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 static inline bool arch_has_pmem_api(void)
  76 {
  77         return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
  78 }
  79
  80 static inline int default_memcpy_from_pmem(void *dst, void __pmem const *src,
  81                 size_t size)
  82 {
  83         memcpy(dst, (void __force *) src, size);
  84         return 0;
  85 }
  86
  87 /*
  88  * memcpy_from_pmem - read from persistent memory with error handling
  89  * @dst: destination buffer
  90  * @src: source buffer
  91  * @size: transfer length
  92  *
  93  * Returns 0 on success negative error code on failure.
  94  */
  95 static inline int memcpy_from_pmem(void *dst, void __pmem const *src,
  96                 size_t size)
  97 {
  98         if (arch_has_pmem_api())
  99                 return arch_memcpy_from_pmem(dst, src, size);
 100         else
 101                 return default_memcpy_from_pmem(dst, src, size);
 102 }
 103
 104 /**
 105  * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
 106  *
 107  * For a given cpu implementation within an architecture it is possible
 108  * that wmb_pmem() resolves to a nop.  In the case this returns
 109  * false, pmem api users are unable to ensure durability and may want to
 110  * fall back to a different data consistency model, or otherwise notify
 111  * the user.
 112  */
 113 static inline bool arch_has_wmb_pmem(void)
 114 {
 115         return arch_has_pmem_api() && __arch_has_wmb_pmem();
 116 }
 117
 118 /*
 119  * These defaults seek to offer decent performance and minimize the
 120  * window between i/o completion and writes being durable on media.
 121  * However, it is undefined / architecture specific whether
 122  * ARCH_MEMREMAP_PMEM + default_memcpy_to_pmem is sufficient for
 123  * making data durable relative to i/o completion.
 124  */
 125 static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src,
 126                 size_t size)
 127 {
 128         memcpy((void __force *) dst, src, size);
 129 }
 130
 131 static inline size_t default_copy_from_iter_pmem(void __pmem *addr,
 132                 size_t bytes, struct iov_iter *i)
 133 {
 134         return copy_from_iter_nocache((void __force *)addr, bytes, i);
 135 }
 136
 137 static inline void default_clear_pmem(void __pmem *addr, size_t size)
 138 {
 139         if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
 140                 clear_page((void __force *)addr);
 141         else
 142                 memset((void __force *)addr, 0, size);
 143 }
 144
 145 /**
 146  * memcpy_to_pmem - copy data to persistent memory
 147  * @dst: destination buffer for the copy
 148  * @src: source buffer for the copy
 149  * @n: length of the copy in bytes
 150  *
 151  * Perform a memory copy that results in the destination of the copy
 152  * being effectively evicted from, or never written to, the processor
 153  * cache hierarchy after the copy completes.  After memcpy_to_pmem()
 154  * data may still reside in cpu or platform buffers, so this operation
 155  * must be followed by a wmb_pmem().
 156  */
 157 static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
 158 {
 159         if (arch_has_pmem_api())
 160                 arch_memcpy_to_pmem(dst, src, n);
 161         else
 162                 default_memcpy_to_pmem(dst, src, n);
 163 }
 164
 165 /**
 166  * wmb_pmem - synchronize writes to persistent memory
 167  *
 168  * After a series of memcpy_to_pmem() operations this drains data from
 169  * cpu write buffers and any platform (memory controller) buffers to
 170  * ensure that written data is durable on persistent memory media.
 171  */
 172 static inline void wmb_pmem(void)
 173 {
 174         if (arch_has_wmb_pmem())
 175                 arch_wmb_pmem();
 176         else
 177                 wmb();
 178 }
 179
 180 /**
 181  * copy_from_iter_pmem - copy data from an iterator to PMEM
 182  * @addr:       PMEM destination address
 183  * @bytes:      number of bytes to copy
 184  * @i:          iterator with source data
 185  *
 186  * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
 187  * This function requires explicit ordering with a wmb_pmem() call.
 188  */
 189 static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
 190                 struct iov_iter *i)
 191 {
 192         if (arch_has_pmem_api())
 193                 return arch_copy_from_iter_pmem(addr, bytes, i);
 194         return default_copy_from_iter_pmem(addr, bytes, i);
 195 }
 196
 197 /**
 198  * clear_pmem - zero a PMEM memory range
 199  * @addr:       virtual start address
 200  * @size:       number of bytes to zero
 201  *
 202  * Write zeros into the memory range starting at 'addr' for 'size' bytes.
 203  * This function requires explicit ordering with a wmb_pmem() call.
 204  */
 205 static inline void clear_pmem(void __pmem *addr, size_t size)
 206 {
 207         if (arch_has_pmem_api())
 208                 arch_clear_pmem(addr, size);
 209         else
 210                 default_clear_pmem(addr, size);
 211 }
 212
 213 /**
 214  * invalidate_pmem - flush a pmem range from the cache hierarchy
 215  * @addr:       virtual start address
 216  * @size:       bytes to invalidate (internally aligned to cache line size)
 217  *
 218  * For platforms that support clearing poison this flushes any poisoned
 219  * ranges out of the cache
 220  */
 221 static inline void invalidate_pmem(void __pmem *addr, size_t size)
 222 {
 223         if (arch_has_pmem_api())
 224                 arch_invalidate_pmem(addr, size);
 225 }
 226
 227 /**
 228  * wb_cache_pmem - write back processor cache for PMEM memory range
 229  * @addr:       virtual start address
 230  * @size:       number of bytes to write back
 231  *
 232  * Write back the processor cache range starting at 'addr' for 'size' bytes.
 233  * This function requires explicit ordering with a wmb_pmem() call.
 234  */
 235 static inline void wb_cache_pmem(void __pmem *addr, size_t size)
 236 {
 237         if (arch_has_pmem_api())
 238                 arch_wb_cache_pmem(addr, size);
 239 }
 240 #endif /* __PMEM_H__ */