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Diffstat (limited to 'xorg-server/os/busfault.c')
-rw-r--r--xorg-server/os/busfault.c150
1 files changed, 150 insertions, 0 deletions
diff --git a/xorg-server/os/busfault.c b/xorg-server/os/busfault.c
new file mode 100644
index 000000000..43bb6ea8a
--- /dev/null
+++ b/xorg-server/os/busfault.c
@@ -0,0 +1,150 @@
+/*
+ * Copyright © 2013 Keith Packard
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission. The copyright holders make no representations
+ * about the suitability of this software for any purpose. It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
+#include <X11/Xos.h>
+#include <X11/Xdefs.h>
+#include "misc.h"
+#include <busfault.h>
+#include <list.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <sys/mman.h>
+#include <signal.h>
+
+struct busfault {
+ struct xorg_list list;
+
+ void *addr;
+ size_t size;
+
+ Bool valid;
+
+ busfault_notify_ptr notify;
+ void *context;
+};
+
+static Bool busfaulted;
+static struct xorg_list busfaults;
+
+struct busfault *
+busfault_register_mmap(void *addr, size_t size, busfault_notify_ptr notify, void *context)
+{
+ struct busfault *busfault;
+
+ busfault = calloc(1, sizeof (struct busfault));
+ if (!busfault)
+ return NULL;
+
+ busfault->addr = addr;
+ busfault->size = size;
+ busfault->notify = notify;
+ busfault->context = context;
+ busfault->valid = TRUE;
+
+ xorg_list_add(&busfault->list, &busfaults);
+ return busfault;
+}
+
+void
+busfault_unregister(struct busfault *busfault)
+{
+ xorg_list_del(&busfault->list);
+ free(busfault);
+}
+
+void
+busfault_check(void)
+{
+ struct busfault *busfault, *tmp;
+
+ if (!busfaulted)
+ return;
+
+ busfaulted = FALSE;
+
+ xorg_list_for_each_entry_safe(busfault, tmp, &busfaults, list) {
+ if (!busfault->valid)
+ (*busfault->notify)(busfault->context);
+ }
+}
+
+static void (*previous_busfault_sigaction)(int sig, siginfo_t *info, void *param);
+
+static void
+busfault_sigaction(int sig, siginfo_t *info, void *param)
+{
+ void *fault = info->si_addr;
+ struct busfault *busfault = NULL;
+ void *new_addr;
+
+ /* Locate the faulting address in our list of shared segments
+ */
+ xorg_list_for_each_entry(busfault, &busfaults, list) {
+ if ((char *) busfault->addr <= (char *) fault && (char *) fault < (char *) busfault->addr + busfault->size) {
+ break;
+ }
+ }
+ if (!busfault)
+ goto panic;
+
+ if (!busfault->valid)
+ goto panic;
+
+ busfault->valid = FALSE;
+ busfaulted = TRUE;
+
+ /* The client truncated the file; unmap the shared file, map
+ * /dev/zero over that area and keep going
+ */
+
+ new_addr = mmap(busfault->addr, busfault->size, PROT_READ|PROT_WRITE,
+ MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
+
+ if (new_addr == MAP_FAILED)
+ goto panic;
+
+ return;
+panic:
+ if (previous_busfault_sigaction)
+ (*previous_busfault_sigaction)(sig, info, param);
+ else
+ FatalError("bus error");
+}
+
+Bool
+busfault_init(void)
+{
+ struct sigaction act, old_act;
+
+ act.sa_sigaction = busfault_sigaction;
+ act.sa_flags = SA_SIGINFO;
+ if (sigaction(SIGBUS, &act, &old_act) < 0)
+ return FALSE;
+ previous_busfault_sigaction = old_act.sa_sigaction;
+ xorg_list_init(&busfaults);
+ return TRUE;
+}