1 /* $NetBSD: linux_kmap.c,v 1.12 2015/01/01 01:15:43 mrg 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 1.12 2015/01/01 01:15:43 mrg Exp $");
34
35 #include <sys/types.h>
36 #include <sys/kmem.h>
37 #include <sys/mutex.h>
38 #include <sys/rbtree.h>
39
40 #ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
41 #include <dev/mm.h>
42 #endif
43
44 #include <uvm/uvm_extern.h>
45
46 #include <linux/highmem.h>
47
48 /*
49 * XXX Kludgerific implementation of Linux kmap_atomic, which is
50 * required not to fail. To accomodate this, we reserve one page of
51 * kva at boot (or load) and limit the system to at most kmap_atomic in
52 * use at a time.
53 */
54
55 static kmutex_t linux_kmap_atomic_lock;
56 static vaddr_t linux_kmap_atomic_vaddr;
57
58 static kmutex_t linux_kmap_lock;
59 static rb_tree_t linux_kmap_entries;
60
61 struct linux_kmap_entry {
62 paddr_t lke_paddr;
63 vaddr_t lke_vaddr;
64 unsigned int lke_refcnt;
65 rb_node_t lke_node;
66 };
67
68 static int
lke_compare_nodes(void * ctx __unused,const void * an,const void * bn)69 lke_compare_nodes(void *ctx __unused, const void *an, const void *bn)
70 {
71 const struct linux_kmap_entry *const a = an;
72 const struct linux_kmap_entry *const b = bn;
73
74 if (a->lke_paddr < b->lke_paddr)
75 return -1;
76 else if (a->lke_paddr > b->lke_paddr)
77 return +1;
78 else
79 return 0;
80 }
81
82 static int
lke_compare_key(void * ctx __unused,const void * node,const void * key)83 lke_compare_key(void *ctx __unused, const void *node, const void *key)
84 {
85 const struct linux_kmap_entry *const lke = node;
86 const paddr_t *const paddrp = key;
87
88 if (lke->lke_paddr < *paddrp)
89 return -1;
90 else if (lke->lke_paddr > *paddrp)
91 return +1;
92 else
93 return 0;
94 }
95
96 static const rb_tree_ops_t linux_kmap_entry_ops = {
97 .rbto_compare_nodes = &lke_compare_nodes,
98 .rbto_compare_key = &lke_compare_key,
99 .rbto_node_offset = offsetof(struct linux_kmap_entry, lke_node),
100 .rbto_context = NULL,
101 };
102
103 int
linux_kmap_init(void)104 linux_kmap_init(void)
105 {
106
107 /* IPL_VM since interrupt handlers use kmap_atomic. */
108 mutex_init(&linux_kmap_atomic_lock, MUTEX_DEFAULT, IPL_VM);
109
110 linux_kmap_atomic_vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
111 (UVM_KMF_VAONLY | UVM_KMF_WAITVA));
112
113 KASSERT(linux_kmap_atomic_vaddr != 0);
114 KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));
115
116 mutex_init(&linux_kmap_lock, MUTEX_DEFAULT, IPL_NONE);
117 rb_tree_init(&linux_kmap_entries, &linux_kmap_entry_ops);
118
119 return 0;
120 }
121
122 void
linux_kmap_fini(void)123 linux_kmap_fini(void)
124 {
125
126 KASSERT(RB_TREE_MIN(&linux_kmap_entries) == NULL);
127 #if 0 /* XXX no rb_tree_destroy */
128 rb_tree_destroy(&linux_kmap_entries);
129 #endif
130 mutex_destroy(&linux_kmap_lock);
131
132 KASSERT(linux_kmap_atomic_vaddr != 0);
133 KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));
134
135 uvm_km_free(kernel_map, linux_kmap_atomic_vaddr, PAGE_SIZE,
136 (UVM_KMF_VAONLY | UVM_KMF_WAITVA));
137
138 mutex_destroy(&linux_kmap_atomic_lock);
139 }
140
141 void *
kmap_atomic(struct page * page)142 kmap_atomic(struct page *page)
143 {
144 const paddr_t paddr = uvm_vm_page_to_phys(&page->p_vmp);
145 vaddr_t vaddr;
146
147 #ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
148 if (mm_md_direct_mapped_phys(paddr, &vaddr))
149 return (void *)vaddr;
150 #endif
151
152 mutex_spin_enter(&linux_kmap_atomic_lock);
153 KASSERT(linux_kmap_atomic_vaddr != 0);
154 KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));
155 vaddr = linux_kmap_atomic_vaddr;
156 pmap_kenter_pa(vaddr, paddr, (VM_PROT_READ | VM_PROT_WRITE), 0);
157 pmap_update(pmap_kernel());
158
159 return (void *)vaddr;
160 }
161
162 void
kunmap_atomic(void * addr)163 kunmap_atomic(void *addr)
164 {
165 const vaddr_t vaddr = (vaddr_t)addr;
166
167 #ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
168 {
169 paddr_t paddr;
170 vaddr_t vaddr1;
171 bool ok __diagused;
172
173 ok = pmap_extract(pmap_kernel(), vaddr, &paddr);
174 KASSERT(ok);
175 if (mm_md_direct_mapped_phys(paddr, &vaddr1) && vaddr1 == vaddr)
176 return;
177 }
178 #endif
179
180 KASSERT(mutex_owned(&linux_kmap_atomic_lock));
181 KASSERT(linux_kmap_atomic_vaddr == vaddr);
182 KASSERT(pmap_extract(pmap_kernel(), vaddr, NULL));
183
184 pmap_kremove(vaddr, PAGE_SIZE);
185 pmap_update(pmap_kernel());
186
187 mutex_spin_exit(&linux_kmap_atomic_lock);
188 }
189
190 void *
kmap(struct page * page)191 kmap(struct page *page)
192 {
193 const paddr_t paddr = VM_PAGE_TO_PHYS(&page->p_vmp);
194 vaddr_t vaddr;
195
196 ASSERT_SLEEPABLE();
197
198 #ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
199 if (mm_md_direct_mapped_phys(paddr, &vaddr))
200 return (void *)vaddr;
201 #endif
202
203 vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
204 (UVM_KMF_VAONLY | UVM_KMF_WAITVA));
205 KASSERT(vaddr != 0);
206
207 struct linux_kmap_entry *const lke = kmem_alloc(sizeof(*lke),
208 KM_SLEEP);
209 lke->lke_paddr = paddr;
210 lke->lke_vaddr = vaddr;
211
212 mutex_enter(&linux_kmap_lock);
213 struct linux_kmap_entry *const collision __diagused =
214 rb_tree_insert_node(&linux_kmap_entries, lke);
215 KASSERT(collision == lke);
216 mutex_exit(&linux_kmap_lock);
217
218 KASSERT(!pmap_extract(pmap_kernel(), vaddr, NULL));
219 pmap_kenter_pa(vaddr, paddr, (VM_PROT_READ | VM_PROT_WRITE), 0);
220 pmap_update(pmap_kernel());
221
222 return (void *)vaddr;
223 }
224
225 void
kunmap(struct page * page)226 kunmap(struct page *page)
227 {
228 const paddr_t paddr = VM_PAGE_TO_PHYS(&page->p_vmp);
229
230 ASSERT_SLEEPABLE();
231
232 #ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
233 {
234 vaddr_t vaddr1;
235
236 if (mm_md_direct_mapped_phys(paddr, &vaddr1))
237 return;
238 }
239 #endif
240
241 mutex_enter(&linux_kmap_lock);
242 struct linux_kmap_entry *const lke =
243 rb_tree_find_node(&linux_kmap_entries, &paddr);
244 KASSERT(lke != NULL);
245 rb_tree_remove_node(&linux_kmap_entries, lke);
246 mutex_exit(&linux_kmap_lock);
247
248 const vaddr_t vaddr = lke->lke_vaddr;
249 kmem_free(lke, sizeof(*lke));
250
251 KASSERT(pmap_extract(pmap_kernel(), vaddr, NULL));
252
253 pmap_kremove(vaddr, PAGE_SIZE);
254 pmap_update(pmap_kernel());
255
256 uvm_km_free(kernel_map, vaddr, PAGE_SIZE, UVM_KMF_VAONLY);
257 }
258