r7 };                     \
 247         ldmia   ip, {r4, r5, r6}
 248
 249 #undef  UNDOARGS_0
 250 #define UNDOARGS_0                                      \
 251         ldr     r7, [sp], #4;                           \
 252         cfi_adjust_cfa_offset (-4);                     \
 253         cfi_restore (r7);                               \
 254         .fnend
 255 #undef  UNDOARGS_1
 256 #define UNDOARGS_1 UNDOARGS_0
 257 #undef  UNDOARGS_2
 258 #define UNDOARGS_2 UNDOARGS_0
 259 #undef  UNDOARGS_3
 260 #define UNDOARGS_3 UNDOARGS_0
 261 #undef  UNDOARGS_4
 262 #define UNDOARGS_4 UNDOARGS_0
 263 #undef  UNDOARGS_5
 264 #define UNDOARGS_5                                      \
 265         ldmfd   sp!, {r4, r7};                          \
 266         cfi_adjust_cfa_offset (-8);                     \
 267         cfi_restore (r4);                               \
 268         cfi_restore (r7);                               \
 269         .fnend
 270 #undef  UNDOARGS_6
 271 #define UNDOARGS_6                                      \
 272         ldmfd   sp!, {r4, r5, r7};                      \
 273         cfi_adjust_cfa_offset (-12);                    \
 274         cfi_restore (r4);                               \
 275         cfi_restore (r5);                               \
 276         cfi_restore (r7);                               \
 277         .fnend
 278 #undef  UNDOARGS_7
 279 #define UNDOARGS_7                                      \
 280         ldmfd   sp!, {r4, r5, r6, r7};                  \
 281         cfi_adjust_cfa_offset (-16);                    \
 282         cfi_restore (r4);                               \
 283         cfi_restore (r5);                               \
 284         cfi_restore (r6);                               \
 285         cfi_restore (r7);                               \
 286         .fnend
 287
 288 #else /* not __ASSEMBLER__ */
 289
 290 /* Define a macro which expands into the inline wrapper code for a system
 291    call.  */
 292 #undef INLINE_SYSCALL
 293 #define INLINE_SYSCALL(name, nr, args...)                               \
 294   ({ unsigned int _sys_result = INTERNAL_SYSCALL (name, , nr, args);    \
 295      if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (_sys_result, ), 0))        \
 296        {                                                                \
 297          __set_errno (INTERNAL_SYSCALL_ERRNO (_sys_result, ));          \
 298          _sys_result = (unsigned int) -1;                               \
 299        }                                                                \
 300      (int) _sys_result; })
 301
 302 #undef INTERNAL_SYSCALL_DECL
 303 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 304
 305 #if defined(__thumb__)
 306 /* We can not expose the use of r7 to the compiler.  GCC (as
 307    of 4.5) uses r7 as the hard frame pointer for Thumb - although
 308    for Thumb-2 it isn't obviously a better choice than r11.
 309    And GCC does not support asms that conflict with the frame
 310    pointer.
 311
 312    This would be easier if syscall numbers never exceeded 255,
 313    but they do.  For the moment the LOAD_ARGS_7 is sacrificed.
 314    We can't use push/pop inside the asm because that breaks
 315    unwinding (i.e. thread cancellation) for this frame.  We can't
 316    locally save and restore r7, because we do not know if this
 317    function uses r7 or if it is our caller's r7; if it is our caller's,
 318    then unwinding will fail higher up the stack.  So we move the
 319    syscall out of line and provide its own unwind information.  */
 320 # undef INTERNAL_SYSCALL_RAW
 321 # define INTERNAL_SYSCALL_RAW(name, err, nr, args...)           \
 322   ({                                                            \
 323       register int _a1 asm ("a1");                              \
 324       int _nametmp = name;                                      \
 325       LOAD_ARGS_##nr (args)                                     \
 326       register int _name asm ("ip") = _nametmp;                 \
 327       asm volatile ("bl      __libc_do_syscall"                 \
 328                     : "=r" (_a1)                                \
 329                     : "r" (_name) ASM_ARGS_##nr                 \
 330                     : "memory", "lr");                          \
 331       _a1; })
 332 #else /* ARM */
 333 # undef INTERNAL_SYSCALL_RAW
 334 # define INTERNAL_SYSCALL_RAW(name, err, nr, args...)           \
 335   ({                                                            \
 336        register int _a1 asm ("r0"), _nr asm ("r7");             \
 337        LOAD_ARGS_##nr (args)                                    \
 338        _nr = name;                                              \
 339        asm volatile ("swi       0x0     @ syscall " #name       \
 340                      : "=r" (_a1)                               \
 341                      : "r" (_nr) ASM_ARGS_##nr                  \
 342                      : "memory");                               \
 343        _a1; })
 344 #endif
 345
 346 #undef INTERNAL_SYSCALL
 347 #define INTERNAL_SYSCALL(name, err, nr, args...)                \
 348         INTERNAL_SYSCALL_RAW(SYS_ify(name), err, nr, args)
 349
 350 #undef INTERNAL_SYSCALL_ARM
 351 #define INTERNAL_SYSCALL_ARM(name, err, nr, args...)            \
 352         INTERNAL_SYSCALL_RAW(__ARM_NR_##name, err, nr, args)
 353
 354 #undef INTERNAL_SYSCALL_ERROR_P
 355 #define INTERNAL_SYSCALL_ERROR_P(val, err) \
 356   ((unsigned int) (val) >= 0xfffff001u)
 357
 358 #undef INTERNAL_SYSCALL_ERRNO
 359 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 360
 361 #define LOAD_ARGS_0()
 362 #define ASM_ARGS_0
 363 #define LOAD_ARGS_1(a1)                         \
 364   int _a1tmp = (int) (a1);                      \
 365   LOAD_ARGS_0 ()                                \
 366   _a1 = _a1tmp;
 367 #define ASM_ARGS_1      ASM_ARGS_0, "r" (_a1)
 368 #define LOAD_ARGS_2(a1, a2)                     \
 369   int _a2tmp = (int) (a2);                      \
 370   LOAD_ARGS_1 (a1)                              \
 371   register int _a2 asm ("a2") = _a2tmp;
 372 #define ASM_ARGS_2      ASM_ARGS_1, "r" (_a2)
 373 #define LOAD_ARGS_3(a1, a2, a3)                 \
 374   int _a3tmp = (int) (a3);                      \
 375   LOAD_ARGS_2 (a1, a2)                          \
 376   register int _a3 asm ("a3") = _a3tmp;
 377 #define ASM_ARGS_3      ASM_ARGS_2, "r" (_a3)
 378 #define LOAD_ARGS_4(a1, a2, a3, a4)             \
 379   int _a4tmp = (int) (a4);                      \
 380   LOAD_ARGS_3 (a1, a2, a3)                      \
 381   register int _a4 asm ("a4") = _a4tmp;
 382 #define ASM_ARGS_4      ASM_ARGS_3, "r" (_a4)
 383 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)         \
 384   int _v1tmp = (int) (a5);                      \
 385   LOAD_ARGS_4 (a1, a2, a3, a4)                  \
 386   register int _v1 asm ("v1") = _v1tmp;
 387 #define ASM_ARGS_5      ASM_ARGS_4, "r" (_v1)
 388 #define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6)     \
 389   int _v2tmp = (int) (a6);                      \
 390   LOAD_ARGS_5 (a1, a2, a3, a4, a5)              \
 391   register int _v2 asm ("v2") = _v2tmp;
 392 #define ASM_ARGS_6      ASM_ARGS_5, "r" (_v2)
 393 #ifndef __thumb__
 394 # define LOAD_ARGS_7(a1, a2, a3, a4, a5, a6, a7)        \
 395   int _v3tmp = (int) (a7);                              \
 396   LOAD_ARGS_6 (a1, a2, a3, a4, a5, a6)                  \
 397   register int _v3 asm ("v3") = _v3tmp;
 398 # define ASM_ARGS_7     ASM_ARGS_6, "r" (_v3)
 399 #endif
 400
 401 /* For EABI, non-constant syscalls are actually pretty easy...  */
 402 #undef INTERNAL_SYSCALL_NCS
 403 #define INTERNAL_SYSCALL_NCS(number, err, nr, args...)          \
 404   INTERNAL_SYSCALL_RAW (number, err, nr, args)
 405
 406 #endif  /* __ASSEMBLER__ */
 407
 408 /* Pointer mangling is not yet supported for ARM.  */
 409 #define PTR_MANGLE(var) (void) (var)
 410 #define PTR_DEMANGLE(var) (void) (var)
 411
 412 #endif /* linux/arm/sysdep.h */