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 <linux/unistd.h> 11 12 #include "compiler.h" 13 #include "crt.h" 14 #include "std.h" 15 16 #if !defined(_ABIO32) && !defined(_ABIN32) && !defined(_ABI64) 17 #error Unsupported MIPS ABI 18 #endif 19 20 /* Syscalls for MIPS ABI O32 : 21 * - WARNING! there's always a delayed slot! 22 * - WARNING again, the syntax is different, registers take a '$' and numbers 23 * do not. 24 * - registers are 32-bit 25 * - stack is 8-byte aligned 26 * - syscall number is passed in v0 (starts at 0xfa0). 27 * - arguments are in a0, a1, a2, a3, then the stack. The caller needs to 28 * leave some room in the stack for the callee to save a0..a3 if needed. 29 * - Many registers are clobbered, in fact only a0..a2 and s0..s8 are 30 * preserved. See: https://www.linux-mips.org/wiki/Syscall as well as 31 * scall32-o32.S in the kernel sources. 32 * - the system call is performed by calling "syscall" 33 * - syscall return comes in v0, and register a3 needs to be checked to know 34 * if an error occurred, in which case errno is in v0. 35 * - the arguments are cast to long and assigned into the target registers 36 * which are then simply passed as registers to the asm code, so that we 37 * don't have to experience issues with register constraints. 38 * 39 * Syscalls for MIPS ABI N32, same as ABI O32 with the following differences : 40 * - arguments are in a0, a1, a2, a3, t0, t1, t2, t3. 41 * t0..t3 are also known as a4..a7. 42 * - stack is 16-byte aligned 43 */ 44 45 #if !defined(__mips_isa_rev) || __mips_isa_rev < 6 46 #define _NOLIBC_SYSCALL_CLOBBER_HI_LO "hi", "lo" 47 #else 48 #define _NOLIBC_SYSCALL_CLOBBER_HI_LO "$0" 49 #endif 50 51 #if defined(_ABIO32) 52 53 #define _NOLIBC_SYSCALL_CLOBBERLIST \ 54 "memory", "cc", "at", "v1", \ 55 "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9", \ 56 _NOLIBC_SYSCALL_CLOBBER_HI_LO 57 58 #define _NOLIBC_SYSCALL_STACK_RESERVE "addiu $sp, $sp, -32\n" 59 #define _NOLIBC_SYSCALL_STACK_UNRESERVE "addiu $sp, $sp, 32\n" 60 61 #define _NOLIBC_SYSCALL_REG register long 62 63 #else /* _ABIN32 || _ABI64 */ 64 65 /* binutils, GCC and clang disagree about register aliases, use numbers instead. */ 66 #define _NOLIBC_SYSCALL_CLOBBERLIST \ 67 "memory", "cc", "at", "v1", \ 68 "10", "11", "12", "13", "14", "15", "24", "25", \ 69 _NOLIBC_SYSCALL_CLOBBER_HI_LO 70 71 #define _NOLIBC_SYSCALL_STACK_RESERVE 72 #define _NOLIBC_SYSCALL_STACK_UNRESERVE 73 74 #define _NOLIBC_SYSCALL_REG register long long 75 #define __NOLIBC_BITS_PER_SYSCALL_ARG 64 76 77 #endif /* _ABIO32 */ 78 79 #define __nolibc_syscall0(num) \ 80 ({ \ 81 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 82 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3"); \ 83 \ 84 __asm__ volatile ( \ 85 _NOLIBC_SYSCALL_STACK_RESERVE \ 86 "syscall\n" \ 87 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 88 : "=r"(_num), "=r"(_arg4) \ 89 : "r"(_num) \ 90 : _NOLIBC_SYSCALL_CLOBBERLIST \ 91 ); \ 92 _arg4 ? -_num : _num; \ 93 }) 94 95 #define __nolibc_syscall1(num, arg1) \ 96 ({ \ 97 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 98 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("a0") = __nolibc_arg_to_reg(arg1); \ 99 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3"); \ 100 \ 101 __asm__ volatile ( \ 102 _NOLIBC_SYSCALL_STACK_RESERVE \ 103 "syscall\n" \ 104 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 105 : "=r"(_num), "=r"(_arg4) \ 106 : "0"(_num), \ 107 "r"(_arg1) \ 108 : _NOLIBC_SYSCALL_CLOBBERLIST \ 109 ); \ 110 _arg4 ? -_num : _num; \ 111 }) 112 113 #define __nolibc_syscall2(num, arg1, arg2) \ 114 ({ \ 115 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 116 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("a0") = __nolibc_arg_to_reg(arg1); \ 117 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("a1") = __nolibc_arg_to_reg(arg2); \ 118 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3"); \ 119 \ 120 __asm__ volatile ( \ 121 _NOLIBC_SYSCALL_STACK_RESERVE \ 122 "syscall\n" \ 123 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 124 : "=r"(_num), "=r"(_arg4) \ 125 : "0"(_num), \ 126 "r"(_arg1), "r"(_arg2) \ 127 : _NOLIBC_SYSCALL_CLOBBERLIST \ 128 ); \ 129 _arg4 ? -_num : _num; \ 130 }) 131 132 #define __nolibc_syscall3(num, arg1, arg2, arg3) \ 133 ({ \ 134 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 135 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("a0") = __nolibc_arg_to_reg(arg1); \ 136 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("a1") = __nolibc_arg_to_reg(arg2); \ 137 _NOLIBC_SYSCALL_REG _arg3 __asm__ ("a2") = __nolibc_arg_to_reg(arg3); \ 138 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3"); \ 139 \ 140 __asm__ volatile ( \ 141 _NOLIBC_SYSCALL_STACK_RESERVE \ 142 "syscall\n" \ 143 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 144 : "=r"(_num), "=r"(_arg4) \ 145 : "0"(_num), \ 146 "r"(_arg1), "r"(_arg2), "r"(_arg3) \ 147 : _NOLIBC_SYSCALL_CLOBBERLIST \ 148 ); \ 149 _arg4 ? -_num : _num; \ 150 }) 151 152 #define __nolibc_syscall4(num, arg1, arg2, arg3, arg4) \ 153 ({ \ 154 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 155 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("a0") = __nolibc_arg_to_reg(arg1); \ 156 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("a1") = __nolibc_arg_to_reg(arg2); \ 157 _NOLIBC_SYSCALL_REG _arg3 __asm__ ("a2") = __nolibc_arg_to_reg(arg3); \ 158 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3") = __nolibc_arg_to_reg(arg4); \ 159 \ 160 __asm__ volatile ( \ 161 _NOLIBC_SYSCALL_STACK_RESERVE \ 162 "syscall\n" \ 163 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 164 : "=r" (_num), "=r"(_arg4) \ 165 : "0"(_num), \ 166 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \ 167 : _NOLIBC_SYSCALL_CLOBBERLIST \ 168 ); \ 169 _arg4 ? -_num : _num; \ 170 }) 171 172 #if defined(_ABIO32) 173 174 #define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ 175 ({ \ 176 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 177 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("a0") = __nolibc_arg_to_reg(arg1); \ 178 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("a1") = __nolibc_arg_to_reg(arg2); \ 179 _NOLIBC_SYSCALL_REG _arg3 __asm__ ("a2") = __nolibc_arg_to_reg(arg3); \ 180 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3") = __nolibc_arg_to_reg(arg4); \ 181 _NOLIBC_SYSCALL_REG _arg5 = __nolibc_arg_to_reg(arg5); \ 182 \ 183 __asm__ volatile ( \ 184 _NOLIBC_SYSCALL_STACK_RESERVE \ 185 "sw %7, 16($sp)\n" \ 186 "syscall\n" \ 187 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 188 : "=r" (_num), "=r"(_arg4) \ 189 : "0"(_num), \ 190 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \ 191 : _NOLIBC_SYSCALL_CLOBBERLIST \ 192 ); \ 193 _arg4 ? -_num : _num; \ 194 }) 195 196 #define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ 197 ({ \ 198 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 199 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("a0") = __nolibc_arg_to_reg(arg1); \ 200 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("a1") = __nolibc_arg_to_reg(arg2); \ 201 _NOLIBC_SYSCALL_REG _arg3 __asm__ ("a2") = __nolibc_arg_to_reg(arg3); \ 202 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("a3") = __nolibc_arg_to_reg(arg4); \ 203 _NOLIBC_SYSCALL_REG _arg5 = __nolibc_arg_to_reg(arg5); \ 204 _NOLIBC_SYSCALL_REG _arg6 = __nolibc_arg_to_reg(arg6); \ 205 \ 206 __asm__ volatile ( \ 207 _NOLIBC_SYSCALL_STACK_RESERVE \ 208 "sw %7, 16($sp)\n" \ 209 "sw %8, 20($sp)\n" \ 210 "syscall\n" \ 211 _NOLIBC_SYSCALL_STACK_UNRESERVE \ 212 : "=r" (_num), "=r"(_arg4) \ 213 : "0"(_num), \ 214 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ 215 "r"(_arg6) \ 216 : _NOLIBC_SYSCALL_CLOBBERLIST \ 217 ); \ 218 _arg4 ? -_num : _num; \ 219 }) 220 221 #else /* _ABIN32 || _ABI64 */ 222 223 #define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ 224 ({ \ 225 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 226 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("$4") = __nolibc_arg_to_reg(arg1); \ 227 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("$5") = __nolibc_arg_to_reg(arg2); \ 228 _NOLIBC_SYSCALL_REG _arg3 __asm__ ("$6") = __nolibc_arg_to_reg(arg3); \ 229 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("$7") = __nolibc_arg_to_reg(arg4); \ 230 _NOLIBC_SYSCALL_REG _arg5 __asm__ ("$8") = __nolibc_arg_to_reg(arg5); \ 231 \ 232 __asm__ volatile ( \ 233 "syscall\n" \ 234 : "=r" (_num), "=r"(_arg4) \ 235 : "0"(_num), \ 236 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \ 237 : _NOLIBC_SYSCALL_CLOBBERLIST \ 238 ); \ 239 _arg4 ? -_num : _num; \ 240 }) 241 242 #define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ 243 ({ \ 244 _NOLIBC_SYSCALL_REG _num __asm__ ("v0") = (num); \ 245 _NOLIBC_SYSCALL_REG _arg1 __asm__ ("$4") = __nolibc_arg_to_reg(arg1); \ 246 _NOLIBC_SYSCALL_REG _arg2 __asm__ ("$5") = __nolibc_arg_to_reg(arg2); \ 247 _NOLIBC_SYSCALL_REG _arg3 __asm__ ("$6") = __nolibc_arg_to_reg(arg3); \ 248 _NOLIBC_SYSCALL_REG _arg4 __asm__ ("$7") = __nolibc_arg_to_reg(arg4); \ 249 _NOLIBC_SYSCALL_REG _arg5 __asm__ ("$8") = __nolibc_arg_to_reg(arg5); \ 250 _NOLIBC_SYSCALL_REG _arg6 __asm__ ("$9") = __nolibc_arg_to_reg(arg6); \ 251 \ 252 __asm__ volatile ( \ 253 "syscall\n" \ 254 : "=r" (_num), "=r"(_arg4) \ 255 : "0"(_num), \ 256 "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ 257 "r"(_arg6) \ 258 : _NOLIBC_SYSCALL_CLOBBERLIST \ 259 ); \ 260 _arg4 ? -_num : _num; \ 261 }) 262 263 #endif /* _ABIO32 */ 264 265 #ifndef NOLIBC_NO_RUNTIME 266 /* startup code, note that it's called __start on MIPS */ 267 void __start(void); 268 void __attribute__((weak, noreturn)) __nolibc_entrypoint __nolibc_no_stack_protector __start(void) 269 { 270 __asm__ volatile ( 271 "move $a0, $sp\n" /* save stack pointer to $a0, as arg1 of _start_c */ 272 #if defined(_ABIO32) 273 "addiu $sp, $sp, -16\n" /* the callee expects to save a0..a3 there */ 274 #endif /* _ABIO32 */ 275 "lui $t9, %hi(_start_c)\n" /* ABI requires current function address in $t9 */ 276 "ori $t9, %lo(_start_c)\n" 277 #if defined(_ABI64) 278 "lui $t0, %highest(_start_c)\n" 279 "ori $t0, %higher(_start_c)\n" 280 "dsll $t0, 0x20\n" 281 "or $t9, $t0\n" 282 #endif /* _ABI64 */ 283 "jalr $t9\n" /* transfer to c runtime */ 284 ); 285 __nolibc_entrypoint_epilogue(); 286 } 287 #endif /* NOLIBC_NO_RUNTIME */ 288 289 #if defined(_ABIO32) 290 #define __NOLIBC_PAD_64BIT_SYSCALL_ARGUMENT_PAIR 291 #endif 292 293 #endif /* _NOLIBC_ARCH_MIPS_H */ 294