sysdeps/mach/hurd/jmp-unwind.c

   1 /* _longjmp_unwind -- Clean up stack frames unwound by longjmp.  Hurd version.
   2    Copyright (C) 1995-2014 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <jmpbuf-unwind.h>
  20 #include <hurd/userlink.h>
  21 #include <hurd/signal.h>
  22 #include <hurd/sigpreempt.h>
  23 #include <assert.h>
  24 #include <stdint.h>
  25
  26
  27 #ifndef _JMPBUF_UNWINDS
  28 #error "<jmpbuf-unwind.h> fails to define _JMPBUF_UNWINDS"
  29 #endif
  30
  31 static inline uintptr_t
  32 demangle_ptr (uintptr_t x)
  33 {
  34 # ifdef PTR_DEMANGLE
  35   PTR_DEMANGLE (x);
  36 # endif
  37   return x;
  38 }
  39
  40 /* This function is called by `longjmp' (with its arguments) to restore
  41    active resources to a sane state before the frames code using them are
  42    jumped out of.  */
  43
  44 void
  45 _longjmp_unwind (jmp_buf env, int val)
  46 {
  47   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  48   struct hurd_userlink *link;
  49
  50   /* All access to SS->active_resources must take place inside a critical
  51      section where signal handlers cannot run.  */
  52   __spin_lock (&ss->lock);
  53   assert (! __spin_lock_locked (&ss->critical_section_lock));
  54   __spin_lock (&ss->critical_section_lock);
  55
  56   /* Remove local signal preemptors being unwound past.  */
  57   while (ss->preemptors &&
  58          _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preemptors, demangle_ptr))
  59     ss->preemptors = ss->preemptors->next;
  60
  61   __spin_unlock (&ss->lock);
  62
  63   /* Iterate over the current thread's list of active resources.
  64      Process the head portion of the list whose links reside
  65      in stack frames being unwound by this jump.  */
  66
  67   for (link = ss->active_resources;
  68        link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link, demangle_ptr);
  69        link = link->thread.next)
  70     /* Remove this link from the resource's users list,
  71        since the frame using the resource is being unwound.
  72        This call returns nonzero if that was the last user.  */
  73     if (_hurd_userlink_unlink (link))
  74       /* One of the frames being unwound by the longjmp was the last user
  75          of its resource.  Call the cleanup function to deallocate it.  */
  76       (*link->cleanup) (link->cleanup_data, env, val);
  77
  78   _hurd_critical_section_unlock (ss);
  79 }