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

   1 /* Copyright (C) 1992, 93, 95-99, 2000 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 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   .type syscall_error,%function;                                              \
  53   ENTRY (name);                                                               \
  54     DO_CALL (args, syscall_name);                                             \
  55     cmn r0, $4096;
  56
  57 #define PSEUDO_RET                                                            \
  58     RETINSTR(movcc, pc, lr);                                                  \
  59     b PLTJMP(__syscall_error)
  60 #undef ret
  61 #define ret PSEUDO_RET
  62
  63 #undef  PSEUDO_END
  64 #define PSEUDO_END(name)                                                      \
  65   SYSCALL_ERROR_HANDLER                                                       \
  66   END (name)
  67
  68 #define SYSCALL_ERROR_HANDLER   /* Nothing here; code in sysdep.S is used.  */
  69
  70 /* Linux takes system call args in registers:
  71         syscall number  in the SWI instruction
  72         arg 1           r0
  73         arg 2           r1
  74         arg 3           r2
  75         arg 4           r3
  76         arg 5           r4      (this is different from the APCS convention)
  77         arg 6           r5
  78         arg 7           r6
  79
  80    The compiler is going to form a call by coming here, through PSEUDO, with
  81    arguments
  82         syscall number  in the DO_CALL macro
  83         arg 1           r0
  84         arg 2           r1
  85         arg 3           r2
  86         arg 4           r3
  87         arg 5           [sp]
  88         arg 6           [sp+4]
  89         arg 7           [sp+8]
  90
  91    We need to shuffle values between R4..R6 and the stack so that the
  92    caller's v1..v3 and stack frame are not corrupted, and the kernel
  93    sees the right arguments.
  94
  95 */
  96
  97 #undef  DO_CALL
  98 #define DO_CALL(args, syscall_name)             \
  99     DOARGS_##args                               \
 100     swi SYS_ify (syscall_name);                 \
 101     UNDOARGS_##args
 102
 103 #define DOARGS_0 /* nothing */
 104 #define DOARGS_1 /* nothing */
 105 #define DOARGS_2 /* nothing */
 106 #define DOARGS_3 /* nothing */
 107 #define DOARGS_4 /* nothing */
 108 #define DOARGS_5 str r4, [sp, $-4]!; ldr r4, [sp, $4];
 109 #define DOARGS_6 mov ip, sp; stmfd sp!, {r4, r5}; ldmia ip, {r4, r5};
 110 #define DOARGS_7 mov ip, sp; stmfd sp!, {r4, r5, r6}; ldmia ip, {r4, r5, r6};
 111
 112 #define UNDOARGS_0 /* nothing */
 113 #define UNDOARGS_1 /* nothing */
 114 #define UNDOARGS_2 /* nothing */
 115 #define UNDOARGS_3 /* nothing */
 116 #define UNDOARGS_4 /* nothing */
 117 #define UNDOARGS_5 ldr r4, [sp], $4;
 118 #define UNDOARGS_6 ldmfd sp!, {r4, r5};
 119 #define UNDOARGS_7 ldmfd sp!, {r4, r5, r6};
 120
 121 #else /* not __ASSEMBLER__ */
 122
 123 /* Define a macro which expands into the inline wrapper code for a system
 124    call.  */
 125 #undef INLINE_SYSCALL
 126 #define INLINE_SYSCALL(name, nr, args...)                       \
 127   ({ unsigned int _sys_result;                                  \
 128      {                                                          \
 129        register int _a1 asm ("a1");                             \
 130        LOAD_ARGS_##nr (args)                                    \
 131        asm volatile ("swi       %1      @ syscall " #name       \
 132                      : "=r" (_a1)                               \
 133                      : "i" (SYS_ify(name)) ASM_ARGS_##nr        \
 134                      : "a1" : "memory");                        \
 135        _sys_result = _a1;                                       \
 136      }                                                          \
 137      if (_sys_result >= (unsigned int) -4095)                   \
 138        {                                                        \
 139          __set_errno (-_sys_result);                            \
 140          _sys_result = (unsigned int) -1;                       \
 141        }                                                        \
 142      (int) _sys_result; })
 143
 144 #define LOAD_ARGS_0()
 145 #define ASM_ARGS_0
 146 #define LOAD_ARGS_1(a1)                         \
 147   _a1 = (int) (a1);                             \
 148   LOAD_ARGS_0 ()
 149 #define ASM_ARGS_1      ASM_ARGS_0, "r" (_a1)
 150 #define LOAD_ARGS_2(a1, a2)                     \
 151   register int _a2 asm ("a2") = (int) (a2);     \
 152   LOAD_ARGS_1 (a1)
 153 #define ASM_ARGS_2      ASM_ARGS_1, "r" (_a2)
 154 #define LOAD_ARGS_3(a1, a2, a3)                 \
 155   register int _a3 asm ("a3") = (int) (a3);     \
 156   LOAD_ARGS_2 (a1, a2)
 157 #define ASM_ARGS_3      ASM_ARGS_2, "r" (_a3)
 158 #define LOAD_ARGS_4(a1, a2, a3, a4)             \
 159   register int _a4 asm ("a4") = (int) (a4);     \
 160   LOAD_ARGS_3 (a1, a2, a3)
 161 #define ASM_ARGS_4      ASM_ARGS_3, "r" (_a4)
 162 #define LOAD_ARGS_5(a1, a2, a3, a4, a5)         \
 163   register int _v1 asm ("v1") = (int) (a5);     \
 164   LOAD_ARGS_4 (a1, a2, a3, a4)
 165 #define ASM_ARGS_5      ASM_ARGS_4, "r" (_v1)
 166 #define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6)     \
 167   register int _v2 asm ("v2") = (int) (a6);     \
 168   LOAD_ARGS_5 (a1, a2, a3, a4, a5)
 169 #define ASM_ARGS_6      ASM_ARGS_5, "r" (_v2)
 170 #define LOAD_ARGS_7(a1, a2, a3, a4, a5, a6, a7) \
 171   register int _v3 asm ("v3") = (int) (a7);     \
 172   LOAD_ARGS_6 (a1, a2, a3, a4, a5, a6)
 173 #define ASM_ARGS_7      ASM_ARGS_6, "r" (_v3)
 174
 175 #endif  /* __ASSEMBLER__ */
 176
 177 #endif /* linux/arm/sysdep.h */