| /* 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 |
| |
| /* 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; \ |
| }) |
| |
| #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; \ |
| }) |
| |
| char **environ __attribute__((weak)); |
| const unsigned long *_auxv __attribute__((weak)); |
| |
| #define __ARCH_SUPPORTS_STACK_PROTECTOR |
| |
| /* 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("omit-frame-pointer"),no_stack_protector)) _start(void) |
| { |
| __asm__ volatile ( |
| #ifdef NOLIBC_STACKPROTECTOR |
| "call __stack_chk_init\n" // initialize stack protector |
| #endif |
| "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) |
| "mov %ecx, environ\n" // save environ |
| "xor %ebp, %ebp\n" // zero the stack frame |
| "mov %ecx, %edx\n" // search for auxv (follows NULL after last env) |
| "0:\n" |
| "add $4, %edx\n" // search for auxv using edx, it follows the |
| "cmp -4(%edx), %ebp\n" // ... NULL after last env (ebp is zero here) |
| "jnz 0b\n" |
| "mov %edx, _auxv\n" // save it into _auxv |
| "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 |
| ); |
| __builtin_unreachable(); |
| } |
| |
| #endif // _NOLIBC_ARCH_I386_H |
