1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */ 2 /* 3 * MIPS specific definitions for NOLIBC 4 * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu> 5 */ 6 7 #ifndef _NOLIBC_ARCH_MIPS_H 8 #define _NOLIBC_ARCH_MIPS_H 9 10 #include "compiler.h" 11 12 /* The struct returned by the stat() syscall. 88 bytes are returned by the 13 * syscall. 14 */ 15 struct sys_stat_struct { 16 unsigned int st_dev; 17 long st_pad1[3]; 18 unsigned long st_ino; 19 unsigned int st_mode; 20 unsigned int st_nlink; 21 unsigned int st_uid; 22 unsigned int st_gid; 23 unsigned int st_rdev; 24 long st_pad2[2]; 25 long st_size; 26 long st_pad3; 27 28 long st_atime; 29 long st_atime_nsec; 30 long st_mtime; 31 long st_mtime_nsec; 32 33 long st_ctime; 34 long st_ctime_nsec; 35 long st_blksize; 36 long st_blocks; 37 long st_pad4[14]; 38 }; 39 40 /* Syscalls for MIPS ABI O32 : 41 * - WARNING! there's always a delayed slot! 42 * - WARNING again, the syntax is different, registers take a '$' and numbers 43 * do not. 44 * - registers are 32-bit 45 * - stack is 8-byte aligned 46 * - syscall number is passed in v0 (starts at 0xfa0). 47 * - arguments are in a0, a1, a2, a3, then the stack. The caller needs to 48 * leave some room in the stack for the callee to save a0..a3 if needed. 49 * - Many registers are clobbered, in fact only a0..a2 and s0..s8 are 50 * preserved. See: https://www.linux-mips.org/wiki/Syscall as well as 51 * scall32-o32.S in the kernel sources. 52 * - the system call is performed by calling "syscall" 53 * - syscall return comes in v0, and register a3 needs to be checked to know 54 * if an error occurred, in which case errno is in v0. 55 * - the arguments are cast to long and assigned into the target registers 56 * which are then simply passed as registers to the asm code, so that we 57 * don't have to experience issues with register constraints. 58 */ 59 60 #define my_syscall0(num) \ 61 ({ \ 62 register long _num __asm__ ("v0") = (num); \ 63 register long _arg4 __asm__ ("a3"); \ 64 \ 65 __asm__ volatile ( \ 66 "addiu $sp, $sp, -32\n" \ 67 "syscall\n" \ 68 "addiu $sp, $sp, 32\n" \ 69 : "=r"(_num), "=r"(_arg4) \ 70 : "r"(_num) \ 71 : "memory", "cc", "at", "v1", "hi", "lo", \ 72 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ 73 ); \ 74 _arg4 ? -_num : _num; \ 75 }) 76 77 #define my_syscall1(num, arg1) \ 78 ({ \ 79 register long _num __asm__ ("v0") = (num); \ 80 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 81 register long _arg4 __asm__ ("a3"); \ 82 \ 83 __asm__ volatile ( \ 84 "addiu $sp, $sp, -32\n" \ 85 "syscall\n" \ 86 "addiu $sp, $sp, 32\n" \ 87 : "=r"(_num), "=r"(_arg4) \ 88 : "0"(_num), \ 89 "r"(_arg1) \ 90 : "memory", "cc", "at", "v1", "hi", "lo", \ 91 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ 92 ); \ 93 _arg4 ? -_num : _num; \ 94 }) 95 96 #define my_syscall2(num, arg1, arg2) \ 97 ({ \ 98 register long _num __asm__ ("v0") = (num); \ 99 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 100 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 101 register long _arg4 __asm__ ("a3"); \ 102 \ 103 __asm__ volatile ( \ 104 "addiu $sp, $sp, -32\n" \ 105 "syscall\n" \ 106 "addiu $sp, $sp, 32\n" \ 107 : "=r"(_num), "=r"(_arg4) \ 108 : "0"(_num), \ 109 "r"(_arg1), "r"(_arg2) \ 110 : "memory", "cc", "at", "v1", "hi", "lo", \ 111 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ 112 ); \ 113 _arg4 ? -_num : _num; \ 114 }) 115 116 #define my_syscall3(num, arg1, arg2, arg3) \ 117 ({ \ 118 register long _num __asm__ ("v0") = (num); \ 119 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 120 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 121 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 122 register long _arg4 __asm__ ("a3"); \ 123 \ 124 __asm__ volatile ( \ 125 "addiu $sp, $sp, -32\n" \ 126 "syscall\n" \ 127 "addiu $sp, $sp, 32\n" \ 128 : "=r"(_num), "=r"(_arg4) \ 129 : "0"(_num), \ 130 "r"(_arg1), "r"(_arg2), "r"(_arg3) \ 131 : "memory", "cc", "at", "v1", "hi", "lo", \ 132 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ 133 ); \ 134 _arg4 ? -_num : _num; \ 135 }) 136 137 #define my_syscall4(num, arg1, arg2, arg3, arg4) \ 138 ({ \ 139 register long _num __asm__ ("v0") = (num); \ 140 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 141 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 142 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 143 register long _arg4 __asm__ ("a3") = (long)(arg4); \ 144 \ 145 __asm__ volatile ( \ 146 "addiu $sp, $sp, -32\n" \ 147 "syscall\n" \ 148 "addiu $sp, $sp, 32\n" \ 149 : "=r" (_num), "=r"(_arg4) \ 150 : "0"(_num), \ 151 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \ 152 : "memory", "cc", "at", "v1", "hi", "lo", \ 153 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ 154 ); \ 155 _arg4 ? -_num : _num; \ 156 }) 157 158 #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ 159 ({ \ 160 register long _num __asm__ ("v0") = (num); \ 161 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 162 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 163 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 164 register long _arg4 __asm__ ("a3") = (long)(arg4); \ 165 register long _arg5 = (long)(arg5); \ 166 \ 167 __asm__ volatile ( \ 168 "addiu $sp, $sp, -32\n" \ 169 "sw %7, 16($sp)\n" \ 170 "syscall\n " \ 171 "addiu $sp, $sp, 32\n" \ 172 : "=r" (_num), "=r"(_arg4) \ 173 : "0"(_num), \ 174 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \ 175 : "memory", "cc", "at", "v1", "hi", "lo", \ 176 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ 177 ); \ 178 _arg4 ? -_num : _num; \ 179 }) 180 181 char **environ __attribute__((weak)); 182 const unsigned long *_auxv __attribute__((weak)); 183 184 /* startup code, note that it's called __start on MIPS */ 185 void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_protector __start(void) 186 { 187 __asm__ volatile ( 188 /*".set nomips16\n"*/ 189 ".set push\n" 190 ".set noreorder\n" 191 ".option pic0\n" 192 #ifdef _NOLIBC_STACKPROTECTOR 193 "jal __stack_chk_init\n" /* initialize stack protector */ 194 "nop\n" /* delayed slot */ 195 #endif 196 /*".ent __start\n"*/ 197 /*"__start:\n"*/ 198 "lw $a0,($sp)\n" /* argc was in the stack */ 199 "addiu $a1, $sp, 4\n" /* argv = sp + 4 */ 200 "sll $a2, $a0, 2\n" /* a2 = argc * 4 */ 201 "add $a2, $a2, $a1\n" /* envp = argv + 4*argc ... */ 202 "addiu $a2, $a2, 4\n" /* ... + 4 */ 203 "lui $a3, %hi(environ)\n" /* load environ into a3 (hi) */ 204 "addiu $a3, %lo(environ)\n" /* load environ into a3 (lo) */ 205 "sw $a2,($a3)\n" /* store envp(a2) into environ */ 206 207 "move $t0, $a2\n" /* iterate t0 over envp, look for NULL */ 208 "0:" /* do { */ 209 "lw $a3, ($t0)\n" /* a3=*(t0); */ 210 "bne $a3, $0, 0b\n" /* } while (a3); */ 211 "addiu $t0, $t0, 4\n" /* delayed slot: t0+=4; */ 212 "lui $a3, %hi(_auxv)\n" /* load _auxv into a3 (hi) */ 213 "addiu $a3, %lo(_auxv)\n" /* load _auxv into a3 (lo) */ 214 "sw $t0, ($a3)\n" /* store t0 into _auxv */ 215 216 "li $t0, -8\n" 217 "and $sp, $sp, $t0\n" /* sp must be 8-byte aligned */ 218 "addiu $sp,$sp,-16\n" /* the callee expects to save a0..a3 there! */ 219 "jal main\n" /* main() returns the status code, we'll exit with it. */ 220 "nop\n" /* delayed slot */ 221 "move $a0, $v0\n" /* retrieve 32-bit exit code from v0 */ 222 "li $v0, 4001\n" /* NR_exit == 4001 */ 223 "syscall\n" 224 /*".end __start\n"*/ 225 ".set pop\n" 226 ); 227 __builtin_unreachable(); 228 } 229 230 #endif /* _NOLIBC_ARCH_MIPS_H */ 231