diff options
Diffstat (limited to 'libdiskfs/disk-pager.c')
| -rw-r--r-- | libdiskfs/disk-pager.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/libdiskfs/disk-pager.c b/libdiskfs/disk-pager.c new file mode 100644 index 00000000..9a0d9d88 --- /dev/null +++ b/libdiskfs/disk-pager.c @@ -0,0 +1,131 @@ +/* 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, int notify_on_evict, + 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, + notify_on_evict); + if (diskfs_disk_pager == NULL) + error (2, errno, "creating diskfs_disk_pager failed"); + + /* 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); +} |