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.
  59  */
  60 static inline void arch_wb_cache_pmem(void *addr, size_t size)
  61 {
  62         u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
  63         unsigned long clflush_mask = x86_clflush_size - 1;
  64         void *vend = addr + size;
  65         void *p;
  66
  67         for (p = (void *)((unsigned long)addr & ~clflush_mask);
  68              p < vend; p += x86_clflush_size)
  69                 clwb(p);
  70 }
  71
  72 /*
  73  * copy_from_iter_nocache() on x86 only uses non-temporal stores for iovec
  74  * iterators, so for other types (bvec & kvec) we must do a cache write-back.
  75  */
  76 static inline bool __iter_needs_pmem_wb(struct iov_iter *i)
  77 {
  78         return iter_is_iovec(i) == false;
  79 }
  80
  81 /**
  82  * arch_copy_from_iter_pmem - copy data from an iterator to PMEM
  83  * @addr:       PMEM destination address
  84  * @bytes:      number of bytes to copy
  85  * @i:          iterator with source data
  86  *
  87  * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
  88  */
  89 static inline size_t arch_copy_from_iter_pmem(void *addr, size_t bytes,
  90                 struct iov_iter *i)
  91 {
  92         size_t len;
  93
  94         /* TODO: skip the write-back by always using non-temporal stores */
  95         len = copy_from_iter_nocache(addr, bytes, i);
  96
  97         if (__iter_needs_pmem_wb(i))
  98                 arch_wb_cache_pmem(addr, bytes);
  99
 100         return len;
 101 }
 102
 103 /**
 104  * arch_clear_pmem - zero a PMEM memory range
 105  * @addr:       virtual start address
 106  * @size:       number of bytes to zero
 107  *
 108  * Write zeros into the memory range starting at 'addr' for 'size' bytes.
 109  */
 110 static inline void arch_clear_pmem(void *addr, size_t size)
 111 {
 112         memset(addr, 0, size);
 113         arch_wb_cache_pmem(addr, size);
 114 }
 115
 116 static inline void arch_invalidate_pmem(void *addr, size_t size)
 117 {
 118         clflush_cache_range(addr, size);
 119 }
 120 #endif /* CONFIG_ARCH_HAS_PMEM_API */
 121 #endif /* __ASM_X86_PMEM_H__ */