1/* Assembler macros for i386.
2 Copyright (C) 1991-2022 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; \
54lose: 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; \
67GET_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; \
850: 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" \
104GET_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__ */
116

source code of glibc/sysdeps/i386/sysdep.h