hurd/catch-exc.c

   1 /* Copyright (C) 1994-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <mach/exc_server.h>
  19 #include <hurd/signal.h>
  20 #include <assert.h>
  21
  22 /* Called by the microkernel when a thread gets an exception.  */
  23
  24 kern_return_t
  25 _S_catch_exception_raise (mach_port_t port,
  26                           thread_t thread,
  27                           task_t task,
  28 #ifdef EXC_MASK_ALL             /* New interface flavor.  */
  29                           exception_type_t exception,
  30                           exception_data_t code,
  31                           mach_msg_type_number_t codeCnt
  32 #else                           /* Vanilla Mach 3.0 interface.  */
  33                           integer_t exception,
  34                           integer_t code, integer_t subcode
  35 #endif
  36                           )
  37 {
  38   struct hurd_sigstate *ss;
  39   int signo;
  40   struct hurd_signal_detail d;
  41
  42   if (task != __mach_task_self ())
  43     /* The sender wasn't the kernel.  */
  44     return EPERM;
  45
  46   d.exc = exception;
  47 #ifdef EXC_MASK_ALL
  48   assert (codeCnt >= 2);
  49   d.exc_code = code[0];
  50   d.exc_subcode = code[1];
  51 #else
  52   d.exc_code = code;
  53   d.exc_subcode = subcode;
  54 #endif
  55
  56   /* Call the machine-dependent function to translate the Mach exception
  57      codes into a signal number and subcode.  */
  58   _hurd_exception2signal (&d, &signo);
  59
  60   /* Find the sigstate structure for the faulting thread.  */
  61   __mutex_lock (&_hurd_siglock);
  62   for (ss = _hurd_sigstates; ss != NULL; ss = ss->next)
  63     if (ss->thread == thread)
  64       break;
  65   __mutex_unlock (&_hurd_siglock);
  66   if (ss == NULL)
  67     ss = _hurd_thread_sigstate (thread); /* Allocate a fresh one.  */
  68
  69   if (__spin_lock_locked (&ss->lock))
  70     {
  71       /* Loser.  The thread faulted with its sigstate lock held.  Its
  72          sigstate data is now suspect.  So we reset the parts of it which
  73          could cause trouble for the signal thread.  Anything else
  74          clobbered therein will just hose this user thread, but it's
  75          faulting already.
  76
  77          This is almost certainly a library bug: unless random memory
  78          clobberation caused the sigstate lock to gratuitously appear held,
  79          no code should do anything that can fault while holding the
  80          sigstate lock.  */
  81
  82       __spin_unlock (&ss->critical_section_lock);
  83       ss->context = NULL;
  84       __spin_unlock (&ss->lock);
  85     }
  86
  87   /* Post the signal.  */
  88   _hurd_internal_post_signal (ss, signo, &d,
  89                               MACH_PORT_NULL, MACH_MSG_TYPE_PORT_SEND,
  90                               0);
  91
  92   return KERN_SUCCESS;
  93 }
  94
  95 #ifdef EXC_MASK_ALL
  96 /* XXX New interface flavor has additional RPCs that we could be using
  97    instead.  These RPCs roll a thread_get_state/thread_set_state into
  98    the message, so the signal thread ought to use these to save some calls.
  99  */
 100 kern_return_t
 101 _S_catch_exception_raise_state (mach_port_t port,
 102                                 exception_type_t exception,
 103                                 exception_data_t code,
 104                                 mach_msg_type_number_t codeCnt,
 105                                 int *flavor,
 106                                 thread_state_t old_state,
 107                                 mach_msg_type_number_t old_stateCnt,
 108                                 thread_state_t new_state,
 109                                 mach_msg_type_number_t *new_stateCnt)
 110 {
 111   abort ();
 112   return KERN_FAILURE;
 113 }
 114
 115 kern_return_t
 116 _S_catch_exception_raise_state_identity (mach_port_t exception_port,
 117                                          thread_t thread,
 118                                          task_t task,
 119                                          exception_type_t exception,
 120                                          exception_data_t code,
 121                                          mach_msg_type_number_t codeCnt,
 122                                          int *flavor,
 123                                          thread_state_t old_state,
 124                                          mach_msg_type_number_t old_stateCnt,
 125                                          thread_state_t new_state,
 126                                          mach_msg_type_number_t *new_stateCnt)
 127 {
 128   abort ();
 129   return KERN_FAILURE;
 130 }
 131 #endif