@@ -28,6 +28,7 @@ config X86
select ARCH_HAS_FAST_MULTIPLIER
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_MEMREMAP
+ select ARCH_HAS_PMEM_API
select ARCH_HAS_SG_CHAIN
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
@@ -4,6 +4,7 @@
/* Caches aren't brain-dead on the intel. */
#include <asm-generic/cacheflush.h>
#include <asm/special_insns.h>
+#include <asm/uaccess.h>
/*
* The set_memory_* API can be used to change various attributes of a virtual
@@ -108,4 +109,74 @@ static inline int rodata_test(void)
}
#endif
+#ifdef ARCH_HAS_NOCACHE_UACCESS
+
+/**
+ * arch_memcpy_to_pmem - copy data to persistent memory
+ * @dst: destination buffer for the copy
+ * @src: source buffer for the copy
+ * @n: length of the copy in bytes
+ *
+ * Copy data to persistent memory media via non-temporal stores so that
+ * a subsequent arch_wmb_pmem() can flush cpu and memory controller
+ * write buffers to guarantee durability.
+ */
+static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
+{
+ int unwritten;
+
+ /*
+ * We are copying between two kernel buffers, if
+ * __copy_from_user_inatomic_nocache() returns an error (page
+ * fault) we would have already reported a general protection fault
+ * before the WARN+BUG.
+ */
+ unwritten = __copy_from_user_inatomic_nocache((void __force *) dst,
+ (void __user *) src, n);
+ if (WARN(unwritten, "%s: fault copying %p <- %p unwritten: %d\n",
+ __func__, dst, src, unwritten))
+ BUG();
+}
+
+/**
+ * arch_wmb_pmem - synchronize writes to persistent memory
+ *
+ * After a series of arch_memcpy_to_pmem() operations this drains data
+ * from cpu write buffers and any platform (memory controller) buffers
+ * to ensure that written data is durable on persistent memory media.
+ */
+static inline void arch_wmb_pmem(void)
+{
+ /*
+ * wmb() to 'sfence' all previous writes such that they are
+ * architecturally visible to 'pcommit'. Note, that we've
+ * already arranged for pmem writes to avoid the cache via
+ * arch_memcpy_to_pmem().
+ */
+ wmb();
+ pcommit_sfence();
+}
+
+static inline bool __arch_has_wmb_pmem(void)
+{
+#ifdef CONFIG_X86_64
+ /*
+ * We require that wmb() be an 'sfence', that is only guaranteed on
+ * 64-bit builds
+ */
+ return static_cpu_has(X86_FEATURE_PCOMMIT);
+#else
+ return false;
+#endif
+}
+#else /* ARCH_HAS_NOCACHE_UACCESS i.e. ARCH=um */
+extern void arch_memcpy_to_pmem(void __pmem *dst, const void *src, size_t n);
+extern void arch_wmb_pmem(void);
+
+static inline bool __arch_has_wmb_pmem(void)
+{
+ return false;
+}
+#endif
+
#endif /* _ASM_X86_CACHEFLUSH_H */
@@ -249,6 +249,12 @@ static inline void flush_write_buffers(void)
#endif
}
+static inline void __pmem *arch_memremap_pmem(resource_size_t offset,
+ unsigned long size)
+{
+ return (void __force __pmem *) ioremap_cache(offset, size);
+}
+
#endif /* __KERNEL__ */
extern void native_io_delay(void);
@@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
+#include <linux/pmem.h>
#include <linux/io.h>
#define PMEM_MINORS 16
@@ -33,26 +34,47 @@ struct pmem_device {
/* One contiguous memory region per device */
phys_addr_t phys_addr;
- void *virt_addr;
+ void __pmem *virt_addr;
size_t size;
};
static int pmem_major;
static atomic_t pmem_index;
+/*
+ * These defaults seek to offer decent performance and minimize the
+ * window between i/o completion and writes being durable on media.
+ * However, it is undefined / architecture specific whether
+ * default_memremap_pmem + default_memcpy_to_pmem is sufficient for
+ * making data durable relative to i/o completion.
+ */
+static void default_memcpy_to_pmem(void __pmem *dst, const void *src, size_t size)
+{
+ memcpy((void __force *) dst, src, size);
+}
+
+static void __pmem *default_memremap_pmem(resource_size_t offset, unsigned long size)
+{
+ return (void __pmem *)memremap_wt(offset, size);
+}
+
static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,
unsigned int len, unsigned int off, int rw,
sector_t sector)
{
void *mem = kmap_atomic(page);
size_t pmem_off = sector << 9;
+ void __pmem *pmem_addr = pmem->virt_addr + pmem_off;
if (rw == READ) {
- memcpy(mem + off, pmem->virt_addr + pmem_off, len);
+ memcpy_from_pmem(mem + off, pmem_addr, len);
flush_dcache_page(page);
} else {
flush_dcache_page(page);
- memcpy(pmem->virt_addr + pmem_off, mem + off, len);
+ if (arch_has_pmem_api())
+ memcpy_to_pmem(pmem_addr, mem + off, len);
+ else
+ default_memcpy_to_pmem(pmem_addr, mem + off, len);
}
kunmap_atomic(mem);
@@ -83,6 +105,8 @@ static void pmem_make_request(struct request_queue *q, struct bio *bio)
sector += bvec.bv_len >> 9;
}
+ if (rw && arch_has_pmem_api())
+ wmb_pmem();
out:
bio_endio(bio, err);
}
@@ -107,7 +131,8 @@ static long pmem_direct_access(struct block_device *bdev, sector_t sector,
if (!pmem)
return -ENODEV;
- *kaddr = pmem->virt_addr + offset;
+ /* FIXME convert DAX to comprehend that this mapping has a lifetime */
+ *kaddr = (void __force *) pmem->virt_addr + offset;
*pfn = (pmem->phys_addr + offset) >> PAGE_SHIFT;
return pmem->size - offset;
@@ -132,6 +157,8 @@ static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
pmem->phys_addr = res->start;
pmem->size = resource_size(res);
+ if (!arch_has_pmem_api())
+ dev_warn(dev, "unable to guarantee persistence of writes\n");
err = -EINVAL;
if (!request_mem_region(pmem->phys_addr, pmem->size, "pmem")) {
@@ -144,7 +171,11 @@ static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
* of the CPU caches in case of a crash.
*/
err = -ENOMEM;
- pmem->virt_addr = memremap_wt(pmem->phys_addr, pmem->size);
+ if (arch_has_pmem_api())
+ pmem->virt_addr = memremap_pmem(pmem->phys_addr, pmem->size);
+ else
+ pmem->virt_addr = default_memremap_pmem(pmem->phys_addr,
+ pmem->size);
if (!pmem->virt_addr)
goto out_release_region;
@@ -180,7 +211,7 @@ static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
out_free_queue:
blk_cleanup_queue(pmem->pmem_queue);
out_unmap:
- memunmap(pmem->virt_addr);
+ memunmap_pmem(pmem->virt_addr);
out_release_region:
release_mem_region(pmem->phys_addr, pmem->size);
out_free_dev:
@@ -194,7 +225,7 @@ static void pmem_free(struct pmem_device *pmem)
del_gendisk(pmem->pmem_disk);
put_disk(pmem->pmem_disk);
blk_cleanup_queue(pmem->pmem_queue);
- memunmap(pmem->virt_addr);
+ memunmap_pmem(pmem->virt_addr);
release_mem_region(pmem->phys_addr, pmem->size);
kfree(pmem);
}
@@ -21,6 +21,7 @@
# define __rcu __attribute__((noderef, address_space(4)))
#else
# define __rcu
+# define __pmem __attribute__((noderef, address_space(5)))
#endif
extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);
@@ -42,6 +43,7 @@ extern void __chk_io_ptr(const volatile void __iomem *);
# define __cond_lock(x,c) (c)
# define __percpu
# define __rcu
+# define __pmem
#endif
/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
new file mode 100644
@@ -0,0 +1,110 @@
+/*
+ * Copyright(c) 2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#ifndef __PMEM_H__
+#define __PMEM_H__
+
+#include <linux/io.h>
+#include <asm/cacheflush.h>
+
+/*
+ * Architectures that define ARCH_HAS_PMEM_API must provide
+ * implementations for arch_memremap_pmem(), arch_memcpy_to_pmem(),
+ * arch_wmb_pmem(), and __arch_has_wmb_pmem().
+ */
+
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+/**
+ * memremap_pmem - map physical persistent memory for pmem api
+ * @offset: physical address of persistent memory
+ * @size: size of the mapping
+ *
+ * Establish a mapping of the architecture specific memory type expected
+ * by memcpy_to_pmem() and wmb_pmem(). For example, it may be
+ * the case that an uncacheable or writethrough mapping is sufficient,
+ * or a writeback mapping provided memcpy_to_pmem() and
+ * wmb_pmem() arrange for the data to be written through the
+ * cache to persistent media.
+ */
+static inline void __pmem *memremap_pmem(resource_size_t offset, unsigned long size)
+{
+ return arch_memremap_pmem(offset, size);
+}
+
+/**
+ * memcpy_to_pmem - copy data to persistent memory
+ * @dst: destination buffer for the copy
+ * @src: source buffer for the copy
+ * @n: length of the copy in bytes
+ *
+ * Perform a memory copy that results in the destination of the copy
+ * being effectively evicted from, or never written to, the processor
+ * cache hierarchy after the copy completes. After memcpy_to_pmem()
+ * data may still reside in cpu or platform buffers, so this operation
+ * must be followed by a wmb_pmem().
+ */
+static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
+{
+ arch_memcpy_to_pmem(dst, src, n);
+}
+
+/**
+ * wmb_pmem - synchronize writes to persistent memory
+ *
+ * After a series of memcpy_to_pmem() operations this drains data from
+ * cpu write buffers and any platform (memory controller) buffers to
+ * ensure that written data is durable on persistent memory media.
+ */
+static inline void wmb_pmem(void)
+{
+ arch_wmb_pmem();
+}
+
+/**
+ * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
+ *
+ * For a given cpu implementation within an architecture it is possible
+ * that wmb_pmem() resolves to a nop. In the case this returns
+ * false, pmem api users are unable to ensure durability and may want to
+ * fall back to a different data consistency model, or otherwise notify
+ * the user.
+ */
+static inline bool arch_has_wmb_pmem(void)
+{
+ return __arch_has_wmb_pmem();
+}
+#else
+/* undefined symbols */
+extern void __pmem *memremap_pmem(resource_size_t offet, unsigned long size);
+extern void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n);
+extern void wmb_pmem(void);
+static inline bool arch_has_wmb_pmem(void)
+{
+ return false;
+}
+#endif /* CONFIG_ARCH_HAS_PMEM_API */
+
+static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
+{
+ memcpy(dst, (void __force const *) src, size);
+}
+
+static inline void memunmap_pmem(void __pmem *addr)
+{
+ memunmap((void __force *) addr);
+}
+
+static inline bool arch_has_pmem_api(void)
+{
+ return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && arch_has_wmb_pmem();
+}
+#endif /* __PMEM_H__ */
@@ -525,4 +525,7 @@ config ARCH_HAS_SG_CHAIN
config ARCH_HAS_MEMREMAP
bool
+config ARCH_HAS_PMEM_API
+ bool
+
endmenu