nptl/unwind.c

   1 /* Copyright (C) 2003-2013 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 <stdlib.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include "pthreadP.h"
  25 #include <jmpbuf-unwind.h>
  26
  27 #ifdef HAVE_FORCED_UNWIND
  28
  29 #ifdef _STACK_GROWS_DOWN
  30 # define FRAME_LEFT(frame, other, adj) \
  31   ((uintptr_t) frame - adj >= (uintptr_t) other - adj)
  32 #elif _STACK_GROWS_UP
  33 # define FRAME_LEFT(frame, other, adj) \
  34   ((uintptr_t) frame - adj <= (uintptr_t) other - adj)
  35 #else
  36 # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
  37 #endif
  38
  39 static _Unwind_Reason_Code
  40 unwind_stop (int version, _Unwind_Action actions,
  41              _Unwind_Exception_Class exc_class,
  42              struct _Unwind_Exception *exc_obj,
  43              struct _Unwind_Context *context, void *stop_parameter)
  44 {
  45   struct pthread_unwind_buf *buf = stop_parameter;
  46   struct pthread *self = THREAD_SELF;
  47   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
  48   int do_longjump = 0;
  49
  50   /* Adjust all pointers used in comparisons, so that top of thread's
  51      stack is at the top of address space.  Without that, things break
  52      if stack is allocated above the main stack.  */
  53   uintptr_t adj = (uintptr_t) self->stackblock + self->stackblock_size;
  54
  55   /* Do longjmp if we're at "end of stack", aka "end of unwind data".
  56      We assume there are only C frame without unwind data in between
  57      here and the jmp_buf target.  Otherwise simply note that the CFA
  58      of a function is NOT within it's stack frame; it's the SP of the
  59      previous frame.  */
  60   if ((actions & _UA_END_OF_STACK)
  61       || ! _JMPBUF_CFA_UNWINDS_ADJ (buf->cancel_jmp_buf[0].jmp_buf, context,
  62                                     adj))
  63     do_longjump = 1;
  64
  65   if (__builtin_expect (curp != NULL, 0))
  66     {
  67       /* Handle the compatibility stuff.  Execute all handlers
  68          registered with the old method which would be unwound by this
  69          step.  */
  70       struct _pthread_cleanup_buffer *oldp = buf->priv.data.cleanup;
  71       void *cfa = (void *) (_Unwind_Ptr) _Unwind_GetCFA (context);
  72
  73       if (curp != oldp && (do_longjump || FRAME_LEFT (cfa, curp, adj)))
  74         {
  75           do
  76             {
  77               /* Pointer to the next element.  */
  78               struct _pthread_cleanup_buffer *nextp = curp->__prev;
  79
  80               /* Call the handler.  */
  81               curp->__routine (curp->__arg);
  82
  83               /* To the next.  */
  84               curp = nextp;
  85             }
  86           while (curp != oldp
  87                  && (do_longjump || FRAME_LEFT (cfa, curp, adj)));
  88
  89           /* Mark the current element as handled.  */
  90           THREAD_SETMEM (self, cleanup, curp);
  91         }
  92     }
  93
  94   if (do_longjump)
  95     __libc_unwind_longjmp ((struct __jmp_buf_tag *) buf->cancel_jmp_buf, 1);
  96
  97   return _URC_NO_REASON;
  98 }
  99
 100
 101 static void
 102 unwind_cleanup (_Unwind_Reason_Code reason, struct _Unwind_Exception *exc)
 103 {
 104   /* When we get here a C++ catch block didn't rethrow the object.  We
 105      cannot handle this case and therefore abort.  */
 106 # define STR_N_LEN(str) str, strlen (str)
 107   INTERNAL_SYSCALL_DECL (err);
 108   INTERNAL_SYSCALL (write, err, 3, STDERR_FILENO,
 109                     STR_N_LEN ("FATAL: exception not rethrown\n"));
 110   abort ();
 111 }
 112
 113 #endif  /* have forced unwind */
 114
 115
 116 void
 117 __cleanup_fct_attribute __attribute ((noreturn))
 118 __pthread_unwind (__pthread_unwind_buf_t *buf)
 119 {
 120   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 121   struct pthread *self = THREAD_SELF;
 122
 123 #ifdef HAVE_FORCED_UNWIND
 124   /* This is not a catchable exception, so don't provide any details about
 125      the exception type.  We do need to initialize the field though.  */
 126   THREAD_SETMEM (self, exc.exception_class, 0);
 127   THREAD_SETMEM (self, exc.exception_cleanup, &unwind_cleanup);
 128
 129   _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
 130 #else
 131   /* Handle the compatibility stuff first.  Execute all handlers
 132      registered with the old method.  We don't execute them in order,
 133      instead, they will run first.  */
 134   struct _pthread_cleanup_buffer *oldp = ibuf->priv.data.cleanup;
 135   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
 136
 137   if (curp != oldp)
 138     {
 139       do
 140         {
 141           /* Pointer to the next element.  */
 142           struct _pthread_cleanup_buffer *nextp = curp->__prev;
 143
 144           /* Call the handler.  */
 145           curp->__routine (curp->__arg);
 146
 147           /* To the next.  */
 148           curp = nextp;
 149         }
 150       while (curp != oldp);
 151
 152       /* Mark the current element as handled.  */
 153       THREAD_SETMEM (self, cleanup, curp);
 154     }
 155
 156   /* We simply jump to the registered setjmp buffer.  */
 157   __libc_unwind_longjmp ((struct __jmp_buf_tag *) ibuf->cancel_jmp_buf, 1);
 158 #endif
 159   /* NOTREACHED */
 160
 161   /* We better do not get here.  */
 162   abort ();
 163 }
 164 hidden_def (__pthread_unwind)
 165
 166
 167 void
 168 __cleanup_fct_attribute __attribute ((noreturn))
 169 __pthread_unwind_next (__pthread_unwind_buf_t *buf)
 170 {
 171   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 172
 173   __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
 174 }
 175 hidden_def (__pthread_unwind_next)