MIPS: use the generic get_user_pages_fast code
The mips code is mostly equivalent to the generic one, minus various bugfixes and an arch override for gup_fast_permitted. Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has pte_special and pte_mkspecial implemented and used in the existing gup code. They are no-op stubs, though which makes me a little unsure if this is really right thing to do. Note that this also adds back a missing cpu_has_dc_aliases check for __get_user_pages_fast, which the old code was only doing for get_user_pages_fast. This clearly looks like an oversight, as any condition that makes get_user_pages_fast unsafe also applies to __get_user_pages_fast. [hch@lst.de: MIPS: don't select ARCH_HAS_PTE_SPECIAL] Link: http://lkml.kernel.org/r/20190701151818.32227-3-hch@lst.de Link: http://lkml.kernel.org/r/20190625143715.1689-5-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Tested-by: Guenter Roeck <linux@roeck-us.net> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: James Hogan <jhogan@kernel.org> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Rich Felker <dalias@libc.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig
Linus Torvalds
parent
39656e83da
commit
446f062bf0
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@ -34,6 +34,7 @@ config MIPS
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select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
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select GENERIC_SMP_IDLE_THREAD
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select GENERIC_TIME_VSYSCALL
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select GUP_GET_PTE_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
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select HANDLE_DOMAIN_IRQ
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select HAVE_ARCH_COMPILER_H
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select HAVE_ARCH_JUMP_LABEL
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@ -55,6 +56,7 @@ config MIPS
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select HAVE_FTRACE_MCOUNT_RECORD
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select HAVE_FUNCTION_GRAPH_TRACER
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select HAVE_FUNCTION_TRACER
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select HAVE_GENERIC_GUP
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select HAVE_IDE
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select HAVE_IOREMAP_PROT
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select HAVE_IRQ_EXIT_ON_IRQ_STACK
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@ -20,6 +20,7 @@
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#include <asm/cmpxchg.h>
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#include <asm/io.h>
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#include <asm/pgtable-bits.h>
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#include <asm/cpu-features.h>
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struct mm_struct;
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struct vm_area_struct;
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@ -626,6 +627,8 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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#define gup_fast_permitted(start, end) (!cpu_has_dc_aliases)
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#include <asm-generic/pgtable.h>
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/*
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@ -7,7 +7,6 @@ obj-y += cache.o
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obj-y += context.o
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obj-y += extable.o
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obj-y += fault.o
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obj-y += gup.o
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obj-y += init.o
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obj-y += mmap.o
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obj-y += page.o
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@ -1,303 +0,0 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Lockless get_user_pages_fast for MIPS
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*
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* Copyright (C) 2008 Nick Piggin
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* Copyright (C) 2008 Novell Inc.
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* Copyright (C) 2011 Ralf Baechle
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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/vmstat.h>
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#include <linux/highmem.h>
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#include <linux/swap.h>
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#include <linux/hugetlb.h>
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#include <asm/cpu-features.h>
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#include <asm/pgtable.h>
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static inline pte_t gup_get_pte(pte_t *ptep)
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{
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#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
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pte_t pte;
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retry:
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pte.pte_low = ptep->pte_low;
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smp_rmb();
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pte.pte_high = ptep->pte_high;
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smp_rmb();
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if (unlikely(pte.pte_low != ptep->pte_low))
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goto retry;
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return pte;
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#else
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return READ_ONCE(*ptep);
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#endif
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}
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static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
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int write, struct page **pages, int *nr)
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{
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pte_t *ptep = pte_offset_map(&pmd, addr);
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do {
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pte_t pte = gup_get_pte(ptep);
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struct page *page;
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if (!pte_present(pte) ||
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pte_special(pte) || (write && !pte_write(pte))) {
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pte_unmap(ptep);
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return 0;
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}
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VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
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page = pte_page(pte);
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get_page(page);
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SetPageReferenced(page);
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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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pte_unmap(ptep - 1);
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return 1;
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}
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static inline void get_head_page_multiple(struct page *page, int nr)
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{
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VM_BUG_ON(page != compound_head(page));
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VM_BUG_ON(page_count(page) == 0);
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page_ref_add(page, nr);
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SetPageReferenced(page);
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}
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static int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end,
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int write, struct page **pages, int *nr)
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{
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pte_t pte = *(pte_t *)&pmd;
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struct page *head, *page;
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int refs;
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if (write && !pte_write(pte))
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return 0;
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/* hugepages are never "special" */
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VM_BUG_ON(pte_special(pte));
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VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
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refs = 0;
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head = pte_page(pte);
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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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get_head_page_multiple(head, refs);
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return 1;
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}
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static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
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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;
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pmdp = pmd_offset(&pud, addr);
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do {
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pmd_t pmd = *pmdp;
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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(pmd, addr, next, write, pages,nr))
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return 0;
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} else {
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if (!gup_pte_range(pmd, addr, next, write, pages,nr))
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return 0;
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}
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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 int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end,
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int write, struct page **pages, int *nr)
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{
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pte_t pte = *(pte_t *)&pud;
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struct page *head, *page;
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int refs;
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if (write && !pte_write(pte))
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return 0;
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/* hugepages are never "special" */
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VM_BUG_ON(pte_special(pte));
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VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
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refs = 0;
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head = pte_page(pte);
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page = head + ((addr & ~PUD_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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get_head_page_multiple(head, refs);
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return 1;
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}
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static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
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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;
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pudp = pud_offset(&pgd, addr);
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do {
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pud_t pud = *pudp;
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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 (unlikely(pud_huge(pud))) {
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if (!gup_huge_pud(pud, addr, next, write, pages,nr))
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return 0;
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} else {
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if (!gup_pmd_range(pud, addr, next, write, pages,nr))
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return 0;
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}
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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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* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
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* back to the regular GUP.
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* Note a difference with get_user_pages_fast: this always returns the
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* number of pages pinned, 0 if no pages were pinned.
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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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unsigned long flags;
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pgd_t *pgdp;
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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 (unlikely(!access_ok((void __user *)start, len)))
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return 0;
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/*
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* XXX: batch / limit 'nr', to avoid large irq off latency
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* needs some instrumenting to determine the common sizes used by
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* important workloads (eg. DB2), and whether limiting the batch
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* size will decrease performance.
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*
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* It seems like we're in the clear for the moment. Direct-IO is
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* the main guy that batches up lots of get_user_pages, and even
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* they are limited to 64-at-a-time which is not so many.
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*/
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/*
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* This doesn't prevent pagetable teardown, but does prevent
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* the pagetables and pages from being freed.
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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 page and take a ref on it.
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*/
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local_irq_save(flags);
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pgdp = pgd_offset(mm, addr);
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do {
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pgd_t pgd = *pgdp;
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next = pgd_addr_end(addr, end);
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if (pgd_none(pgd))
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break;
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if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
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break;
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} while (pgdp++, addr = next, addr != end);
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local_irq_restore(flags);
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return nr;
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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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* @gup_flags: flags modifying pin behaviour
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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,
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unsigned int gup_flags, 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;
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int ret, 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 || cpu_has_dc_aliases)
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goto slow_irqon;
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/* XXX: batch / limit 'nr' */
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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_t pgd = *pgdp;
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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(pgd, addr, next, gup_flags & FOLL_WRITE,
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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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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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ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
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pages, gup_flags);
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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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