sysdeps/unix/sysv/linux/i386/libc-do-syscall.S

   1 /* Out-of-line syscall stub for six-argument syscalls from C.
   2    Copyright (C) 2015-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20
  21 #ifndef OPTIMIZE_FOR_GCC_5
  22
  23 /* %eax, %ecx, %edx and %esi contain the values expected by the kernel.
  24    %edi points to a structure with the values of %ebx, %edi and %ebp.  */
  25
  26         .hidden __libc_do_syscall
  27
  28 ENTRY (__libc_do_syscall)
  29         pushl   %ebx
  30         cfi_adjust_cfa_offset (4)
  31         cfi_rel_offset (ebx, 0)
  32         pushl   %edi
  33         cfi_adjust_cfa_offset (4)
  34         cfi_rel_offset (edi, 0)
  35         pushl   %ebp
  36         cfi_adjust_cfa_offset (4)
  37         cfi_rel_offset (ebp, 0)
  38         movl    0(%edi), %ebx
  39         movl    8(%edi), %ebp
  40         movl    4(%edi), %edi
  41         ENTER_KERNEL
  42         popl    %ebp
  43         cfi_adjust_cfa_offset (-4)
  44         cfi_restore (ebp)
  45         popl    %edi
  46         cfi_adjust_cfa_offset (-4)
  47         cfi_restore (edi)
  48         popl    %ebx
  49         cfi_adjust_cfa_offset (-4)
  50         cfi_restore (ebx)
  51         ret
  52 END (__libc_do_syscall)
  53 #endif