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Commit 1a42010c authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/mm: convert to the generic get_user_pages_fast code 



Define the gup_fast_permitted to check against the asce_limit of the
mm attached to the current task, then replace the s390 specific gup
code with the generic implementation in mm/gup.c.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent d1874a0c

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -149,6 +149,7 @@ config S390 
	select HAVE_FUNCTION_TRACER

	select HAVE_FUTEX_CMPXCHG if FUTEX

	select HAVE_GCC_PLUGINS

	select HAVE_GENERIC_GUP

	select HAVE_KERNEL_BZIP2

	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_LZ4

arch/s390/include/asm/pgtable.h

+12 −0
Original line number Diff line number Diff line
@@ -1265,6 +1265,18 @@ static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address) 
#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)

#define pte_unmap(pte) do { } while (0)



static inline bool gup_fast_permitted(unsigned long start, int nr_pages)

{

	unsigned long len, end;



	len = (unsigned long) nr_pages << PAGE_SHIFT;

	end = start + len;

	if (end < start)

		return false;

	return end <= current->mm->context.asce_limit;

}

#define gup_fast_permitted gup_fast_permitted



#define pfn_pte(pfn,pgprot) mk_pte_phys(__pa((pfn) << PAGE_SHIFT),(pgprot))

#define pte_pfn(x) (pte_val(x) >> PAGE_SHIFT)

#define pte_page(x) pfn_to_page(pte_pfn(x))

arch/s390/mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 
#



obj-y		:= init.o fault.o extmem.o mmap.o vmem.o maccess.o

obj-y		+= page-states.o gup.o pageattr.o pgtable.o pgalloc.o

obj-y		+= page-states.o pageattr.o pgtable.o pgalloc.o



obj-$(CONFIG_CMM)		+= cmm.o

obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o

arch/s390/mm/gup.c

deleted100644 → 0
+0 −291
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 *  Lockless get_user_pages_fast for s390

 *

 *  Copyright IBM Corp. 2010

 *  Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>

 */

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/hugetlb.h>

#include <linux/vmstat.h>

#include <linux/pagemap.h>

#include <linux/rwsem.h>

#include <asm/pgtable.h>



/*

 * The performance critical leaf functions are made noinline otherwise gcc

 * inlines everything into a single function which results in too much

 * register pressure.

 */

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

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

{

	struct page *head, *page;

	unsigned long mask;

	pte_t *ptep, pte;



	mask = (write ? _PAGE_PROTECT : 0) | _PAGE_INVALID | _PAGE_SPECIAL;



	ptep = pte_offset_map(&pmd, addr);

	do {

		pte = *ptep;

		barrier();

		/* Similar to the PMD case, NUMA hinting must take slow path */

		if (pte_protnone(pte))

			return 0;

		if ((pte_val(pte) & mask) != 0)

			return 0;

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

		page = pte_page(pte);

		head = compound_head(page);

		if (!page_cache_get_speculative(head))

			return 0;

		if (unlikely(pte_val(pte) != pte_val(*ptep))) {

			put_page(head);

			return 0;

		}

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

		pages[*nr] = page;

		(*nr)++;



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



	return 1;

}



static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,

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

{

	struct page *head, *page;

	unsigned long mask;

	int refs;



	mask = (write ? _SEGMENT_ENTRY_PROTECT : 0) | _SEGMENT_ENTRY_INVALID;

	if ((pmd_val(pmd) & mask) != 0)

		return 0;

	VM_BUG_ON(!pfn_valid(pmd_val(pmd) >> PAGE_SHIFT));



	refs = 0;

	head = pmd_page(pmd);

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

	do {

		VM_BUG_ON(compound_head(page) != head);

		pages[*nr] = page;

		(*nr)++;

		page++;

		refs++;

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



	if (!page_cache_add_speculative(head, refs)) {

		*nr -= refs;

		return 0;

	}



	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {

		*nr -= refs;

		while (refs--)

			put_page(head);

		return 0;

	}



	return 1;

}





static inline int gup_pmd_range(pud_t pud, unsigned long addr,

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

{

	unsigned long next;

	pmd_t *pmdp, pmd;



	pmdp = pmd_offset(&pud, addr);

	do {

		pmd = *pmdp;

		barrier();

		next = pmd_addr_end(addr, end);

		if (pmd_none(pmd))

			return 0;

		if (unlikely(pmd_large(pmd))) {

			/*

			 * NUMA hinting faults need to be handled in the GUP

			 * slowpath for accounting purposes and so that they

			 * can be serialised against THP migration.

			 */

			if (pmd_protnone(pmd))

				return 0;

			if (!gup_huge_pmd(pmdp, pmd, addr, next,

					  write, pages, nr))

				return 0;

		} else if (!gup_pte_range(pmd, addr, next,

					  write, pages, nr))

			return 0;

	} while (pmdp++, addr = next, addr != end);



	return 1;

}



static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,

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

{

	struct page *head, *page;

	unsigned long mask;

	int refs;



	mask = (write ? _REGION_ENTRY_PROTECT : 0) | _REGION_ENTRY_INVALID;

	if ((pud_val(pud) & mask) != 0)

		return 0;

	VM_BUG_ON(!pfn_valid(pud_pfn(pud)));



	refs = 0;

	head = pud_page(pud);

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

	do {

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

		pages[*nr] = page;

		(*nr)++;

		page++;

		refs++;

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



	if (!page_cache_add_speculative(head, refs)) {

		*nr -= refs;

		return 0;

	}



	if (unlikely(pud_val(pud) != pud_val(*pudp))) {

		*nr -= refs;

		while (refs--)

			put_page(head);

		return 0;

	}



	return 1;

}



static inline int gup_pud_range(p4d_t p4d, unsigned long addr,

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

{

	unsigned long next;

	pud_t *pudp, pud;



	pudp = pud_offset(&p4d, addr);

	do {

		pud = *pudp;

		barrier();

		next = pud_addr_end(addr, end);

		if (pud_none(pud))

			return 0;

		if (unlikely(pud_large(pud))) {

			if (!gup_huge_pud(pudp, pud, addr, next, write, pages,

					  nr))

				return 0;

		} else if (!gup_pmd_range(pud, addr, next, write, pages,

					  nr))

			return 0;

	} while (pudp++, addr = next, addr != end);



	return 1;

}



static inline int gup_p4d_range(pgd_t pgd, unsigned long addr,

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

{

	unsigned long next;

	p4d_t *p4dp, p4d;



	p4dp = p4d_offset(&pgd, addr);

	do {

		p4d = *p4dp;

		barrier();

		next = p4d_addr_end(addr, end);

		if (p4d_none(p4d))

			return 0;

		if (!gup_pud_range(p4d, addr, next, write, pages, nr))

			return 0;

	} while (p4dp++, addr = next, addr != end);



	return 1;

}



/*

 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall

 * back to the regular GUP.

 * Note a difference with get_user_pages_fast: this always returns the

 * number of pages pinned, 0 if no pages were pinned.

 */

int __get_user_pages_fast(unsigned long start, int nr_pages, int write,

			  struct page **pages)

{

	struct mm_struct *mm = current->mm;

	unsigned long addr, len, end;

	unsigned long next, flags;

	pgd_t *pgdp, pgd;

	int nr = 0;



	start &= PAGE_MASK;

	addr = start;

	len = (unsigned long) nr_pages << PAGE_SHIFT;

	end = start + len;

	if ((end <= start) || (end > mm->context.asce_limit))

		return 0;

	/*

	 * local_irq_save() doesn't prevent pagetable teardown, but does

	 * prevent the pagetables from being freed on s390.

	 *

	 * So long as we atomically load page table pointers versus teardown,

	 * we can follow the address down to the the page and take a ref on it.

	 */

	local_irq_save(flags);

	pgdp = pgd_offset(mm, addr);

	do {

		pgd = *pgdp;

		barrier();

		next = pgd_addr_end(addr, end);

		if (pgd_none(pgd))

			break;

		if (!gup_p4d_range(pgd, addr, next, write, pages, &nr))

			break;

	} while (pgdp++, addr = next, addr != end);

	local_irq_restore(flags);



	return nr;

}



/**

 * get_user_pages_fast() - pin user pages in memory

 * @start:	starting user address

 * @nr_pages:	number of pages from start to pin

 * @write:	whether pages will be written to

 * @pages:	array that receives pointers to the pages pinned.

 *		Should be at least nr_pages long.

 *

 * Attempt to pin user pages in memory without taking mm->mmap_sem.

 * If not successful, it will fall back to taking the lock and

 * calling get_user_pages().

 *

 * Returns number of pages pinned. This may be fewer than the number

 * requested. If nr_pages is 0 or negative, returns 0. If no pages

 * were pinned, returns -errno.

 */

int get_user_pages_fast(unsigned long start, int nr_pages, int write,

			struct page **pages)

{

	int nr, ret;



	might_sleep();

	start &= PAGE_MASK;

	nr = __get_user_pages_fast(start, nr_pages, write, pages);

	if (nr == nr_pages)

		return nr;



	/* Try to get the remaining pages with get_user_pages */

	start += nr << PAGE_SHIFT;

	pages += nr;

	ret = get_user_pages_unlocked(start, nr_pages - nr, pages,

				      write ? FOLL_WRITE : 0);

	/* Have to be a bit careful with return values */

	if (nr > 0)

		ret = (ret < 0) ? nr : ret + nr;

	return ret;

}