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 arch_wmb_pmem() can flush cpu and memory controller
  30  * write buffers to guarantee durability.
  31  */
  32 static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
  33                 size_t n)
  34 {
  35         int unwritten;
  36
  37         /*
  38          * We are copying between two kernel buffers, if
  39          * __copy_from_user_inatomic_nocache() returns an error (page
  40          * fault) we would have already reported a general protection fault
  41          * before the WARN+BUG.
  42          */
  43         unwritten = __copy_from_user_inatomic_nocache((void __force *) dst,
  44                         (void __user *) src, n);
  45         if (WARN(unwritten, "%s: fault copying %p <- %p unwritten: %d\n",
  46                                 __func__, dst, src, unwritten))
  47                 BUG();
  48 }
  49
  50 static inline int arch_memcpy_from_pmem(void *dst, const void __pmem *src,
  51                 size_t n)
  52 {
  53         if (static_cpu_has(X86_FEATURE_MCE_RECOVERY))
  54                 return memcpy_mcsafe(dst, (void __force *) src, n);
  55         memcpy(dst, (void __force *) src, n);
  56         return 0;
  57 }
  58
  59 /**
  60  * arch_wmb_pmem - synchronize writes to persistent memory
  61  *
  62  * After a series of arch_memcpy_to_pmem() operations this drains data
  63  * from cpu write buffers and any platform (memory controller) buffers
  64  * to ensure that written data is durable on persistent memory media.
  65  */
  66 static inline void arch_wmb_pmem(void)
  67 {
  68         /*
  69          * wmb() to 'sfence' all previous writes such that they are
  70          * architecturally visible to 'pcommit'.  Note, that we've
  71          * already arranged for pmem writes to avoid the cache via
  72          * arch_memcpy_to_pmem().
  73          */
  74         wmb();
  75         pcommit_sfence();
  76 }
  77
  78 /**
  79  * arch_wb_cache_pmem - write back a cache range with CLWB
  80  * @vaddr:      virtual start address
  81  * @size:       number of bytes to write back
  82  *
  83  * Write back a cache range using the CLWB (cache line write back)
  84  * instruction.  This function requires explicit ordering with an
  85  * arch_wmb_pmem() call.
  86  */
  87 static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
  88 {
  89         u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
  90         unsigned long clflush_mask = x86_clflush_size - 1;
  91         void *vaddr = (void __force *)addr;
  92         void *vend = vaddr + size;
  93         void *p;
  94
  95         for (p = (void *)((unsigned long)vaddr & ~clflush_mask);
  96              p < vend; p += x86_clflush_size)
  97                 clwb(p);
  98 }
  99
 100 /*
 101  * copy_from_iter_nocache() on x86 only uses non-temporal stores for iovec
 102  * iterators, so for other types (bvec & kvec) we must do a cache write-back.
 103  */
 104 static inline bool __iter_needs_pmem_wb(struct iov_iter *i)
 105 {
 106         return iter_is_iovec(i) == false;
 107 }
 108
 109 /**
 110  * arch_copy_from_iter_pmem - copy data from an iterator to PMEM
 111  * @addr:       PMEM destination address
 112  * @bytes:      number of bytes to copy
 113  * @i:          iterator with source data
 114  *
 115  * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
 116  * This function requires explicit ordering with an arch_wmb_pmem() call.
 117  */
 118 static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
 119                 struct iov_iter *i)
 120 {
 121         void *vaddr = (void __force *)addr;
 122         size_t len;
 123
 124         /* TODO: skip the write-back by always using non-temporal stores */
 125         len = copy_from_iter_nocache(vaddr, bytes, i);
 126
 127         if (__iter_needs_pmem_wb(i))
 128                 arch_wb_cache_pmem(addr, bytes);
 129
 130         return len;
 131 }
 132
 133 /**
 134  * arch_clear_pmem - zero a PMEM memory range
 135  * @addr:       virtual start address
 136  * @size:       number of bytes to zero
 137  *
 138  * Write zeros into the memory range starting at 'addr' for 'size' bytes.
 139  * This function requires explicit ordering with an arch_wmb_pmem() call.
 140  */
 141 static inline void arch_clear_pmem(void __pmem *addr, size_t size)
 142 {
 143         void *vaddr = (void __force *)addr;
 144
 145         memset(vaddr, 0, size);
 146         arch_wb_cache_pmem(addr, size);
 147 }
 148
 149 static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
 150 {
 151         clflush_cache_range((void __force *) addr, size);
 152 }
 153
 154 static inline bool __arch_has_wmb_pmem(void)
 155 {
 156         /*
 157          * We require that wmb() be an 'sfence', that is only guaranteed on
 158          * 64-bit builds
 159          */
 160         return static_cpu_has(X86_FEATURE_PCOMMIT);
 161 }
 162 #endif /* CONFIG_ARCH_HAS_PMEM_API */
 163 #endif /* __ASM_X86_PMEM_H__ */