/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ /* * i386 specific definitions for NOLIBC * Copyright (C) 2017-2022 Willy Tarreau */ #ifndef _NOLIBC_ARCH_I386_H #define _NOLIBC_ARCH_I386_H /* O_* macros for fcntl/open are architecture-specific */ #define O_RDONLY 0 #define O_WRONLY 1 #define O_RDWR 2 #define O_CREAT 0x40 #define O_EXCL 0x80 #define O_NOCTTY 0x100 #define O_TRUNC 0x200 #define O_APPEND 0x400 #define O_NONBLOCK 0x800 #define O_DIRECTORY 0x10000 /* The struct returned by the stat() syscall, 32-bit only, the syscall returns * exactly 56 bytes (stops before the unused array). */ struct sys_stat_struct { unsigned long st_dev; unsigned long st_ino; unsigned short st_mode; unsigned short st_nlink; unsigned short st_uid; unsigned short st_gid; unsigned long st_rdev; unsigned long st_size; unsigned long st_blksize; unsigned long st_blocks; unsigned long st_atime; unsigned long st_atime_nsec; unsigned long st_mtime; unsigned long st_mtime_nsec; unsigned long st_ctime; unsigned long st_ctime_nsec; unsigned long __unused[2]; }; /* Syscalls for i386 : * - mostly similar to x86_64 * - registers are 32-bit * - syscall number is passed in eax * - arguments are in ebx, ecx, edx, esi, edi, ebp respectively * - all registers are preserved (except eax of course) * - the system call is performed by calling int $0x80 * - syscall return comes in eax * - 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. * - the syscall number is always specified last in order to allow to force * some registers before (gcc refuses a %-register at the last position). * * Also, i386 supports the old_select syscall if newselect is not available */ #define __ARCH_WANT_SYS_OLD_SELECT #define my_syscall0(num) \ ({ \ long _ret; \ register long _num asm("eax") = (num); \ \ asm volatile ( \ "int $0x80\n" \ : "=a" (_ret) \ : "0"(_num) \ : "memory", "cc" \ ); \ _ret; \ }) #define my_syscall1(num, arg1) \ ({ \ long _ret; \ register long _num asm("eax") = (num); \ register long _arg1 asm("ebx") = (long)(arg1); \ \ asm volatile ( \ "int $0x80\n" \ : "=a" (_ret) \ : "r"(_arg1), \ "0"(_num) \ : "memory", "cc" \ ); \ _ret; \ }) #define my_syscall2(num, arg1, arg2) \ ({ \ long _ret; \ register long _num asm("eax") = (num); \ register long _arg1 asm("ebx") = (long)(arg1); \ register long _arg2 asm("ecx") = (long)(arg2); \ \ asm volatile ( \ "int $0x80\n" \ : "=a" (_ret) \ : "r"(_arg1), "r"(_arg2), \ "0"(_num) \ : "memory", "cc" \ ); \ _ret; \ }) #define my_syscall3(num, arg1, arg2, arg3) \ ({ \ long _ret; \ register long _num asm("eax") = (num); \ register long _arg1 asm("ebx") = (long)(arg1); \ register long _arg2 asm("ecx") = (long)(arg2); \ register long _arg3 asm("edx") = (long)(arg3); \ \ asm volatile ( \ "int $0x80\n" \ : "=a" (_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), \ "0"(_num) \ : "memory", "cc" \ ); \ _ret; \ }) #define my_syscall4(num, arg1, arg2, arg3, arg4) \ ({ \ long _ret; \ register long _num asm("eax") = (num); \ register long _arg1 asm("ebx") = (long)(arg1); \ register long _arg2 asm("ecx") = (long)(arg2); \ register long _arg3 asm("edx") = (long)(arg3); \ register long _arg4 asm("esi") = (long)(arg4); \ \ asm volatile ( \ "int $0x80\n" \ : "=a" (_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \ "0"(_num) \ : "memory", "cc" \ ); \ _ret; \ }) #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ ({ \ long _ret; \ register long _num asm("eax") = (num); \ register long _arg1 asm("ebx") = (long)(arg1); \ register long _arg2 asm("ecx") = (long)(arg2); \ register long _arg3 asm("edx") = (long)(arg3); \ register long _arg4 asm("esi") = (long)(arg4); \ register long _arg5 asm("edi") = (long)(arg5); \ \ asm volatile ( \ "int $0x80\n" \ : "=a" (_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ "0"(_num) \ : "memory", "cc" \ ); \ _ret; \ }) /* startup code */ /* * i386 System V ABI mandates: * 1) last pushed argument must be 16-byte aligned. * 2) The deepest stack frame should be set to zero * */ asm(".section .text\n" ".weak _start\n" "_start:\n" "pop %eax\n" // argc (first arg, %eax) "mov %esp, %ebx\n" // argv[] (second arg, %ebx) "lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx) "xor %ebp, %ebp\n" // zero the stack frame "and $-16, %esp\n" // x86 ABI : esp must be 16-byte aligned before "sub $4, %esp\n" // the call instruction (args are aligned) "push %ecx\n" // push all registers on the stack so that we "push %ebx\n" // support both regparm and plain stack modes "push %eax\n" "call main\n" // main() returns the status code in %eax "mov %eax, %ebx\n" // retrieve exit code (32-bit int) "movl $1, %eax\n" // NR_exit == 1 "int $0x80\n" // exit now "hlt\n" // ensure it does not ""); #endif // _NOLIBC_ARCH_I386_H