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Commit 5de490da authored by Ross Zwisler's avatar Ross Zwisler Committed by Dan Williams
Browse files

pmem: add copy_from_iter_pmem() and clear_pmem() 



Add support for two new PMEM APIs, copy_from_iter_pmem() and
clear_pmem().  copy_from_iter_pmem() is used to copy data from an
iterator into a PMEM buffer.  clear_pmem() zeros a PMEM memory range.

Both of these new APIs must be explicitly ordered using a wmb_pmem()
function call and are implemented in such a way that the wmb_pmem()
will make the stores to PMEM durable.  Because both APIs are unordered
they can be called as needed without introducing any unwanted memory
barriers.

Signed-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 4a370df5

arch/x86/include/asm/pmem.h

+75 −0
Original line number Diff line number Diff line
@@ -66,6 +66,81 @@ static inline void arch_wmb_pmem(void) 
	pcommit_sfence();

}



/**

 * __arch_wb_cache_pmem - write back a cache range with CLWB

 * @vaddr:	virtual start address

 * @size:	number of bytes to write back

 *

 * Write back a cache range using the CLWB (cache line write back)

 * instruction.  This function requires explicit ordering with an

 * arch_wmb_pmem() call.  This API is internal to the x86 PMEM implementation.

 */

static inline void __arch_wb_cache_pmem(void *vaddr, size_t size)

{

	u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;

	unsigned long clflush_mask = x86_clflush_size - 1;

	void *vend = vaddr + size;

	void *p;



	for (p = (void *)((unsigned long)vaddr & ~clflush_mask);

	     p < vend; p += x86_clflush_size)

		clwb(p);

}



/*

 * copy_from_iter_nocache() on x86 only uses non-temporal stores for iovec

 * iterators, so for other types (bvec & kvec) we must do a cache write-back.

 */

static inline bool __iter_needs_pmem_wb(struct iov_iter *i)

{

	return iter_is_iovec(i) == false;

}



/**

 * arch_copy_from_iter_pmem - copy data from an iterator to PMEM

 * @addr:	PMEM destination address

 * @bytes:	number of bytes to copy

 * @i:		iterator with source data

 *

 * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.

 * This function requires explicit ordering with an arch_wmb_pmem() call.

 */

static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,

		struct iov_iter *i)

{

	void *vaddr = (void __force *)addr;

	size_t len;



	/* TODO: skip the write-back by always using non-temporal stores */

	len = copy_from_iter_nocache(vaddr, bytes, i);



	if (__iter_needs_pmem_wb(i))

		__arch_wb_cache_pmem(vaddr, bytes);



	return len;

}



/**

 * arch_clear_pmem - zero a PMEM memory range

 * @addr:	virtual start address

 * @size:	number of bytes to zero

 *

 * Write zeros into the memory range starting at 'addr' for 'size' bytes.

 * This function requires explicit ordering with an arch_wmb_pmem() call.

 */

static inline void arch_clear_pmem(void __pmem *addr, size_t size)

{

	void *vaddr = (void __force *)addr;



	/* TODO: implement the zeroing via non-temporal writes */

	if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0)

		clear_page(vaddr);

	else

		memset(vaddr, 0, size);



	__arch_wb_cache_pmem(vaddr, size);

}



static inline bool arch_has_wmb_pmem(void)

{

#ifdef CONFIG_X86_64

include/linux/pmem.h

+62 −2
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#define __PMEM_H__



#include <linux/io.h>

#include <linux/uio.h>



#ifdef CONFIG_ARCH_HAS_PMEM_API

#include <asm/pmem.h>
@@ -33,12 +34,24 @@ static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src, 
{

	BUG();

}



static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,

		struct iov_iter *i)

{

	BUG();

	return 0;

}



static inline void arch_clear_pmem(void __pmem *addr, size_t size)

{

	BUG();

}

#endif



/*

 * Architectures that define ARCH_HAS_PMEM_API must provide

 * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(), and

 * arch_has_wmb_pmem().

 * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),

 * arch_copy_from_iter_pmem(), arch_clear_pmem() and arch_has_wmb_pmem().

 */



static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
@@ -78,6 +91,20 @@ static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src, 
	memcpy((void __force *) dst, src, size);

}



static inline size_t default_copy_from_iter_pmem(void __pmem *addr,

		size_t bytes, struct iov_iter *i)

{

	return copy_from_iter_nocache((void __force *)addr, bytes, i);

}



static inline void default_clear_pmem(void __pmem *addr, size_t size)

{

	if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)

		clear_page((void __force *)addr);

	else

		memset((void __force *)addr, 0, size);

}



/**

 * memremap_pmem - map physical persistent memory for pmem api

 * @offset: physical address of persistent memory
@@ -134,4 +161,37 @@ static inline void wmb_pmem(void) 
	if (arch_has_pmem_api())

		arch_wmb_pmem();

}



/**

 * copy_from_iter_pmem - copy data from an iterator to PMEM

 * @addr:	PMEM destination address

 * @bytes:	number of bytes to copy

 * @i:		iterator with source data

 *

 * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.

 * This function requires explicit ordering with a wmb_pmem() call.

 */

static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,

		struct iov_iter *i)

{

	if (arch_has_pmem_api())

		return arch_copy_from_iter_pmem(addr, bytes, i);

	return default_copy_from_iter_pmem(addr, bytes, i);

}



/**

 * clear_pmem - zero a PMEM memory range

 * @addr:	virtual start address

 * @size:	number of bytes to zero

 *

 * Write zeros into the memory range starting at 'addr' for 'size' bytes.

 * This function requires explicit ordering with a wmb_pmem() call.

 */

static inline void clear_pmem(void __pmem *addr, size_t size)

{

	if (arch_has_pmem_api())

		arch_clear_pmem(addr, size);

	else

		default_clear_pmem(addr, size);

}

#endif /* __PMEM_H__ */