1 /* $NetBSD: pmap_pvt.c,v 1.10 2020/03/16 20:07:44 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 2014, 2020 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Taylor R. Campbell. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __RCSID("$NetBSD: pmap_pvt.c,v 1.10 2020/03/16 20:07:44 ad Exp $"); 34 35 #include <sys/atomic.h> 36 #include <sys/kmem.h> 37 #include <sys/pserialize.h> 38 39 #include <uvm/uvm.h> 40 #include <uvm/pmap/pmap_pvt.h> 41 42 /* 43 * unmanaged pv-tracked ranges 44 * 45 * This is a linear list for now because the only user are the DRM 46 * graphics drivers, with a single tracked range per device, for the 47 * graphics aperture, so there are expected to be few of them. 48 * 49 * This is used only after the VM system is initialized well enough 50 * that we can use kmem_alloc. 51 */ 52 53 struct pv_track { 54 paddr_t pvt_start; 55 psize_t pvt_size; 56 struct pv_track *pvt_next; 57 struct pmap_page pvt_pages[]; 58 }; 59 60 static struct { 61 kmutex_t lock; 62 pserialize_t psz; 63 struct pv_track *list; 64 } pv_unmanaged __cacheline_aligned; 65 66 void 67 pmap_pv_init(void) 68 { 69 70 mutex_init(&pv_unmanaged.lock, MUTEX_DEFAULT, IPL_NONE); 71 pv_unmanaged.psz = pserialize_create(); 72 pv_unmanaged.list = NULL; 73 } 74 75 void 76 pmap_pv_track(paddr_t start, psize_t size) 77 { 78 struct pv_track *pvt; 79 size_t npages; 80 81 KASSERT(start == trunc_page(start)); 82 KASSERT(size == trunc_page(size)); 83 84 /* We may sleep for allocation. */ 85 ASSERT_SLEEPABLE(); 86 87 npages = size >> PAGE_SHIFT; 88 pvt = kmem_zalloc(offsetof(struct pv_track, pvt_pages[npages]), 89 KM_SLEEP); 90 pvt->pvt_start = start; 91 pvt->pvt_size = size; 92 93 #ifdef PMAP_PAGE_INIT 94 for (size_t i = 0; i < npages; i++) 95 PMAP_PAGE_INIT(&pvt->pvt_pages[i]); 96 #endif 97 98 mutex_enter(&pv_unmanaged.lock); 99 pvt->pvt_next = pv_unmanaged.list; 100 atomic_store_release(&pv_unmanaged.list, pvt); 101 mutex_exit(&pv_unmanaged.lock); 102 } 103 104 void 105 pmap_pv_untrack(paddr_t start, psize_t size) 106 { 107 struct pv_track **pvtp, *pvt; 108 size_t npages; 109 110 KASSERT(start == trunc_page(start)); 111 KASSERT(size == trunc_page(size)); 112 113 /* We may sleep for pserialize_perform. */ 114 ASSERT_SLEEPABLE(); 115 116 mutex_enter(&pv_unmanaged.lock); 117 for (pvtp = &pv_unmanaged.list; 118 (pvt = *pvtp) != NULL; 119 pvtp = &pvt->pvt_next) { 120 if (pvt->pvt_start != start) 121 continue; 122 if (pvt->pvt_size != size) 123 panic("pmap_pv_untrack: pv-tracking at 0x%"PRIxPADDR 124 ": 0x%"PRIxPSIZE" bytes, not 0x%"PRIxPSIZE" bytes", 125 pvt->pvt_start, pvt->pvt_size, size); 126 127 /* 128 * Remove from list. Readers can safely see the old 129 * and new states of the list. 130 */ 131 atomic_store_relaxed(pvtp, pvt->pvt_next); 132 133 /* Wait for readers who can see the old state to finish. */ 134 pserialize_perform(pv_unmanaged.psz); 135 136 /* 137 * We now have exclusive access to pvt and can destroy 138 * it. Poison it to catch bugs. 139 */ 140 explicit_memset(&pvt->pvt_next, 0x1a, sizeof pvt->pvt_next); 141 goto out; 142 } 143 panic("pmap_pv_untrack: pages not pv-tracked at 0x%"PRIxPADDR 144 " (0x%"PRIxPSIZE" bytes)", 145 start, size); 146 out: mutex_exit(&pv_unmanaged.lock); 147 148 npages = size >> PAGE_SHIFT; 149 kmem_free(pvt, offsetof(struct pv_track, pvt_pages[npages])); 150 } 151 152 struct pmap_page * 153 pmap_pv_tracked(paddr_t pa) 154 { 155 struct pv_track *pvt; 156 size_t pgno; 157 int s; 158 159 KASSERT(pa == trunc_page(pa)); 160 161 s = pserialize_read_enter(); 162 for (pvt = atomic_load_consume(&pv_unmanaged.list); 163 pvt != NULL; 164 pvt = pvt->pvt_next) { 165 if ((pvt->pvt_start <= pa) && 166 ((pa - pvt->pvt_start) < pvt->pvt_size)) 167 break; 168 } 169 pserialize_read_exit(s); 170 171 if (pvt == NULL) 172 return NULL; 173 KASSERT(pvt->pvt_start <= pa); 174 KASSERT((pa - pvt->pvt_start) < pvt->pvt_size); 175 pgno = (pa - pvt->pvt_start) >> PAGE_SHIFT; 176 return &pvt->pvt_pages[pgno]; 177 } 178 179