Linux kernel mirror (for testing)
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1/*
2 * Copyright(c) 2015 Intel Corporation. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of version 2 of the GNU General Public License as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 */
13#ifndef __PMEM_H__
14#define __PMEM_H__
15
16#include <linux/io.h>
17#include <linux/uio.h>
18
19#ifdef CONFIG_ARCH_HAS_PMEM_API
20#define ARCH_MEMREMAP_PMEM MEMREMAP_WB
21#include <asm/pmem.h>
22#else
23#define ARCH_MEMREMAP_PMEM MEMREMAP_WT
24/*
25 * These are simply here to enable compilation, all call sites gate
26 * calling these symbols with arch_has_pmem_api() and redirect to the
27 * implementation in asm/pmem.h.
28 */
29static inline bool __arch_has_wmb_pmem(void)
30{
31 return false;
32}
33
34static inline void arch_wmb_pmem(void)
35{
36 BUG();
37}
38
39static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
40 size_t n)
41{
42 BUG();
43}
44
45static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
46 struct iov_iter *i)
47{
48 BUG();
49 return 0;
50}
51
52static inline void arch_clear_pmem(void __pmem *addr, size_t size)
53{
54 BUG();
55}
56
57static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
58{
59 BUG();
60}
61#endif
62
63/*
64 * Architectures that define ARCH_HAS_PMEM_API must provide
65 * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
66 * arch_copy_from_iter_pmem(), arch_clear_pmem(), arch_wb_cache_pmem()
67 * and arch_has_wmb_pmem().
68 */
69static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
70{
71 memcpy(dst, (void __force const *) src, size);
72}
73
74static inline bool arch_has_pmem_api(void)
75{
76 return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
77}
78
79/**
80 * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
81 *
82 * For a given cpu implementation within an architecture it is possible
83 * that wmb_pmem() resolves to a nop. In the case this returns
84 * false, pmem api users are unable to ensure durability and may want to
85 * fall back to a different data consistency model, or otherwise notify
86 * the user.
87 */
88static inline bool arch_has_wmb_pmem(void)
89{
90 return arch_has_pmem_api() && __arch_has_wmb_pmem();
91}
92
93/*
94 * These defaults seek to offer decent performance and minimize the
95 * window between i/o completion and writes being durable on media.
96 * However, it is undefined / architecture specific whether
97 * ARCH_MEMREMAP_PMEM + default_memcpy_to_pmem is sufficient for
98 * making data durable relative to i/o completion.
99 */
100static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src,
101 size_t size)
102{
103 memcpy((void __force *) dst, src, size);
104}
105
106static inline size_t default_copy_from_iter_pmem(void __pmem *addr,
107 size_t bytes, struct iov_iter *i)
108{
109 return copy_from_iter_nocache((void __force *)addr, bytes, i);
110}
111
112static inline void default_clear_pmem(void __pmem *addr, size_t size)
113{
114 if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
115 clear_page((void __force *)addr);
116 else
117 memset((void __force *)addr, 0, size);
118}
119
120/**
121 * memcpy_to_pmem - copy data to persistent memory
122 * @dst: destination buffer for the copy
123 * @src: source buffer for the copy
124 * @n: length of the copy in bytes
125 *
126 * Perform a memory copy that results in the destination of the copy
127 * being effectively evicted from, or never written to, the processor
128 * cache hierarchy after the copy completes. After memcpy_to_pmem()
129 * data may still reside in cpu or platform buffers, so this operation
130 * must be followed by a wmb_pmem().
131 */
132static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
133{
134 if (arch_has_pmem_api())
135 arch_memcpy_to_pmem(dst, src, n);
136 else
137 default_memcpy_to_pmem(dst, src, n);
138}
139
140/**
141 * wmb_pmem - synchronize writes to persistent memory
142 *
143 * After a series of memcpy_to_pmem() operations this drains data from
144 * cpu write buffers and any platform (memory controller) buffers to
145 * ensure that written data is durable on persistent memory media.
146 */
147static inline void wmb_pmem(void)
148{
149 if (arch_has_wmb_pmem())
150 arch_wmb_pmem();
151 else
152 wmb();
153}
154
155/**
156 * copy_from_iter_pmem - copy data from an iterator to PMEM
157 * @addr: PMEM destination address
158 * @bytes: number of bytes to copy
159 * @i: iterator with source data
160 *
161 * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
162 * This function requires explicit ordering with a wmb_pmem() call.
163 */
164static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
165 struct iov_iter *i)
166{
167 if (arch_has_pmem_api())
168 return arch_copy_from_iter_pmem(addr, bytes, i);
169 return default_copy_from_iter_pmem(addr, bytes, i);
170}
171
172/**
173 * clear_pmem - zero a PMEM memory range
174 * @addr: virtual start address
175 * @size: number of bytes to zero
176 *
177 * Write zeros into the memory range starting at 'addr' for 'size' bytes.
178 * This function requires explicit ordering with a wmb_pmem() call.
179 */
180static inline void clear_pmem(void __pmem *addr, size_t size)
181{
182 if (arch_has_pmem_api())
183 arch_clear_pmem(addr, size);
184 else
185 default_clear_pmem(addr, size);
186}
187
188/**
189 * wb_cache_pmem - write back processor cache for PMEM memory range
190 * @addr: virtual start address
191 * @size: number of bytes to write back
192 *
193 * Write back the processor cache range starting at 'addr' for 'size' bytes.
194 * This function requires explicit ordering with a wmb_pmem() call.
195 */
196static inline void wb_cache_pmem(void __pmem *addr, size_t size)
197{
198 if (arch_has_pmem_api())
199 arch_wb_cache_pmem(addr, size);
200}
201#endif /* __PMEM_H__ */