1/* Assembler macros for i386.
2 Copyright (C) 1991-2024 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#define CET_ENABLED 0
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/* Define an entry point visible from C. */
43#define ENTRY_P2ALIGN(name, alignment) \
44 .globl C_SYMBOL_NAME(name); \
45 .type C_SYMBOL_NAME(name),@function; \
46 .align ALIGNARG(alignment); \
47 C_LABEL(name) \
48 cfi_startproc; \
49 CALL_MCOUNT
50
51/* If compiled for profiling, call `mcount' at the start of each function. */
52#ifdef PROF
53/* The mcount code relies on a normal frame pointer being on the stack
54 to locate our caller, so push one just for its benefit. */
55#define CALL_MCOUNT \
56 pushl %ebp; cfi_adjust_cfa_offset (4); movl %esp, %ebp; \
57 cfi_def_cfa_register (ebp); call JUMPTARGET(mcount); \
58 popl %ebp; cfi_def_cfa (esp, 4);
59#else
60#define CALL_MCOUNT /* Do nothing. */
61#endif
62
63#define PSEUDO(name, syscall_name, args) \
64 .globl syscall_error; \
65lose: SYSCALL_PIC_SETUP \
66 jmp JUMPTARGET(syscall_error); \
67 ENTRY (name) \
68 DO_CALL (syscall_name, args); \
69 jb lose
70
71# define SETUP_PIC_REG(reg) \
72 .ifndef GET_PC_THUNK(reg); \
73 .section .text.GET_PC_THUNK(reg),"axG",@progbits,GET_PC_THUNK(reg),comdat; \
74 .globl GET_PC_THUNK(reg); \
75 .hidden GET_PC_THUNK(reg); \
76 .p2align 4; \
77 .type GET_PC_THUNK(reg),@function; \
78GET_PC_THUNK(reg): \
79 movl (%esp), %e##reg; \
80 ret; \
81 .size GET_PC_THUNK(reg), . - GET_PC_THUNK(reg); \
82 .previous; \
83 .endif; \
84 call GET_PC_THUNK(reg)
85
86# define LOAD_PIC_REG(reg) \
87 SETUP_PIC_REG(reg); addl $_GLOBAL_OFFSET_TABLE_, %e##reg
88
89#undef JUMPTARGET
90#ifdef PIC
91#define JUMPTARGET(name) name##@PLT
92#define SYSCALL_PIC_SETUP \
93 pushl %ebx; \
94 cfi_adjust_cfa_offset (4); \
95 call 0f; \
960: popl %ebx; \
97 cfi_adjust_cfa_offset (-4); \
98 addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx;
99
100#else
101#define JUMPTARGET(name) name
102#define SYSCALL_PIC_SETUP /* Nothing. */
103#endif
104
105#else /* __ASSEMBLER__ */
106
107# define SETUP_PIC_REG_STR(reg) \
108 ".ifndef " GET_PC_THUNK_STR (reg) "\n" \
109 ".section .text." GET_PC_THUNK_STR (reg) ",\"axG\",@progbits," \
110 GET_PC_THUNK_STR (reg) ",comdat\n" \
111 ".globl " GET_PC_THUNK_STR (reg) "\n" \
112 ".hidden " GET_PC_THUNK_STR (reg) "\n" \
113 ".p2align 4\n" \
114 ".type " GET_PC_THUNK_STR (reg) ",@function\n" \
115GET_PC_THUNK_STR (reg) ":" \
116 "movl (%%esp), %%e" #reg "\n" \
117 "ret\n" \
118 ".size " GET_PC_THUNK_STR (reg) ", . - " GET_PC_THUNK_STR (reg) "\n" \
119 ".previous\n" \
120 ".endif\n" \
121 "call " GET_PC_THUNK_STR (reg)
122
123# define LOAD_PIC_REG_STR(reg) \
124 SETUP_PIC_REG_STR (reg) "\naddl $_GLOBAL_OFFSET_TABLE_, %%e" #reg
125
126#endif /* __ASSEMBLER__ */
127

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