sysdeps/unix/sysv/linux/ia64/__start_context.S

   1 /* Copyright (C) 2001, 2004 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by David Mosberger-Tang <davidm@hpl.hp.com>.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <sysdep.h>
  21 #include <features.h>
  22
  23 /* When a context set up by __makecontext() is activated, control
  24    transfers to __start_context.  When we get here:
  25
  26         b1 = entry point of function to call
  27         in0 = address of UCP to resume after function returns
  28         in1 = global pointer for __start_context
  29         out0 .. outN = arguments for function  */
  30
  31 ENTRY(__start_context)
  32         .prologue
  33         alloc r2 = ar.pfs, 2, 0, 8, 0
  34
  35         .save rp, r4            // terminate call chain with a NULL rp
  36         mov r4 = r0
  37         ;;
  38
  39         .body
  40         br.call.sptk rp = b1
  41 1:
  42         mov gp = in1                    // restore gp
  43         cmp.ne p6,p0 = in0, r0          // uc_link != 0 ?
  44         ;;
  45 (p6)    mov out0 = in0
  46 (p6)    br.call.sptk rp = __setcontext
  47 .Lexit:
  48         mov out0 = 0
  49         br.call.sptk rp = HIDDEN_JUMPTARGET(exit)
  50
  51 1:      br.cond.sptk .Lexit
  52 END(__start_context)