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 #include "crt.h" 12 13 #if !defined(_ABIO32) && !defined(_ABIN32) && !defined(_ABI64) 14 #error Unsupported MIPS ABI 15 #endif 16 17 /* Syscalls for MIPS ABI O32 : 18 * - WARNING! there's always a delayed slot! 19 * - WARNING again, the syntax is different, registers take a '$' and numbers 20 * do not. 21 * - registers are 32-bit 22 * - stack is 8-byte aligned 23 * - syscall number is passed in v0 (starts at 0xfa0). 24 * - arguments are in a0, a1, a2, a3, then the stack. The caller needs to 25 * leave some room in the stack for the callee to save a0..a3 if needed. 26 * - Many registers are clobbered, in fact only a0..a2 and s0..s8 are 27 * preserved. See: https://www.linux-mips.org/wiki/Syscall as well as 28 * scall32-o32.S in the kernel sources. 29 * - the system call is performed by calling "syscall" 30 * - syscall return comes in v0, and register a3 needs to be checked to know 31 * if an error occurred, in which case errno is in v0. 32 * - the arguments are cast to long and assigned into the target registers 33 * which are then simply passed as registers to the asm code, so that we 34 * don't have to experience issues with register constraints. 35 * 36 * Syscalls for MIPS ABI N32, same as ABI O32 with the following differences : 37 * - arguments are in a0, a1, a2, a3, t0, t1, t2, t3. 38 * t0..t3 are also known as a4..a7. 39 * - stack is 16-byte aligned 40 */ 41 42 #if !defined(__mips_isa_rev) || __mips_isa_rev < 6 43 #define _NOLIBC_SYSCALL_CLOBBER_HI_LO "hi", "lo" 44 #else 45 #define _NOLIBC_SYSCALL_CLOBBER_HI_LO "$0" 46 #endif 47 48 #if defined(_ABIO32) 49 50 #define _NOLIBC_SYSCALL_CLOBBERLIST \ 51 "memory", "cc", "at", "v1", \ 52 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9", \ 53 _NOLIBC_SYSCALL_CLOBBER_HI_LO 54 55 #define _NOLIBC_SYSCALL_STACK_RESERVE "addiu $sp, $sp, -32\n" 56 #define _NOLIBC_SYSCALL_STACK_UNRESERVE "addiu $sp, $sp, 32\n" 57 58 #else /* _ABIN32 || _ABI64 */ 59 60 /* binutils, GCC and clang disagree about register aliases, use numbers instead. */ 61 #define _NOLIBC_SYSCALL_CLOBBERLIST \ 62 "memory", "cc", "at", "v1", \ 63 "10", "11", "12", "13", "14", "15", "24", "25", \ 64 _NOLIBC_SYSCALL_CLOBBER_HI_LO 65 66 #define _NOLIBC_SYSCALL_STACK_RESERVE 67 #define _NOLIBC_SYSCALL_STACK_UNRESERVE 68 69 #endif /* _ABIO32 */ 70 71 #define __nolibc_syscall0(num) \ 72 ({ \ 73 register long _num __asm__ ("v0") = (num); \ 74 register long _arg4 __asm__ ("a3"); \ 75 \ 76 __asm__ volatile ( \ 77 _NOLIBC_SYSCALL_STACK_RESERVE \ 78 "syscall\n" \ 79 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 80 : "=r"(_num), "=r"(_arg4) \ 81 : "r"(_num) \ 82 : _NOLIBC_SYSCALL_CLOBBERLIST \ 83 ); \ 84 _arg4 ? -_num : _num; \ 85 }) 86 87 #define __nolibc_syscall1(num, arg1) \ 88 ({ \ 89 register long _num __asm__ ("v0") = (num); \ 90 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 91 register long _arg4 __asm__ ("a3"); \ 92 \ 93 __asm__ volatile ( \ 94 _NOLIBC_SYSCALL_STACK_RESERVE \ 95 "syscall\n" \ 96 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 97 : "=r"(_num), "=r"(_arg4) \ 98 : "0"(_num), \ 99 "r"(_arg1) \ 100 : _NOLIBC_SYSCALL_CLOBBERLIST \ 101 ); \ 102 _arg4 ? -_num : _num; \ 103 }) 104 105 #define __nolibc_syscall2(num, arg1, arg2) \ 106 ({ \ 107 register long _num __asm__ ("v0") = (num); \ 108 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 109 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 110 register long _arg4 __asm__ ("a3"); \ 111 \ 112 __asm__ volatile ( \ 113 _NOLIBC_SYSCALL_STACK_RESERVE \ 114 "syscall\n" \ 115 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 116 : "=r"(_num), "=r"(_arg4) \ 117 : "0"(_num), \ 118 "r"(_arg1), "r"(_arg2) \ 119 : _NOLIBC_SYSCALL_CLOBBERLIST \ 120 ); \ 121 _arg4 ? -_num : _num; \ 122 }) 123 124 #define __nolibc_syscall3(num, arg1, arg2, arg3) \ 125 ({ \ 126 register long _num __asm__ ("v0") = (num); \ 127 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 128 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 129 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 130 register long _arg4 __asm__ ("a3"); \ 131 \ 132 __asm__ volatile ( \ 133 _NOLIBC_SYSCALL_STACK_RESERVE \ 134 "syscall\n" \ 135 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 136 : "=r"(_num), "=r"(_arg4) \ 137 : "0"(_num), \ 138 "r"(_arg1), "r"(_arg2), "r"(_arg3) \ 139 : _NOLIBC_SYSCALL_CLOBBERLIST \ 140 ); \ 141 _arg4 ? -_num : _num; \ 142 }) 143 144 #define __nolibc_syscall4(num, arg1, arg2, arg3, arg4) \ 145 ({ \ 146 register long _num __asm__ ("v0") = (num); \ 147 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 148 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 149 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 150 register long _arg4 __asm__ ("a3") = (long)(arg4); \ 151 \ 152 __asm__ volatile ( \ 153 _NOLIBC_SYSCALL_STACK_RESERVE \ 154 "syscall\n" \ 155 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 156 : "=r" (_num), "=r"(_arg4) \ 157 : "0"(_num), \ 158 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \ 159 : _NOLIBC_SYSCALL_CLOBBERLIST \ 160 ); \ 161 _arg4 ? -_num : _num; \ 162 }) 163 164 #if defined(_ABIO32) 165 166 #define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ 167 ({ \ 168 register long _num __asm__ ("v0") = (num); \ 169 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 170 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 171 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 172 register long _arg4 __asm__ ("a3") = (long)(arg4); \ 173 register long _arg5 = (long)(arg5); \ 174 \ 175 __asm__ volatile ( \ 176 _NOLIBC_SYSCALL_STACK_RESERVE \ 177 "sw %7, 16($sp)\n" \ 178 "syscall\n" \ 179 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 180 : "=r" (_num), "=r"(_arg4) \ 181 : "0"(_num), \ 182 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \ 183 : _NOLIBC_SYSCALL_CLOBBERLIST \ 184 ); \ 185 _arg4 ? -_num : _num; \ 186 }) 187 188 #define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ 189 ({ \ 190 register long _num __asm__ ("v0") = (num); \ 191 register long _arg1 __asm__ ("a0") = (long)(arg1); \ 192 register long _arg2 __asm__ ("a1") = (long)(arg2); \ 193 register long _arg3 __asm__ ("a2") = (long)(arg3); \ 194 register long _arg4 __asm__ ("a3") = (long)(arg4); \ 195 register long _arg5 = (long)(arg5); \ 196 register long _arg6 = (long)(arg6); \ 197 \ 198 __asm__ volatile ( \ 199 _NOLIBC_SYSCALL_STACK_RESERVE \ 200 "sw %7, 16($sp)\n" \ 201 "sw %8, 20($sp)\n" \ 202 "syscall\n" \ 203 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 204 : "=r" (_num), "=r"(_arg4) \ 205 : "0"(_num), \ 206 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ 207 "r"(_arg6) \ 208 : _NOLIBC_SYSCALL_CLOBBERLIST \ 209 ); \ 210 _arg4 ? -_num : _num; \ 211 }) 212 213 #else /* _ABIN32 || _ABI64 */ 214 215 #define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ 216 ({ \ 217 register long _num __asm__ ("v0") = (num); \ 218 register long _arg1 __asm__ ("$4") = (long)(arg1); \ 219 register long _arg2 __asm__ ("$5") = (long)(arg2); \ 220 register long _arg3 __asm__ ("$6") = (long)(arg3); \ 221 register long _arg4 __asm__ ("$7") = (long)(arg4); \ 222 register long _arg5 __asm__ ("$8") = (long)(arg5); \ 223 \ 224 __asm__ volatile ( \ 225 "syscall\n" \ 226 : "=r" (_num), "=r"(_arg4) \ 227 : "0"(_num), \ 228 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \ 229 : _NOLIBC_SYSCALL_CLOBBERLIST \ 230 ); \ 231 _arg4 ? -_num : _num; \ 232 }) 233 234 #define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ 235 ({ \ 236 register long _num __asm__ ("v0") = (num); \ 237 register long _arg1 __asm__ ("$4") = (long)(arg1); \ 238 register long _arg2 __asm__ ("$5") = (long)(arg2); \ 239 register long _arg3 __asm__ ("$6") = (long)(arg3); \ 240 register long _arg4 __asm__ ("$7") = (long)(arg4); \ 241 register long _arg5 __asm__ ("$8") = (long)(arg5); \ 242 register long _arg6 __asm__ ("$9") = (long)(arg6); \ 243 \ 244 __asm__ volatile ( \ 245 "syscall\n" \ 246 : "=r" (_num), "=r"(_arg4) \ 247 : "0"(_num), \ 248 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ 249 "r"(_arg6) \ 250 : _NOLIBC_SYSCALL_CLOBBERLIST \ 251 ); \ 252 _arg4 ? -_num : _num; \ 253 }) 254 255 #endif /* _ABIO32 */ 256 257 #ifndef NOLIBC_NO_RUNTIME 258 /* startup code, note that it's called __start on MIPS */ 259 void __start(void); 260 void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector __start(void) 261 { 262 __asm__ volatile ( 263 "move $a0, $sp\n" /* save stack pointer to $a0, as arg1 of _start_c */ 264 #if defined(_ABIO32) 265 "addiu $sp, $sp, -16\n" /* the callee expects to save a0..a3 there */ 266 #endif /* _ABIO32 */ 267 "lui $t9, %hi(_start_c)\n" /* ABI requires current function address in $t9 */ 268 "ori $t9, %lo(_start_c)\n" 269 #if defined(_ABI64) 270 "lui $t0, %highest(_start_c)\n" 271 "ori $t0, %higher(_start_c)\n" 272 "dsll $t0, 0x20\n" 273 "or $t9, $t0\n" 274 #endif /* _ABI64 */ 275 "jalr $t9\n" /* transfer to c runtime */ 276 ); 277 __nolibc_entrypoint_epilogue(); 278 } 279 #endif /* NOLIBC_NO_RUNTIME */ 280 281 #endif /* _NOLIBC_ARCH_MIPS_H */ 282