nptl/unwind.c

   1 /* Copyright (C) 2003-2015 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <setjmp.h>
  21 #include <stdio.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 (__glibc_unlikely (curp != NULL))
  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_Ptr) _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   __libc_fatal ("FATAL: exception not rethrown\n");
 108 }
 109
 110 #endif  /* have forced unwind */
 111
 112
 113 void
 114 __cleanup_fct_attribute __attribute ((noreturn))
 115 __pthread_unwind (__pthread_unwind_buf_t *buf)
 116 {
 117   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 118   struct pthread *self = THREAD_SELF;
 119
 120 #ifdef HAVE_FORCED_UNWIND
 121   /* This is not a catchable exception, so don't provide any details about
 122      the exception type.  We do need to initialize the field though.  */
 123   THREAD_SETMEM (self, exc.exception_class, 0);
 124   THREAD_SETMEM (self, exc.exception_cleanup, &unwind_cleanup);
 125
 126   _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
 127 #else
 128   /* Handle the compatibility stuff first.  Execute all handlers
 129      registered with the old method.  We don't execute them in order,
 130      instead, they will run first.  */
 131   struct _pthread_cleanup_buffer *oldp = ibuf->priv.data.cleanup;
 132   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
 133
 134   if (curp != oldp)
 135     {
 136       do
 137         {
 138           /* Pointer to the next element.  */
 139           struct _pthread_cleanup_buffer *nextp = curp->__prev;
 140
 141           /* Call the handler.  */
 142           curp->__routine (curp->__arg);
 143
 144           /* To the next.  */
 145           curp = nextp;
 146         }
 147       while (curp != oldp);
 148
 149       /* Mark the current element as handled.  */
 150       THREAD_SETMEM (self, cleanup, curp);
 151     }
 152
 153   /* We simply jump to the registered setjmp buffer.  */
 154   __libc_unwind_longjmp ((struct __jmp_buf_tag *) ibuf->cancel_jmp_buf, 1);
 155 #endif
 156   /* NOTREACHED */
 157
 158   /* We better do not get here.  */
 159   abort ();
 160 }
 161 hidden_def (__pthread_unwind)
 162
 163
 164 void
 165 __cleanup_fct_attribute __attribute ((noreturn))
 166 __pthread_unwind_next (__pthread_unwind_buf_t *buf)
 167 {
 168   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 169
 170   __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
 171 }
 172 hidden_def (__pthread_unwind_next)