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: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 566f0b4..1c3fcf1 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -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

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index d48be9c..394bec3 100644 (file)
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -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))

diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index f5880bf..3175413 100644 (file)
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -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

diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
deleted file mode 100644 (file)
index a5ffcb1..0000000
--- a/arch/s390/mm/gup.c
+++ /dev/null
@@ -1,291 +0,0 @@
-// 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;
-}