2022-02-07 17:23:17 +01:00
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
* i386 specific definitions for NOLIBC
* Copyright ( C ) 2017 - 2022 Willy Tarreau < w @ 1 wt . eu >
*/
# 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 "
2022-02-07 17:23:45 +01:00
" .weak _start \n "
2022-02-07 17:23:17 +01:00
" .global _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
