sysdeps/i386/sysdep.h

   1 /* Assembler macros for i386.
   2    Copyright (C) 1991-2017 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 # define GET_PC_THUNK(reg) __x86.get_pc_thunk.reg
  34 #else
  35 # define GET_PC_THUNK_STR(reg) "__x86.get_pc_thunk." #reg
  36 #endif
  37
  38 #ifdef  __ASSEMBLER__
  39
  40 /* Syntactic details of assembler.  */
  41
  42 /* ELF uses byte-counts for .align, most others use log2 of count of bytes.  */
  43 #define ALIGNARG(log2) 1<<log2
  44 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
  45
  46
  47 /* Define an entry point visible from C.
  48
  49    There is currently a bug in gdb which prevents us from specifying
  50    incomplete stabs information.  Fake some entries here which specify
  51    the current source file.  */
  52 #define ENTRY(name)                                                           \
  53   .globl C_SYMBOL_NAME(name);                                                 \
  54   .type C_SYMBOL_NAME(name),@function;                                        \
  55   .align ALIGNARG(4);                                                         \
  56   C_LABEL(name)                                                               \
  57   cfi_startproc;                                                              \
  58   CALL_MCOUNT
  59
  60 #undef  END
  61 #define END(name)                                                             \
  62   cfi_endproc;                                                                \
  63   ASM_SIZE_DIRECTIVE(name)
  64
  65 #define ENTRY_CHK(name) ENTRY (name)
  66 #define END_CHK(name) END (name)
  67
  68 /* If compiled for profiling, call `mcount' at the start of each function.  */
  69 #ifdef  PROF
  70 /* The mcount code relies on a normal frame pointer being on the stack
  71    to locate our caller, so push one just for its benefit.  */
  72 #define CALL_MCOUNT \
  73   pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \
  74   cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \
  75   popl %ebp; cfi_def_cfa (esp, 4);
  76 #else
  77 #define CALL_MCOUNT             /* Do nothing.  */
  78 #endif
  79
  80 /* Since C identifiers are not normally prefixed with an underscore
  81    on this system, the asm identifier `syscall_error' intrudes on the
  82    C name space.  Make sure we use an innocuous name.  */
  83 #define syscall_error   __syscall_error
  84 #define mcount          _mcount
  85
  86 #define PSEUDO(name, syscall_name, args)                                      \
  87   .globl syscall_error;                                                       \
  88 lose: SYSCALL_PIC_SETUP                                                       \
  89   jmp JUMPTARGET(syscall_error);                                              \
  90   ENTRY (name)                                                                \
  91   DO_CALL (syscall_name, args);                                               \
  92   jb lose
  93
  94 #undef  PSEUDO_END
  95 #define PSEUDO_END(name)                                                      \
  96   END (name)
  97
  98 # define SETUP_PIC_REG(reg) \
  99   .ifndef GET_PC_THUNK(reg);                                                  \
 100   .section .gnu.linkonce.t.GET_PC_THUNK(reg),"ax",@progbits;                  \
 101   .globl GET_PC_THUNK(reg);                                                   \
 102   .hidden GET_PC_THUNK(reg);                                                  \
 103   .p2align 4;                                                                 \
 104   .type GET_PC_THUNK(reg),@function;                                          \
 105 GET_PC_THUNK(reg):                                                            \
 106   movl (%esp), %e##reg;                                                       \
 107   ret;                                                                        \
 108   .size GET_PC_THUNK(reg), . - GET_PC_THUNK(reg);                             \
 109   .previous;                                                                  \
 110   .endif;                                                                     \
 111   call GET_PC_THUNK(reg)
 112
 113 # define LOAD_PIC_REG(reg) \
 114   SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg
 115
 116 #undef JUMPTARGET
 117 #ifdef PIC
 118 #define JUMPTARGET(name)        name##@PLT
 119 #define SYSCALL_PIC_SETUP \
 120     pushl %ebx;                                                               \
 121     cfi_adjust_cfa_offset (4);                                                \
 122     call 0f;                                                                  \
 123 0:  popl %ebx;                                                                \
 124     cfi_adjust_cfa_offset (-4);                                               \
 125     addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx;
 126
 127 #else
 128 #define JUMPTARGET(name)        name
 129 #define SYSCALL_PIC_SETUP       /* Nothing.  */
 130 #endif
 131
 132 /* Local label name for asm code. */
 133 #ifndef L
 134 #define L(name)         .L##name
 135 #endif
 136
 137 #define atom_text_section .section ".text.atom", "ax"
 138
 139 #else /* __ASSEMBLER__ */
 140
 141 # define SETUP_PIC_REG_STR(reg)                                         \
 142   ".ifndef " GET_PC_THUNK_STR (reg) "\n"                                \
 143   ".section .gnu.linkonce.t." GET_PC_THUNK_STR (reg) ",\"ax\",@progbits\n" \
 144   ".globl " GET_PC_THUNK_STR (reg) "\n"                                 \
 145   ".hidden " GET_PC_THUNK_STR (reg) "\n"                                \
 146   ".p2align 4\n"                                                        \
 147   ".type " GET_PC_THUNK_STR (reg) ",@function\n"                        \
 148 GET_PC_THUNK_STR (reg) ":"                                              \
 149   "movl (%%esp), %%e" #reg "\n"                                         \
 150   "ret\n"                                                               \
 151   ".size " GET_PC_THUNK_STR (reg) ", . - " GET_PC_THUNK_STR (reg) "\n"  \
 152   ".previous\n"                                                         \
 153   ".endif\n"                                                            \
 154   "call " GET_PC_THUNK_STR (reg)
 155
 156 # define LOAD_PIC_REG_STR(reg) \
 157   SETUP_PIC_REG_STR (reg) "\naddl $_GLOBAL_OFFSET_TABLE_, %%e" #reg
 158
 159 #endif  /* __ASSEMBLER__ */