sysdeps/i386/sysdep.h

   1 /* Assembler macros for i386.
   2    Copyright (C) 1991-2015 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 <sysdeps/generic/sysdep.h>
  20
  21 #include <features.h> /* For __GNUC_PREREQ.  */
  22
  23 /* It is desirable that the names of PIC thunks match those used by
  24    GCC so that multiple copies are eliminated by the linker.  Because
  25    GCC 4.6 and earlier use __i686 in the names, it is necessary to
  26    override that predefined macro.  */
  27 #if defined __i686 && defined __ASSEMBLER__
  28 #undef __i686
  29 #define __i686 __i686
  30 #endif
  31
  32 #ifdef  __ASSEMBLER__
  33 # if __GNUC_PREREQ (4, 7)
  34 #  define GET_PC_THUNK(reg) __x86.get_pc_thunk.reg
  35 # else
  36 #  define GET_PC_THUNK(reg) __i686.get_pc_thunk.reg
  37 # endif
  38 #else
  39 # if __GNUC_PREREQ (4, 7)
  40 #  define GET_PC_THUNK_STR(reg) "__x86.get_pc_thunk." #reg
  41 # else
  42 #  define GET_PC_THUNK_STR(reg) "__i686.get_pc_thunk." #reg
  43 # endif
  44 #endif
  45
  46 #ifdef  __ASSEMBLER__
  47
  48 /* Syntactic details of assembler.  */
  49
  50 /* ELF uses byte-counts for .align, most others use log2 of count of bytes.  */
  51 #define ALIGNARG(log2) 1<<log2
  52 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
  53
  54
  55 /* Define an entry point visible from C.
  56
  57    There is currently a bug in gdb which prevents us from specifying
  58    incomplete stabs information.  Fake some entries here which specify
  59    the current source file.  */
  60 #define ENTRY(name)                                                           \
  61   .globl C_SYMBOL_NAME(name);                                                 \
  62   .type C_SYMBOL_NAME(name),@function;                                        \
  63   .align ALIGNARG(4);                                                         \
  64   C_LABEL(name)                                                               \
  65   cfi_startproc;                                                              \
  66   CALL_MCOUNT
  67
  68 #undef  END
  69 #define END(name)                                                             \
  70   cfi_endproc;                                                                \
  71   ASM_SIZE_DIRECTIVE(name)
  72
  73 #define ENTRY_CHK(name) ENTRY (name)
  74 #define END_CHK(name) END (name)
  75
  76 /* If compiled for profiling, call `mcount' at the start of each function.  */
  77 #ifdef  PROF
  78 /* The mcount code relies on a normal frame pointer being on the stack
  79    to locate our caller, so push one just for its benefit.  */
  80 #define CALL_MCOUNT \
  81   pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \
  82   cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \
  83   popl %ebp; cfi_def_cfa (esp, 4);
  84 #else
  85 #define CALL_MCOUNT             /* Do nothing.  */
  86 #endif
  87
  88 /* Since C identifiers are not normally prefixed with an underscore
  89    on this system, the asm identifier `syscall_error' intrudes on the
  90    C name space.  Make sure we use an innocuous name.  */
  91 #define syscall_error   __syscall_error
  92 #define mcount          _mcount
  93
  94 #define PSEUDO(name, syscall_name, args)                                      \
  95   .globl syscall_error;                                                       \
  96 lose: SYSCALL_PIC_SETUP                                                       \
  97   jmp JUMPTARGET(syscall_error);                                              \
  98   ENTRY (name)                                                                \
  99   DO_CALL (syscall_name, args);                                               \
 100   jb lose
 101
 102 #undef  PSEUDO_END
 103 #define PSEUDO_END(name)                                                      \
 104   END (name)
 105
 106 # define SETUP_PIC_REG(reg) \
 107   .ifndef GET_PC_THUNK(reg);                                                  \
 108   .section .gnu.linkonce.t.GET_PC_THUNK(reg),"ax",@progbits;                  \
 109   .globl GET_PC_THUNK(reg);                                                   \
 110   .hidden GET_PC_THUNK(reg);                                                  \
 111   .p2align 4;                                                                 \
 112   .type GET_PC_THUNK(reg),@function;                                          \
 113 GET_PC_THUNK(reg):                                                            \
 114   movl (%esp), %e##reg;                                                       \
 115   ret;                                                                        \
 116   .size GET_PC_THUNK(reg), . - GET_PC_THUNK(reg);                             \
 117   .previous;                                                                  \
 118   .endif;                                                                     \
 119   call GET_PC_THUNK(reg)
 120
 121 # define LOAD_PIC_REG(reg) \
 122   SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg
 123
 124 #undef JUMPTARGET
 125 #ifdef PIC
 126 #define JUMPTARGET(name)        name##@PLT
 127 #define SYSCALL_PIC_SETUP \
 128     pushl %ebx;                                                               \
 129     cfi_adjust_cfa_offset (4);                                                \
 130     call 0f;                                                                  \
 131 0:  popl %ebx;                                                                \
 132     cfi_adjust_cfa_offset (-4);                                               \
 133     addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx;
 134
 135 #else
 136 #define JUMPTARGET(name)        name
 137 #define SYSCALL_PIC_SETUP       /* Nothing.  */
 138 #endif
 139
 140 /* Local label name for asm code. */
 141 #ifndef L
 142 #define L(name)         .L##name
 143 #endif
 144
 145 #define atom_text_section .section ".text.atom", "ax"
 146
 147 #else /* __ASSEMBLER__ */
 148
 149 # define SETUP_PIC_REG_STR(reg)                                         \
 150   ".ifndef " GET_PC_THUNK_STR (reg) "\n"                                \
 151   ".section .gnu.linkonce.t." GET_PC_THUNK_STR (reg) ",\"ax\",@progbits\n" \
 152   ".globl " GET_PC_THUNK_STR (reg) "\n"                                 \
 153   ".hidden " GET_PC_THUNK_STR (reg) "\n"                                \
 154   ".p2align 4\n"                                                        \
 155   ".type " GET_PC_THUNK_STR (reg) ",@function\n"                        \
 156 GET_PC_THUNK_STR (reg) ":"                                              \
 157   "movl (%%esp), %%e" #reg "\n"                                         \
 158   "ret\n"                                                               \
 159   ".size " GET_PC_THUNK_STR (reg) ", . - " GET_PC_THUNK_STR (reg) "\n"  \
 160   ".previous\n"                                                         \
 161   ".endif\n"                                                            \
 162   "call " GET_PC_THUNK_STR (reg)
 163
 164 # define LOAD_PIC_REG_STR(reg) \
 165   SETUP_PIC_REG_STR (reg) "\naddl $_GLOBAL_OFFSET_TABLE_, %%e" #reg
 166
 167 #endif  /* __ASSEMBLER__ */