/* 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 #include "compiler.h" /* 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; \ }) char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); /* startup code, note that it's called __start on MIPS */ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_protector __start(void) { __asm__ volatile ( /*".set nomips16\n"*/ ".set push\n" ".set noreorder\n" ".option pic0\n" #ifdef _NOLIBC_STACKPROTECTOR "jal __stack_chk_init\n" /* initialize stack protector */ "nop\n" /* delayed slot */ #endif /*".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 */ "lui $a3, %hi(environ)\n" /* load environ into a3 (hi) */ "addiu $a3, %lo(environ)\n" /* load environ into a3 (lo) */ "sw $a2,($a3)\n" /* store envp(a2) into environ */ "move $t0, $a2\n" /* iterate t0 over envp, look for NULL */ "0:" /* do { */ "lw $a3, ($t0)\n" /* a3=*(t0); */ "bne $a3, $0, 0b\n" /* } while (a3); */ "addiu $t0, $t0, 4\n" /* delayed slot: t0+=4; */ "lui $a3, %hi(_auxv)\n" /* load _auxv into a3 (hi) */ "addiu $a3, %lo(_auxv)\n" /* load _auxv into a3 (lo) */ "sw $t0, ($a3)\n" /* store t0 into _auxv */ "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" ); __builtin_unreachable(); } #endif /* _NOLIBC_ARCH_MIPS_H */