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/x86/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 /* If compiled for profiling, call `mcount' at the start of each function.  */
  43 #ifdef  PROF
  44 /* The mcount code relies on a normal frame pointer being on the stack
  45    to locate our caller, so push one just for its benefit.  */
  46 #define CALL_MCOUNT \
  47   pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \
  48   cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \
  49   popl %ebp; cfi_def_cfa (esp, 4);
  50 #else
  51 #define CALL_MCOUNT             /* Do nothing.  */
  52 #endif
  53
  54 #define PSEUDO(name, syscall_name, args)                                      \
  55   .globl syscall_error;                                                       \
  56 lose: SYSCALL_PIC_SETUP                                                       \
  57   jmp JUMPTARGET(syscall_error);                                              \
  58   ENTRY (name)                                                                \
  59   DO_CALL (syscall_name, args);                                               \
  60   jb lose
  61
  62 # define SETUP_PIC_REG(reg) \
  63   .ifndef GET_PC_THUNK(reg);                                                  \
  64   .section .gnu.linkonce.t.GET_PC_THUNK(reg),"ax",@progbits;                  \
  65   .globl GET_PC_THUNK(reg);                                                   \
  66   .hidden GET_PC_THUNK(reg);                                                  \
  67   .p2align 4;                                                                 \
  68   .type GET_PC_THUNK(reg),@function;                                          \
  69 GET_PC_THUNK(reg):                                                            \
  70   movl (%esp), %e##reg;                                                       \
  71   ret;                                                                        \
  72   .size GET_PC_THUNK(reg), . - GET_PC_THUNK(reg);                             \
  73   .previous;                                                                  \
  74   .endif;                                                                     \
  75   call GET_PC_THUNK(reg)
  76
  77 # define LOAD_PIC_REG(reg) \
  78   SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg
  79
  80 #undef JUMPTARGET
  81 #ifdef PIC
  82 #define JUMPTARGET(name)        name##@PLT
  83 #define SYSCALL_PIC_SETUP \
  84     pushl %ebx;                                                               \
  85     cfi_adjust_cfa_offset (4);                                                \
  86     call 0f;                                                                  \
  87 0:  popl %ebx;                                                                \
  88     cfi_adjust_cfa_offset (-4);                                               \
  89     addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx;
  90
  91 #else
  92 #define JUMPTARGET(name)        name
  93 #define SYSCALL_PIC_SETUP       /* Nothing.  */
  94 #endif
  95
  96 #else /* __ASSEMBLER__ */
  97
  98 # define SETUP_PIC_REG_STR(reg)                                         \
  99   ".ifndef " GET_PC_THUNK_STR (reg) "\n"                                \
 100   ".section .gnu.linkonce.t." GET_PC_THUNK_STR (reg) ",\"ax\",@progbits\n" \
 101   ".globl " GET_PC_THUNK_STR (reg) "\n"                                 \
 102   ".hidden " GET_PC_THUNK_STR (reg) "\n"                                \
 103   ".p2align 4\n"                                                        \
 104   ".type " GET_PC_THUNK_STR (reg) ",@function\n"                        \
 105 GET_PC_THUNK_STR (reg) ":"                                              \
 106   "movl (%%esp), %%e" #reg "\n"                                         \
 107   "ret\n"                                                               \
 108   ".size " GET_PC_THUNK_STR (reg) ", . - " GET_PC_THUNK_STR (reg) "\n"  \
 109   ".previous\n"                                                         \
 110   ".endif\n"                                                            \
 111   "call " GET_PC_THUNK_STR (reg)
 112
 113 # define LOAD_PIC_REG_STR(reg) \
 114   SETUP_PIC_REG_STR (reg) "\naddl $_GLOBAL_OFFSET_TABLE_, %%e" #reg
 115
 116 #endif  /* __ASSEMBLER__ */