diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/Kconfig | 3 | ||||
| -rw-r--r-- | arch/powerpc/mm/Makefile | 3 | ||||
| -rw-r--r-- | arch/powerpc/mm/gup.c | 280 |
3 files changed, 285 insertions, 1 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 587da5e0990..63c9cafda9c 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -42,6 +42,9 @@ config GENERIC_HARDIRQS bool default y +config HAVE_GET_USER_PAGES_FAST + def_bool PPC64 + config HAVE_SETUP_PER_CPU_AREA def_bool PPC64 diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile index 1c00e0196f6..e7392b45a5e 100644 --- a/arch/powerpc/mm/Makefile +++ b/arch/powerpc/mm/Makefile @@ -12,7 +12,8 @@ obj-y := fault.o mem.o \ mmu_context_$(CONFIG_WORD_SIZE).o hash-$(CONFIG_PPC_NATIVE) := hash_native_64.o obj-$(CONFIG_PPC64) += hash_utils_64.o \ - slb_low.o slb.o stab.o mmap.o $(hash-y) + slb_low.o slb.o stab.o \ + gup.o mmap.o $(hash-y) obj-$(CONFIG_PPC_STD_MMU_32) += ppc_mmu_32.o obj-$(CONFIG_PPC_STD_MMU) += hash_low_$(CONFIG_WORD_SIZE).o \ tlb_$(CONFIG_WORD_SIZE).o diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c new file mode 100644 index 00000000000..9fdf4d6335e --- /dev/null +++ b/arch/powerpc/mm/gup.c @@ -0,0 +1,280 @@ +/* + * Lockless get_user_pages_fast for powerpc + * + * Copyright (C) 2008 Nick Piggin + * Copyright (C) 2008 Novell Inc. + */ +#undef DEBUG + +#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 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; + + result = _PAGE_PRESENT|_PAGE_USER; + if (write) + result |= _PAGE_RW; + mask = result | _PAGE_SPECIAL; + + ptep = pte_offset_kernel(&pmd, addr); + do { + pte_t pte = *ptep; + struct page *page; + + if ((pte_val(pte) & mask) != result) + return 0; + VM_BUG_ON(!pfn_valid(pte_pfn(pte))); + page = pte_page(pte); + if (!page_cache_get_speculative(page)) + return 0; + if (unlikely(pte != *ptep)) { + put_page(page); + return 0; + } + pages[*nr] = page; + (*nr)++; + + } while (ptep++, addr += PAGE_SIZE, addr != end); + + return 1; +} + +#ifdef CONFIG_HUGETLB_PAGE +static noinline int gup_huge_pte(pte_t *ptep, struct hstate *hstate, + unsigned long *addr, unsigned long end, + int write, struct page **pages, int *nr) +{ + unsigned long mask; + unsigned long pte_end; + struct page *head, *page; + pte_t pte; + int refs; + + pte_end = (*addr + huge_page_size(hstate)) & huge_page_mask(hstate); + if (pte_end < end) + end = pte_end; + + pte = *ptep; + mask = _PAGE_PRESENT|_PAGE_USER; + if (write) + mask |= _PAGE_RW; + if ((pte_val(pte) & mask) != mask) + return 0; + /* hugepages are never "special" */ + VM_BUG_ON(!pfn_valid(pte_pfn(pte))); + + refs = 0; + head = pte_page(pte); + page = head + ((*addr & ~huge_page_mask(hstate)) >> 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(pte != *ptep)) { + /* Could be optimized better */ + while (*nr) { + put_page(page); + (*nr)--; + } + } + + return 1; +} +#endif /* CONFIG_HUGETLB_PAGE */ + +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 (!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 (!gup_pmd_range(pud, addr, next, write, pages, nr)) + return 0; + } while (pudp++, addr = next, addr != end); + + return 1; +} + +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; + pgd_t *pgdp; + int psize, nr = 0; + unsigned int shift; + + pr_debug("%s(%lx,%x,%s)\n", __func__, start, nr_pages, write ? "write" : "read"); + + start &= PAGE_MASK; + addr = start; + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; + + if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, + start, len))) + goto slow_irqon; + + pr_debug(" aligned: %lx .. %lx\n", start, end); + +#ifdef CONFIG_HUGETLB_PAGE + /* We bail out on slice boundary crossing when hugetlb is + * enabled in order to not have to deal with two different + * page table formats + */ + if (addr < SLICE_LOW_TOP) { + if (end > SLICE_LOW_TOP) + goto slow_irqon; + + if (unlikely(GET_LOW_SLICE_INDEX(addr) != + GET_LOW_SLICE_INDEX(end - 1))) + goto slow_irqon; + } else { + if (unlikely(GET_HIGH_SLICE_INDEX(addr) != + GET_HIGH_SLICE_INDEX(end - 1))) + goto slow_irqon; + } +#endif /* CONFIG_HUGETLB_PAGE */ + + /* + * 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 powerpc. + * + * 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(); + + psize = get_slice_psize(mm, addr); + shift = mmu_psize_defs[psize].shift; + +#ifdef CONFIG_HUGETLB_PAGE + if (unlikely(mmu_huge_psizes[psize])) { + pte_t *ptep; + unsigned long a = addr; + unsigned long sz = ((1UL) << shift); + struct hstate *hstate = size_to_hstate(sz); + + BUG_ON(!hstate); + /* + * XXX: could be optimized to avoid hstate + * lookup entirely (just use shift) + */ + + do { + VM_BUG_ON(shift != mmu_psize_defs[get_slice_psize(mm, a)].shift); + ptep = huge_pte_offset(mm, a); + pr_debug(" %016lx: huge ptep %p\n", a, ptep); + if (!ptep || !gup_huge_pte(ptep, hstate, &a, end, write, pages, + &nr)) + goto slow; + } while (a != end); + } else +#endif /* CONFIG_HUGETLB_PAGE */ + { + pgdp = pgd_offset(mm, addr); + do { + pgd_t pgd = *pgdp; + + VM_BUG_ON(shift != mmu_psize_defs[get_slice_psize(mm, addr)].shift); + pr_debug(" %016lx: normal pgd %p\n", addr, (void *)pgd); + next = pgd_addr_end(addr, end); + if (pgd_none(pgd)) + goto slow; + if (!gup_pud_range(pgd, addr, next, 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(); +slow_irqon: + pr_debug(" slow path ! nr = %d\n", nr); + + /* Try to get the remaining pages with get_user_pages */ + start += nr << PAGE_SHIFT; + pages += nr; + + down_read(&mm->mmap_sem); + ret = get_user_pages(current, mm, start, + (end - start) >> PAGE_SHIFT, write, 0, pages, NULL); + up_read(&mm->mmap_sem); + + /* Have to be a bit careful with return values */ + if (nr > 0) { + if (ret < 0) + ret = nr; + else + ret += nr; + } + + return ret; + } +} |