1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
3 * MIPS specific definitions for NOLIBC
4 * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
7 #ifndef _NOLIBC_ARCH_MIPS_H
8 #define _NOLIBC_ARCH_MIPS_H
10 /* O_* macros for fcntl/open are architecture-specific */
14 #define O_APPEND 0x0008
15 #define O_NONBLOCK 0x0080
16 #define O_CREAT 0x0100
17 #define O_TRUNC 0x0200
19 #define O_NOCTTY 0x0800
20 #define O_DIRECTORY 0x10000
22 /* The struct returned by the stat() syscall. 88 bytes are returned by the
25 struct sys_stat_struct {
30 unsigned int st_nlink;
50 /* Syscalls for MIPS ABI O32 :
51 * - WARNING! there's always a delayed slot!
52 * - WARNING again, the syntax is different, registers take a '$' and numbers
54 * - registers are 32-bit
55 * - stack is 8-byte aligned
56 * - syscall number is passed in v0 (starts at 0xfa0).
57 * - arguments are in a0, a1, a2, a3, then the stack. The caller needs to
58 * leave some room in the stack for the callee to save a0..a3 if needed.
59 * - Many registers are clobbered, in fact only a0..a2 and s0..s8 are
60 * preserved. See: https://www.linux-mips.org/wiki/Syscall as well as
61 * scall32-o32.S in the kernel sources.
62 * - the system call is performed by calling "syscall"
63 * - syscall return comes in v0, and register a3 needs to be checked to know
64 * if an error occurred, in which case errno is in v0.
65 * - the arguments are cast to long and assigned into the target registers
66 * which are then simply passed as registers to the asm code, so that we
67 * don't have to experience issues with register constraints.
70 #define my_syscall0(num) \
72 register long _num __asm__ ("v0") = (num); \
73 register long _arg4 __asm__ ("a3"); \
76 "addiu $sp, $sp, -32\n" \
78 "addiu $sp, $sp, 32\n" \
79 : "=r"(_num), "=r"(_arg4) \
81 : "memory", "cc", "at", "v1", "hi", "lo", \
82 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
84 _arg4 ? -_num : _num; \
87 #define my_syscall1(num, arg1) \
89 register long _num __asm__ ("v0") = (num); \
90 register long _arg1 __asm__ ("a0") = (long)(arg1); \
91 register long _arg4 __asm__ ("a3"); \
94 "addiu $sp, $sp, -32\n" \
96 "addiu $sp, $sp, 32\n" \
97 : "=r"(_num), "=r"(_arg4) \
100 : "memory", "cc", "at", "v1", "hi", "lo", \
101 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
103 _arg4 ? -_num : _num; \
106 #define my_syscall2(num, arg1, arg2) \
108 register long _num __asm__ ("v0") = (num); \
109 register long _arg1 __asm__ ("a0") = (long)(arg1); \
110 register long _arg2 __asm__ ("a1") = (long)(arg2); \
111 register long _arg4 __asm__ ("a3"); \
114 "addiu $sp, $sp, -32\n" \
116 "addiu $sp, $sp, 32\n" \
117 : "=r"(_num), "=r"(_arg4) \
119 "r"(_arg1), "r"(_arg2) \
120 : "memory", "cc", "at", "v1", "hi", "lo", \
121 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
123 _arg4 ? -_num : _num; \
126 #define my_syscall3(num, arg1, arg2, arg3) \
128 register long _num __asm__ ("v0") = (num); \
129 register long _arg1 __asm__ ("a0") = (long)(arg1); \
130 register long _arg2 __asm__ ("a1") = (long)(arg2); \
131 register long _arg3 __asm__ ("a2") = (long)(arg3); \
132 register long _arg4 __asm__ ("a3"); \
135 "addiu $sp, $sp, -32\n" \
137 "addiu $sp, $sp, 32\n" \
138 : "=r"(_num), "=r"(_arg4) \
140 "r"(_arg1), "r"(_arg2), "r"(_arg3) \
141 : "memory", "cc", "at", "v1", "hi", "lo", \
142 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
144 _arg4 ? -_num : _num; \
147 #define my_syscall4(num, arg1, arg2, arg3, arg4) \
149 register long _num __asm__ ("v0") = (num); \
150 register long _arg1 __asm__ ("a0") = (long)(arg1); \
151 register long _arg2 __asm__ ("a1") = (long)(arg2); \
152 register long _arg3 __asm__ ("a2") = (long)(arg3); \
153 register long _arg4 __asm__ ("a3") = (long)(arg4); \
156 "addiu $sp, $sp, -32\n" \
158 "addiu $sp, $sp, 32\n" \
159 : "=r" (_num), "=r"(_arg4) \
161 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \
162 : "memory", "cc", "at", "v1", "hi", "lo", \
163 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
165 _arg4 ? -_num : _num; \
168 #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
170 register long _num __asm__ ("v0") = (num); \
171 register long _arg1 __asm__ ("a0") = (long)(arg1); \
172 register long _arg2 __asm__ ("a1") = (long)(arg2); \
173 register long _arg3 __asm__ ("a2") = (long)(arg3); \
174 register long _arg4 __asm__ ("a3") = (long)(arg4); \
175 register long _arg5 = (long)(arg5); \
178 "addiu $sp, $sp, -32\n" \
181 "addiu $sp, $sp, 32\n" \
182 : "=r" (_num), "=r"(_arg4) \
184 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \
185 : "memory", "cc", "at", "v1", "hi", "lo", \
186 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
188 _arg4 ? -_num : _num; \
191 /* startup code, note that it's called __start on MIPS */
192 __asm__ (".section .text\n"
199 "lw $a0,($sp)\n" // argc was in the stack
200 "addiu $a1, $sp, 4\n" // argv = sp + 4
201 "sll $a2, $a0, 2\n" // a2 = argc * 4
202 "add $a2, $a2, $a1\n" // envp = argv + 4*argc ...
203 "addiu $a2, $a2, 4\n" // ... + 4
205 "and $sp, $sp, $t0\n" // sp must be 8-byte aligned
206 "addiu $sp,$sp,-16\n" // the callee expects to save a0..a3 there!
207 "jal main\n" // main() returns the status code, we'll exit with it.
208 "nop\n" // delayed slot
209 "move $a0, $v0\n" // retrieve 32-bit exit code from v0
210 "li $v0, 4001\n" // NR_exit == 4001
215 #endif // _NOLIBC_ARCH_MIPS_H