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

   1 /* Copyright (C) 1992, 93, 1995-2000, 2002, 2003 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    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  (0x900000)
  33 #define SYS_ify(syscall_name)   (__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 R0
  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
  49 #undef  PSEUDO
  50 #define PSEUDO(name, syscall_name, args)                                      \
  51   .text;                                                                      \
  52   ENTRY (name);                                                               \
  53     DO_CALL (syscall_name, args);                                             \
  54     cmn r0, $4096;
  55
  56 #define PSEUDO_RET                                                            \
  57     RETINSTR(movcc, pc, lr);                                                  \
  58     b PLTJMP(SYSCALL_ERROR)
  59 #undef ret
  60 #define ret PSEUDO_RET
  61
  62 #undef  PSEUDO_END
  63 #define PSEUDO_END(name)                                                      \
  64   SYSCALL_ERROR_HANDLER                                                       \
  65   END (name)
  66
  67 #if NOT_IN_libc
  68 # define SYSCALL_ERROR __local_syscall_error
  69 # define SYSCALL_ERROR_HANDLER                                  \
  70 __local_syscall_error:                                          \
  71         str     lr, [sp, #-4]!;                                 \
  72         str     r0, [sp, #-4]!;                                 \
  73         bl      PLTJMP(C_SYMBOL_NAME(__errno_location));        \
  74         ldr     r1, [sp], #4;                                   \
  75         rsb     r1, r1, #0;                                     \
  76         str     r1, [r0];                                       \
  77         mvn     r0, #0;                                         \
  78         ldr     pc, [sp], #4;
  79 #else
  80 # define SYSCALL_ERROR_HANDLER  /* Nothing here; code in sysdep.S is used.  */
  81 # define SYSCALL_ERROR __syscall_error
  82 #endif
  83
  84 /* Linux takes system call args in registers:
  85         syscall number  in the SWI instruction
  86         arg 1           r0
  87         arg 2           r1
  88         arg 3           r2
  89         arg 4           r3
  90         arg 5           r4      (this is different from the APCS convention)
  91         arg 6           r5
  92         arg 7           r6
  93
  94    The compiler is going to form a call by coming here, through PSEUDO, with
  95    arguments
  96         syscall number  in the DO_CALL macro
  97         arg 1           r0
  98         arg 2           r1
  99         arg 3           r2
 100         arg 4           r3
 101         arg 5           [sp]
 102         arg 6           [sp+4]
 103         arg 7           [sp+8]
 104
 105    We need to shuffle values between R4..R6 and the stack so that the
 106    caller's v1..v3 and stack frame are not corrupted, and the kernel
 107    sees the right arguments.
 108
 109 */
 110
 111 #undef  DO_CALL
 112 #define DO_CALL(syscall_name, args)             \
 113     DOARGS_##args                               \
 114     swi SYS_ify (syscall_name);                 \
 115     UNDOARGS_##args
 116
 117 #define DOARGS_0 /* nothing */
 118 #define DOARGS_1 /* nothing */
 119 #define DOARGS_2 /* nothing */
 120 #define DOARGS_3 /* nothing */
 121 #define DOARGS_4 /* nothing */
 122 #define DOARGS_5 str r4, [sp, $-4]!; ldr r4, [sp, $4];
 123 #define DOARGS_6 mov ip, sp; stmfd sp!, {r4, r5}; ldmia ip, {r4, r5};
 124 #define DOARGS_7 mov ip, sp; stmfd sp!, {r4, r5, r6}; ldmia ip, {r4, r5, r6};
 125
 126 #define UNDOARGS_0 /* nothing */
 127 #define UNDOARGS_1 /* nothing */
 128 #define UNDOARGS_2 /* nothing */
 129 #define UNDOARGS_3 /* nothing */
 130 #define UNDOARGS_4 /* nothing */
 131 #define UNDOARGS_5 ldr r4, [sp], $4;
 132 #define UNDOARGS_6 ldmfd sp!, {r4, r5};
 133 #define UNDOARGS_7 ldmfd sp!, {r4, r5, r6};
 134
 135 #else /* not __ASSEMBLER__ */
 136
 137 /* Define a macro which expands into the inline wrapper code for a system
 138    call.  */
 139 #undef INLINE_SYSCALL
 140 #define INLINE_SYSCALL(name, nr, args...)                               \
 141   ({ unsigned int _sys_result = INTERNAL_SYSCALL (name, , nr, args);    \
 142      if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (_sys_result, ), 0))        \
 143        {                                                                \
 144          __set_errno (INTERNAL_SYSCALL_ERRNO (_sys_result, ));          \
 145          _sys_result = (unsigned int) -1;                               \
 146        }                                                                \
 147      (int) _sys_result; })
 148
 149 #undef INTERNAL_SYSCALL_DECL
 150 #define INTERNAL_SYSCALL_DECL(err) do { } while (0)
 151
 152 #undef INTERNAL_SYSCALL
 153 #define INTERNAL_SYSCALL(name, err, nr, args...)                \
 154   ({ unsigned int _sys_result;                                  \
 155      {                                                          \
 156        register int _a1 asm ("a1");                             \
 157        LOAD_ARGS_##nr (args)                                    \
 158        asm volatile ("swi       %1      @ syscall " #name       \
 159                      : "=r" (_a1)                               \
 160                      : "i" (SYS_ify(name)) ASM_ARGS_##nr        \
 161                      : "a1", "memory");                         \
 162        _sys_result = _a1;                                       \
 163      }                                                          \
 164      (int) _sys_result; })
 165
 166 #undef INTERNAL_SYSCALL_ERROR_P
 167 #define INTERNAL_SYSCALL_ERROR_P(val, err) \
 168   ((unsigned int) (val) >= 0xfffff001u)
 169
 170 #undef INTERNAL_SYSCALL_ERRNO
 171 #define INTERNAL_SYSCALL_ERRNO(val, err)        (-(val))
 172
 173 #define LOAD_ARGS_0()
 174 #define ASM_ARGS_0
 175 #define LOAD_ARGS_1(a1)                         \
 176   _a1 = (int) (a1);                             \
 177   LOAD_ARGS_0 ()
 178 #define ASM_ARGS_1      ASM_ARGS_0, "r" (_a1)
 179 #define LOAD_ARGS_2(a1, a2)                     \
 180   register int _a2 asm ("a2") = (int) (a2);     \
 181   LOAD_ARGS_1 (a1)
 182 #define ASM_ARGS_2      ASM_ARGS_1, "r" (_a2)
 183 #define LOAD_ARGS_3(a1, a2, a3)                 \
 184   register int _a3 asm ("a3") = (int) (a3);     \
 185   LOAD_ARGS_2 (a1, a2)
 186 #define ASM_ARGS_3      ASM_ARGS_2, "r" (_a3)
 187 #define LOAD_ARGS_4(a1, a2, a3, a4)             \
 188   register int _a4 asm ("a4") = (int) (a4);     \
 189   LOAD_ARGS_3 (a1, a2, a3)
 190 #define ASM_ARGS_4      ASM_ARGS_3, "r" (_a4)
 191 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)         \
 192   register int _v1 asm ("v1") = (int) (a5);     \
 193   LOAD_ARGS_4 (a1, a2, a3, a4)
 194 #define ASM_ARGS_5      ASM_ARGS_4, "r" (_v1)
 195 #define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6)     \
 196   register int _v2 asm ("v2") = (int) (a6);     \
 197   LOAD_ARGS_5 (a1, a2, a3, a4, a5)
 198 #define ASM_ARGS_6      ASM_ARGS_5, "r" (_v2)
 199 #define LOAD_ARGS_7(a1, a2, a3, a4, a5, a6, a7) \
 200   register int _v3 asm ("v3") = (int) (a7);     \
 201   LOAD_ARGS_6 (a1, a2, a3, a4, a5, a6)
 202 #define ASM_ARGS_7      ASM_ARGS_6, "r" (_v3)
 203
 204 #endif  /* __ASSEMBLER__ */
 205
 206 #endif /* linux/arm/sysdep.h */