arch/x86/include/asm/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 __ASM_X86_PMEM_H__
  14 #define __ASM_X86_PMEM_H__
  15
  16 #include <linux/uaccess.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/cpufeature.h>
  19 #include <asm/special_insns.h>
  20
  21 #ifdef CONFIG_ARCH_HAS_PMEM_API
  22 /**
  23  * arch_memcpy_to_pmem - copy data to persistent memory
  24  * @dst: destination buffer for the copy
  25  * @src: source buffer for the copy
  26  * @n: length of the copy in bytes
  27  *
  28  * Copy data to persistent memory media via non-temporal stores so that
  29  * a subsequent pmem driver flush operation will drain posted write queues.
  30  */
  31 static inline void arch_memcpy_to_pmem(void *dst, const void *src, size_t n)
  32 {
  33         int rem;
  34
  35         /*
  36          * We are copying between two kernel buffers, if
  37          * __copy_from_user_inatomic_nocache() returns an error (page
  38          * fault) we would have already reported a general protection fault
  39          * before the WARN+BUG.
  40          */
  41         rem = __copy_from_user_inatomic_nocache(dst, (void __user *) src, n);
  42         if (WARN(rem, "%s: fault copying %p <- %p unwritten: %d\n",
  43                                 __func__, dst, src, rem))
  44                 BUG();
  45 }
  46
  47 static inline int arch_memcpy_from_pmem(void *dst, const void *src, size_t n)
  48 {
  49         return memcpy_mcsafe(dst, src, n);
  50 }
  51
  52 /**
  53  * arch_wb_cache_pmem - write back a cache range with CLWB
  54  * @vaddr:      virtual start address
  55  * @size:       number of bytes to write back
  56  *
  57  * Write back a cache range using the CLWB (cache line write back)
  58  * instruction. Note that @size is internally rounded up to be cache
  59  * line size aligned.
  60  */
  61 static inline void arch_wb_cache_pmem(void *addr, size_t size)
  62 {
  63         u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
  64         unsigned long clflush_mask = x86_clflush_size - 1;
  65         void *vend = addr + size;
  66         void *p;
  67
  68         for (p = (void *)((unsigned long)addr & ~clflush_mask);
  69              p < vend; p += x86_clflush_size)
  70                 clwb(p);
  71 }
  72
  73 /**
  74  * arch_copy_from_iter_pmem - copy data from an iterator to PMEM
  75  * @addr:       PMEM destination address
  76  * @bytes:      number of bytes to copy
  77  * @i:          iterator with source data
  78  *
  79  * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
  80  */
  81 static inline size_t arch_copy_from_iter_pmem(void *addr, size_t bytes,
  82                 struct iov_iter *i)
  83 {
  84         size_t len;
  85
  86         /* TODO: skip the write-back by always using non-temporal stores */
  87         len = copy_from_iter_nocache(addr, bytes, i);
  88
  89         /*
  90          * In the iovec case on x86_64 copy_from_iter_nocache() uses
  91          * non-temporal stores for the bulk of the transfer, but we need
  92          * to manually flush if the transfer is unaligned. A cached
  93          * memory copy is used when destination or size is not naturally
  94          * aligned. That is:
  95          *   - Require 8-byte alignment when size is 8 bytes or larger.
  96          *   - Require 4-byte alignment when size is 4 bytes.
  97          *
  98          * In the non-iovec case the entire destination needs to be
  99          * flushed.
 100          */
 101         if (iter_is_iovec(i)) {
 102                 unsigned long flushed, dest = (unsigned long) addr;
 103
 104                 if (bytes < 8) {
 105                         if (!IS_ALIGNED(dest, 4) || (bytes != 4))
 106                                 arch_wb_cache_pmem(addr, 1);
 107                 } else {
 108                         if (!IS_ALIGNED(dest, 8)) {
 109                                 dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);
 110                                 arch_wb_cache_pmem(addr, 1);
 111                         }
 112
 113                         flushed = dest - (unsigned long) addr;
 114                         if (bytes > flushed && !IS_ALIGNED(bytes - flushed, 8))
 115                                 arch_wb_cache_pmem(addr + bytes - 1, 1);
 116                 }
 117         } else
 118                 arch_wb_cache_pmem(addr, bytes);
 119
 120         return len;
 121 }
 122
 123 /**
 124  * arch_clear_pmem - zero a PMEM memory range
 125  * @addr:       virtual start address
 126  * @size:       number of bytes to zero
 127  *
 128  * Write zeros into the memory range starting at 'addr' for 'size' bytes.
 129  */
 130 static inline void arch_clear_pmem(void *addr, size_t size)
 131 {
 132         memset(addr, 0, size);
 133         arch_wb_cache_pmem(addr, size);
 134 }
 135
 136 static inline void arch_invalidate_pmem(void *addr, size_t size)
 137 {
 138         clflush_cache_range(addr, size);
 139 }
 140 #endif /* CONFIG_ARCH_HAS_PMEM_API */
 141 #endif /* __ASM_X86_PMEM_H__ */