1/*	$NetBSD: linux_kmap.c,v 1.16 2018/08/27 15:28:53 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 1.16 2018/08/27 15:28:53 riastradh Exp $");
34
35#include <sys/types.h>
36#include <sys/kmem.h>
37#include <sys/mutex.h>
38#include <sys/rbtree.h>
39#include <sys/sdt.h>
40
41#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
42#include <dev/mm.h>
43#endif
44
45#include <uvm/uvm_extern.h>
46
47#include <linux/highmem.h>
48
49SDT_PROBE_DEFINE2(sdt, linux, kmap, map,
50    "paddr_t"/*paddr*/, "vaddr_t"/*vaddr*/);
51SDT_PROBE_DEFINE2(sdt, linux, kmap, unmap,
52    "paddr_t"/*paddr*/, "vaddr_t"/*vaddr*/);
53SDT_PROBE_DEFINE2(sdt, linux, kmap, map__atomic,
54    "paddr_t"/*paddr*/, "vaddr_t"/*vaddr*/);
55SDT_PROBE_DEFINE2(sdt, linux, kmap, unmap__atomic,
56    "paddr_t"/*paddr*/, "vaddr_t"/*vaddr*/);
57
58/*
59 * XXX Kludgerific implementation of Linux kmap_atomic, which is
60 * required not to fail.  To accomodate this, we reserve one page of
61 * kva at boot (or load) and limit the system to at most kmap_atomic in
62 * use at a time.
63 */
64
65static kmutex_t linux_kmap_atomic_lock;
66static vaddr_t linux_kmap_atomic_vaddr;
67
68static kmutex_t linux_kmap_lock;
69static rb_tree_t linux_kmap_entries;
70
71struct linux_kmap_entry {
72	paddr_t		lke_paddr;
73	vaddr_t		lke_vaddr;
74	unsigned int	lke_refcnt;
75	rb_node_t	lke_node;
76};
77
78static int
79lke_compare_nodes(void *ctx __unused, const void *an, const void *bn)
80{
81	const struct linux_kmap_entry *const a = an;
82	const struct linux_kmap_entry *const b = bn;
83
84	if (a->lke_paddr < b->lke_paddr)
85		return -1;
86	else if (a->lke_paddr > b->lke_paddr)
87		return +1;
88	else
89		return 0;
90}
91
92static int
93lke_compare_key(void *ctx __unused, const void *node, const void *key)
94{
95	const struct linux_kmap_entry *const lke = node;
96	const paddr_t *const paddrp = key;
97
98	if (lke->lke_paddr < *paddrp)
99		return -1;
100	else if (lke->lke_paddr > *paddrp)
101		return +1;
102	else
103		return 0;
104}
105
106static const rb_tree_ops_t linux_kmap_entry_ops = {
107	.rbto_compare_nodes = &lke_compare_nodes,
108	.rbto_compare_key = &lke_compare_key,
109	.rbto_node_offset = offsetof(struct linux_kmap_entry, lke_node),
110	.rbto_context = NULL,
111};
112
113int
114linux_kmap_init(void)
115{
116
117	/* IPL_VM since interrupt handlers use kmap_atomic.  */
118	mutex_init(&linux_kmap_atomic_lock, MUTEX_DEFAULT, IPL_VM);
119
120	linux_kmap_atomic_vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
121	    (UVM_KMF_VAONLY | UVM_KMF_WAITVA));
122
123	KASSERT(linux_kmap_atomic_vaddr != 0);
124	KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));
125
126	mutex_init(&linux_kmap_lock, MUTEX_DEFAULT, IPL_NONE);
127	rb_tree_init(&linux_kmap_entries, &linux_kmap_entry_ops);
128
129	return 0;
130}
131
132void
133linux_kmap_fini(void)
134{
135
136	KASSERT(RB_TREE_MIN(&linux_kmap_entries) == NULL);
137#if 0				/* XXX no rb_tree_destroy */
138	rb_tree_destroy(&linux_kmap_entries);
139#endif
140	mutex_destroy(&linux_kmap_lock);
141
142	KASSERT(linux_kmap_atomic_vaddr != 0);
143	KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));
144
145	uvm_km_free(kernel_map, linux_kmap_atomic_vaddr, PAGE_SIZE,
146	    (UVM_KMF_VAONLY | UVM_KMF_WAITVA));
147
148	mutex_destroy(&linux_kmap_atomic_lock);
149}
150
151void *
152kmap_atomic(struct page *page)
153{
154	const paddr_t paddr = uvm_vm_page_to_phys(&page->p_vmp);
155	vaddr_t vaddr;
156
157#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
158	if (mm_md_direct_mapped_phys(paddr, &vaddr))
159		goto out;
160#endif
161
162	mutex_spin_enter(&linux_kmap_atomic_lock);
163	KASSERT(linux_kmap_atomic_vaddr != 0);
164	KASSERT(!pmap_extract(pmap_kernel(), linux_kmap_atomic_vaddr, NULL));
165	vaddr = linux_kmap_atomic_vaddr;
166	pmap_kenter_pa(vaddr, paddr, (VM_PROT_READ | VM_PROT_WRITE), 0);
167	pmap_update(pmap_kernel());
168
169#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
170out:
171#endif
172	SDT_PROBE2(sdt, linux, kmap, map__atomic,  paddr, vaddr);
173	return (void *)vaddr;
174}
175
176void
177kunmap_atomic(void *addr)
178{
179	const vaddr_t vaddr = (vaddr_t)addr;
180	paddr_t paddr;
181	bool ok __diagused;
182
183	ok = pmap_extract(pmap_kernel(), vaddr, &paddr);
184	KASSERT(ok);
185
186	SDT_PROBE2(sdt, linux, kmap, unmap__atomic,  paddr, vaddr);
187
188#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
189    {
190	vaddr_t vaddr1;
191	if (mm_md_direct_mapped_phys(paddr, &vaddr1) && vaddr1 == vaddr)
192		return;
193    }
194#endif
195
196	KASSERT(mutex_owned(&linux_kmap_atomic_lock));
197	KASSERT(linux_kmap_atomic_vaddr == vaddr);
198
199	pmap_kremove(vaddr, PAGE_SIZE);
200	pmap_update(pmap_kernel());
201
202	mutex_spin_exit(&linux_kmap_atomic_lock);
203}
204
205void *
206kmap(struct page *page)
207{
208	const paddr_t paddr = VM_PAGE_TO_PHYS(&page->p_vmp);
209	vaddr_t vaddr;
210
211	ASSERT_SLEEPABLE();
212
213#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
214	if (mm_md_direct_mapped_phys(paddr, &vaddr))
215		goto out;
216#endif
217
218	vaddr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
219	    (UVM_KMF_VAONLY | UVM_KMF_WAITVA));
220	KASSERT(vaddr != 0);
221
222	struct linux_kmap_entry *const lke = kmem_alloc(sizeof(*lke),
223	    KM_SLEEP);
224	lke->lke_paddr = paddr;
225	lke->lke_vaddr = vaddr;
226
227	mutex_enter(&linux_kmap_lock);
228	struct linux_kmap_entry *const collision __diagused =
229	    rb_tree_insert_node(&linux_kmap_entries, lke);
230	KASSERT(collision == lke);
231	mutex_exit(&linux_kmap_lock);
232
233	KASSERT(!pmap_extract(pmap_kernel(), vaddr, NULL));
234	pmap_kenter_pa(vaddr, paddr, (VM_PROT_READ | VM_PROT_WRITE), 0);
235	pmap_update(pmap_kernel());
236
237#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
238out:
239#endif
240	SDT_PROBE2(sdt, linux, kmap, map,  paddr, vaddr);
241	return (void *)vaddr;
242}
243
244void
245kunmap(struct page *page)
246{
247	const paddr_t paddr = VM_PAGE_TO_PHYS(&page->p_vmp);
248	vaddr_t vaddr;
249
250	ASSERT_SLEEPABLE();
251
252#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
253	if (mm_md_direct_mapped_phys(paddr, &vaddr))
254		goto out;
255#endif
256
257	mutex_enter(&linux_kmap_lock);
258	struct linux_kmap_entry *const lke =
259	    rb_tree_find_node(&linux_kmap_entries, &paddr);
260	KASSERT(lke != NULL);
261	rb_tree_remove_node(&linux_kmap_entries, lke);
262	mutex_exit(&linux_kmap_lock);
263
264	vaddr = lke->lke_vaddr;
265	kmem_free(lke, sizeof(*lke));
266
267	KASSERT(pmap_extract(pmap_kernel(), vaddr, NULL));
268
269	pmap_kremove(vaddr, PAGE_SIZE);
270	pmap_update(pmap_kernel());
271
272	uvm_km_free(kernel_map, vaddr, PAGE_SIZE, UVM_KMF_VAONLY);
273
274#ifdef __HAVE_MM_MD_DIRECT_MAPPED_PHYS
275out:
276#endif
277	SDT_PROBE2(sdt, linux, kmap, unmap,  paddr, vaddr);
278}
279