1  /* Assembler macros for i386.
       2     Copyright (C) 1991-2023 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     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <sysdeps/x86/sysdep.h>
      20  
      21  /* It is desirable that the names of PIC thunks match those used by
      22     GCC so that multiple copies are eliminated by the linker.  Because
      23     GCC 4.6 and earlier use __i686 in the names, it is necessary to
      24     override that predefined macro.  */
      25  #if defined __i686 && defined __ASSEMBLER__
      26  #undef __i686
      27  #define __i686 __i686
      28  #endif
      29  
      30  #ifdef	__ASSEMBLER__
      31  # define GET_PC_THUNK(reg) __x86.get_pc_thunk.reg
      32  #else
      33  # define GET_PC_THUNK_STR(reg) "__x86.get_pc_thunk." #reg
      34  #endif
      35  
      36  #ifdef	__ASSEMBLER__
      37  
      38  /* Syntactic details of assembler.  */
      39  
      40  /* If compiled for profiling, call `mcount' at the start of each function.  */
      41  #ifdef	PROF
      42  /* The mcount code relies on a normal frame pointer being on the stack
      43     to locate our caller, so push one just for its benefit.  */
      44  #define CALL_MCOUNT \
      45    pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \
      46    cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \
      47    popl %ebp; cfi_def_cfa (esp, 4);
      48  #else
      49  #define CALL_MCOUNT		/* Do nothing.  */
      50  #endif
      51  
      52  #define	PSEUDO(name, syscall_name, args)				      \
      53    .globl syscall_error;							      \
      54  lose: SYSCALL_PIC_SETUP							      \
      55    jmp JUMPTARGET(syscall_error);					      \
      56    ENTRY (name)								      \
      57    DO_CALL (syscall_name, args);						      \
      58    jb lose
      59  
      60  # define SETUP_PIC_REG(reg) \
      61    .ifndef GET_PC_THUNK(reg);						      \
      62    .section .text.GET_PC_THUNK(reg),"axG",@progbits,GET_PC_THUNK(reg),comdat;  \
      63    .globl GET_PC_THUNK(reg);						      \
      64    .hidden GET_PC_THUNK(reg);						      \
      65    .p2align 4;								      \
      66    .type GET_PC_THUNK(reg),@function;					      \
      67  GET_PC_THUNK(reg):							      \
      68    movl (%esp), %e##reg;							      \
      69    ret;									      \
      70    .size GET_PC_THUNK(reg), . - GET_PC_THUNK(reg);			      \
      71    .previous;								      \
      72    .endif;								      \
      73    call GET_PC_THUNK(reg)
      74  
      75  # define LOAD_PIC_REG(reg) \
      76    SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg
      77  
      78  #undef JUMPTARGET
      79  #ifdef PIC
      80  #define JUMPTARGET(name)	name##@PLT
      81  #define SYSCALL_PIC_SETUP \
      82      pushl %ebx;								      \
      83      cfi_adjust_cfa_offset (4);						      \
      84      call 0f;								      \
      85  0:  popl %ebx;								      \
      86      cfi_adjust_cfa_offset (-4);						      \
      87      addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx;
      88  
      89  #else
      90  #define JUMPTARGET(name)	name
      91  #define SYSCALL_PIC_SETUP	/* Nothing.  */
      92  #endif
      93  
      94  #else /* __ASSEMBLER__ */
      95  
      96  # define SETUP_PIC_REG_STR(reg)						\
      97    ".ifndef " GET_PC_THUNK_STR (reg) "\n"				\
      98    ".section .text." GET_PC_THUNK_STR (reg) ",\"axG\",@progbits,"	\
      99      GET_PC_THUNK_STR (reg) ",comdat\n"					\
     100    ".globl " GET_PC_THUNK_STR (reg) "\n"					\
     101    ".hidden " GET_PC_THUNK_STR (reg) "\n"				\
     102    ".p2align 4\n"							\
     103    ".type " GET_PC_THUNK_STR (reg) ",@function\n"			\
     104  GET_PC_THUNK_STR (reg) ":"						\
     105    "movl (%%esp), %%e" #reg "\n"						\
     106    "ret\n"								\
     107    ".size " GET_PC_THUNK_STR (reg) ", . - " GET_PC_THUNK_STR (reg) "\n"	\
     108    ".previous\n"								\
     109    ".endif\n"								\
     110    "call " GET_PC_THUNK_STR (reg)
     111  
     112  # define LOAD_PIC_REG_STR(reg) \
     113    SETUP_PIC_REG_STR (reg) "\naddl $_GLOBAL_OFFSET_TABLE_, %%e" #reg
     114  
     115  #endif	/* __ASSEMBLER__ */