1 /* $NetBSD: pmap_pvt.c,v 1.15 2022/05/08 22:03:02 rin 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 1.15 2022/05/08 22:03:02 rin Exp $"); 34 35 #include <sys/param.h> 36 #include <sys/atomic.h> 37 #include <sys/kmem.h> 38 #include <sys/pserialize.h> 39 40 #include <uvm/uvm.h> 41 #include <uvm/pmap/pmap_pvt.h> 42 43 #if !defined(PMAP_PV_TRACK_ONLY_STUBS) 44 /* 45 * unmanaged pv-tracked ranges 46 * 47 * This is a linear list for now because the only user are the DRM 48 * graphics drivers, with a single tracked range per device, for the 49 * graphics aperture, so there are expected to be few of them. 50 * 51 * This is used only after the VM system is initialized well enough 52 * that we can use kmem_alloc. 53 */ 54 55 struct pv_track { 56 paddr_t pvt_start; 57 psize_t pvt_size; 58 struct pv_track *pvt_next; 59 struct pmap_page pvt_pages[]; 60 }; 61 62 static struct { 63 kmutex_t lock; 64 pserialize_t psz; 65 struct pv_track *list; 66 } pv_unmanaged __cacheline_aligned; 67 68 void 69 pmap_pv_init(void) 70 { 71 72 mutex_init(&pv_unmanaged.lock, MUTEX_DEFAULT, IPL_NONE); 73 pv_unmanaged.psz = pserialize_create(); 74 pv_unmanaged.list = NULL; 75 } 76 77 void 78 pmap_pv_track(paddr_t start, psize_t size) 79 { 80 struct pv_track *pvt; 81 size_t npages; 82 83 KASSERT(start == trunc_page(start)); 84 KASSERT(size == trunc_page(size)); 85 86 /* We may sleep for allocation. */ 87 ASSERT_SLEEPABLE(); 88 89 npages = size >> PAGE_SHIFT; 90 pvt = kmem_zalloc(offsetof(struct pv_track, pvt_pages[npages]), 91 KM_SLEEP); 92 pvt->pvt_start = start; 93 pvt->pvt_size = size; 94 95 #ifdef PMAP_PAGE_INIT 96 for (size_t i = 0; i < npages; i++) 97 PMAP_PAGE_INIT(&pvt->pvt_pages[i]); 98 #endif 99 100 mutex_enter(&pv_unmanaged.lock); 101 pvt->pvt_next = pv_unmanaged.list; 102 atomic_store_release(&pv_unmanaged.list, pvt); 103 mutex_exit(&pv_unmanaged.lock); 104 } 105 106 void 107 pmap_pv_untrack(paddr_t start, psize_t size) 108 { 109 struct pv_track **pvtp, *pvt; 110 size_t npages; 111 112 KASSERT(start == trunc_page(start)); 113 KASSERT(size == trunc_page(size)); 114 115 /* We may sleep for pserialize_perform. */ 116 ASSERT_SLEEPABLE(); 117 118 mutex_enter(&pv_unmanaged.lock); 119 for (pvtp = &pv_unmanaged.list; 120 (pvt = *pvtp) != NULL; 121 pvtp = &pvt->pvt_next) { 122 if (pvt->pvt_start != start) 123 continue; 124 if (pvt->pvt_size != size) 125 panic("pmap_pv_untrack: pv-tracking at 0x%"PRIxPADDR 126 ": 0x%"PRIxPSIZE" bytes, not 0x%"PRIxPSIZE" bytes", 127 pvt->pvt_start, pvt->pvt_size, size); 128 129 /* 130 * Remove from list. Readers can safely see the old 131 * and new states of the list. 132 */ 133 atomic_store_relaxed(pvtp, pvt->pvt_next); 134 135 /* Wait for readers who can see the old state to finish. */ 136 pserialize_perform(pv_unmanaged.psz); 137 138 /* 139 * We now have exclusive access to pvt and can destroy 140 * it. Poison it to catch bugs. 141 */ 142 explicit_memset(&pvt->pvt_next, 0x1a, sizeof pvt->pvt_next); 143 goto out; 144 } 145 panic("pmap_pv_untrack: pages not pv-tracked at 0x%"PRIxPADDR 146 " (0x%"PRIxPSIZE" bytes)", 147 start, size); 148 out: mutex_exit(&pv_unmanaged.lock); 149 150 npages = size >> PAGE_SHIFT; 151 kmem_free(pvt, offsetof(struct pv_track, pvt_pages[npages])); 152 } 153 154 struct pmap_page * 155 pmap_pv_tracked(paddr_t pa) 156 { 157 struct pv_track *pvt; 158 size_t pgno; 159 int s; 160 161 KASSERT(pa == trunc_page(pa)); 162 163 s = pserialize_read_enter(); 164 for (pvt = atomic_load_consume(&pv_unmanaged.list); 165 pvt != NULL; 166 pvt = pvt->pvt_next) { 167 if ((pvt->pvt_start <= pa) && 168 ((pa - pvt->pvt_start) < pvt->pvt_size)) 169 break; 170 } 171 pserialize_read_exit(s); 172 173 if (pvt == NULL) 174 return NULL; 175 KASSERT(pvt->pvt_start <= pa); 176 KASSERT((pa - pvt->pvt_start) < pvt->pvt_size); 177 pgno = (pa - pvt->pvt_start) >> PAGE_SHIFT; 178 return &pvt->pvt_pages[pgno]; 179 } 180 181 #else /* PMAP_PV_TRACK_ONLY_STUBS */ 182 /* 183 * Provide empty stubs just for MODULAR kernels. 184 */ 185 186 void 187 pmap_pv_init(void) 188 { 189 190 } 191 192 struct pmap_page * 193 pmap_pv_tracked(paddr_t pa) 194 { 195 196 return NULL; 197 } 198 199 #if notdef 200 /* 201 * pmap_pv_{,un}track() are intentionally commented out. If modules 202 * call these functions, the result should be an inconsistent state. 203 * 204 * Such modules require real PV-tracking support. Let us make the 205 * two symbols undefined, and prevent these modules from loaded. 206 */ 207 void 208 pmap_pv_track(paddr_t start, psize_t size) 209 { 210 211 panic("PV-tracking not supported"); 212 } 213 214 void 215 pmap_pv_untrack(paddr_t start, psize_t size) 216 { 217 218 panic("PV-tracking not supported"); 219 } 220 #endif /* notdef */ 221 222 #endif /* PMAP_PV_TRACK_ONLY_STUBS */ 223