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Commit b59f65fa authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Ingo Molnar
Browse files

mm/gup: Implement the dev_pagemap() logic in the generic get_user_pages_fast() function 



This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

Prepare generic GUP_fast() to handle dev_pagemap(). At the moment, it's
only implemented on x86. On non-x86, the new code will be compiled out.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-6-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e9348053

include/linux/mm.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -430,6 +430,10 @@ static inline int pud_devmap(pud_t pud) 
{

{

	return 0;

	return 0;

}

}

static inline int pgd_devmap(pgd_t pgd)

{

	return 0;

}

#endif

#endif





/*

/*

mm/gup.c

+85 −2
Original line number Original line Diff line number Diff line
@@ -1200,12 +1200,23 @@ static inline pte_t gup_get_pte(pte_t *ptep) 
}

}

#endif

#endif





static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)

{

	while ((*nr) - nr_start) {

		struct page *page = pages[--(*nr)];



		ClearPageReferenced(page);

		put_page(page);

	}

}



#ifdef __HAVE_ARCH_PTE_SPECIAL

#ifdef __HAVE_ARCH_PTE_SPECIAL

static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,

static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,

			 int write, struct page **pages, int *nr)

			 int write, struct page **pages, int *nr)

{

{

	struct dev_pagemap *pgmap = NULL;

	int nr_start = *nr, ret = 0;

	pte_t *ptep, *ptem;

	pte_t *ptep, *ptem;

	int ret = 0;





	ptem = ptep = pte_offset_map(&pmd, addr);

	ptem = ptep = pte_offset_map(&pmd, addr);

	do {

	do {
@@ -1222,7 +1233,13 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, 
		if (!pte_access_permitted(pte, write))

		if (!pte_access_permitted(pte, write))

			goto pte_unmap;

			goto pte_unmap;





		if (pte_special(pte))

		if (pte_devmap(pte)) {

			pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);

			if (unlikely(!pgmap)) {

				undo_dev_pagemap(nr, nr_start, pages);

				goto pte_unmap;

			}

		} else if (pte_special(pte))

			goto pte_unmap;

			goto pte_unmap;





		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));

		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
@@ -1239,6 +1256,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, 




		VM_BUG_ON_PAGE(compound_head(page) != head, page);

		VM_BUG_ON_PAGE(compound_head(page) != head, page);





		put_dev_pagemap(pgmap);

		SetPageReferenced(page);

		SetPageReferenced(page);

		pages[*nr] = page;

		pages[*nr] = page;

		(*nr)++;

		(*nr)++;
@@ -1269,6 +1287,64 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, 
}

}

#endif /* __HAVE_ARCH_PTE_SPECIAL */

#endif /* __HAVE_ARCH_PTE_SPECIAL */





#ifdef __HAVE_ARCH_PTE_DEVMAP

static int __gup_device_huge(unsigned long pfn, unsigned long addr,

		unsigned long end, struct page **pages, int *nr)

{

	int nr_start = *nr;

	struct dev_pagemap *pgmap = NULL;



	do {

		struct page *page = pfn_to_page(pfn);



		pgmap = get_dev_pagemap(pfn, pgmap);

		if (unlikely(!pgmap)) {

			undo_dev_pagemap(nr, nr_start, pages);

			return 0;

		}

		SetPageReferenced(page);

		pages[*nr] = page;

		get_page(page);

		put_dev_pagemap(pgmap);

		(*nr)++;

		pfn++;

	} while (addr += PAGE_SIZE, addr != end);

	return 1;

}



static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,

		unsigned long end, struct page **pages, int *nr)

{

	unsigned long fault_pfn;



	fault_pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);

	return __gup_device_huge(fault_pfn, addr, end, pages, nr);

}



static int __gup_device_huge_pud(pud_t pud, unsigned long addr,

		unsigned long end, struct page **pages, int *nr)

{

	unsigned long fault_pfn;



	fault_pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);

	return __gup_device_huge(fault_pfn, addr, end, pages, nr);

}

#else

static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,

		unsigned long end, struct page **pages, int *nr)

{

	BUILD_BUG();

	return 0;

}



static int __gup_device_huge_pud(pud_t pud, unsigned long addr,

		unsigned long end, struct page **pages, int *nr)

{

	BUILD_BUG();

	return 0;

}

#endif



static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,

static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,

		unsigned long end, int write, struct page **pages, int *nr)

		unsigned long end, int write, struct page **pages, int *nr)

{

{
@@ -1278,6 +1354,9 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, 
	if (!pmd_access_permitted(orig, write))

	if (!pmd_access_permitted(orig, write))

		return 0;

		return 0;





	if (pmd_devmap(orig))

		return __gup_device_huge_pmd(orig, addr, end, pages, nr);



	refs = 0;

	refs = 0;

	head = pmd_page(orig);

	head = pmd_page(orig);

	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);

	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
@@ -1314,6 +1393,9 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, 
	if (!pud_access_permitted(orig, write))

	if (!pud_access_permitted(orig, write))

		return 0;

		return 0;





	if (pud_devmap(orig))

		return __gup_device_huge_pud(orig, addr, end, pages, nr);



	refs = 0;

	refs = 0;

	head = pud_page(orig);

	head = pud_page(orig);

	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);

	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
@@ -1351,6 +1433,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr, 
	if (!pgd_access_permitted(orig, write))

	if (!pgd_access_permitted(orig, write))

		return 0;

		return 0;





	BUILD_BUG_ON(pgd_devmap(orig));

	refs = 0;

	refs = 0;

	head = pgd_page(orig);

	head = pgd_page(orig);

	page = head + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);

	page = head + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);