/* $OpenBSD: uvm_device.c,v 1.68 2024/12/15 11:02:59 mpi Exp $ */ /* $NetBSD: uvm_device.c,v 1.30 2000/11/25 06:27:59 chs Exp $ */ /* * Copyright (c) 1997 Charles D. Cranor and Washington University. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * from: Id: uvm_device.c,v 1.1.2.9 1998/02/06 05:11:47 chs Exp */ /* * uvm_device.c: the device pager. */ #include <sys/param.h> #include <sys/systm.h> #include <sys/conf.h> #include <sys/malloc.h> #include <sys/mutex.h> #include <uvm/uvm.h> #include <uvm/uvm_device.h> #include "drm.h" /* * private global data structure * * we keep a list of active device objects in the system. */ LIST_HEAD(, uvm_device) udv_list = LIST_HEAD_INITIALIZER(udv_list); struct mutex udv_lock = MUTEX_INITIALIZER(IPL_NONE); /* * functions */ static void udv_reference(struct uvm_object *); static void udv_detach(struct uvm_object *); static int udv_fault(struct uvm_faultinfo *, vaddr_t, vm_page_t *, int, int, vm_fault_t, vm_prot_t, int); static boolean_t udv_flush(struct uvm_object *, voff_t, voff_t, int); /* * master pager structure */ const struct uvm_pagerops uvm_deviceops = { .pgo_reference = udv_reference, .pgo_detach = udv_detach, .pgo_fault = udv_fault, .pgo_flush = udv_flush, }; /* * the ops! */ /* * udv_attach * * get a VM object that is associated with a device. allocate a new * one if needed. * * => nothing should be locked so that we can sleep here. * * The last two arguments (off and size) are only used for access checking. */ struct uvm_object * udv_attach(dev_t device, vm_prot_t accessprot, voff_t off, vsize_t size) { struct uvm_device *udv, *lcv; paddr_t (*mapfn)(dev_t, off_t, int); #if NDRM > 0 struct uvm_object *obj; #endif /* * before we do anything, ensure this device supports mmap */ mapfn = cdevsw[major(device)].d_mmap; if (mapfn == NULL || mapfn == (paddr_t (*)(dev_t, off_t, int)) enodev || mapfn == (paddr_t (*)(dev_t, off_t, int)) nullop) return(NULL); /* * Negative offsets on the object are not allowed. */ if (off < 0) return(NULL); #if NDRM > 0 obj = udv_attach_drm(device, accessprot, off, size); if (obj) return(obj); #endif /* * Check that the specified range of the device allows the * desired protection. * * XXX clobbers off and size, but nothing else here needs them. */ while (size != 0) { if ((*mapfn)(device, off, accessprot) == -1) return (NULL); off += PAGE_SIZE; size -= PAGE_SIZE; } /* * keep looping until we get it */ for (;;) { /* * first, attempt to find it on the main list */ mtx_enter(&udv_lock); LIST_FOREACH(lcv, &udv_list, u_list) { if (device == lcv->u_device) break; } /* * got it on main list. put a hold on it and unlock udv_lock. */ if (lcv) { /* * if someone else has a hold on it, sleep and start * over again. Else, we need take HOLD flag so we * don't have to re-order locking here. */ if (lcv->u_flags & UVM_DEVICE_HOLD) { lcv->u_flags |= UVM_DEVICE_WANTED; msleep_nsec(lcv, &udv_lock, PVM | PNORELOCK, "udv_attach", INFSLP); continue; } /* we are now holding it */ lcv->u_flags |= UVM_DEVICE_HOLD; mtx_leave(&udv_lock); /* * bump reference count, unhold, return. */ rw_enter(lcv->u_obj.vmobjlock, RW_WRITE); lcv->u_obj.uo_refs++; rw_exit(lcv->u_obj.vmobjlock); mtx_enter(&udv_lock); if (lcv->u_flags & UVM_DEVICE_WANTED) wakeup(lcv); lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); mtx_leave(&udv_lock); return(&lcv->u_obj); } /* * Did not find it on main list. Need to allocate a new one. */ mtx_leave(&udv_lock); /* NOTE: we could sleep in the following malloc() */ udv = malloc(sizeof(*udv), M_TEMP, M_WAITOK); uvm_obj_init(&udv->u_obj, &uvm_deviceops, 1); mtx_enter(&udv_lock); /* * now we have to double check to make sure no one added it * to the list while we were sleeping... */ LIST_FOREACH(lcv, &udv_list, u_list) { if (device == lcv->u_device) break; } /* * did we lose a race to someone else? * free our memory and retry. */ if (lcv) { mtx_leave(&udv_lock); uvm_obj_destroy(&udv->u_obj); free(udv, M_TEMP, sizeof(*udv)); continue; } /* * we have it! init the data structures, add to list * and return. */ udv->u_flags = 0; udv->u_device = device; LIST_INSERT_HEAD(&udv_list, udv, u_list); mtx_leave(&udv_lock); return(&udv->u_obj); } /*NOTREACHED*/ } /* * udv_reference * * add a reference to a VM object. Note that the reference count must * already be one (the passed in reference) so there is no chance of the * udv being released or locked out here. */ static void udv_reference(struct uvm_object *uobj) { rw_enter(uobj->vmobjlock, RW_WRITE); uobj->uo_refs++; rw_exit(uobj->vmobjlock); } /* * udv_detach * * remove a reference to a VM object. */ static void udv_detach(struct uvm_object *uobj) { struct uvm_device *udv = (struct uvm_device *)uobj; /* * loop until done */ again: rw_enter(uobj->vmobjlock, RW_WRITE); if (uobj->uo_refs > 1) { uobj->uo_refs--; rw_exit(uobj->vmobjlock); return; } KASSERT(uobj->uo_npages == 0 && RBT_EMPTY(uvm_objtree, &uobj->memt)); /* * is it being held? if so, wait until others are done. */ mtx_enter(&udv_lock); if (udv->u_flags & UVM_DEVICE_HOLD) { udv->u_flags |= UVM_DEVICE_WANTED; rw_exit(uobj->vmobjlock); msleep_nsec(udv, &udv_lock, PVM | PNORELOCK, "udv_detach", INFSLP); goto again; } /* * got it! nuke it now. */ LIST_REMOVE(udv, u_list); if (udv->u_flags & UVM_DEVICE_WANTED) wakeup(udv); mtx_leave(&udv_lock); rw_exit(uobj->vmobjlock); uvm_obj_destroy(uobj); free(udv, M_TEMP, sizeof(*udv)); } /* * udv_flush * * flush pages out of a uvm object. a no-op for devices. */ static boolean_t udv_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags) { return(TRUE); } /* * udv_fault: non-standard fault routine for device "pages" * * => rather than having a "get" function, we have a fault routine * since we don't return vm_pages we need full control over the * pmap_enter map in * => on return, we unlock all fault data structures * => flags: PGO_ALLPAGES: get all of the pages * PGO_LOCKED: fault data structures are locked * XXX: currently PGO_LOCKED is always required ... consider removing * it as a flag * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx] */ static int udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, vm_page_t *pps, int npages, int centeridx, vm_fault_t fault_type, vm_prot_t access_type, int flags) { struct vm_map_entry *entry = ufi->entry; struct uvm_object *uobj = entry->object.uvm_obj; struct uvm_device *udv = (struct uvm_device *)uobj; vaddr_t curr_va; off_t curr_offset; paddr_t paddr; int lcv, retval; dev_t device; paddr_t (*mapfn)(dev_t, off_t, int); vm_prot_t mapprot; KERNEL_ASSERT_LOCKED(); /* * we do not allow device mappings to be mapped copy-on-write * so we kill any attempt to do so here. */ if (UVM_ET_ISCOPYONWRITE(entry)) { uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); return EACCES; } /* * get device map function. */ device = udv->u_device; mapfn = cdevsw[major(device)].d_mmap; /* * now we must determine the offset in udv to use and the VA to * use for pmap_enter. note that we always use orig_map's pmap * for pmap_enter (even if we have a submap). since virtual * addresses in a submap must match the main map, this is ok. */ /* udv offset = (offset from start of entry) + entry's offset */ curr_offset = entry->offset + (vaddr - entry->start); /* pmap va = vaddr (virtual address of pps[0]) */ curr_va = vaddr; /* * loop over the page range entering in as needed */ retval = 0; for (lcv = 0 ; lcv < npages ; lcv++, curr_offset += PAGE_SIZE, curr_va += PAGE_SIZE) { if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx) continue; if (pps[lcv] == PGO_DONTCARE) continue; paddr = (*mapfn)(device, curr_offset, access_type); if (paddr == -1) { retval = EACCES; /* XXX */ break; } mapprot = ufi->entry->protection; if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, mapprot, PMAP_CANFAIL | mapprot) != 0) { /* * pmap_enter() didn't have the resource to * enter this mapping. Unlock everything, * wait for the pagedaemon to free up some * pages, and then tell uvm_fault() to start * the fault again. * * XXX Needs some rethinking for the PGO_ALLPAGES * XXX case. */ uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); /* sync what we have so far */ pmap_update(ufi->orig_map->pmap); uvm_wait("udv_fault"); return ERESTART; } } uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); pmap_update(ufi->orig_map->pmap); return retval; }
