libpthread/nptl/unwind.c

   1 /* Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>
   4    and Richard Henderson <rth@redhat.com>, 2003.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <setjmp.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include "pthreadP.h"
  26 #include <jmpbuf-unwind.h>
  27
  28 #ifdef HAVE_FORCED_UNWIND
  29
  30 #ifdef _STACK_GROWS_DOWN
  31 # define FRAME_LEFT(frame, other, adj) \
  32   ((uintptr_t) frame - adj >= (uintptr_t) other - adj)
  33 #elif _STACK_GROWS_UP
  34 # define FRAME_LEFT(frame, other, adj) \
  35   ((uintptr_t) frame - adj <= (uintptr_t) other - adj)
  36 #else
  37 # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
  38 #endif
  39
  40 static _Unwind_Reason_Code
  41 unwind_stop (int version, _Unwind_Action actions,
  42              _Unwind_Exception_Class exc_class,
  43              struct _Unwind_Exception *exc_obj,
  44              struct _Unwind_Context *context, void *stop_parameter)
  45 {
  46   struct pthread_unwind_buf *buf = stop_parameter;
  47   struct pthread *self = THREAD_SELF;
  48   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
  49   int do_longjump = 0;
  50
  51   /* Adjust all pointers used in comparisons, so that top of thread's
  52      stack is at the top of address space.  Without that, things break
  53      if stack is allocated above the main stack.  */
  54   uintptr_t adj = (uintptr_t) self->stackblock + self->stackblock_size;
  55
  56   /* Do longjmp if we're at "end of stack", aka "end of unwind data".
  57      We assume there are only C frame without unwind data in between
  58      here and the jmp_buf target.  Otherwise simply note that the CFA
  59      of a function is NOT within it's stack frame; it's the SP of the
  60      previous frame.  */
  61   if ((actions & _UA_END_OF_STACK)
  62       || ! _JMPBUF_CFA_UNWINDS_ADJ (buf->cancel_jmp_buf[0].jmp_buf, context,
  63                                     adj))
  64     do_longjump = 1;
  65
  66   if (__builtin_expect (curp != NULL, 0))
  67     {
  68       /* Handle the compatibility stuff.  Execute all handlers
  69          registered with the old method which would be unwound by this
  70          step.  */
  71       struct _pthread_cleanup_buffer *oldp = buf->priv.data.cleanup;
  72       void *cfa = (void *) _Unwind_GetCFA (context);
  73
  74       if (curp != oldp && (do_longjump || FRAME_LEFT (cfa, curp, adj)))
  75         {
  76           do
  77             {
  78               /* Pointer to the next element.  */
  79               struct _pthread_cleanup_buffer *nextp = curp->__prev;
  80
  81               /* Call the handler.  */
  82               curp->__routine (curp->__arg);
  83
  84               /* To the next.  */
  85               curp = nextp;
  86             }
  87           while (curp != oldp
  88                  && (do_longjump || FRAME_LEFT (cfa, curp, adj)));
  89
  90           /* Mark the current element as handled.  */
  91           THREAD_SETMEM (self, cleanup, curp);
  92         }
  93     }
  94
  95   if (do_longjump)
  96     __libc_unwind_longjmp ((struct __jmp_buf_tag *) buf->cancel_jmp_buf, 1);
  97
  98   return _URC_NO_REASON;
  99 }
 100
 101
 102 static void
 103 unwind_cleanup (_Unwind_Reason_Code reason, struct _Unwind_Exception *exc)
 104 {
 105   /* When we get here a C++ catch block didn't rethrow the object.  We
 106      cannot handle this case and therefore abort.  */
 107 # define STR_N_LEN(str) str, strlen (str)
 108   INTERNAL_SYSCALL_DECL (err);
 109   INTERNAL_SYSCALL (write, err, 3, STDERR_FILENO,
 110                     STR_N_LEN ("FATAL: exception not rethrown\n"));
 111   abort ();
 112 }
 113
 114 #endif  /* have forced unwind */
 115
 116
 117 void
 118 attribute_protected
 119 __cleanup_fct_attribute __attribute ((noreturn))
 120 __pthread_unwind (__pthread_unwind_buf_t *buf)
 121 {
 122   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 123   struct pthread *self = THREAD_SELF;
 124
 125 #ifdef HAVE_FORCED_UNWIND
 126   /* This is not a catchable exception, so don't provide any details about
 127      the exception type.  We do need to initialize the field though.  */
 128   THREAD_SETMEM (self, exc.exception_class, 0);
 129   THREAD_SETMEM (self, exc.exception_cleanup, unwind_cleanup);
 130
 131   _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
 132 #else
 133   /* Handle the compatibility stuff first.  Execute all handlers
 134      registered with the old method.  We don't execute them in order,
 135      instead, they will run first.  */
 136   struct _pthread_cleanup_buffer *oldp = ibuf->priv.data.cleanup;
 137   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
 138
 139   if (curp != oldp)
 140     {
 141       do
 142         {
 143           /* Pointer to the next element.  */
 144           struct _pthread_cleanup_buffer *nextp = curp->__prev;
 145
 146           /* Call the handler.  */
 147           curp->__routine (curp->__arg);
 148
 149           /* To the next.  */
 150           curp = nextp;
 151         }
 152       while (curp != oldp);
 153
 154       /* Mark the current element as handled.  */
 155       THREAD_SETMEM (self, cleanup, curp);
 156     }
 157
 158   /* We simply jump to the registered setjmp buffer.  */
 159   __libc_unwind_longjmp ((struct __jmp_buf_tag *) ibuf->cancel_jmp_buf, 1);
 160 #endif
 161   /* NOTREACHED */
 162
 163   /* We better do not get here.  */
 164   abort ();
 165 }
 166 hidden_def (__pthread_unwind)
 167
 168
 169 void
 170 __cleanup_fct_attribute __attribute ((noreturn))
 171 __pthread_unwind_next (__pthread_unwind_buf_t *buf)
 172 {
 173   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 174
 175   __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
 176 }
 177 hidden_def (__pthread_unwind_next)