Linux kernel mirror (for testing)
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linux
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 int arch_memcpy_from_pmem(void *dst, const void __pmem *src,
46 size_t n)
47{
48 BUG();
49 return -EFAULT;
50}
51
52static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
53 struct iov_iter *i)
54{
55 BUG();
56 return 0;
57}
58
59static inline void arch_clear_pmem(void __pmem *addr, size_t size)
60{
61 BUG();
62}
63
64static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
65{
66 BUG();
67}
68
69static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
70{
71 BUG();
72}
73#endif
74
75/*
76 * memcpy_from_pmem - read from persistent memory with error handling
77 * @dst: destination buffer
78 * @src: source buffer
79 * @size: transfer length
80 *
81 * Returns 0 on success negative error code on failure.
82 */
83static inline int memcpy_from_pmem(void *dst, void __pmem const *src,
84 size_t size)
85{
86 return arch_memcpy_from_pmem(dst, src, size);
87}
88
89static inline bool arch_has_pmem_api(void)
90{
91 return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
92}
93
94/**
95 * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
96 *
97 * For a given cpu implementation within an architecture it is possible
98 * that wmb_pmem() resolves to a nop. In the case this returns
99 * false, pmem api users are unable to ensure durability and may want to
100 * fall back to a different data consistency model, or otherwise notify
101 * the user.
102 */
103static inline bool arch_has_wmb_pmem(void)
104{
105 return arch_has_pmem_api() && __arch_has_wmb_pmem();
106}
107
108/*
109 * These defaults seek to offer decent performance and minimize the
110 * window between i/o completion and writes being durable on media.
111 * However, it is undefined / architecture specific whether
112 * ARCH_MEMREMAP_PMEM + default_memcpy_to_pmem is sufficient for
113 * making data durable relative to i/o completion.
114 */
115static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src,
116 size_t size)
117{
118 memcpy((void __force *) dst, src, size);
119}
120
121static inline size_t default_copy_from_iter_pmem(void __pmem *addr,
122 size_t bytes, struct iov_iter *i)
123{
124 return copy_from_iter_nocache((void __force *)addr, bytes, i);
125}
126
127static inline void default_clear_pmem(void __pmem *addr, size_t size)
128{
129 if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
130 clear_page((void __force *)addr);
131 else
132 memset((void __force *)addr, 0, size);
133}
134
135/**
136 * memcpy_to_pmem - copy data to persistent memory
137 * @dst: destination buffer for the copy
138 * @src: source buffer for the copy
139 * @n: length of the copy in bytes
140 *
141 * Perform a memory copy that results in the destination of the copy
142 * being effectively evicted from, or never written to, the processor
143 * cache hierarchy after the copy completes. After memcpy_to_pmem()
144 * data may still reside in cpu or platform buffers, so this operation
145 * must be followed by a wmb_pmem().
146 */
147static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
148{
149 if (arch_has_pmem_api())
150 arch_memcpy_to_pmem(dst, src, n);
151 else
152 default_memcpy_to_pmem(dst, src, n);
153}
154
155/**
156 * wmb_pmem - synchronize writes to persistent memory
157 *
158 * After a series of memcpy_to_pmem() operations this drains data from
159 * cpu write buffers and any platform (memory controller) buffers to
160 * ensure that written data is durable on persistent memory media.
161 */
162static inline void wmb_pmem(void)
163{
164 if (arch_has_wmb_pmem())
165 arch_wmb_pmem();
166 else
167 wmb();
168}
169
170/**
171 * copy_from_iter_pmem - copy data from an iterator to PMEM
172 * @addr: PMEM destination address
173 * @bytes: number of bytes to copy
174 * @i: iterator with source data
175 *
176 * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
177 * This function requires explicit ordering with a wmb_pmem() call.
178 */
179static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
180 struct iov_iter *i)
181{
182 if (arch_has_pmem_api())
183 return arch_copy_from_iter_pmem(addr, bytes, i);
184 return default_copy_from_iter_pmem(addr, bytes, i);
185}
186
187/**
188 * clear_pmem - zero a PMEM memory range
189 * @addr: virtual start address
190 * @size: number of bytes to zero
191 *
192 * Write zeros into the memory range starting at 'addr' for 'size' bytes.
193 * This function requires explicit ordering with a wmb_pmem() call.
194 */
195static inline void clear_pmem(void __pmem *addr, size_t size)
196{
197 if (arch_has_pmem_api())
198 arch_clear_pmem(addr, size);
199 else
200 default_clear_pmem(addr, size);
201}
202
203/**
204 * invalidate_pmem - flush a pmem range from the cache hierarchy
205 * @addr: virtual start address
206 * @size: bytes to invalidate (internally aligned to cache line size)
207 *
208 * For platforms that support clearing poison this flushes any poisoned
209 * ranges out of the cache
210 */
211static inline void invalidate_pmem(void __pmem *addr, size_t size)
212{
213 if (arch_has_pmem_api())
214 arch_invalidate_pmem(addr, size);
215}
216
217/**
218 * wb_cache_pmem - write back processor cache for PMEM memory range
219 * @addr: virtual start address
220 * @size: number of bytes to write back
221 *
222 * Write back the processor cache range starting at 'addr' for 'size' bytes.
223 * This function requires explicit ordering with a wmb_pmem() call.
224 */
225static inline void wb_cache_pmem(void __pmem *addr, size_t size)
226{
227 if (arch_has_pmem_api())
228 arch_wb_cache_pmem(addr, size);
229}
230#endif /* __PMEM_H__ */