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Diffstat (limited to 'tools/include/nolibc/arch-i386.h')
| -rw-r--r-- | tools/include/nolibc/arch-i386.h | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h new file mode 100644 index 000000000..28c26a00a --- /dev/null +++ b/tools/include/nolibc/arch-i386.h @@ -0,0 +1,180 @@ +/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ +/* + * i386 specific definitions for NOLIBC + * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu> + */ + +#ifndef _NOLIBC_ARCH_I386_H +#define _NOLIBC_ARCH_I386_H + +#include "compiler.h" +#include "crt.h" + +/* 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; \ +}) + +#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ +({ \ + long _eax = (long)(num); \ + long _arg6 = (long)(arg6); /* Always in memory */ \ + __asm__ volatile ( \ + "pushl %[_arg6]\n\t" \ + "pushl %%ebp\n\t" \ + "movl 4(%%esp),%%ebp\n\t" \ + "int $0x80\n\t" \ + "popl %%ebp\n\t" \ + "addl $4,%%esp\n\t" \ + : "+a"(_eax) /* %eax */ \ + : "b"(arg1), /* %ebx */ \ + "c"(arg2), /* %ecx */ \ + "d"(arg3), /* %edx */ \ + "S"(arg4), /* %esi */ \ + "D"(arg5), /* %edi */ \ + [_arg6]"m"(_arg6) /* memory */ \ + : "memory", "cc" \ + ); \ + _eax; \ +}) + +/* 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 + * + */ +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) +{ + __asm__ volatile ( + "xor %ebp, %ebp\n" /* zero the stack frame */ + "mov %esp, %eax\n" /* save stack pointer to %eax, as arg1 of _start_c */ + "add $12, %esp\n" /* avoid over-estimating after the 'and' & 'sub' below */ + "and $-16, %esp\n" /* the %esp must be 16-byte aligned on 'call' */ + "sub $12, %esp\n" /* sub 12 to keep it aligned after the push %eax */ + "push %eax\n" /* push arg1 on stack to support plain stack modes too */ + "call _start_c\n" /* transfer to c runtime */ + "hlt\n" /* ensure it does not return */ + ); + __builtin_unreachable(); +} + +#endif /* _NOLIBC_ARCH_I386_H */ |