include/linux/pmem.h

   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  */
  29 static inline bool __arch_has_wmb_pmem(void)
  30 {
  31         return false;
  32 }
  33
  34 static inline void arch_wmb_pmem(void)
  35 {
  36         BUG();
  37 }
  38
  39 static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
  40                 size_t n)
  41 {
  42         BUG();
  43 }
  44
  45 static inline int arch_memcpy_from_pmem(void *dst, const void __pmem *src,
  46                 size_t n)
  47 {
  48         BUG();
  49         return -EFAULT;
  50 }
  51
  52 static 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
  59 static inline void arch_clear_pmem(void __pmem *addr, size_t size)
  60 {
  61         BUG();
  62 }
  63
  64 static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
  65 {
  66         BUG();
  67 }
  68
  69 static 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  */
  83 static 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
  89 static 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  */
 103 static 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  */
 115 static 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
 121 static 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
 127 static 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  */
 147 static 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  */
 162 static 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  */
 179 static 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  */
 195 static 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  */
 211 static 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  */
 225 static 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__ */