nptl/unwind.c

   1 /* Copyright (C) 2003-2018 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 _STACK_GROWS_DOWN
  29 # define FRAME_LEFT(frame, other, adj) \
  30   ((uintptr_t) frame - adj >= (uintptr_t) other - adj)
  31 #elif _STACK_GROWS_UP
  32 # define FRAME_LEFT(frame, other, adj) \
  33   ((uintptr_t) frame - adj <= (uintptr_t) other - adj)
  34 #else
  35 # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
  36 #endif
  37
  38 static _Unwind_Reason_Code
  39 unwind_stop (int version, _Unwind_Action actions,
  40              _Unwind_Exception_Class exc_class,
  41              struct _Unwind_Exception *exc_obj,
  42              struct _Unwind_Context *context, void *stop_parameter)
  43 {
  44   struct pthread_unwind_buf *buf = stop_parameter;
  45   struct pthread *self = THREAD_SELF;
  46   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
  47   int do_longjump = 0;
  48
  49   /* Adjust all pointers used in comparisons, so that top of thread's
  50      stack is at the top of address space.  Without that, things break
  51      if stack is allocated above the main stack.  */
  52   uintptr_t adj = (uintptr_t) self->stackblock + self->stackblock_size;
  53
  54   /* Do longjmp if we're at "end of stack", aka "end of unwind data".
  55      We assume there are only C frame without unwind data in between
  56      here and the jmp_buf target.  Otherwise simply note that the CFA
  57      of a function is NOT within it's stack frame; it's the SP of the
  58      previous frame.  */
  59   if ((actions & _UA_END_OF_STACK)
  60       || ! _JMPBUF_CFA_UNWINDS_ADJ (buf->cancel_jmp_buf[0].jmp_buf, context,
  61                                     adj))
  62     do_longjump = 1;
  63
  64   if (__glibc_unlikely (curp != NULL))
  65     {
  66       /* Handle the compatibility stuff.  Execute all handlers
  67          registered with the old method which would be unwound by this
  68          step.  */
  69       struct _pthread_cleanup_buffer *oldp = buf->priv.data.cleanup;
  70       void *cfa = (void *) (_Unwind_Ptr) _Unwind_GetCFA (context);
  71
  72       if (curp != oldp && (do_longjump || FRAME_LEFT (cfa, curp, adj)))
  73         {
  74           do
  75             {
  76               /* Pointer to the next element.  */
  77               struct _pthread_cleanup_buffer *nextp = curp->__prev;
  78
  79               /* Call the handler.  */
  80               curp->__routine (curp->__arg);
  81
  82               /* To the next.  */
  83               curp = nextp;
  84             }
  85           while (curp != oldp
  86                  && (do_longjump || FRAME_LEFT (cfa, curp, adj)));
  87
  88           /* Mark the current element as handled.  */
  89           THREAD_SETMEM (self, cleanup, curp);
  90         }
  91     }
  92
  93   if (do_longjump)
  94     __libc_unwind_longjmp ((struct __jmp_buf_tag *) buf->cancel_jmp_buf, 1);
  95
  96   return _URC_NO_REASON;
  97 }
  98
  99
 100 static void
 101 unwind_cleanup (_Unwind_Reason_Code reason, struct _Unwind_Exception *exc)
 102 {
 103   /* When we get here a C++ catch block didn't rethrow the object.  We
 104      cannot handle this case and therefore abort.  */
 105   __libc_fatal ("FATAL: exception not rethrown\n");
 106 }
 107
 108
 109 void
 110 __cleanup_fct_attribute __attribute ((noreturn))
 111 __pthread_unwind (__pthread_unwind_buf_t *buf)
 112 {
 113   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 114   struct pthread *self = THREAD_SELF;
 115
 116   /* This is not a catchable exception, so don't provide any details about
 117      the exception type.  We do need to initialize the field though.  */
 118   THREAD_SETMEM (self, exc.exception_class, 0);
 119   THREAD_SETMEM (self, exc.exception_cleanup, &unwind_cleanup);
 120
 121   _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
 122   /* NOTREACHED */
 123
 124   /* We better do not get here.  */
 125   abort ();
 126 }
 127 hidden_def (__pthread_unwind)
 128
 129
 130 void
 131 __cleanup_fct_attribute __attribute ((noreturn))
 132 __pthread_unwind_next (__pthread_unwind_buf_t *buf)
 133 {
 134   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 135
 136   __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
 137 }
 138 hidden_def (__pthread_unwind_next)