sysdeps/unix/sysv/linux/tile/vfork.S

   1 /* Copyright (C) 2011-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
   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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20 #define __ASSEMBLY__  /* for kernel headers */
  21 #include <linux/sched.h>
  22 #include <asm/signal.h>
  23 #include <tcb-offsets.h>
  24
  25 /* Clone the calling process, but without copying the whole address space.
  26    The calling process is suspended until the new process exits or is
  27    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
  28    and the process ID of the new process to the old process.  */
  29
  30         .text
  31 ENTRY (__vfork)
  32         {
  33          addli r11, tp, PID_OFFSET      /* Point at PID. */
  34          movei r13, 1
  35         }
  36         {
  37          LD4U r12, r11                  /* Load the saved PID.  */
  38          shli r13, r13, 31              /* Build 0x80000000. */
  39         }
  40         sub r12, zero, r12              /* Negate it.  */
  41         CMOVEQZ r12, r12, r13           /* Replace zero pids.  */
  42         ST4 r11, r12                    /* Store the temporary PID.  */
  43
  44         {
  45          moveli r0, CLONE_VFORK | CLONE_VM | SIGCHLD
  46          move r1, zero
  47         }
  48         {
  49          move r2, zero
  50          move r3, zero
  51         }
  52         moveli TREG_SYSCALL_NR_NAME, __NR_clone
  53         swint1
  54
  55         BEQZ r0, 1f                     /* If we are the parent... */
  56         {
  57          addli r11, tp, PID_OFFSET      /* Point at PID. */
  58          movei r13, 1
  59         }
  60         {
  61          LD4U r12, r11                  /* Load the saved PID.  */
  62          shli r13, r13, 31              /* Build 0x80000000. */
  63         }
  64         {
  65          CMPEQ r13, r12, r12            /* Test for that value. */
  66          sub r12, zero, r12             /* Re-negate it.  */
  67         }
  68         CMOVNEZ r12, r13, zero          /* Replace zero pids.  */
  69         ST4 r11, r12                    /* Restore the PID.  */
  70 1:
  71         BNEZ r1, 0f
  72         jrp lr
  73 PSEUDO_END (__vfork)
  74 libc_hidden_def (__vfork)
  75
  76 weak_alias (__vfork, vfork)
  77 strong_alias (__vfork, __libc_vfork)