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arch-i386.h
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arch-i386.h
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/*
* i386 specific definitions for NOLIBC
* Copyright (C) 2017-2022 Willy Tarreau <[email protected]>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#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"
".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