libc/sysdeps/linux/xtensa/sysdep.h

   1 /* Assembler macros for Xtensa processors.
   2    Copyright (C) 2001, 2007 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 #include <sys/syscall.h>
  20
  21 #ifdef __ASSEMBLER__
  22
  23 #define ALIGNARG(log2) 1 << log2
  24 #define ASM_TYPE_DIRECTIVE(name, typearg) .type name, typearg
  25 #define ASM_SIZE_DIRECTIVE(name) .size name, . - name
  26
  27 #ifdef __STDC__
  28 #define C_LABEL(name)   name :
  29 #else
  30 #define C_LABEL(name)   name/**/:
  31 #endif
  32
  33 #define ENTRY(name)                                                     \
  34   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);                             \
  35   ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name), @function);                  \
  36   .align ALIGNARG(2);                                                   \
  37   LITERAL_POSITION;                                                     \
  38   C_LABEL(name)                                                         \
  39   entry sp, FRAMESIZE;                                                  \
  40   CALL_MCOUNT
  41
  42 #define HIDDEN_ENTRY(name)                                              \
  43   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);                             \
  44   .hidden C_SYMBOL_NAME(name);                                          \
  45   ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name), @function);                  \
  46   .align ALIGNARG(2);                                                   \
  47   LITERAL_POSITION;                                                     \
  48   C_LABEL(name)                                                         \
  49   entry sp, FRAMESIZE;                                                  \
  50   CALL_MCOUNT
  51
  52 #undef END
  53 #define END(name) ASM_SIZE_DIRECTIVE(name)
  54
  55 /* Define a macro for this directive so it can be removed in a few places.  */
  56 #define LITERAL_POSITION .literal_position
  57
  58 #undef JUMPTARGET
  59 #ifdef __PIC__
  60 /* The "@PLT" suffix is currently a no-op for non-shared linking, but
  61    it doesn't hurt to use it conditionally for PIC code in case that
  62    changes someday.  */
  63 #define JUMPTARGET(name) name##@PLT
  64 #else
  65 #define JUMPTARGET(name) name
  66 #endif
  67
  68 #define FRAMESIZE 16
  69 #define CALL_MCOUNT             /* Do nothing.  */
  70
  71
  72 /* Linux uses a negative return value to indicate syscall errors,
  73    unlike most Unices, which use the condition codes' carry flag.
  74
  75    Since version 2.1 the return value of a system call might be
  76    negative even if the call succeeded.  E.g., the `lseek' system call
  77    might return a large offset.  Therefore we must not anymore test
  78    for < 0, but test for a real error by making sure the value in a2
  79    is a real error number.  Linus said he will make sure the no syscall
  80    returns a value in -1 .. -4095 as a valid result so we can safely
  81    test with -4095.  */
  82
  83 /* We don't want the label for the error handler to be global when we define
  84    it here.  */
  85 #define SYSCALL_ERROR_LABEL 0f
  86
  87 #undef  PSEUDO
  88 #define PSEUDO(name, syscall_name, args)                                      \
  89   .text;                                                                      \
  90   ENTRY (name)                                                                \
  91         DO_CALL (syscall_name, args);                                         \
  92         movi    a4, -4095;                                                    \
  93         bgeu    a2, a4, SYSCALL_ERROR_LABEL;                                  \
  94   .Lpseudo_end:
  95
  96 #undef  PSEUDO_END
  97 #define PSEUDO_END(name)                                                      \
  98   SYSCALL_ERROR_HANDLER                                                       \
  99   END (name)
 100
 101 #undef  PSEUDO_NOERRNO
 102 #define PSEUDO_NOERRNO(name, syscall_name, args)                              \
 103   .text;                                                                      \
 104   ENTRY (name)                                                                \
 105         DO_CALL (syscall_name, args)
 106
 107 #undef  PSEUDO_END_NOERRNO
 108 #define PSEUDO_END_NOERRNO(name)                                              \
 109   END (name)
 110
 111 #undef  ret_NOERRNO
 112 #define ret_NOERRNO retw
 113
 114 /* The function has to return the error code.  */
 115 #undef  PSEUDO_ERRVAL
 116 #define PSEUDO_ERRVAL(name, syscall_name, args)                               \
 117   .text;                                                                      \
 118   ENTRY (name)                                                                \
 119         DO_CALL (syscall_name, args);                                         \
 120         neg     a2, a2
 121
 122 #undef  PSEUDO_END_ERRVAL
 123 #define PSEUDO_END_ERRVAL(name)                                               \
 124   END (name)
 125
 126 #define ret_ERRVAL retw
 127
 128 #if defined RTLD_PRIVATE_ERRNO
 129 # define SYSCALL_ERROR_HANDLER                                                \
 130 0:      movi    a4, rtld_errno;                                               \
 131         neg     a2, a2;                                                       \
 132         s32i    a2, a4, 0;                                                    \
 133         movi    a2, -1;                                                       \
 134         j       .Lpseudo_end;
 135
 136 #elif defined _LIBC_REENTRANT
 137
 138 # if defined USE___THREAD
 139 #  ifndef NOT_IN_libc
 140 #   define SYSCALL_ERROR_ERRNO __libc_errno
 141 #  else
 142 #   define SYSCALL_ERROR_ERRNO errno
 143 #  endif
 144 #  define SYSCALL_ERROR_HANDLER                                               \
 145 0:      rur     a4, THREADPTR;                                                \
 146         movi    a3, SYSCALL_ERROR_ERRNO@TPOFF;                                \
 147         neg     a2, a2;                                                       \
 148         add     a4, a4, a3;                                                   \
 149         s32i    a2, a4, 0;                                                    \
 150         movi    a2, -1;                                                       \
 151         j       .Lpseudo_end;
 152 # else /* !USE___THREAD */
 153 #  define SYSCALL_ERROR_HANDLER                                               \
 154 0:      neg     a2, a2;                                                       \
 155         mov     a6, a2;                                                       \
 156         movi    a4, __errno_location@PLT;                                     \
 157         callx4  a4;                                                           \
 158         s32i    a2, a6, 0;                                                    \
 159         movi    a2, -1;                                                       \
 160         j       .Lpseudo_end;
 161 # endif /* !USE___THREAD */
 162 #else /* !_LIBC_REENTRANT */
 163 #define SYSCALL_ERROR_HANDLER                                                 \
 164 0:      movi    a4, errno;                                                    \
 165         neg     a2, a2;                                                       \
 166         s32i    a2, a4, 0;                                                    \
 167         movi    a2, -1;                                                       \
 168         j       .Lpseudo_end;
 169 #endif /* _LIBC_REENTRANT */
 170
 171 #endif  /* __ASSEMBLER__ */