diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1a2cbf641667692f72b3d605ad3a1c91cf687ee8..62564ddf7f78e5f5694d17a5742a9cf52531dc48 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -27,6 +27,7 @@ config X86
select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
select ARCH_HAS_FAST_MULTIPLIER
select ARCH_HAS_GCOV_PROFILE_ALL
+ select ARCH_HAS_PMEM_API
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select HAVE_AOUT if X86_32
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 47c8e32f621a0efd0ee3d9dd3cfb8c8c4f440292..ec23bb753a3eb2723e0ea9b6b074359369a50212 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -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
@@ -104,4 +105,75 @@ 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 */
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 34a5b93704d3ecb1d98190f6a12437a9acab7204..c60c3f3b018349d2fac20caca5688614eb2916f5 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -247,6 +247,12 @@ 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);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 42b766f33e59678f5ce2a5618e7fb07ffaebe127..ade9eb917a4d945b4ff9bd69ebbed1b3fedfd742 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
+#include <linux/pmem.h>
#include <linux/nd.h>
#include "nd.h"
@@ -32,7 +33,7 @@ struct pmem_device {
/* One contiguous memory region per device */
phys_addr_t phys_addr;
- void *virt_addr;
+ void __pmem *virt_addr;
size_t size;
};
@@ -44,13 +45,14 @@ static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,
{
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);
+ memcpy_to_pmem(pmem_addr, mem + off, len);
}
kunmap_atomic(mem);
@@ -71,6 +73,10 @@ static void pmem_make_request(struct request_queue *q, struct bio *bio)
bio_data_dir(bio), iter.bi_sector);
if (do_acct)
nd_iostat_end(bio, start);
+
+ if (bio_data_dir(bio))
+ wmb_pmem();
+
bio_endio(bio, 0);
}
@@ -94,7 +100,8 @@ 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;
@@ -118,6 +125,8 @@ static struct pmem_device *pmem_alloc(struct device *dev,
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");
if (!request_mem_region(pmem->phys_addr, pmem->size, dev_name(dev))) {
dev_warn(dev, "could not reserve region [0x%pa:0x%zx]\n",
@@ -126,11 +135,7 @@ static struct pmem_device *pmem_alloc(struct device *dev,
return ERR_PTR(-EBUSY);
}
- /*
- * Map the memory as non-cachable, as we can't write back the contents
- * of the CPU caches in case of a crash.
- */
- pmem->virt_addr = ioremap_nocache(pmem->phys_addr, pmem->size);
+ pmem->virt_addr = memremap_pmem(pmem->phys_addr, pmem->size);
if (!pmem->virt_addr) {
release_mem_region(pmem->phys_addr, pmem->size);
kfree(pmem);
@@ -195,16 +200,18 @@ static int pmem_rw_bytes(struct nd_namespace_common *ndns,
}
if (rw == READ)
- memcpy(buf, pmem->virt_addr + offset, size);
- else
- memcpy(pmem->virt_addr + offset, buf, size);
+ memcpy_from_pmem(buf, pmem->virt_addr + offset, size);
+ else {
+ memcpy_to_pmem(pmem->virt_addr + offset, buf, size);
+ wmb_pmem();
+ }
return 0;
}
static void pmem_free(struct pmem_device *pmem)
{
- iounmap(pmem->virt_addr);
+ memunmap_pmem(pmem->virt_addr);
release_mem_region(pmem->phys_addr, pmem->size);
kfree(pmem);
}
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 867722591be2c7e026e1b97c241e65e27e3b9d1b..9a528d94549840126720897cbc98d6a2cdb2e9ae 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -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__. */
diff --git a/include/linux/pmem.h b/include/linux/pmem.h
new file mode 100644
index 0000000000000000000000000000000000000000..f6481a0b1d4f9a6304d7ca072546d886e6e9fe38
--- /dev/null
+++ b/include/linux/pmem.h
@@ -0,0 +1,153 @@
+/*
+ * 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>
+
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+#include <asm/cacheflush.h>
+#else
+static inline void arch_wmb_pmem(void)
+{
+ BUG();
+}
+
+static inline bool __arch_has_wmb_pmem(void)
+{
+ return false;
+}
+
+static inline void __pmem *arch_memremap_pmem(resource_size_t offset,
+ unsigned long size)
+{
+ return NULL;
+}
+
+static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
+ size_t n)
+{
+ BUG();
+}
+#endif
+
+/*
+ * 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().
+ */
+
+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)
+{
+ iounmap((void __force __iomem *) addr);
+}
+
+/**
+ * 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)
+{
+ if (IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
+ return __arch_has_wmb_pmem();
+ return false;
+}
+
+static inline bool arch_has_pmem_api(void)
+{
+ return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && arch_has_wmb_pmem();
+}
+
+/*
+ * 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)
+{
+ /* TODO: convert to ioremap_wt() */
+ return (void __pmem __force *)ioremap_nocache(offset, size);
+}
+
+/**
+ * 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)
+{
+ if (arch_has_pmem_api())
+ return arch_memremap_pmem(offset, size);
+ return default_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)
+{
+ if (arch_has_pmem_api())
+ arch_memcpy_to_pmem(dst, src, n);
+ else
+ default_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)
+{
+ if (arch_has_pmem_api())
+ arch_wmb_pmem();
+}
+#endif /* __PMEM_H__ */
diff --git a/lib/Kconfig b/lib/Kconfig
index 601965a948e8d40a3deff542882a772ab873e093..d27c13a91c2813e4ae45f678172233cc33394d61 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -522,4 +522,7 @@ source "lib/fonts/Kconfig"
config ARCH_HAS_SG_CHAIN
def_bool n
+config ARCH_HAS_PMEM_API
+ bool
+
endmenu