[S390] lockless get_user_pages_fast()
Implement get_user_pages_fast without locking in the fastpath on s390. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
Martin Schwidefsky
parent
87799ebab7
commit
80217147a3
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@ -101,6 +101,7 @@ config S390
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select HAVE_KERNEL_BZIP2
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select HAVE_KERNEL_LZMA
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select HAVE_KERNEL_LZO
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select HAVE_GET_USER_PAGES_FAST
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select ARCH_INLINE_SPIN_TRYLOCK
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select ARCH_INLINE_SPIN_TRYLOCK_BH
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select ARCH_INLINE_SPIN_LOCK
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@ -21,9 +21,11 @@
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unsigned long *crst_table_alloc(struct mm_struct *, int);
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void crst_table_free(struct mm_struct *, unsigned long *);
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void crst_table_free_rcu(struct mm_struct *, unsigned long *);
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unsigned long *page_table_alloc(struct mm_struct *);
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void page_table_free(struct mm_struct *, unsigned long *);
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void page_table_free_rcu(struct mm_struct *, unsigned long *);
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void disable_noexec(struct mm_struct *, struct task_struct *);
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static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
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@ -176,4 +178,6 @@ static inline void pmd_populate(struct mm_struct *mm,
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#define pte_free_kernel(mm, pte) page_table_free(mm, (unsigned long *) pte)
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#define pte_free(mm, pte) page_table_free(mm, (unsigned long *) pte)
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extern void rcu_table_freelist_finish(void);
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#endif /* _S390_PGALLOC_H */
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@ -316,6 +316,7 @@ extern unsigned long VMALLOC_START;
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/* Bits in the segment table entry */
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#define _SEGMENT_ENTRY_ORIGIN 0x7fffffc0UL /* page table origin */
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#define _SEGMENT_ENTRY_RO 0x200 /* page protection bit */
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#define _SEGMENT_ENTRY_INV 0x20 /* invalid segment table entry */
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#define _SEGMENT_ENTRY_COMMON 0x10 /* common segment bit */
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#define _SEGMENT_ENTRY_PTL 0x0f /* page table length */
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@ -64,10 +64,9 @@ static inline void tlb_flush_mmu(struct mmu_gather *tlb,
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if (!tlb->fullmm && (tlb->nr_ptes > 0 || tlb->nr_pxds < TLB_NR_PTRS))
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__tlb_flush_mm(tlb->mm);
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while (tlb->nr_ptes > 0)
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pte_free(tlb->mm, tlb->array[--tlb->nr_ptes]);
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page_table_free_rcu(tlb->mm, tlb->array[--tlb->nr_ptes]);
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while (tlb->nr_pxds < TLB_NR_PTRS)
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/* pgd_free frees the pointer as region or segment table */
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pgd_free(tlb->mm, tlb->array[tlb->nr_pxds++]);
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crst_table_free_rcu(tlb->mm, tlb->array[tlb->nr_pxds++]);
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}
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static inline void tlb_finish_mmu(struct mmu_gather *tlb,
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@ -75,6 +74,8 @@ static inline void tlb_finish_mmu(struct mmu_gather *tlb,
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{
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tlb_flush_mmu(tlb, start, end);
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rcu_table_freelist_finish();
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/* keep the page table cache within bounds */
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check_pgt_cache();
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@ -103,7 +104,7 @@ static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
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if (tlb->nr_ptes >= tlb->nr_pxds)
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tlb_flush_mmu(tlb, 0, 0);
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} else
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pte_free(tlb->mm, pte);
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page_table_free(tlb->mm, (unsigned long *) pte);
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}
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/*
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@ -124,7 +125,7 @@ static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
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if (tlb->nr_ptes >= tlb->nr_pxds)
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tlb_flush_mmu(tlb, 0, 0);
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} else
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pmd_free(tlb->mm, pmd);
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crst_table_free(tlb->mm, (unsigned long *) pmd);
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#endif
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}
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@ -146,7 +147,7 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
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if (tlb->nr_ptes >= tlb->nr_pxds)
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tlb_flush_mmu(tlb, 0, 0);
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} else
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pud_free(tlb->mm, pud);
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crst_table_free(tlb->mm, (unsigned long *) pud);
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#endif
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}
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@ -3,6 +3,6 @@
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#
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obj-y := init.o fault.o extmem.o mmap.o vmem.o pgtable.o maccess.o \
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page-states.o
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page-states.o gup.o
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obj-$(CONFIG_CMM) += cmm.o
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obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
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@ -0,0 +1,225 @@
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/*
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* Lockless get_user_pages_fast for s390
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*
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* Copyright IBM Corp. 2010
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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*/
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/vmstat.h>
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#include <linux/pagemap.h>
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#include <linux/rwsem.h>
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#include <asm/pgtable.h>
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/*
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* The performance critical leaf functions are made noinline otherwise gcc
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* inlines everything into a single function which results in too much
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* register pressure.
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*/
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static inline int gup_pte_range(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
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unsigned long end, int write, struct page **pages, int *nr)
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{
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unsigned long mask, result;
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pte_t *ptep, pte;
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struct page *page;
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result = write ? 0 : _PAGE_RO;
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mask = result | _PAGE_INVALID | _PAGE_SPECIAL;
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ptep = ((pte_t *) pmd_deref(pmd)) + pte_index(addr);
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do {
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pte = *ptep;
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barrier();
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if ((pte_val(pte) & mask) != result)
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return 0;
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VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
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page = pte_page(pte);
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if (!page_cache_get_speculative(page))
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return 0;
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if (unlikely(pte_val(pte) != pte_val(*ptep))) {
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put_page(page);
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return 0;
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}
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pages[*nr] = page;
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(*nr)++;
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} while (ptep++, addr += PAGE_SIZE, addr != end);
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return 1;
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}
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static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
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unsigned long end, int write, struct page **pages, int *nr)
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{
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unsigned long mask, result;
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struct page *head, *page;
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int refs;
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result = write ? 0 : _SEGMENT_ENTRY_RO;
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mask = result | _SEGMENT_ENTRY_INV;
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if ((pmd_val(pmd) & mask) != result)
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return 0;
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VM_BUG_ON(!pfn_valid(pmd_val(pmd) >> PAGE_SHIFT));
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refs = 0;
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head = pmd_page(pmd);
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page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
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do {
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VM_BUG_ON(compound_head(page) != head);
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pages[*nr] = page;
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(*nr)++;
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page++;
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refs++;
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} while (addr += PAGE_SIZE, addr != end);
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if (!page_cache_add_speculative(head, refs)) {
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*nr -= refs;
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return 0;
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}
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if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
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*nr -= refs;
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while (refs--)
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put_page(head);
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}
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return 1;
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}
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static inline int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr,
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unsigned long end, int write, struct page **pages, int *nr)
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{
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unsigned long next;
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pmd_t *pmdp, pmd;
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pmdp = (pmd_t *) pudp;
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#ifdef CONFIG_64BIT
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if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
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pmdp = (pmd_t *) pud_deref(pud);
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pmdp += pmd_index(addr);
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#endif
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do {
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pmd = *pmdp;
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barrier();
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next = pmd_addr_end(addr, end);
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if (pmd_none(pmd))
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return 0;
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if (unlikely(pmd_huge(pmd))) {
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if (!gup_huge_pmd(pmdp, pmd, addr, next,
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write, pages, nr))
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return 0;
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} else if (!gup_pte_range(pmdp, pmd, addr, next,
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write, pages, nr))
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return 0;
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} while (pmdp++, addr = next, addr != end);
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return 1;
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}
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static inline int gup_pud_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
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unsigned long end, int write, struct page **pages, int *nr)
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{
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unsigned long next;
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pud_t *pudp, pud;
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pudp = (pud_t *) pgdp;
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#ifdef CONFIG_64BIT
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if ((pgd_val(pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
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pudp = (pud_t *) pgd_deref(pgd);
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pudp += pud_index(addr);
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#endif
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do {
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pud = *pudp;
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barrier();
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next = pud_addr_end(addr, end);
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if (pud_none(pud))
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return 0;
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if (!gup_pmd_range(pudp, pud, addr, next, write, pages, nr))
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return 0;
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} while (pudp++, addr = next, addr != end);
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return 1;
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}
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/**
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* get_user_pages_fast() - pin user pages in memory
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* @start: starting user address
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* @nr_pages: number of pages from start to pin
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* @write: whether pages will be written to
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* @pages: array that receives pointers to the pages pinned.
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* Should be at least nr_pages long.
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*
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* Attempt to pin user pages in memory without taking mm->mmap_sem.
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* If not successful, it will fall back to taking the lock and
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* calling get_user_pages().
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*
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* Returns number of pages pinned. This may be fewer than the number
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* requested. If nr_pages is 0 or negative, returns 0. If no pages
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* were pinned, returns -errno.
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*/
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int get_user_pages_fast(unsigned long start, int nr_pages, int write,
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struct page **pages)
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{
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struct mm_struct *mm = current->mm;
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unsigned long addr, len, end;
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unsigned long next;
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pgd_t *pgdp, pgd;
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int nr = 0;
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start &= PAGE_MASK;
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addr = start;
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len = (unsigned long) nr_pages << PAGE_SHIFT;
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end = start + len;
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if (end < start)
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goto slow_irqon;
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/*
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* local_irq_disable() doesn't prevent pagetable teardown, but does
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* prevent the pagetables from being freed on s390.
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*
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* So long as we atomically load page table pointers versus teardown,
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* we can follow the address down to the the page and take a ref on it.
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*/
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local_irq_disable();
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pgdp = pgd_offset(mm, addr);
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do {
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pgd = *pgdp;
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barrier();
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next = pgd_addr_end(addr, end);
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if (pgd_none(pgd))
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goto slow;
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if (!gup_pud_range(pgdp, pgd, addr, next, write, pages, &nr))
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goto slow;
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} while (pgdp++, addr = next, addr != end);
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local_irq_enable();
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VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
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return nr;
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{
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int ret;
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slow:
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local_irq_enable();
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slow_irqon:
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/* Try to get the remaining pages with get_user_pages */
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start += nr << PAGE_SHIFT;
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pages += nr;
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down_read(&mm->mmap_sem);
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ret = get_user_pages(current, mm, start,
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(end - start) >> PAGE_SHIFT, write, 0, pages, NULL);
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up_read(&mm->mmap_sem);
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/* Have to be a bit careful with return values */
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if (nr > 0) {
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if (ret < 0)
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ret = nr;
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else
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ret += nr;
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}
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return ret;
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}
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}
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@ -68,7 +68,7 @@ void arch_release_hugepage(struct page *page)
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ptep = (pte_t *) page[1].index;
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if (!ptep)
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return;
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pte_free(&init_mm, ptep);
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page_table_free(&init_mm, (unsigned long *) ptep);
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page[1].index = 0;
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}
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@ -38,8 +38,6 @@
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#include <asm/tlbflush.h>
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#include <asm/sections.h>
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DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
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pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((__aligned__(PAGE_SIZE)));
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unsigned long empty_zero_page, zero_page_mask;
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@ -15,6 +15,7 @@
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#include <linux/spinlock.h>
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#include <linux/module.h>
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#include <linux/quicklist.h>
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#include <linux/rcupdate.h>
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#include <asm/system.h>
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#include <asm/pgtable.h>
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@ -23,6 +24,67 @@
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#include <asm/tlbflush.h>
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#include <asm/mmu_context.h>
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struct rcu_table_freelist {
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struct rcu_head rcu;
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struct mm_struct *mm;
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unsigned int pgt_index;
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unsigned int crst_index;
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unsigned long *table[0];
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};
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#define RCU_FREELIST_SIZE \
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((PAGE_SIZE - sizeof(struct rcu_table_freelist)) \
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/ sizeof(unsigned long))
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DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
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static DEFINE_PER_CPU(struct rcu_table_freelist *, rcu_table_freelist);
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static void __page_table_free(struct mm_struct *mm, unsigned long *table);
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static void __crst_table_free(struct mm_struct *mm, unsigned long *table);
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static struct rcu_table_freelist *rcu_table_freelist_get(struct mm_struct *mm)
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{
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struct rcu_table_freelist **batchp = &__get_cpu_var(rcu_table_freelist);
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struct rcu_table_freelist *batch = *batchp;
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if (batch)
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return batch;
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batch = (struct rcu_table_freelist *) __get_free_page(GFP_ATOMIC);
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if (batch) {
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batch->mm = mm;
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batch->pgt_index = 0;
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batch->crst_index = RCU_FREELIST_SIZE;
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*batchp = batch;
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}
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return batch;
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}
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static void rcu_table_freelist_callback(struct rcu_head *head)
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{
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struct rcu_table_freelist *batch =
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container_of(head, struct rcu_table_freelist, rcu);
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while (batch->pgt_index > 0)
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__page_table_free(batch->mm, batch->table[--batch->pgt_index]);
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while (batch->crst_index < RCU_FREELIST_SIZE)
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__crst_table_free(batch->mm, batch->table[batch->crst_index++]);
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free_page((unsigned long) batch);
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}
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void rcu_table_freelist_finish(void)
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{
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struct rcu_table_freelist *batch = __get_cpu_var(rcu_table_freelist);
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if (!batch)
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return;
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call_rcu(&batch->rcu, rcu_table_freelist_callback);
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__get_cpu_var(rcu_table_freelist) = NULL;
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}
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static void smp_sync(void *arg)
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{
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}
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#ifndef CONFIG_64BIT
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#define ALLOC_ORDER 1
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#define TABLES_PER_PAGE 4
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@ -78,23 +140,53 @@ unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec)
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}
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page->index = page_to_phys(shadow);
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}
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spin_lock(&mm->context.list_lock);
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spin_lock_bh(&mm->context.list_lock);
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list_add(&page->lru, &mm->context.crst_list);
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spin_unlock(&mm->context.list_lock);
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spin_unlock_bh(&mm->context.list_lock);
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return (unsigned long *) page_to_phys(page);
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}
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static void __crst_table_free(struct mm_struct *mm, unsigned long *table)
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{
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unsigned long *shadow = get_shadow_table(table);
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if (shadow)
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free_pages((unsigned long) shadow, ALLOC_ORDER);
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free_pages((unsigned long) table, ALLOC_ORDER);
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}
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void crst_table_free(struct mm_struct *mm, unsigned long *table)
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{
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unsigned long *shadow = get_shadow_table(table);
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struct page *page = virt_to_page(table);
|
||||
|
||||
spin_lock(&mm->context.list_lock);
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
list_del(&page->lru);
|
||||
spin_unlock(&mm->context.list_lock);
|
||||
if (shadow)
|
||||
free_pages((unsigned long) shadow, ALLOC_ORDER);
|
||||
free_pages((unsigned long) table, ALLOC_ORDER);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
__crst_table_free(mm, table);
|
||||
}
|
||||
|
||||
void crst_table_free_rcu(struct mm_struct *mm, unsigned long *table)
|
||||
{
|
||||
struct rcu_table_freelist *batch;
|
||||
struct page *page = virt_to_page(table);
|
||||
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
list_del(&page->lru);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
if (atomic_read(&mm->mm_users) < 2 &&
|
||||
cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {
|
||||
__crst_table_free(mm, table);
|
||||
return;
|
||||
}
|
||||
batch = rcu_table_freelist_get(mm);
|
||||
if (!batch) {
|
||||
smp_call_function(smp_sync, NULL, 1);
|
||||
__crst_table_free(mm, table);
|
||||
return;
|
||||
}
|
||||
batch->table[--batch->crst_index] = table;
|
||||
if (batch->pgt_index >= batch->crst_index)
|
||||
rcu_table_freelist_finish();
|
||||
}
|
||||
|
||||
#ifdef CONFIG_64BIT
|
||||
|
|
@ -108,7 +200,7 @@ repeat:
|
|||
table = crst_table_alloc(mm, mm->context.noexec);
|
||||
if (!table)
|
||||
return -ENOMEM;
|
||||
spin_lock(&mm->page_table_lock);
|
||||
spin_lock_bh(&mm->page_table_lock);
|
||||
if (mm->context.asce_limit < limit) {
|
||||
pgd = (unsigned long *) mm->pgd;
|
||||
if (mm->context.asce_limit <= (1UL << 31)) {
|
||||
|
|
@ -130,7 +222,7 @@ repeat:
|
|||
mm->task_size = mm->context.asce_limit;
|
||||
table = NULL;
|
||||
}
|
||||
spin_unlock(&mm->page_table_lock);
|
||||
spin_unlock_bh(&mm->page_table_lock);
|
||||
if (table)
|
||||
crst_table_free(mm, table);
|
||||
if (mm->context.asce_limit < limit)
|
||||
|
|
@ -182,7 +274,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
|
|||
unsigned long bits;
|
||||
|
||||
bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
|
||||
spin_lock(&mm->context.list_lock);
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
page = NULL;
|
||||
if (!list_empty(&mm->context.pgtable_list)) {
|
||||
page = list_first_entry(&mm->context.pgtable_list,
|
||||
|
|
@ -191,7 +283,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
|
|||
page = NULL;
|
||||
}
|
||||
if (!page) {
|
||||
spin_unlock(&mm->context.list_lock);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
|
||||
if (!page)
|
||||
return NULL;
|
||||
|
|
@ -202,7 +294,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
|
|||
clear_table_pgstes(table);
|
||||
else
|
||||
clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
|
||||
spin_lock(&mm->context.list_lock);
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
list_add(&page->lru, &mm->context.pgtable_list);
|
||||
}
|
||||
table = (unsigned long *) page_to_phys(page);
|
||||
|
|
@ -213,10 +305,25 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
|
|||
page->flags |= bits;
|
||||
if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
|
||||
list_move_tail(&page->lru, &mm->context.pgtable_list);
|
||||
spin_unlock(&mm->context.list_lock);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
return table;
|
||||
}
|
||||
|
||||
static void __page_table_free(struct mm_struct *mm, unsigned long *table)
|
||||
{
|
||||
struct page *page;
|
||||
unsigned long bits;
|
||||
|
||||
bits = ((unsigned long) table) & 15;
|
||||
table = (unsigned long *)(((unsigned long) table) ^ bits);
|
||||
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
|
||||
page->flags ^= bits;
|
||||
if (!(page->flags & FRAG_MASK)) {
|
||||
pgtable_page_dtor(page);
|
||||
__free_page(page);
|
||||
}
|
||||
}
|
||||
|
||||
void page_table_free(struct mm_struct *mm, unsigned long *table)
|
||||
{
|
||||
struct page *page;
|
||||
|
|
@ -225,7 +332,7 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
|
|||
bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
|
||||
bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long);
|
||||
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
|
||||
spin_lock(&mm->context.list_lock);
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
page->flags ^= bits;
|
||||
if (page->flags & FRAG_MASK) {
|
||||
/* Page now has some free pgtable fragments. */
|
||||
|
|
@ -234,18 +341,48 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
|
|||
} else
|
||||
/* All fragments of the 4K page have been freed. */
|
||||
list_del(&page->lru);
|
||||
spin_unlock(&mm->context.list_lock);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
if (page) {
|
||||
pgtable_page_dtor(page);
|
||||
__free_page(page);
|
||||
}
|
||||
}
|
||||
|
||||
void page_table_free_rcu(struct mm_struct *mm, unsigned long *table)
|
||||
{
|
||||
struct rcu_table_freelist *batch;
|
||||
struct page *page;
|
||||
unsigned long bits;
|
||||
|
||||
if (atomic_read(&mm->mm_users) < 2 &&
|
||||
cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {
|
||||
page_table_free(mm, table);
|
||||
return;
|
||||
}
|
||||
batch = rcu_table_freelist_get(mm);
|
||||
if (!batch) {
|
||||
smp_call_function(smp_sync, NULL, 1);
|
||||
page_table_free(mm, table);
|
||||
return;
|
||||
}
|
||||
bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
|
||||
bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long);
|
||||
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
/* Delayed freeing with rcu prevents reuse of pgtable fragments */
|
||||
list_del_init(&page->lru);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
table = (unsigned long *)(((unsigned long) table) | bits);
|
||||
batch->table[batch->pgt_index++] = table;
|
||||
if (batch->pgt_index >= batch->crst_index)
|
||||
rcu_table_freelist_finish();
|
||||
}
|
||||
|
||||
void disable_noexec(struct mm_struct *mm, struct task_struct *tsk)
|
||||
{
|
||||
struct page *page;
|
||||
|
||||
spin_lock(&mm->context.list_lock);
|
||||
spin_lock_bh(&mm->context.list_lock);
|
||||
/* Free shadow region and segment tables. */
|
||||
list_for_each_entry(page, &mm->context.crst_list, lru)
|
||||
if (page->index) {
|
||||
|
|
@ -255,7 +392,7 @@ void disable_noexec(struct mm_struct *mm, struct task_struct *tsk)
|
|||
/* "Free" second halves of page tables. */
|
||||
list_for_each_entry(page, &mm->context.pgtable_list, lru)
|
||||
page->flags &= ~SECOND_HALVES;
|
||||
spin_unlock(&mm->context.list_lock);
|
||||
spin_unlock_bh(&mm->context.list_lock);
|
||||
mm->context.noexec = 0;
|
||||
update_mm(mm, tsk);
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue