nptl/unwind.c

   1 /* Copyright (C) 2003 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_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 __cleanup_fct_attribute __attribute ((noreturn))
 119 __pthread_unwind (__pthread_unwind_buf_t *buf)
 120 {
 121   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 122   struct pthread *self = THREAD_SELF;
 123
 124 #ifdef HAVE_FORCED_UNWIND
 125   /* This is not a catchable exception, so don't provide any details about
 126      the exception type.  We do need to initialize the field though.  */
 127   THREAD_SETMEM (self, exc.exception_class, 0);
 128   THREAD_SETMEM (self, exc.exception_cleanup, unwind_cleanup);
 129
 130   _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
 131 #else
 132   /* Handle the compatibility stuff first.  Execute all handlers
 133      registered with the old method.  We don't execute them in order,
 134      instead, they will run first.  */
 135   struct _pthread_cleanup_buffer *oldp = ibuf->priv.data.cleanup;
 136   struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
 137
 138   if (curp != oldp)
 139     {
 140       do
 141         {
 142           /* Pointer to the next element.  */
 143           struct _pthread_cleanup_buffer *nextp = curp->__prev;
 144
 145           /* Call the handler.  */
 146           curp->__routine (curp->__arg);
 147
 148           /* To the next.  */
 149           curp = nextp;
 150         }
 151       while (curp != oldp);
 152
 153       /* Mark the current element as handled.  */
 154       THREAD_SETMEM (self, cleanup, curp);
 155     }
 156
 157   /* We simply jump to the registered setjmp buffer.  */
 158   __libc_longjmp ((struct __jmp_buf_tag *) ibuf->cancel_jmp_buf, 1);
 159 #endif
 160   /* NOTREACHED */
 161
 162   /* We better do not get here.  */
 163   abort ();
 164 }
 165 hidden_def (__pthread_unwind)
 166
 167
 168 void
 169 __cleanup_fct_attribute __attribute ((noreturn))
 170 __pthread_unwind_next (__pthread_unwind_buf_t *buf)
 171 {
 172   struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
 173
 174   __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
 175 }
 176 hidden_def (__pthread_unwind_next)