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/* Map the disk image and handle faults accessing it.
Copyright (C) 1996,97,99,2001,02 Free Software Foundation, Inc.
Written by Roland McGrath.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "priv.h"
#include "diskfs-pager.h"
#include <hurd/sigpreempt.h>
#include <error.h>
__thread struct disk_image_user *diskfs_exception_diu;
struct pager *diskfs_disk_pager;
static void fault_handler (int sig, long int sigcode, struct sigcontext *scp);
static struct hurd_signal_preemptor preemptor =
{
signals: sigmask (SIGSEGV) | sigmask (SIGBUS),
preemptor: NULL,
handler: (sighandler_t) &fault_handler,
};
/* A top-level function for the paging thread that just services paging
requests. */
static void *
service_paging_requests (void *arg)
{
struct port_bucket *pager_bucket = arg;
for (;;)
ports_manage_port_operations_multithread (pager_bucket,
pager_demuxer,
1000 * 60 * 2,
1000 * 60 * 10, 0);
return NULL;
}
void
diskfs_start_disk_pager (struct user_pager_info *upi,
struct port_bucket *pager_bucket, int may_cache,
size_t size, void **image)
{
pthread_t thread;
error_t err;
mach_port_t disk_pager_port;
/* Make a thread to service paging requests. */
err = pthread_create (&thread, NULL, service_paging_requests, pager_bucket);
if (!err)
pthread_detach (thread);
else
{
errno = err;
perror ("pthread_create");
}
/* Create the pager. */
diskfs_disk_pager = pager_create (upi, pager_bucket,
may_cache, MEMORY_OBJECT_COPY_NONE);
assert (diskfs_disk_pager);
/* Get a port to the disk pager. */
disk_pager_port = pager_get_port (diskfs_disk_pager);
mach_port_insert_right (mach_task_self (), disk_pager_port, disk_pager_port,
MACH_MSG_TYPE_MAKE_SEND);
/* Now map the disk image. */
err = vm_map (mach_task_self (), (vm_address_t *)image, size,
0, 1, disk_pager_port, 0, 0,
VM_PROT_READ | (diskfs_readonly ? 0 : VM_PROT_WRITE),
VM_PROT_READ | VM_PROT_WRITE,
VM_INHERIT_NONE);
if (err)
error (2, err, "cannot vm_map whole disk");
/* Set up the signal preemptor to catch faults on the disk image. */
preemptor.first = (vm_address_t) *image;
preemptor.last = ((vm_address_t) *image + size);
hurd_preempt_signals (&preemptor);
/* We have the mapping; we no longer need the send right. */
mach_port_deallocate (mach_task_self (), disk_pager_port);
}
static void
fault_handler (int sig, long int sigcode, struct sigcontext *scp)
{
error_t err;
#ifndef NDEBUG
if (diskfs_exception_diu == NULL)
{
error (0, 0,
"BUG: unexpected fault on disk image (%d, %#lx) in [%#lx,%#lx)"
" eip %#zx err %#x",
sig, sigcode,
preemptor.first, preemptor.last,
scp->sc_pc, scp->sc_error);
assert (scp->sc_error == EKERN_MEMORY_ERROR);
err = pager_get_error (diskfs_disk_pager, sigcode);
assert (err);
assert_perror (err);
}
#endif
/* Clear the record, since the faulting thread will not. */
diskfs_exception_diu = NULL;
/* Fetch the error code from the pager. */
assert (scp->sc_error == EKERN_MEMORY_ERROR);
err = pager_get_error (diskfs_disk_pager, sigcode);
assert (err);
/* Make `diskfault_catch' return the error code. */
longjmp (diskfs_exception_diu->env, err);
}
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