libc/sysdeps/linux/arm/sysdep.h

   1 /* Assembler macros for ARM.
   2    Copyright (C) 1997, 1998, 2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _LINUX_ARM_SYSDEP_H
  20 #define _LINUX_ARM_SYSDEP_H 1
  21
  22 #include <common/sysdep.h>
  23 #include <bits/arm_bx.h>
  24
  25 #include <sys/syscall.h>
  26 /* For Linux we can use the system call table in the header file
  27         /usr/include/asm/unistd.h
  28    of the kernel.  But these symbols do not follow the SYS_* syntax
  29    so we have to redefine the `SYS_ify' macro here.  */
  30 #undef SYS_ify
  31 #define SWI_BASE  (0x900000)
  32 #define SYS_ify(syscall_name)   (__NR_##syscall_name)
  33
  34 #ifdef  __ASSEMBLER__
  35
  36 /* Syntactic details of assembler.  */
  37
  38 #define ALIGNARG(log2) log2
  39 /* For ELF we need the `.type' directive to make shared libs work right.  */
  40 #define ASM_TYPE_DIRECTIVE(name,typearg) .type name,%##typearg;
  41 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name
  42
  43 /* In ELF C symbols are asm symbols.  */
  44 #undef  NO_UNDERSCORES
  45 #define NO_UNDERSCORES
  46
  47 #define PLTJMP(_x)      _x##(PLT)
  48
  49 /* APCS-32 doesn't preserve the condition codes across function call. */
  50 #ifdef __APCS_32__
  51 #define LOADREGS(cond, base, reglist...)\
  52         ldm##cond       base,reglist
  53 #ifdef __USE_BX__
  54 #define RETINSTR(cond, reg)     \
  55         bx##cond        reg
  56 #define DO_RET(_reg)            \
  57         bx _reg
  58 #else
  59 #define RETINSTR(cond, reg)     \
  60         mov##cond       pc, reg
  61 #define DO_RET(_reg)            \
  62         mov pc, _reg
  63 #endif
  64 #else  /* APCS-26 */
  65 #define LOADREGS(cond, base, reglist...)        \
  66         ldm##cond       base,reglist^
  67 #define RETINSTR(cond, reg)     \
  68         mov##cond##s    pc, reg
  69 #define DO_RET(_reg)            \
  70         movs pc, _reg
  71 #endif
  72
  73 /* Define an entry point visible from C.  */
  74 #define ENTRY(name)                                             \
  75   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);                     \
  76   ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),function)             \
  77   .align ALIGNARG(4);                                           \
  78   name##:                                                       \
  79   CALL_MCOUNT
  80
  81 #undef  END
  82 #define END(name)                                               \
  83   ASM_SIZE_DIRECTIVE(name)
  84
  85 /* If compiled for profiling, call `mcount' at the start of each function.  */
  86 #ifdef  PROF
  87 #define CALL_MCOUNT                     \
  88         str     lr,[sp, #-4]!   ;       \
  89         bl      PLTJMP(mcount)  ;       \
  90         ldr     lr, [sp], #4    ;
  91 #else
  92 #define CALL_MCOUNT             /* Do nothing.  */
  93 #endif
  94
  95 #ifdef  NO_UNDERSCORES
  96 /* Since C identifiers are not normally prefixed with an underscore
  97    on this system, the asm identifier `syscall_error' intrudes on the
  98    C name space.  Make sure we use an innocuous name.  */
  99 #define syscall_error   __syscall_error
 100 #define mcount          _mcount
 101 #endif
 102 /* Linux uses a negative return value to indicate syscall errors,
 103    unlike most Unices, which use the condition codes' carry flag.
 104
 105    Since version 2.1 the return value of a system call might be
 106    negative even if the call succeeded.  E.g., the `lseek' system call
 107    might return a large offset.  Therefore we must not anymore test
 108    for < 0, but test for a real error by making sure the value in R0
 109    is a real error number.  Linus said he will make sure the no syscall
 110    returns a value in -1 .. -4095 as a valid result so we can safely
 111    test with -4095.  */
 112
 113 #undef  PSEUDO
 114 #define PSEUDO(name, syscall_name, args)                                \
 115   .text;                                                                \
 116   ENTRY (name);                                                         \
 117     DO_CALL (syscall_name, args);                                       \
 118     cmn r0, $4096;
 119
 120 #define PSEUDO_RET                                                      \
 121     RETINSTR(cc, lr);                                                   \
 122     b PLTJMP(SYSCALL_ERROR)
 123 #undef ret
 124 #define ret PSEUDO_RET
 125
 126 #undef  PSEUDO_END
 127 #define PSEUDO_END(name)                                                \
 128   SYSCALL_ERROR_HANDLER                                                 \
 129   END (name)
 130
 131 #undef  PSEUDO_NOERRNO
 132 #define PSEUDO_NOERRNO(name, syscall_name, args)                        \
 133   .text;                                                                \
 134   ENTRY (name);                                                         \
 135     DO_CALL (syscall_name, args);
 136
 137 #define PSEUDO_RET_NOERRNO                                              \
 138     DO_RET (lr);
 139
 140 #undef ret_NOERRNO
 141 #define ret_NOERRNO PSEUDO_RET_NOERRNO
 142
 143 #undef  PSEUDO_END_NOERRNO
 144 #define PSEUDO_END_NOERRNO(name)                                        \
 145   END (name)
 146
 147 /* The function has to return the error code.  */
 148 #undef  PSEUDO_ERRVAL
 149 #define PSEUDO_ERRVAL(name, syscall_name, args) \
 150   .text;                                                                \
 151   ENTRY (name)                                                          \
 152     DO_CALL (syscall_name, args);                                       \
 153     rsb r0, r0, #0
 154
 155 #undef  PSEUDO_END_ERRVAL
 156 #define PSEUDO_END_ERRVAL(name) \
 157   END (name)
 158
 159 #undef ret_ERRVAL
 160 #define ret_ERRVAL PSEUDO_RET_NOERRNO
 161
 162 #if defined NOT_IN_libc
 163 # define SYSCALL_ERROR __local_syscall_error
 164 # ifdef RTLD_PRIVATE_ERRNO
 165 #  define SYSCALL_ERROR_HANDLER                                 \
 166 __local_syscall_error:                                          \
 167        ldr     r1, 1f;                                          \
 168        rsb     r0, r0, #0;                                      \
 169 0:     str     r0, [pc, r1];                                    \
 170        mvn     r0, #0;                                          \
 171        DO_RET(lr);                                              \
 172 1:     .word C_SYMBOL_NAME(rtld_errno) - 0b - 8;
 173 # else
 174 #  define SYSCALL_ERROR_HANDLER                                 \
 175 __local_syscall_error:                                          \
 176         str     lr, [sp, #-4]!;                                 \
 177         str     r0, [sp, #-4]!;                                 \
 178         bl      PLTJMP(C_SYMBOL_NAME(__errno_location));        \
 179         ldr     r1, [sp], #4;                                   \
 180         rsb     r1, r1, #0;                                     \
 181         str     r1, [r0];                                       \
 182         mvn     r0, #0;                                         \
 183         ldr     pc, [sp], #4;
 184 # endif
 185 #else
 186 # define SYSCALL_ERROR_HANDLER  /* Nothing here; code in sysdep.S is used.  */
 187 # define SYSCALL_ERROR __syscall_error
 188 #endif
 189
 190 /* Linux takes system call args in registers:
 191         syscall number  in the SWI instruction
 192         arg 1           r0
 193         arg 2           r1
 194         arg 3           r2
 195         arg 4           r3
 196         arg 5           r4      (this is different from the APCS convention)
 197         arg 6           r5
 198         arg 7           r6
 199
 200    The compiler is going to form a call by coming here, through PSEUDO, with
 201    arguments
 202         syscall number  in the DO_CALL macro
 203         arg 1           r0
 204         arg 2           r1
 205         arg 3           r2
 206         arg 4           r3
 207         arg 5           [sp]
 208         arg 6           [sp+4]
 209         arg 7           [sp+8]
 210
 211    We need to shuffle values between R4..R6 and the stack so that the
 212    caller's v1..v3 and stack frame are not corrupted, and the kernel
 213    sees the right arguments.
 214
 215 */
 216 #if __ARM_ARCH > 6 || defined (__ARM_ARCH_6K__) || defined (__ARM_ARCH_6ZK__)
 217 # define ARCH_HAS_HARD_TP
 218 #endif
 219
 220 # ifdef __thumb2__
 221 #  define NEGOFF_ADJ_BASE(R, OFF)       add R, R, $OFF
 222 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   add D, S, $OFF
 223 #  define NEGOFF_OFF1(R, OFF)           [R]
 224 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $((OFFA) - (OFFB))]
 225 # else
 226 #  define NEGOFF_ADJ_BASE(R, OFF)
 227 #  define NEGOFF_ADJ_BASE2(D, S, OFF)   mov D, S
 228 #  define NEGOFF_OFF1(R, OFF)           [R, $OFF]
 229 #  define NEGOFF_OFF2(R, OFFA, OFFB)    [R, $OFFA]
 230 # endif
 231
 232 # ifdef ARCH_HAS_HARD_TP
 233 /* If the cpu has cp15 available, use it.  */
 234 #  define GET_TLS(TMP)          mrc p15, 0, r0, c13, c0, 3
 235 # else
 236 /* At this generic level we have no tricks to pull.  Call the ABI routine.  */
 237 #  define GET_TLS(TMP)                                  \
 238         push    { r1, r2, r3, lr };                     \
 239         cfi_remember_state;                             \
 240         cfi_adjust_cfa_offset (16);                     \
 241         cfi_rel_offset (r1, 0);                         \
 242         cfi_rel_offset (r2, 4);                         \
 243         cfi_rel_offset (r3, 8);                         \
 244         cfi_rel_offset (lr, 12);                        \
 245         bl      __aeabi_read_tp;                        \
 246         pop     { r1, r2, r3, lr };                     \
 247         cfi_restore_state
 248 # endif /* ARCH_HAS_HARD_TP */
 249
 250
 251
 252
 253 #undef  DO_CALL
 254 #if defined(__ARM_EABI__)
 255 #define DO_CALL(syscall_name, args)             \
 256     DOARGS_##args                               \
 257     mov ip, r7;                                 \
 258     ldr r7, =SYS_ify (syscall_name);            \
 259     swi 0x0;                                    \
 260     mov r7, ip;                                 \
 261     UNDOARGS_##args
 262 #else
 263 #define DO_CALL(syscall_name, args)             \
 264     DOARGS_##args                               \
 265     swi SYS_ify (syscall_name);                 \
 266     UNDOARGS_##args
 267 #endif
 268
 269 #define DOARGS_0 /* nothing */
 270 #define DOARGS_1 /* nothing */
 271 #define DOARGS_2 /* nothing */
 272 #define DOARGS_3 /* nothing */
 273 #define DOARGS_4 /* nothing */
 274 #define DOARGS_5 str r4, [sp, $-4]!; ldr r4, [sp, $4];
 275 #define DOARGS_6 mov ip, sp; stmfd sp!, {r4, r5}; ldmia ip, {r4, r5};
 276 #define DOARGS_7 mov ip, sp; stmfd sp!, {r4, r5, r6}; ldmia ip, {r4, r5, r6};
 277
 278 #define UNDOARGS_0 /* nothing */
 279 #define UNDOARGS_1 /* nothing */
 280 #define UNDOARGS_2 /* nothing */
 281 #define UNDOARGS_3 /* nothing */
 282 #define UNDOARGS_4 /* nothing */
 283 #define UNDOARGS_5 ldr r4, [sp], $4;
 284 #define UNDOARGS_6 ldmfd sp!, {r4, r5};
 285 #define UNDOARGS_7 ldmfd sp!, {r4, r5, r6};
 286
 287 #else /* not __ASSEMBLER__ */
 288 /* Define a macro which expands into the inline wrapper code for a system
 289    call.  */
 290 #undef INLINE_SYSCALL
 291 #define INLINE_SYSCALL(name, nr, args...)                                       \
 292   ({ unsigned int _inline_sys_result = INTERNAL_SYSCALL (name, , nr, args);     \
 293      if (unlikely (INTERNAL_SYSCALL_ERROR_P (_inline_sys_result, )))    \
 294        {                                                                        \
 295          __set_errno (INTERNAL_SYSCALL_ERRNO (_inline_sys_result, ));           \
 296          _inline_sys_result = (unsigned int) -1;                                \
 297        }                                                                        \
 298      (int) _inline_sys_result; })
 299
 300 #undef INTERNAL_SYSCALL_DECL
 301 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 302
 303 #undef INTERNAL_SYSCALL_RAW
 304 #if defined(__thumb__)
 305 /* Hide the use of r7 from the compiler, this would be a lot
 306  * easier but for the fact that the syscalls can exceed 255.
 307  * For the moment the LOAD_ARG_7 is sacrificed.
 308  * We can't use push/pop inside the asm because that breaks
 309  * unwinding (ie. thread cancellation).
 310  */
 311 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
 312   ({ unsigned int _internal_sys_result;                         \
 313     {                                                           \
 314       int _sys_buf[2];                                          \
 315       register int __a1 __asm__ ("a1");                         \
 316       register int *_v3 __asm__ ("v3") = _sys_buf;              \
 317       LOAD_ARGS_##nr (args)                                     \
 318       *_v3 = (int) (name);                                      \
 319       __asm__ __volatile__ ("str        r7, [v3, #4]\n"         \
 320                     "\tldr      r7, [v3]\n"                     \
 321                     "\tswi      0       @ syscall " #name "\n"  \
 322                     "\tldr      r7, [v3, #4]"                   \
 323                    : "=r" (__a1)                                \
 324                     : "r" (_v3) ASM_ARGS_##nr                   \
 325                     : "memory");                                \
 326       _internal_sys_result = __a1;                              \
 327     }                                                           \
 328     (int) _internal_sys_result; })
 329 #elif defined(__ARM_EABI__)
 330 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
 331   ({unsigned int _internal_sys_result;                          \
 332      {                                                          \
 333        register int __a1 __asm__ ("r0"), _nr __asm__ ("r7");    \
 334        LOAD_ARGS_##nr (args)                                    \
 335        _nr = name;                                              \
 336        __asm__ __volatile__ ("swi       0x0 @ syscall " #name   \
 337                      : "=r" (__a1)                              \
 338                      : "r" (_nr) ASM_ARGS_##nr                  \
 339                      : "memory");                               \
 340        _internal_sys_result = __a1;                             \
 341      }                                                          \
 342      (int) _internal_sys_result; })
 343 #else /* !defined(__ARM_EABI__) */
 344 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
 345   ({ unsigned int _internal_sys_result;                         \
 346      {                                                          \
 347        register int __a1 __asm__ ("a1");                        \
 348        LOAD_ARGS_##nr (args)                                    \
 349        __asm__ __volatile__ ("swi       %1 @ syscall " #name    \
 350                      : "=r" (__a1)                              \
 351                      : "i" (name) ASM_ARGS_##nr                 \
 352                      : "memory");                               \
 353        _internal_sys_result = __a1;                             \
 354      }                                                          \
 355      (int) _internal_sys_result; })
 356 #endif
 357
 358 #undef INTERNAL_SYSCALL
 359 #define INTERNAL_SYSCALL(name, err, nr, args...)                \
 360         INTERNAL_SYSCALL_RAW(SYS_ify(name), err, nr, args)
 361
 362 #undef INTERNAL_SYSCALL_ARM
 363 #define INTERNAL_SYSCALL_ARM(name, err, nr, args...)            \
 364         INTERNAL_SYSCALL_RAW(__ARM_NR_##name, err, nr, args)
 365
 366 #undef INTERNAL_SYSCALL_ERROR_P
 367 #define INTERNAL_SYSCALL_ERROR_P(val, err) \
 368   ((unsigned int) (val) >= 0xfffff001u)
 369
 370 #undef INTERNAL_SYSCALL_ERRNO
 371 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 372
 373 #if defined(__ARM_EABI__)
 374 #undef INTERNAL_SYSCALL_NCS
 375 #define INTERNAL_SYSCALL_NCS(number, err, nr, args...)          \
 376         INTERNAL_SYSCALL_RAW(number, err, nr, args)
 377 #else
 378 /* We can't implement non-constant syscalls directly since the syscall
 379    number is normally encoded in the instruction.  So use SYS_syscall.  */
 380 #undef INTERNAL_SYSCALL_NCS
 381 #define INTERNAL_SYSCALL_NCS(number, err, nr, args...)          \
 382         INTERNAL_SYSCALL_NCS_##nr (number, err, args)
 383
 384 #define INTERNAL_SYSCALL_NCS_0(number, err, args...)            \
 385         INTERNAL_SYSCALL (syscall, err, 1, number, args)
 386 #define INTERNAL_SYSCALL_NCS_1(number, err, args...)            \
 387         INTERNAL_SYSCALL (syscall, err, 2, number, args)
 388 #define INTERNAL_SYSCALL_NCS_2(number, err, args...)            \
 389         INTERNAL_SYSCALL (syscall, err, 3, number, args)
 390 #define INTERNAL_SYSCALL_NCS_3(number, err, args...)            \
 391         INTERNAL_SYSCALL (syscall, err, 4, number, args)
 392 #define INTERNAL_SYSCALL_NCS_4(number, err, args...)            \
 393         INTERNAL_SYSCALL (syscall, err, 5, number, args)
 394 #define INTERNAL_SYSCALL_NCS_5(number, err, args...)            \
 395         INTERNAL_SYSCALL (syscall, err, 6, number, args)
 396 #endif
 397
 398 #endif  /* __ASSEMBLER__ */
 399
 400 /* Pointer mangling is not yet supported for ARM.  */
 401 #define PTR_MANGLE(var) (void) (var)
 402 #define PTR_DEMANGLE(var) (void) (var)
 403
 404 #endif /* linux/arm/sysdep.h */