+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for sparc, cribbed from powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-#include <asm/adi.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 noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
- unsigned long end, int write, struct page **pages, int *nr)
-{
- unsigned long mask, result;
- pte_t *ptep;
-
- if (tlb_type == hypervisor) {
- result = _PAGE_PRESENT_4V|_PAGE_P_4V;
- if (write)
- result |= _PAGE_WRITE_4V;
- } else {
- result = _PAGE_PRESENT_4U|_PAGE_P_4U;
- if (write)
- result |= _PAGE_WRITE_4U;
- }
- mask = result | _PAGE_SPECIAL;
-
- ptep = pte_offset_kernel(&pmd, addr);
- do {
- struct page *page, *head;
- pte_t pte = *ptep;
-
- if ((pte_val(pte) & mask) != result)
- return 0;
- VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
- /* The hugepage case is simplified on sparc64 because
- * we encode the sub-page pfn offsets into the
- * hugepage PTEs. We could optimize this in the future
- * use page_cache_add_speculative() for the hugepage case.
- */
- 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;
- }
-
- pages[*nr] = page;
- (*nr)++;
- } while (ptep++, addr += PAGE_SIZE, addr != end);
-
- return 1;
-}
-
-static 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;
- int refs;
-
- if (!(pmd_val(pmd) & _PAGE_VALID))
- return 0;
-
- if (write && !pmd_write(pmd))
- return 0;
-
- refs = 0;
- page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
- head = compound_head(page);
- 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 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;
- int refs;
-
- if (!(pud_val(pud) & _PAGE_VALID))
- return 0;
-
- if (write && !pud_write(pud))
- return 0;
-
- refs = 0;
- page = pud_page(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
- head = compound_head(page);
- 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(pud_val(pud) != pud_val(*pudp))) {
- *nr -= refs;
- while (refs--)
- put_page(head);
- return 0;
- }
-
- return 1;
-}
-
-static 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;
-
- pmdp = pmd_offset(&pud, addr);
- do {
- pmd_t pmd = *pmdp;
-
- next = pmd_addr_end(addr, end);
- if (pmd_none(pmd))
- return 0;
- if (unlikely(pmd_large(pmd))) {
- 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_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
- int write, struct page **pages, int *nr)
-{
- unsigned long next;
- pud_t *pudp;
-
- pudp = pud_offset(&pgd, addr);
- do {
- pud_t pud = *pudp;
-
- 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;
-}
-
-/*
- * 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;
- int nr = 0;
-
-#ifdef CONFIG_SPARC64
- if (adi_capable()) {
- long addr = start;
-
- /* If userspace has passed a versioned address, kernel
- * will not find it in the VMAs since it does not store
- * the version tags in the list of VMAs. Storing version
- * tags in list of VMAs is impractical since they can be
- * changed any time from userspace without dropping into
- * kernel. Any address search in VMAs will be done with
- * non-versioned addresses. Ensure the ADI version bits
- * are dropped here by sign extending the last bit before
- * ADI bits. IOMMU does not implement version tags.
- */
- addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
- start = addr;
- }
-#endif
- start &= PAGE_MASK;
- addr = start;
- len = (unsigned long) nr_pages << PAGE_SHIFT;
- end = start + len;
-
- local_irq_save(flags);
- pgdp = pgd_offset(mm, addr);
- do {
- pgd_t pgd = *pgdp;
-
- next = pgd_addr_end(addr, end);
- if (pgd_none(pgd))
- break;
- if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
- break;
- } while (pgdp++, addr = next, addr != end);
- local_irq_restore(flags);
-
- return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages,
- unsigned int gup_flags, struct page **pages)
-{
- struct mm_struct *mm = current->mm;
- unsigned long addr, len, end;
- unsigned long next;
- pgd_t *pgdp;
- int nr = 0;
-
-#ifdef CONFIG_SPARC64
- if (adi_capable()) {
- long addr = start;
-
- /* If userspace has passed a versioned address, kernel
- * will not find it in the VMAs since it does not store
- * the version tags in the list of VMAs. Storing version
- * tags in list of VMAs is impractical since they can be
- * changed any time from userspace without dropping into
- * kernel. Any address search in VMAs will be done with
- * non-versioned addresses. Ensure the ADI version bits
- * are dropped here by sign extending the last bit before
- * ADI bits. IOMMU does not implements version tags,
- */
- addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
- start = addr;
- }
-#endif
- start &= PAGE_MASK;
- addr = start;
- len = (unsigned long) nr_pages << PAGE_SHIFT;
- end = start + len;
-
- /*
- * XXX: batch / limit 'nr', to avoid large irq off latency
- * needs some instrumenting to determine the common sizes used by
- * important workloads (eg. DB2), and whether limiting the batch size
- * will decrease performance.
- *
- * It seems like we're in the clear for the moment. Direct-IO is
- * the main guy that batches up lots of get_user_pages, and even
- * they are limited to 64-at-a-time which is not so many.
- */
- /*
- * This doesn't prevent pagetable teardown, but does prevent
- * the pagetables from being freed on sparc.
- *
- * 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_disable();
-
- pgdp = pgd_offset(mm, addr);
- do {
- pgd_t pgd = *pgdp;
-
- next = pgd_addr_end(addr, end);
- if (pgd_none(pgd))
- goto slow;
- if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
- pages, &nr))
- goto slow;
- } while (pgdp++, addr = next, addr != end);
-
- local_irq_enable();
-
- VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
- return nr;
-
- {
- int ret;
-
-slow:
- local_irq_enable();
-
- /* Try to get the remaining pages with get_user_pages */
- start += nr << PAGE_SHIFT;
- pages += nr;
-
- ret = get_user_pages_unlocked(start,
- (end - start) >> PAGE_SHIFT, pages,
- gup_flags);
-
- /* Have to be a bit careful with return values */
- if (nr > 0) {
- if (ret < 0)
- ret = nr;
- else
- ret += nr;
- }
-
- return ret;
- }
-}
projects / openwrt / staging / blogic.git / commitdiff