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1 | /* SPDX-License-Identifier: LGPL-2.1 OR MIT */ |
---|---|
2 | /* |
3 | * i386 specific definitions for NOLIBC |
4 | * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu> |
5 | */ |
6 | |
7 | #ifndef _NOLIBC_ARCH_I386_H |
8 | #define _NOLIBC_ARCH_I386_H |
9 | |
10 | #include "compiler.h" |
11 | #include "crt.h" |
12 | |
13 | /* Syscalls for i386 : |
14 | * - mostly similar to x86_64 |
15 | * - registers are 32-bit |
16 | * - syscall number is passed in eax |
17 | * - arguments are in ebx, ecx, edx, esi, edi, ebp respectively |
18 | * - all registers are preserved (except eax of course) |
19 | * - the system call is performed by calling int $0x80 |
20 | * - syscall return comes in eax |
21 | * - the arguments are cast to long and assigned into the target registers |
22 | * which are then simply passed as registers to the asm code, so that we |
23 | * don't have to experience issues with register constraints. |
24 | * - the syscall number is always specified last in order to allow to force |
25 | * some registers before (gcc refuses a %-register at the last position). |
26 | * |
27 | * Also, i386 supports the old_select syscall if newselect is not available |
28 | */ |
29 | #define __ARCH_WANT_SYS_OLD_SELECT |
30 | |
31 | #define my_syscall0(num) \ |
32 | ({ \ |
33 | long _ret; \ |
34 | register long _num __asm__ ("eax") = (num); \ |
35 | \ |
36 | __asm__ volatile ( \ |
37 | "int $0x80\n" \ |
38 | : "=a" (_ret) \ |
39 | : "0"(_num) \ |
40 | : "memory", "cc" \ |
41 | ); \ |
42 | _ret; \ |
43 | }) |
44 | |
45 | #define my_syscall1(num, arg1) \ |
46 | ({ \ |
47 | long _ret; \ |
48 | register long _num __asm__ ("eax") = (num); \ |
49 | register long _arg1 __asm__ ("ebx") = (long)(arg1); \ |
50 | \ |
51 | __asm__ volatile ( \ |
52 | "int $0x80\n" \ |
53 | : "=a" (_ret) \ |
54 | : "r"(_arg1), \ |
55 | "0"(_num) \ |
56 | : "memory", "cc" \ |
57 | ); \ |
58 | _ret; \ |
59 | }) |
60 | |
61 | #define my_syscall2(num, arg1, arg2) \ |
62 | ({ \ |
63 | long _ret; \ |
64 | register long _num __asm__ ("eax") = (num); \ |
65 | register long _arg1 __asm__ ("ebx") = (long)(arg1); \ |
66 | register long _arg2 __asm__ ("ecx") = (long)(arg2); \ |
67 | \ |
68 | __asm__ volatile ( \ |
69 | "int $0x80\n" \ |
70 | : "=a" (_ret) \ |
71 | : "r"(_arg1), "r"(_arg2), \ |
72 | "0"(_num) \ |
73 | : "memory", "cc" \ |
74 | ); \ |
75 | _ret; \ |
76 | }) |
77 | |
78 | #define my_syscall3(num, arg1, arg2, arg3) \ |
79 | ({ \ |
80 | long _ret; \ |
81 | register long _num __asm__ ("eax") = (num); \ |
82 | register long _arg1 __asm__ ("ebx") = (long)(arg1); \ |
83 | register long _arg2 __asm__ ("ecx") = (long)(arg2); \ |
84 | register long _arg3 __asm__ ("edx") = (long)(arg3); \ |
85 | \ |
86 | __asm__ volatile ( \ |
87 | "int $0x80\n" \ |
88 | : "=a" (_ret) \ |
89 | : "r"(_arg1), "r"(_arg2), "r"(_arg3), \ |
90 | "0"(_num) \ |
91 | : "memory", "cc" \ |
92 | ); \ |
93 | _ret; \ |
94 | }) |
95 | |
96 | #define my_syscall4(num, arg1, arg2, arg3, arg4) \ |
97 | ({ \ |
98 | long _ret; \ |
99 | register long _num __asm__ ("eax") = (num); \ |
100 | register long _arg1 __asm__ ("ebx") = (long)(arg1); \ |
101 | register long _arg2 __asm__ ("ecx") = (long)(arg2); \ |
102 | register long _arg3 __asm__ ("edx") = (long)(arg3); \ |
103 | register long _arg4 __asm__ ("esi") = (long)(arg4); \ |
104 | \ |
105 | __asm__ volatile ( \ |
106 | "int $0x80\n" \ |
107 | : "=a" (_ret) \ |
108 | : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \ |
109 | "0"(_num) \ |
110 | : "memory", "cc" \ |
111 | ); \ |
112 | _ret; \ |
113 | }) |
114 | |
115 | #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ |
116 | ({ \ |
117 | long _ret; \ |
118 | register long _num __asm__ ("eax") = (num); \ |
119 | register long _arg1 __asm__ ("ebx") = (long)(arg1); \ |
120 | register long _arg2 __asm__ ("ecx") = (long)(arg2); \ |
121 | register long _arg3 __asm__ ("edx") = (long)(arg3); \ |
122 | register long _arg4 __asm__ ("esi") = (long)(arg4); \ |
123 | register long _arg5 __asm__ ("edi") = (long)(arg5); \ |
124 | \ |
125 | __asm__ volatile ( \ |
126 | "int $0x80\n" \ |
127 | : "=a" (_ret) \ |
128 | : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ |
129 | "0"(_num) \ |
130 | : "memory", "cc" \ |
131 | ); \ |
132 | _ret; \ |
133 | }) |
134 | |
135 | #define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ |
136 | ({ \ |
137 | long _eax = (long)(num); \ |
138 | long _arg6 = (long)(arg6); /* Always in memory */ \ |
139 | __asm__ volatile ( \ |
140 | "pushl %[_arg6]\n\t" \ |
141 | "pushl %%ebp\n\t" \ |
142 | "movl 4(%%esp),%%ebp\n\t" \ |
143 | "int $0x80\n\t" \ |
144 | "popl %%ebp\n\t" \ |
145 | "addl $4,%%esp\n\t" \ |
146 | : "+a"(_eax) /* %eax */ \ |
147 | : "b"(arg1), /* %ebx */ \ |
148 | "c"(arg2), /* %ecx */ \ |
149 | "d"(arg3), /* %edx */ \ |
150 | "S"(arg4), /* %esi */ \ |
151 | "D"(arg5), /* %edi */ \ |
152 | [_arg6]"m"(_arg6) /* memory */ \ |
153 | : "memory", "cc" \ |
154 | ); \ |
155 | _eax; \ |
156 | }) |
157 | |
158 | /* startup code */ |
159 | /* |
160 | * i386 System V ABI mandates: |
161 | * 1) last pushed argument must be 16-byte aligned. |
162 | * 2) The deepest stack frame should be set to zero |
163 | * |
164 | */ |
165 | void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) |
166 | { |
167 | __asm__ volatile ( |
168 | "xor %ebp, %ebp\n" /* zero the stack frame */ |
169 | "mov %esp, %eax\n" /* save stack pointer to %eax, as arg1 of _start_c */ |
170 | "add $12, %esp\n" /* avoid over-estimating after the 'and' & 'sub' below */ |
171 | "and $-16, %esp\n" /* the %esp must be 16-byte aligned on 'call' */ |
172 | "sub $12, %esp\n" /* sub 12 to keep it aligned after the push %eax */ |
173 | "push %eax\n" /* push arg1 on stack to support plain stack modes too */ |
174 | "call _start_c\n" /* transfer to c runtime */ |
175 | "hlt\n" /* ensure it does not return */ |
176 | ); |
177 | __builtin_unreachable(); |
178 | } |
179 | |
180 | #endif /* _NOLIBC_ARCH_I386_H */ |
181 |
Warning: This file is not a C or C++ file. It does not have highlighting.