153 lines
4.0 KiB
C
153 lines
4.0 KiB
C
/*
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* Copyright © 2013 Keith Packard
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*
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* Permission to use, copy, modify, distribute, and sell this software and its
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* documentation for any purpose is hereby granted without fee, provided that
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* the above copyright notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting documentation, and
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* that the name of the copyright holders not be used in advertising or
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* publicity pertaining to distribution of the software without specific,
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* written prior permission. The copyright holders make no representations
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* about the suitability of this software for any purpose. It is provided "as
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* is" without express or implied warranty.
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*
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* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
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* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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* OF THIS SOFTWARE.
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*/
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#include <dix-config.h>
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#include <X11/Xos.h>
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#include <X11/Xdefs.h>
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#include "os/busfault.h"
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#include "misc.h"
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#include <list.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <sys/mman.h>
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#include <signal.h>
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struct busfault {
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struct xorg_list list;
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void *addr;
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size_t size;
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Bool valid;
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busfault_notify_ptr notify;
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void *context;
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};
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static Bool busfaulted;
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static struct xorg_list busfaults;
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struct busfault *
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busfault_register_mmap(void *addr, size_t size, busfault_notify_ptr notify, void *context)
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{
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struct busfault *busfault;
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busfault = calloc(1, sizeof (struct busfault));
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if (!busfault)
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return NULL;
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busfault->addr = addr;
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busfault->size = size;
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busfault->notify = notify;
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busfault->context = context;
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busfault->valid = TRUE;
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xorg_list_add(&busfault->list, &busfaults);
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return busfault;
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}
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void
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busfault_unregister(struct busfault *busfault)
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{
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xorg_list_del(&busfault->list);
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free(busfault);
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}
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void
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busfault_check(void)
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{
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struct busfault *busfault, *tmp;
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if (!busfaulted)
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return;
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busfaulted = FALSE;
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xorg_list_for_each_entry_safe(busfault, tmp, &busfaults, list) {
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if (!busfault->valid)
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(*busfault->notify)(busfault->context);
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}
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}
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static void (*previous_busfault_sigaction)(int sig, siginfo_t *info, void *param);
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static void
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busfault_sigaction(int sig, siginfo_t *info, void *param)
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{
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void *fault = info->si_addr;
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struct busfault *iter, *busfault = NULL;
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void *new_addr;
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/* Locate the faulting address in our list of shared segments
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*/
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xorg_list_for_each_entry(iter, &busfaults, list) {
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if ((char *) iter->addr <= (char *) fault && (char *) fault < (char *) iter->addr + iter->size) {
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busfault = iter;
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break;
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}
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}
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if (!busfault)
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goto panic;
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if (!busfault->valid)
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goto panic;
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busfault->valid = FALSE;
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busfaulted = TRUE;
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/* The client truncated the file; unmap the shared file, map
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* /dev/zero over that area and keep going
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*/
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new_addr = mmap(busfault->addr, busfault->size, PROT_READ|PROT_WRITE,
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MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
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if (new_addr == MAP_FAILED)
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goto panic;
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return;
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panic:
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if (previous_busfault_sigaction)
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(*previous_busfault_sigaction)(sig, info, param);
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else
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FatalError("bus error\n");
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}
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Bool
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busfault_init(void)
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{
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struct sigaction act, old_act;
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act.sa_sigaction = busfault_sigaction;
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act.sa_flags = SA_SIGINFO;
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sigemptyset(&act.sa_mask);
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if (sigaction(SIGBUS, &act, &old_act) < 0)
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return FALSE;
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previous_busfault_sigaction = old_act.sa_sigaction;
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xorg_list_init(&busfaults);
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return TRUE;
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}
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