root/mtcp/NOTES-x86_64/syscall.S

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   1 /* Copyright (C) 2001, 2003 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3 
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8 
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13 
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18 
  19 #include <sysdep.h>
  20 
  21 /* Please consult the file sysdeps/unix/sysv/linux/x86-64/sysdep.h for
  22    more information about the value -4095 used below.  */
  23 
  24 /* Usage: long syscall (syscall_number, arg1, arg2, arg3, arg4, arg5, arg6)
  25    We need to do some arg shifting, the syscall_number will be in
  26    rax.  */
  27 
  28 
  29         .text
  30 ENTRY (syscall)
  31         movq %rdi, %rax         /* Syscall number -> rax.  */
  32         movq %rsi, %rdi         /* shift arg1 - arg5.  */
  33         movq %rdx, %rsi
  34         movq %rcx, %rdx
  35         movq %r8, %r10
  36         movq %r9, %r8
  37         movq 8(%rsp),%r9        /* arg6 is on the stack.  */
  38         syscall                 /* Do the system call.  */
  39         cmpq $-4095, %rax       /* Check %rax for error.  */
  40         jae SYSCALL_ERROR_LABEL /* Jump to error handler if error.  */
  41 L(pseudo_end):
  42         ret                     /* Return to caller.  */
  43 
  44 PSEUDO_END (syscall)

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