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

   1 /* Copyright (C) 2005, 2006, 2007, 2009
   2    Free Software Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    Contributed by Daniel Jacobowitz <dan@codesourcery.com>, Oct 2005.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library.  If not, see
  20    <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef _LINUX_ARM_EABI_SYSDEP_H
  23 #define _LINUX_ARM_EABI_SYSDEP_H 1
  24
  25 #include <arm/sysdep.h>
  26
  27 #include <tls.h>
  28
  29 #if __NR_SYSCALL_BASE != 0
  30 # error Kernel headers are too old
  31 #endif
  32
  33 /* Don't use stime, even if the kernel headers define it.  We have
  34    settimeofday, and some EABI kernels have removed stime.  Similarly
  35    use setitimer to implement alarm.  */
  36 #undef __NR_stime
  37 #undef __NR_alarm
  38
  39 /* The ARM EABI user interface passes the syscall number in r7, instead
  40    of in the swi.  This is more efficient, because the kernel does not need
  41    to fetch the swi from memory to find out the number; which can be painful
  42    with separate I-cache and D-cache.  Make sure to use 0 for the SWI
  43    argument; otherwise the (optional) compatibility code for APCS binaries
  44    may be invoked.  */
  45
  46 #if defined(__thumb__)
  47 /* We can not expose the use of r7 to the compiler.  GCC (as
  48    of 4.5) uses r7 as the hard frame pointer for Thumb - although
  49    for Thumb-2 it isn't obviously a better choice than r11.
  50    And GCC does not support asms that conflict with the frame
  51    pointer.
  52
  53    This would be easier if syscall numbers never exceeded 255,
  54    but they do.  For the moment the LOAD_ARGS_7 is sacrificed.
  55    We can't use push/pop inside the asm because that breaks
  56    unwinding (i.e. thread cancellation) for this frame.  We can't
  57    locally save and restore r7, because we do not know if this
  58    function uses r7 or if it is our caller's r7; if it is our caller's,
  59    then unwinding will fail higher up the stack.  So we move the
  60    syscall out of line and provide its own unwind information.  */
  61 #undef LOAD_ARGS_7
  62 #undef INTERNAL_SYSCALL_RAW
  63 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
  64   ({                                                            \
  65       register int _a1 asm ("a1");                              \
  66       int _nametmp = name;                                      \
  67       LOAD_ARGS_##nr (args)                                     \
  68       register int _name asm ("ip") = _nametmp;                 \
  69       asm volatile ("bl      __libc_do_syscall"                 \
  70                     : "=r" (_a1)                                \
  71                     : "r" (_name) ASM_ARGS_##nr                 \
  72                     : "memory", "lr");                          \
  73       _a1; })
  74 #else /* ARM */
  75 #undef INTERNAL_SYSCALL_RAW
  76 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
  77   ({                                                            \
  78        register int _a1 asm ("r0"), _nr asm ("r7");             \
  79        LOAD_ARGS_##nr (args)                                    \
  80        _nr = name;                                              \
  81        asm volatile ("swi       0x0     @ syscall " #name       \
  82                      : "=r" (_a1)                               \
  83                      : "r" (_nr) ASM_ARGS_##nr                  \
  84                      : "memory");                               \
  85        _a1; })
  86 #endif
  87
  88 /* For EABI, non-constant syscalls are actually pretty easy...  */
  89 #undef INTERNAL_SYSCALL_NCS
  90 #define INTERNAL_SYSCALL_NCS(number, err, nr, args...)          \
  91   INTERNAL_SYSCALL_RAW (number, err, nr, args)
  92
  93 /* We must save and restore r7 (call-saved) for the syscall number.
  94    We never make function calls from inside here (only potentially
  95    signal handlers), so we do not bother with doubleword alignment.
  96
  97    Just like the APCS syscall convention, the EABI syscall convention uses
  98    r0 through r6 for up to seven syscall arguments.  None are ever passed to
  99    the kernel on the stack, although incoming arguments are on the stack for
 100    syscalls with five or more arguments.
 101
 102    The assembler will convert the literal pool load to a move for most
 103    syscalls.  */
 104
 105 #undef  DO_CALL
 106 #define DO_CALL(syscall_name, args)             \
 107     DOARGS_##args;                              \
 108     ldr r7, =SYS_ify (syscall_name);            \
 109     swi 0x0;                                    \
 110     UNDOARGS_##args
 111
 112 #undef  DOARGS_0
 113 #define DOARGS_0 \
 114   .fnstart; \
 115   str r7, [sp, #-4]!; \
 116   cfi_adjust_cfa_offset (4); \
 117   cfi_rel_offset (r7, 0); \
 118   .save { r7 }
 119 #undef  DOARGS_1
 120 #define DOARGS_1 DOARGS_0
 121 #undef  DOARGS_2
 122 #define DOARGS_2 DOARGS_0
 123 #undef  DOARGS_3
 124 #define DOARGS_3 DOARGS_0
 125 #undef  DOARGS_4
 126 #define DOARGS_4 DOARGS_0
 127 #undef  DOARGS_5
 128 #define DOARGS_5 \
 129   .fnstart; \
 130   stmfd sp!, {r4, r7}; \
 131   cfi_adjust_cfa_offset (8); \
 132   cfi_rel_offset (r4, 0); \
 133   cfi_rel_offset (r7, 4); \
 134   .save { r4, r7 }; \
 135   ldr r4, [sp, #8]
 136 #undef  DOARGS_6
 137 #define DOARGS_6 \
 138   .fnstart; \
 139   mov ip, sp; \
 140   stmfd sp!, {r4, r5, r7}; \
 141   cfi_adjust_cfa_offset (12); \
 142   cfi_rel_offset (r4, 0); \
 143   cfi_rel_offset (r5, 4); \
 144   cfi_rel_offset (r7, 8); \
 145   .save { r4, r5, r7 }; \
 146   ldmia ip, {r4, r5}
 147 #undef  DOARGS_7
 148 #define DOARGS_7 \
 149   .fnstart; \
 150   mov ip, sp; \
 151   stmfd sp!, {r4, r5, r6, r7}; \
 152   cfi_adjust_cfa_offset (16); \
 153   cfi_rel_offset (r4, 0); \
 154   cfi_rel_offset (r5, 4); \
 155   cfi_rel_offset (r6, 8); \
 156   cfi_rel_offset (r7, 12); \
 157   .save { r4, r5, r6, r7 }; \
 158   ldmia ip, {r4, r5, r6}
 159
 160 #undef  UNDOARGS_0
 161 #define UNDOARGS_0 \
 162   ldr r7, [sp], #4; \
 163   cfi_adjust_cfa_offset (-4); \
 164   cfi_restore (r7); \
 165   .fnend
 166 #undef  UNDOARGS_1
 167 #define UNDOARGS_1 UNDOARGS_0
 168 #undef  UNDOARGS_2
 169 #define UNDOARGS_2 UNDOARGS_0
 170 #undef  UNDOARGS_3
 171 #define UNDOARGS_3 UNDOARGS_0
 172 #undef  UNDOARGS_4
 173 #define UNDOARGS_4 UNDOARGS_0
 174 #undef  UNDOARGS_5
 175 #define UNDOARGS_5 \
 176   ldmfd sp!, {r4, r7}; \
 177   cfi_adjust_cfa_offset (-8); \
 178   cfi_restore (r4); \
 179   cfi_restore (r7); \
 180   .fnend
 181 #undef  UNDOARGS_6
 182 #define UNDOARGS_6 \
 183   ldmfd sp!, {r4, r5, r7}; \
 184   cfi_adjust_cfa_offset (-12); \
 185   cfi_restore (r4); \
 186   cfi_restore (r5); \
 187   cfi_restore (r7); \
 188   .fnend
 189 #undef  UNDOARGS_7
 190 #define UNDOARGS_7 \
 191   ldmfd sp!, {r4, r5, r6, r7}; \
 192   cfi_adjust_cfa_offset (-16); \
 193   cfi_restore (r4); \
 194   cfi_restore (r5); \
 195   cfi_restore (r6); \
 196   cfi_restore (r7); \
 197   .fnend
 198
 199 #endif /* _LINUX_ARM_EABI_SYSDEP_H */