220 lines
10 KiB
C
220 lines
10 KiB
C
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/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* i386 specific definitions for NOLIBC
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* Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
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*/
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#ifndef _NOLIBC_ARCH_I386_H
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#define _NOLIBC_ARCH_I386_H
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/* O_* macros for fcntl/open are architecture-specific */
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#define O_RDONLY 0
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#define O_WRONLY 1
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#define O_RDWR 2
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#define O_CREAT 0x40
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#define O_EXCL 0x80
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#define O_NOCTTY 0x100
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#define O_TRUNC 0x200
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#define O_APPEND 0x400
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#define O_NONBLOCK 0x800
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#define O_DIRECTORY 0x10000
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/* The struct returned by the stat() syscall, 32-bit only, the syscall returns
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* exactly 56 bytes (stops before the unused array).
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*/
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struct sys_stat_struct {
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unsigned long st_dev;
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unsigned long st_ino;
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unsigned short st_mode;
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unsigned short st_nlink;
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unsigned short st_uid;
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unsigned short st_gid;
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unsigned long st_rdev;
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unsigned long st_size;
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unsigned long st_blksize;
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unsigned long st_blocks;
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unsigned long st_atime;
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unsigned long st_atime_nsec;
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unsigned long st_mtime;
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unsigned long st_mtime_nsec;
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unsigned long st_ctime;
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unsigned long st_ctime_nsec;
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unsigned long __unused[2];
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};
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/* Syscalls for i386 :
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* - mostly similar to x86_64
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* - registers are 32-bit
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* - syscall number is passed in eax
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* - arguments are in ebx, ecx, edx, esi, edi, ebp respectively
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* - all registers are preserved (except eax of course)
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* - the system call is performed by calling int $0x80
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* - syscall return comes in eax
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* - the arguments are cast to long and assigned into the target registers
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* which are then simply passed as registers to the asm code, so that we
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* don't have to experience issues with register constraints.
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* - the syscall number is always specified last in order to allow to force
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* some registers before (gcc refuses a %-register at the last position).
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*
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* Also, i386 supports the old_select syscall if newselect is not available
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*/
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#define __ARCH_WANT_SYS_OLD_SELECT
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#define my_syscall0(num) \
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({ \
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long _ret; \
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register long _num __asm__ ("eax") = (num); \
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\
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__asm__ volatile ( \
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"int $0x80\n" \
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: "=a" (_ret) \
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: "0"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall1(num, arg1) \
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({ \
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long _ret; \
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register long _num __asm__ ("eax") = (num); \
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register long _arg1 __asm__ ("ebx") = (long)(arg1); \
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\
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__asm__ volatile ( \
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"int $0x80\n" \
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: "=a" (_ret) \
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: "r"(_arg1), \
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"0"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall2(num, arg1, arg2) \
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({ \
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long _ret; \
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register long _num __asm__ ("eax") = (num); \
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register long _arg1 __asm__ ("ebx") = (long)(arg1); \
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register long _arg2 __asm__ ("ecx") = (long)(arg2); \
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\
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__asm__ volatile ( \
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"int $0x80\n" \
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: "=a" (_ret) \
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: "r"(_arg1), "r"(_arg2), \
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"0"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall3(num, arg1, arg2, arg3) \
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({ \
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long _ret; \
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register long _num __asm__ ("eax") = (num); \
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register long _arg1 __asm__ ("ebx") = (long)(arg1); \
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register long _arg2 __asm__ ("ecx") = (long)(arg2); \
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register long _arg3 __asm__ ("edx") = (long)(arg3); \
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\
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__asm__ volatile ( \
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"int $0x80\n" \
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: "=a" (_ret) \
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: "r"(_arg1), "r"(_arg2), "r"(_arg3), \
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"0"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall4(num, arg1, arg2, arg3, arg4) \
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({ \
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long _ret; \
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register long _num __asm__ ("eax") = (num); \
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register long _arg1 __asm__ ("ebx") = (long)(arg1); \
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register long _arg2 __asm__ ("ecx") = (long)(arg2); \
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register long _arg3 __asm__ ("edx") = (long)(arg3); \
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register long _arg4 __asm__ ("esi") = (long)(arg4); \
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\
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__asm__ volatile ( \
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"int $0x80\n" \
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: "=a" (_ret) \
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: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
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"0"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
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({ \
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long _ret; \
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register long _num __asm__ ("eax") = (num); \
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register long _arg1 __asm__ ("ebx") = (long)(arg1); \
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register long _arg2 __asm__ ("ecx") = (long)(arg2); \
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register long _arg3 __asm__ ("edx") = (long)(arg3); \
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register long _arg4 __asm__ ("esi") = (long)(arg4); \
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register long _arg5 __asm__ ("edi") = (long)(arg5); \
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\
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__asm__ volatile ( \
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"int $0x80\n" \
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: "=a" (_ret) \
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: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
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"0"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
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({ \
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long _eax = (long)(num); \
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long _arg6 = (long)(arg6); /* Always in memory */ \
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__asm__ volatile ( \
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"pushl %[_arg6]\n\t" \
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"pushl %%ebp\n\t" \
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"movl 4(%%esp),%%ebp\n\t" \
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"int $0x80\n\t" \
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"popl %%ebp\n\t" \
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"addl $4,%%esp\n\t" \
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: "+a"(_eax) /* %eax */ \
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: "b"(arg1), /* %ebx */ \
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"c"(arg2), /* %ecx */ \
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"d"(arg3), /* %edx */ \
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"S"(arg4), /* %esi */ \
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"D"(arg5), /* %edi */ \
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[_arg6]"m"(_arg6) /* memory */ \
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: "memory", "cc" \
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); \
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_eax; \
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})
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/* startup code */
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/*
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* i386 System V ABI mandates:
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* 1) last pushed argument must be 16-byte aligned.
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* 2) The deepest stack frame should be set to zero
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*
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*/
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__asm__ (".section .text\n"
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".weak _start\n"
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"_start:\n"
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"pop %eax\n" // argc (first arg, %eax)
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"mov %esp, %ebx\n" // argv[] (second arg, %ebx)
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"lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx)
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"xor %ebp, %ebp\n" // zero the stack frame
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"and $-16, %esp\n" // x86 ABI : esp must be 16-byte aligned before
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"sub $4, %esp\n" // the call instruction (args are aligned)
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"push %ecx\n" // push all registers on the stack so that we
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"push %ebx\n" // support both regparm and plain stack modes
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"push %eax\n"
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"call main\n" // main() returns the status code in %eax
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"mov %eax, %ebx\n" // retrieve exit code (32-bit int)
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"movl $1, %eax\n" // NR_exit == 1
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"int $0x80\n" // exit now
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"hlt\n" // ensure it does not
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"");
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#endif // _NOLIBC_ARCH_I386_H
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