1 /* $NetBSD: linux_kmap.c,v 1.4 2014/03/28 23:22:27 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2013 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 __KERNEL_RCSID(0, "$NetBSD: linux_kmap.c,v 1.4 2014/03/28 23:22:27 riastradh Exp $"); 34 35 #include <sys/types.h> 36 #include <sys/kmem.h> 37 #include <sys/mutex.h> 38 #include <sys/rbtree.h> 39 40 #include <uvm/uvm_extern.h> 41 42 #include <linux/highmem.h> 43 44 /* 45 * XXX Kludgerific implementation of Linux kmap_atomic, which is 46 * required not to fail. To accomodate this, we reserve one page of 47 * kva at boot (or load) and limit the system to at most kmap_atomic in 48 * use at a time. 49 */ 50 51 /* 52 * XXX Use direct-mapped physical pages where available, e.g. amd64. 53 * 54 * XXX ...or add an abstraction to uvm for this. (uvm_emap?) 55 */ 56 57 static kmutex_t linux_kmap_atomic_lock; 58 static vaddr_t linux_kmap_atomic_vaddr; 59 60 static kmutex_t linux_kmap_lock; 61 static rb_tree_t linux_kmap_entries; 62 63 struct linux_kmap_entry { 64 paddr_t lke_paddr; 65 vaddr_t lke_vaddr; 66 unsigned int lke_refcnt; 67 rb_node_t lke_node; 68 }; 69 70 static int 71 lke_compare_nodes(void *ctx __unused, const void *an, const void *bn) 72 { 73 const struct linux_kmap_entry *const a = an; 74 const struct linux_kmap_entry *const b = bn; 75 76 if (a->lke_paddr < b->lke_paddr) 77 return -1; 78 else if (a->lke_paddr > b->lke_paddr) 79 return +1; 80 else 81 return 0; 82 } 83 84 static int 85 lke_compare_key(void *ctx __unused, const void *node, const void *key) 86 { 87 const struct linux_kmap_entry *const lke = node; 88 const paddr_t *const paddrp = key; 89 90 if (lke->lke_paddr < *paddrp) 91 return -1; 92 else if (lke->lke_paddr > *paddrp) 93 return +1; 94 else 95 return 0; 96 } 97 98 static const rb_tree_ops_t linux_kmap_entry_ops = { 99 .rbto_compare_nodes = &lke_compare_nodes, 100 .rbto_compare_key = &lke_compare_key, 101 .rbto_node_offset = offsetof(struct linux_kmap_entry, lke_node), 102 .rbto_context = NULL, 103 }; 104 105 int 106 linux_kmap_init(void) 107 { 108 109 /* IPL_VM is needed to block pmap_kenter_pa. */ 110 mutex_init(&linux_kmap_atomic_lock, MUTEX_DEFAULT, IPL_VM); 111 112 linux_kmap_atomic_vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0, 113 (UVM_KMF_VAONLY | UVM_KMF_WAITVA)); 114 115 KASSERT(linux_kmap_atomic_vaddr != 0); 116 KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL)); 117 118 mutex_init(&linux_kmap_lock, MUTEX_DEFAULT, IPL_VM); 119 rb_tree_init(&linux_kmap_entries, &linux_kmap_entry_ops); 120 121 return 0; 122 } 123 124 void 125 linux_kmap_fini(void) 126 { 127 128 KASSERT(rb_tree_iterate(&linux_kmap_entries, NULL, RB_DIR_RIGHT) == 129 NULL); 130 #if 0 /* XXX no rb_tree_destroy*/ 131 rb_tree_destroy(&linux_kmap_entries); 132 #endif 133 mutex_destroy(&linux_kmap_lock); 134 135 KASSERT(linux_kmap_atomic_vaddr != 0); 136 KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL)); 137 138 uvm_km_free(kernel_map, linux_kmap_atomic_vaddr, PAGE_SIZE, 139 (UVM_KMF_VAONLY | UVM_KMF_WAITVA)); 140 141 mutex_destroy(&linux_kmap_atomic_lock); 142 } 143 144 void * 145 kmap_atomic(struct page *page) 146 { 147 const paddr_t paddr = uvm_vm_page_to_phys(&page->p_vmp); 148 149 mutex_spin_enter(&linux_kmap_atomic_lock); 150 151 KASSERT(linux_kmap_atomic_vaddr != 0); 152 KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL)); 153 154 const vaddr_t vaddr = linux_kmap_atomic_vaddr; 155 const int prot = (VM_PROT_READ | VM_PROT_WRITE); 156 const int flags = 0; 157 pmap_kenter_pa(vaddr, paddr, prot, flags); 158 pmap_update(pmap_kernel()); 159 160 return (void *)vaddr; 161 } 162 163 void 164 kunmap_atomic(void *addr) 165 { 166 const vaddr_t vaddr = (vaddr_t)addr; 167 168 KASSERT(mutex_owned(&linux_kmap_atomic_lock)); 169 KASSERT(linux_kmap_atomic_vaddr == vaddr); 170 KASSERT(pmap_extract(pmap_kernel(), vaddr, NULL)); 171 172 pmap_kremove(vaddr, PAGE_SIZE); 173 pmap_update(pmap_kernel()); 174 175 mutex_spin_exit(&linux_kmap_atomic_lock); 176 } 177 178 void * 179 kmap(struct page *page) 180 { 181 const paddr_t paddr = VM_PAGE_TO_PHYS(&page->p_vmp); 182 const vaddr_t vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0, 183 (UVM_KMF_VAONLY | UVM_KMF_WAITVA)); 184 KASSERT(vaddr != 0); 185 186 struct linux_kmap_entry *const lke = kmem_alloc(sizeof(*lke), 187 KM_SLEEP); 188 lke->lke_paddr = paddr; 189 lke->lke_vaddr = vaddr; 190 191 mutex_spin_enter(&linux_kmap_lock); 192 struct linux_kmap_entry *const collision __unused = 193 rb_tree_insert_node(&linux_kmap_entries, lke); 194 KASSERT(collision == lke); 195 mutex_spin_exit(&linux_kmap_lock); 196 197 KASSERT(!pmap_extract(pmap_kernel(), vaddr, NULL)); 198 const int prot = (VM_PROT_READ | VM_PROT_WRITE); 199 const int flags = 0; 200 pmap_kenter_pa(vaddr, paddr, prot, flags); 201 pmap_update(pmap_kernel()); 202 203 return (void *)vaddr; 204 } 205 206 void 207 kunmap(struct page *page) 208 { 209 const paddr_t paddr = VM_PAGE_TO_PHYS(&page->p_vmp); 210 211 mutex_spin_enter(&linux_kmap_lock); 212 struct linux_kmap_entry *const lke = 213 rb_tree_find_node(&linux_kmap_entries, &paddr); 214 KASSERT(lke != NULL); 215 rb_tree_remove_node(&linux_kmap_entries, lke); 216 mutex_spin_exit(&linux_kmap_lock); 217 218 const vaddr_t vaddr = lke->lke_vaddr; 219 kmem_free(lke, sizeof(*lke)); 220 221 KASSERT(pmap_extract(pmap_kernel(), vaddr, NULL)); 222 223 pmap_kremove(vaddr, PAGE_SIZE); 224 pmap_update(pmap_kernel()); 225 226 uvm_km_free(kernel_map, vaddr, PAGE_SIZE, UVM_KMF_VAONLY); 227 } 228