1/* $OpenBSD: uvm_pmemrange.h,v 1.20 2026/01/28 21:09:41 deraadt Exp $ */
2
3/*
4 * Copyright (c) 2009 Ariane van der Steldt <ariane@stack.nl>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19/*
20 * uvm_pmemrange.h: describe and manage free physical memory.
21 */
22
23#ifndef _UVM_UVM_PMEMRANGE_H_
24#define _UVM_UVM_PMEMRANGE_H_
25
26RBT_HEAD(uvm_pmr_addr, vm_page);
27RBT_HEAD(uvm_pmr_size, vm_page);
28
29/*
30 * Page types available:
31 * - DIRTY: this page may contain random data.
32 * - ZERO: this page has been zeroed.
33 */
34#define UVM_PMR_MEMTYPE_DIRTY 0
35#define UVM_PMR_MEMTYPE_ZERO 1
36#define UVM_PMR_MEMTYPE_MAX 2
37
38/*
39 * An address range of memory.
40 */
41struct uvm_pmemrange {
42 struct uvm_pmr_addr addr; /* Free page chunks, sorted by addr. */
43 struct uvm_pmr_size size[UVM_PMR_MEMTYPE_MAX];
44 /* Free page chunks, sorted by size. */
45 TAILQ_HEAD(, vm_page) single[UVM_PMR_MEMTYPE_MAX];
46 /* single page regions (uses pageq) */
47
48 paddr_t low; /* Start of address range (pgno). */
49 paddr_t high; /* End +1 (pgno). */
50 int use; /* Use counter. */
51 psize_t nsegs; /* Current range count. */
52
53 TAILQ_ENTRY(uvm_pmemrange) pmr_use;
54 /* pmr, sorted by use */
55 RBT_ENTRY(uvm_pmemrange) pmr_addr;
56 /* pmr, sorted by address */
57};
58
59/*
60 * Description of failing memory allocation.
61 *
62 * Every descriptor corresponds to a request for the page daemon to release
63 * pages in a given memory range. There is one global descriptor for nowait
64 * allocations, all others are sitting on the stack of processes waiting for
65 * physical pages.
66 *
67 * There are multiple ways physical pages can become available:
68 * [1] unmanaged pages are released by shrinkers (bufbackoff(), drmbackoff()...)
69 * [2] page daemon drops them (we notice because they are freed)
70 * [3] a process calls free or exit
71 *
72 * The buffer cache and page daemon can decide that they don't have the
73 * ability to make pages available in the requested range. In that case,
74 * the FAIL bit will be set.
75 * XXX There's a possibility that a page is no longer on the queues but
76 * XXX has not yet been freed, or that a page was busy.
77 * XXX Also, wired pages are not considered for paging, so they could
78 * XXX cause a failure that may be recoverable.
79 *
80 * Locks used to protect struct members in this file:
81 * F uvm_lock_fpageq
82 * I immutable after creation
83 */
84struct uvm_pmalloc {
85 TAILQ_ENTRY(uvm_pmalloc) pmq; /* [F] next request */
86 struct uvm_constraint_range pm_constraint; /* [I] memory range */
87 psize_t pm_size; /* [I] # pages */
88 int pm_flags; /* [F] states flags */
89};
90
91/*
92 * Indicate to the page daemon that a nowait call failed and it should
93 * recover at least some memory in the most restricted region (assumed
94 * to be dma_constraint).
95 */
96extern struct uvm_pmalloc nowait_pma; /* [F] */
97
98
99/*
100 * uvm_pmalloc flags.
101 */
102#define UVM_PMA_LINKED 0x01 /* uvm_pmalloc is on list */
103#define UVM_PMA_FAIL 0x10 /* page daemon cannot free pages */
104#define UVM_PMA_FREED 0x20 /* at least one page in the range was freed */
105
106RBT_HEAD(uvm_pmemrange_addr, uvm_pmemrange);
107TAILQ_HEAD(uvm_pmemrange_use, uvm_pmemrange);
108
109/*
110 * pmr control structure. Contained in uvm.pmr_control.
111 */
112struct uvm_pmr_control {
113 struct uvm_pmemrange_addr addr;
114 struct uvm_pmemrange_use use;
115
116 /* Only changed while fpageq is locked. */
117 TAILQ_HEAD(, uvm_pmalloc) allocs;
118};
119
120void uvm_pmr_freepages(struct vm_page *, psize_t);
121void uvm_pmr_freepageq(struct pglist *);
122int uvm_pmr_getpages(psize_t, paddr_t, paddr_t, paddr_t, paddr_t,
123 int, int, struct pglist *);
124void uvm_pmr_init(void);
125int uvm_wait_pla(paddr_t, paddr_t, paddr_t, int);
126void uvm_wakeup_pla(paddr_t, psize_t);
127
128#if defined(DDB) || defined(DEBUG)
129int uvm_pmr_isfree(struct vm_page *pg);
130#endif
131
132/*
133 * Internal tree logic.
134 */
135
136int uvm_pmr_addr_cmp(const struct vm_page *, const struct vm_page *);
137int uvm_pmr_size_cmp(const struct vm_page *, const struct vm_page *);
138
139RBT_PROTOTYPE(uvm_pmr_addr, vm_page, objt, uvm_pmr_addr_cmp);
140RBT_PROTOTYPE(uvm_pmr_size, vm_page, objt, uvm_pmr_size_cmp);
141RBT_PROTOTYPE(uvm_pmemrange_addr, uvm_pmemrange, pmr_addr,
142 uvm_pmemrange_addr_cmp);
143
144struct vm_page *uvm_pmr_insert_addr(struct uvm_pmemrange *,
145 struct vm_page *, int);
146void uvm_pmr_insert_size(struct uvm_pmemrange *,
147 struct vm_page *);
148struct vm_page *uvm_pmr_insert(struct uvm_pmemrange *,
149 struct vm_page *, int);
150void uvm_pmr_remove_addr(struct uvm_pmemrange *,
151 struct vm_page *);
152void uvm_pmr_remove_size(struct uvm_pmemrange *,
153 struct vm_page *);
154void uvm_pmr_remove(struct uvm_pmemrange *,
155 struct vm_page *);
156struct vm_page *uvm_pmr_extract_range(struct uvm_pmemrange *,
157 struct vm_page *, paddr_t, paddr_t,
158 struct pglist *);
159struct vm_page *uvm_pmr_cache_get(int);
160void uvm_pmr_cache_put(struct vm_page *);
161unsigned int uvm_pmr_cache_drain(void);
162
163
164#endif /* _UVM_UVM_PMEMRANGE_H_ */