/* $NetBSD: uvm_device.c,v 1.80 2022/07/07 13:27:02 riastradh 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 __KERNEL_RCSID(0, "$NetBSD: uvm_device.c,v 1.80 2022/07/07 13:27:02 riastradh Exp $"); #include "opt_uvmhist.h" #include #include #include #include #include #include #include #include /* * private global data structure * * we keep a list of active device objects in the system. */ LIST_HEAD(udv_list_struct, uvm_device); static struct udv_list_struct udv_list; static kmutex_t udv_lock __cacheline_aligned; /* * functions */ static void udv_init(void); static void udv_reference(struct uvm_object *); static void udv_detach(struct uvm_object *); static int udv_fault(struct uvm_faultinfo *, vaddr_t, struct vm_page **, int, int, vm_prot_t, int); /* * master pager structure */ const struct uvm_pagerops uvm_deviceops = { .pgo_init = udv_init, .pgo_reference = udv_reference, .pgo_detach = udv_detach, .pgo_fault = udv_fault, }; /* * the ops! */ /* * udv_init * * init pager private data structures. */ static void udv_init(void) { LIST_INIT(&udv_list); mutex_init(&udv_lock, MUTEX_DEFAULT, IPL_NONE); } /* * udv_attach * * get a VM object that is associated with a device. allocate a new * one if needed. * * => caller must _not_ already be holding the lock on the uvm_object. * => in fact, nothing should be locked so that we can sleep here. */ struct uvm_object * udv_attach(dev_t device, vm_prot_t accessprot, voff_t off, /* used only for access check */ vsize_t size /* used only for access check */) { struct uvm_device *udv, *lcv; const struct cdevsw *cdev; dev_mmap_t *mapfn; UVMHIST_FUNC(__func__); UVMHIST_CALLARGS(maphist, "(device=%#jx)", device,0,0,0); KASSERT(size > 0); /* * before we do anything, ensure this device supports mmap */ cdev = cdevsw_lookup(device); if (cdev == NULL) { return NULL; } mapfn = cdev->d_mmap; if (mapfn == NULL || mapfn == nommap) { return NULL; } /* * Negative offsets on the object are not allowed, unless the * device has affirmatively set D_NEGOFFSAFE. */ if ((cdev->d_flag & D_NEGOFFSAFE) == 0 && off != UVM_UNKNOWN_OFFSET) { if (off < 0) return NULL; #if SIZE_MAX > UINT32_MAX /* XXX -Wtype-limits */ if (size > __type_max(voff_t)) return NULL; #endif if (off > __type_max(voff_t) - size) return NULL; } /* * Check that the specified range of the device allows the * desired protection. * * XXX assumes VM_PROT_* == PROT_* * XXX clobbers off and size, but nothing else here needs them. */ do { KASSERTMSG((off % PAGE_SIZE) == 0, "off=%jd", (intmax_t)off); KASSERTMSG(size >= PAGE_SIZE, "size=%"PRIuVSIZE, size); if (cdev_mmap(device, off, accessprot) == -1) return NULL; KASSERT(off <= __type_max(voff_t) - PAGE_SIZE || (cdev->d_flag & D_NEGOFFSAFE) != 0); if (__predict_false(off > __type_max(voff_t) - PAGE_SIZE)) { /* * off += PAGE_SIZE, with two's-complement * wraparound, or * * off += PAGE_SIZE - 2*(VOFF_MAX + 1). */ CTASSERT(MIN_PAGE_SIZE >= 2); off -= __type_max(voff_t); off += PAGE_SIZE - 2; off -= __type_max(voff_t); } else { off += PAGE_SIZE; } size -= PAGE_SIZE; } while (size != 0); /* * keep looping until we get it */ for (;;) { /* * first, attempt to find it on the main list */ mutex_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. */ if (lcv->u_flags & UVM_DEVICE_HOLD) { lcv->u_flags |= UVM_DEVICE_WANTED; UVM_UNLOCK_AND_WAIT(lcv, &udv_lock, false, "udv_attach",0); continue; } /* we are now holding it */ lcv->u_flags |= UVM_DEVICE_HOLD; mutex_exit(&udv_lock); /* * bump reference count, unhold, return. */ rw_enter(lcv->u_obj.vmobjlock, RW_WRITER); lcv->u_obj.uo_refs++; rw_exit(lcv->u_obj.vmobjlock); mutex_enter(&udv_lock); if (lcv->u_flags & UVM_DEVICE_WANTED) wakeup(lcv); lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD); mutex_exit(&udv_lock); return &lcv->u_obj; } /* * Did not find it on main list. Need to allocate a new one. */ mutex_exit(&udv_lock); /* Note: both calls may allocate memory and sleep. */ udv = kmem_alloc(sizeof(*udv), KM_SLEEP); uvm_obj_init(&udv->u_obj, &uvm_deviceops, true, 1); mutex_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) { mutex_exit(&udv_lock); uvm_obj_destroy(&udv->u_obj, true); kmem_free(udv, 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); mutex_exit(&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. * * => caller must call with object unlocked. */ static void udv_reference(struct uvm_object *uobj) { UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); rw_enter(uobj->vmobjlock, RW_WRITER); uobj->uo_refs++; UVMHIST_LOG(maphist, "<- done (uobj=%#jx, ref = %jd)", (uintptr_t)uobj, uobj->uo_refs,0,0); rw_exit(uobj->vmobjlock); } /* * udv_detach * * remove a reference to a VM object. * * => caller must call with object unlocked and map locked. */ static void udv_detach(struct uvm_object *uobj) { struct uvm_device *udv = (struct uvm_device *)uobj; UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); /* * loop until done */ again: rw_enter(uobj->vmobjlock, RW_WRITER); if (uobj->uo_refs > 1) { uobj->uo_refs--; rw_exit(uobj->vmobjlock); UVMHIST_LOG(maphist," <- done, uobj=%#jx, ref=%jd", (uintptr_t)uobj,uobj->uo_refs,0,0); return; } /* * is it being held? if so, wait until others are done. */ mutex_enter(&udv_lock); if (udv->u_flags & UVM_DEVICE_HOLD) { udv->u_flags |= UVM_DEVICE_WANTED; rw_exit(uobj->vmobjlock); UVM_UNLOCK_AND_WAIT(udv, &udv_lock, false, "udv_detach",0); goto again; } /* * got it! nuke it now. */ LIST_REMOVE(udv, u_list); if (udv->u_flags & UVM_DEVICE_WANTED) wakeup(udv); mutex_exit(&udv_lock); rw_exit(uobj->vmobjlock); uvm_obj_destroy(uobj, true); kmem_free(udv, sizeof(*udv)); UVMHIST_LOG(maphist," <- done, freed uobj=%#jx", (uintptr_t)uobj, 0, 0, 0); } /* * 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 * => all the usual fault data structured are locked by the caller * (i.e. maps(read), amap (if any), uobj) * => 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, struct vm_page **pps, int npages, int centeridx, 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, mdpgno; u_int mmapflags; int lcv, retval; dev_t device; vm_prot_t mapprot; UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist," flags=%#jx", flags,0,0,0); /* * 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)) { UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=%#jx)", entry->etype, 0,0,0); uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); return EIO; } /* * get device map function. */ device = udv->u_device; if (cdevsw_lookup(device) == NULL) { /* XXX This should not happen */ uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); return EIO; } /* * 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; mdpgno = cdev_mmap(device, curr_offset, access_type); if (mdpgno == -1) { retval = EIO; break; } paddr = pmap_phys_address(mdpgno); mmapflags = pmap_mmap_flags(mdpgno); mapprot = ufi->entry->protection; UVMHIST_LOG(maphist, " MAPPING: device: pm=%#jx, va=%#jx, pa=%#jx, at=%jd", (uintptr_t)ufi->orig_map->pmap, curr_va, paddr, mapprot); if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr, mapprot, PMAP_CANFAIL | mapprot | mmapflags) != 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. */ pmap_update(ufi->orig_map->pmap); /* sync what we have so far */ uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); return ENOMEM; } } pmap_update(ufi->orig_map->pmap); uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj); return retval; }