/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ /* * MIPS specific definitions for NOLIBC * Copyright (C) 2017-2022 Willy Tarreau */ #ifndef _NOLIBC_ARCH_MIPS_H #define _NOLIBC_ARCH_MIPS_H /* O_* macros for fcntl/open are architecture-specific */ #define O_RDONLY 0 #define O_WRONLY 1 #define O_RDWR 2 #define O_APPEND 0x0008 #define O_NONBLOCK 0x0080 #define O_CREAT 0x0100 #define O_TRUNC 0x0200 #define O_EXCL 0x0400 #define O_NOCTTY 0x0800 #define O_DIRECTORY 0x10000 /* The struct returned by the stat() syscall. 88 bytes are returned by the * syscall. */ struct sys_stat_struct { unsigned int st_dev; long st_pad1[3]; unsigned long st_ino; unsigned int st_mode; unsigned int st_nlink; unsigned int st_uid; unsigned int st_gid; unsigned int st_rdev; long st_pad2[2]; long st_size; long st_pad3; long st_atime; long st_atime_nsec; long st_mtime; long st_mtime_nsec; long st_ctime; long st_ctime_nsec; long st_blksize; long st_blocks; long st_pad4[14]; }; /* Syscalls for MIPS ABI O32 : * - WARNING! there's always a delayed slot! * - WARNING again, the syntax is different, registers take a '$' and numbers * do not. * - registers are 32-bit * - stack is 8-byte aligned * - syscall number is passed in v0 (starts at 0xfa0). * - arguments are in a0, a1, a2, a3, then the stack. The caller needs to * leave some room in the stack for the callee to save a0..a3 if needed. * - Many registers are clobbered, in fact only a0..a2 and s0..s8 are * preserved. See: https://www.linux-mips.org/wiki/Syscall as well as * scall32-o32.S in the kernel sources. * - the system call is performed by calling "syscall" * - syscall return comes in v0, and register a3 needs to be checked to know * if an error occurred, in which case errno is in v0. * - the arguments are cast to long and assigned into the target registers * which are then simply passed as registers to the asm code, so that we * don't have to experience issues with register constraints. */ #define my_syscall0(num) \ ({ \ register long _num asm("v0") = (num); \ register long _arg4 asm("a3"); \ \ asm volatile ( \ "addiu $sp, $sp, -32\n" \ "syscall\n" \ "addiu $sp, $sp, 32\n" \ : "=r"(_num), "=r"(_arg4) \ : "r"(_num) \ : "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ ); \ _arg4 ? -_num : _num; \ }) #define my_syscall1(num, arg1) \ ({ \ register long _num asm("v0") = (num); \ register long _arg1 asm("a0") = (long)(arg1); \ register long _arg4 asm("a3"); \ \ asm volatile ( \ "addiu $sp, $sp, -32\n" \ "syscall\n" \ "addiu $sp, $sp, 32\n" \ : "=r"(_num), "=r"(_arg4) \ : "0"(_num), \ "r"(_arg1) \ : "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ ); \ _arg4 ? -_num : _num; \ }) #define my_syscall2(num, arg1, arg2) \ ({ \ register long _num asm("v0") = (num); \ register long _arg1 asm("a0") = (long)(arg1); \ register long _arg2 asm("a1") = (long)(arg2); \ register long _arg4 asm("a3"); \ \ asm volatile ( \ "addiu $sp, $sp, -32\n" \ "syscall\n" \ "addiu $sp, $sp, 32\n" \ : "=r"(_num), "=r"(_arg4) \ : "0"(_num), \ "r"(_arg1), "r"(_arg2) \ : "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ ); \ _arg4 ? -_num : _num; \ }) #define my_syscall3(num, arg1, arg2, arg3) \ ({ \ register long _num asm("v0") = (num); \ register long _arg1 asm("a0") = (long)(arg1); \ register long _arg2 asm("a1") = (long)(arg2); \ register long _arg3 asm("a2") = (long)(arg3); \ register long _arg4 asm("a3"); \ \ asm volatile ( \ "addiu $sp, $sp, -32\n" \ "syscall\n" \ "addiu $sp, $sp, 32\n" \ : "=r"(_num), "=r"(_arg4) \ : "0"(_num), \ "r"(_arg1), "r"(_arg2), "r"(_arg3) \ : "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ ); \ _arg4 ? -_num : _num; \ }) #define my_syscall4(num, arg1, arg2, arg3, arg4) \ ({ \ register long _num asm("v0") = (num); \ register long _arg1 asm("a0") = (long)(arg1); \ register long _arg2 asm("a1") = (long)(arg2); \ register long _arg3 asm("a2") = (long)(arg3); \ register long _arg4 asm("a3") = (long)(arg4); \ \ asm volatile ( \ "addiu $sp, $sp, -32\n" \ "syscall\n" \ "addiu $sp, $sp, 32\n" \ : "=r" (_num), "=r"(_arg4) \ : "0"(_num), \ "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \ : "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ ); \ _arg4 ? -_num : _num; \ }) #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ ({ \ register long _num asm("v0") = (num); \ register long _arg1 asm("a0") = (long)(arg1); \ register long _arg2 asm("a1") = (long)(arg2); \ register long _arg3 asm("a2") = (long)(arg3); \ register long _arg4 asm("a3") = (long)(arg4); \ register long _arg5 = (long)(arg5); \ \ asm volatile ( \ "addiu $sp, $sp, -32\n" \ "sw %7, 16($sp)\n" \ "syscall\n " \ "addiu $sp, $sp, 32\n" \ : "=r" (_num), "=r"(_arg4) \ : "0"(_num), \ "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \ : "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \ ); \ _arg4 ? -_num : _num; \ }) /* startup code, note that it's called __start on MIPS */ asm(".section .text\n" ".weak __start\n" ".set nomips16\n" ".set push\n" ".set noreorder\n" ".option pic0\n" ".ent __start\n" "__start:\n" "lw $a0,($sp)\n" // argc was in the stack "addiu $a1, $sp, 4\n" // argv = sp + 4 "sll $a2, $a0, 2\n" // a2 = argc * 4 "add $a2, $a2, $a1\n" // envp = argv + 4*argc ... "addiu $a2, $a2, 4\n" // ... + 4 "li $t0, -8\n" "and $sp, $sp, $t0\n" // sp must be 8-byte aligned "addiu $sp,$sp,-16\n" // the callee expects to save a0..a3 there! "jal main\n" // main() returns the status code, we'll exit with it. "nop\n" // delayed slot "move $a0, $v0\n" // retrieve 32-bit exit code from v0 "li $v0, 4001\n" // NR_exit == 4001 "syscall\n" ".end __start\n" ".set pop\n" ""); #endif // _NOLIBC_ARCH_MIPS_H