sysdeps/i386/sysdep.h

   1 /* Assembler macros for i386.
   2    Copyright (C) 1991-93,95,96,98,2002,2003,2005,2006,2011,2012
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <sysdeps/generic/sysdep.h>
  21
  22 #include <features.h> /* For __GNUC_PREREQ.  */
  23
  24 /* It is desirable that the names of PIC thunks match those used by
  25    GCC so that multiple copies are eliminated by the linker.  Because
  26    GCC 4.6 and earlier use __i686 in the names, it is necessary to
  27    override that predefined macro.  */
  28 #if defined __i686 && defined __ASSEMBLER__
  29 #undef __i686
  30 #define __i686 __i686
  31 #endif
  32
  33 #ifdef  __ASSEMBLER__
  34 # if __GNUC_PREREQ (4, 7)
  35 #  define GET_PC_THUNK(reg) __x86.get_pc_thunk.reg
  36 # else
  37 #  define GET_PC_THUNK(reg) __i686.get_pc_thunk.reg
  38 # endif
  39 #else
  40 # if __GNUC_PREREQ (4, 7)
  41 #  define GET_PC_THUNK_STR(reg) "__x86.get_pc_thunk." #reg
  42 # else
  43 #  define GET_PC_THUNK_STR(reg) "__i686.get_pc_thunk." #reg
  44 # endif
  45 #endif
  46
  47 #ifdef  __ASSEMBLER__
  48
  49 /* Syntactic details of assembler.  */
  50
  51 /* ELF uses byte-counts for .align, most others use log2 of count of bytes.  */
  52 #define ALIGNARG(log2) 1<<log2
  53 /* For ELF we need the `.type' directive to make shared libs work right.  */
  54 #define ASM_TYPE_DIRECTIVE(name,typearg) .type name,typearg;
  55 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
  56
  57
  58 /* Define an entry point visible from C.
  59
  60    There is currently a bug in gdb which prevents us from specifying
  61    incomplete stabs information.  Fake some entries here which specify
  62    the current source file.  */
  63 #define ENTRY(name)                                                           \
  64   STABS_CURRENT_FILE1("")                                                     \
  65   STABS_CURRENT_FILE(name)                                                    \
  66   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);                                   \
  67   ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function)                          \
  68   .align ALIGNARG(4);                                                         \
  69   STABS_FUN(name)                                                             \
  70   C_LABEL(name)                                                               \
  71   cfi_startproc;                                                              \
  72   CALL_MCOUNT
  73
  74 #undef  END
  75 #define END(name)                                                             \
  76   cfi_endproc;                                                                \
  77   ASM_SIZE_DIRECTIVE(name)                                                    \
  78   STABS_FUN_END(name)
  79
  80 #define ENTRY_CHK(name) ENTRY (name)
  81 #define END_CHK(name) END (name)
  82
  83 #ifdef HAVE_CPP_ASM_DEBUGINFO
  84 /* Disable that goop, because we just pass -g through to the assembler
  85    and it generates proper line number information directly.  */
  86 # define STABS_CURRENT_FILE1(name)
  87 # define STABS_CURRENT_FILE(name)
  88 # define STABS_FUN(name)
  89 # define STABS_FUN_END(name)
  90 #else
  91 /* Remove the following two lines once the gdb bug is fixed.  */
  92 #define STABS_CURRENT_FILE(name)                                              \
  93   STABS_CURRENT_FILE1 (#name)
  94 #define STABS_CURRENT_FILE1(name)                                             \
  95   1: .stabs name,100,0,0,1b;
  96 /* Emit stabs definition lines.  We use F(0,1) and define t(0,1) as `int',
  97    the same way gcc does it.  */
  98 #define STABS_FUN(name) STABS_FUN2(name, name##:F(0,1))
  99 #define STABS_FUN2(name, namestr)                                             \
 100   .stabs "int:t(0,1)=r(0,1);-2147483648;2147483647;",128,0,0,0;               \
 101   .stabs #namestr,36,0,0,name;
 102 #define STABS_FUN_END(name)                                                   \
 103   1: .stabs "",36,0,0,1b-name;
 104 #endif
 105
 106 /* If compiled for profiling, call `mcount' at the start of each function.  */
 107 #ifdef  PROF
 108 /* The mcount code relies on a normal frame pointer being on the stack
 109    to locate our caller, so push one just for its benefit.  */
 110 #define CALL_MCOUNT \
 111   pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \
 112   cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \
 113   popl %ebp; cfi_def_cfa (esp, 4);
 114 #else
 115 #define CALL_MCOUNT             /* Do nothing.  */
 116 #endif
 117
 118 /* Since C identifiers are not normally prefixed with an underscore
 119    on this system, the asm identifier `syscall_error' intrudes on the
 120    C name space.  Make sure we use an innocuous name.  */
 121 #define syscall_error   __syscall_error
 122 #define mcount          _mcount
 123
 124 #define PSEUDO(name, syscall_name, args)                                      \
 125   .globl syscall_error;                                                       \
 126 lose: SYSCALL_PIC_SETUP                                                       \
 127   jmp JUMPTARGET(syscall_error);                                              \
 128   ENTRY (name)                                                                \
 129   DO_CALL (syscall_name, args);                                               \
 130   jb lose
 131
 132 #undef  PSEUDO_END
 133 #define PSEUDO_END(name)                                                      \
 134   END (name)
 135
 136 # define SETUP_PIC_REG(reg) \
 137   .ifndef GET_PC_THUNK(reg);                                                  \
 138   .section .gnu.linkonce.t.GET_PC_THUNK(reg),"ax",@progbits;                  \
 139   .globl GET_PC_THUNK(reg);                                                   \
 140   .hidden GET_PC_THUNK(reg);                                                  \
 141   .p2align 4;                                                                 \
 142   .type GET_PC_THUNK(reg),@function;                                          \
 143 GET_PC_THUNK(reg):                                                            \
 144   movl (%esp), %e##reg;                                                       \
 145   ret;                                                                        \
 146   .size GET_PC_THUNK(reg), . - GET_PC_THUNK(reg);                             \
 147   .previous;                                                                  \
 148   .endif;                                                                     \
 149   call GET_PC_THUNK(reg)
 150
 151 # define LOAD_PIC_REG(reg) \
 152   SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg
 153
 154 #undef JUMPTARGET
 155 #ifdef PIC
 156 #define JUMPTARGET(name)        name##@PLT
 157 #define SYSCALL_PIC_SETUP \
 158     pushl %ebx;                                                               \
 159     cfi_adjust_cfa_offset (4);                                                \
 160     call 0f;                                                                  \
 161 0:  popl %ebx;                                                                \
 162     cfi_adjust_cfa_offset (-4);                                               \
 163     addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx;
 164
 165 #else
 166 #define JUMPTARGET(name)        name
 167 #define SYSCALL_PIC_SETUP       /* Nothing.  */
 168 #endif
 169
 170 /* Local label name for asm code. */
 171 #ifndef L
 172 #define L(name)         .L##name
 173 #endif
 174
 175 #define atom_text_section .section ".text.atom", "ax"
 176
 177 #else /* __ASSEMBLER__ */
 178
 179 # define SETUP_PIC_REG_STR(reg)                                         \
 180   ".ifndef " GET_PC_THUNK_STR (reg) "\n"                                \
 181   ".section .gnu.linkonce.t." GET_PC_THUNK_STR (reg) ",\"ax\",@progbits\n" \
 182   ".globl " GET_PC_THUNK_STR (reg) "\n"                                 \
 183   ".hidden " GET_PC_THUNK_STR (reg) "\n"                                \
 184   ".p2align 4\n"                                                        \
 185   ".type " GET_PC_THUNK_STR (reg) ",@function\n"                        \
 186 GET_PC_THUNK_STR (reg) ":"                                              \
 187   "movl (%%esp), %%e" #reg "\n"                                         \
 188   "ret\n"                                                               \
 189   ".size " GET_PC_THUNK_STR (reg) ", . - " GET_PC_THUNK_STR (reg) "\n"  \
 190   ".previous\n"                                                         \
 191   ".endif\n"                                                            \
 192   "call " GET_PC_THUNK_STR (reg)
 193
 194 # define LOAD_PIC_REG_STR(reg) \
 195   SETUP_PIC_REG_STR (reg) "\naddl $_GLOBAL_OFFSET_TABLE_, %%e" #reg
 196
 197 #endif  /* __ASSEMBLER__ */