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

   1 /* Copyright (C) 2001-2022 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, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <sysdep.h>
  19 #include <features.h>
  20
  21 /* When a context set up by __makecontext() is activated, control
  22    transfers to __start_context.  When we get here:
  23
  24         b1 = entry point of function to call
  25         in0 = address of UCP to resume after function returns
  26         in1 = global pointer for __start_context
  27         out0 .. outN = arguments for function  */
  28
  29 ENTRY(__start_context)
  30         .prologue
  31         alloc r2 = ar.pfs, 2, 0, 8, 0
  32
  33         .save rp, r4            // terminate call chain with a NULL rp
  34         mov r4 = r0
  35         ;;
  36
  37         .body
  38         br.call.sptk rp = b1
  39 1:
  40         mov gp = in1                    // restore gp
  41         cmp.ne p6,p0 = in0, r0          // uc_link != 0 ?
  42         ;;
  43 (p6)    mov out0 = in0
  44 (p6)    br.call.sptk rp = __setcontext
  45 .Lexit:
  46         mov out0 = 0
  47         br.call.sptk rp = HIDDEN_JUMPTARGET(exit)
  48
  49 1:      br.cond.sptk .Lexit
  50 END(__start_context)