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, write to the Free
  20    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21    02111-1307 USA.  */
  22
  23 #ifndef _LINUX_ARM_EABI_SYSDEP_H
  24 #define _LINUX_ARM_EABI_SYSDEP_H 1
  25
  26 #include <arm/sysdep.h>
  27
  28 #include <tls.h>
  29
  30 #if __NR_SYSCALL_BASE != 0
  31 # error Kernel headers are too old
  32 #endif
  33
  34 /* Don't use stime, even if the kernel headers define it.  We have
  35    settimeofday, and some EABI kernels have removed stime.  Similarly
  36    use setitimer to implement alarm.  */
  37 #undef __NR_stime
  38 #undef __NR_alarm
  39
  40 /* The ARM EABI user interface passes the syscall number in r7, instead
  41    of in the swi.  This is more efficient, because the kernel does not need
  42    to fetch the swi from memory to find out the number; which can be painful
  43    with separate I-cache and D-cache.  Make sure to use 0 for the SWI
  44    argument; otherwise the (optional) compatibility code for APCS binaries
  45    may be invoked.  */
  46
  47 #ifdef __thumb__
  48 /* Hide the use of r7 from the compiler, this would be a lot
  49    easier but for the fact that the syscalls can exceed 255.
  50    For the moment the LOAD_ARGS_7 is sacrificed.
  51    We can't use push/pop inside the asm because that breaks
  52    unwinding (ie. thread cancellation).  */
  53 /* FIXME: the str / ldr of r7 are not covered by CFI information.  */
  54 #undef LOAD_ARGS_7
  55 #undef INTERNAL_SYSCALL_RAW
  56 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
  57   ({                                                            \
  58       int _sys_buf[2];                                          \
  59       register int _a1 asm ("a1");                              \
  60       register int *_r6 asm ("r6") = _sys_buf;                  \
  61       *_r6 = name;                                              \
  62       LOAD_ARGS_##nr (args)                                     \
  63       asm volatile ("str        r7, [r6, #4]\n\t"               \
  64                     "ldr      r7, [r6]\n\t"                     \
  65                     "swi      0       @ syscall " #name "\n\t"  \
  66                     "ldr      r7, [r6, #4]"                     \
  67                    : "=r" (_a1)                                 \
  68                     : "r" (_r6) ASM_ARGS_##nr                   \
  69                     : "memory");                                \
  70        _a1; })
  71 #else /* ARM */
  72 #undef INTERNAL_SYSCALL_RAW
  73 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)            \
  74   ({                                                            \
  75        register int _a1 asm ("r0"), _nr asm ("r7");             \
  76        LOAD_ARGS_##nr (args)                                    \
  77        _nr = name;                                              \
  78        asm volatile ("swi       0x0     @ syscall " #name       \
  79                      : "=r" (_a1)                               \
  80                      : "r" (_nr) ASM_ARGS_##nr                  \
  81                      : "memory");                               \
  82        _a1; })
  83 #endif
  84
  85 /* For EABI, non-constant syscalls are actually pretty easy...  */
  86 #undef INTERNAL_SYSCALL_NCS
  87 #define INTERNAL_SYSCALL_NCS(number, err, nr, args...)          \
  88   INTERNAL_SYSCALL_RAW (number, err, nr, args)
  89
  90 /* We must save and restore r7 (call-saved) for the syscall number.
  91    We never make function calls from inside here (only potentially
  92    signal handlers), so we do not bother with doubleword alignment.
  93
  94    Just like the APCS syscall convention, the EABI syscall convention uses
  95    r0 through r6 for up to seven syscall arguments.  None are ever passed to
  96    the kernel on the stack, although incoming arguments are on the stack for
  97    syscalls with five or more arguments.
  98
  99    The assembler will convert the literal pool load to a move for most
 100    syscalls.  */
 101
 102 #undef  DO_CALL
 103 #define DO_CALL(syscall_name, args)             \
 104     DOARGS_##args;                              \
 105     mov ip, r7;                                 \
 106     cfi_register (r7, ip);                      \
 107     ldr r7, =SYS_ify (syscall_name);            \
 108     swi 0x0;                                    \
 109     mov r7, ip;                                 \
 110     cfi_restore (r7);                           \
 111     UNDOARGS_##args
 112
 113 #endif /* _LINUX_ARM_EABI_SYSDEP_H */