From: Christoph Hellwig <hch@xxxxxx> Subject: sh: use the generic get_user_pages_fast code The sh code is mostly equivalent to the generic one, minus various bugfixes and two arch overrides that this patch adds to pgtable.h. Link: http://lkml.kernel.org/r/20190625143715.1689-7-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: David Miller <davem@xxxxxxxxxxxxx> Cc: James Hogan <jhogan@xxxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Cc: Khalid Aziz <khalid.aziz@xxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Nicholas Piggin <npiggin@xxxxxxxxx> Cc: Paul Burton <paul.burton@xxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: Rich Felker <dalias@xxxxxxxx> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/sh/Kconfig | 2 arch/sh/include/asm/pgtable.h | 37 ++++ arch/sh/mm/Makefile | 2 arch/sh/mm/gup.c | 277 -------------------------------- 4 files changed, 40 insertions(+), 278 deletions(-) --- a/arch/sh/include/asm/pgtable.h~sh-use-the-generic-get_user_pages_fast-code +++ a/arch/sh/include/asm/pgtable.h @@ -149,6 +149,43 @@ extern void paging_init(void); extern void page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd); +static inline bool __pte_access_permitted(pte_t pte, u64 prot) +{ + return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot; +} + +#ifdef CONFIG_X2TLB +static inline bool pte_access_permitted(pte_t pte, bool write) +{ + u64 prot = _PAGE_PRESENT; + + prot |= _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ); + if (write) + prot |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE); + return __pte_access_permitted(pte, prot); +} +#elif defined(CONFIG_SUPERH64) +static inline bool pte_access_permitted(pte_t pte, bool write) +{ + u64 prot = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ; + + if (write) + prot |= _PAGE_WRITE; + return __pte_access_permitted(pte, prot); +} +#else +static inline bool pte_access_permitted(pte_t pte, bool write) +{ + u64 prot = _PAGE_PRESENT | _PAGE_USER; + + if (write) + prot |= _PAGE_RW; + return __pte_access_permitted(pte, prot); +} +#endif + +#define pte_access_permitted pte_access_permitted + /* arch/sh/mm/mmap.c */ #define HAVE_ARCH_UNMAPPED_AREA #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN --- a/arch/sh/Kconfig~sh-use-the-generic-get_user_pages_fast-code +++ a/arch/sh/Kconfig @@ -15,6 +15,7 @@ config SUPERH select HAVE_ARCH_TRACEHOOK select HAVE_PERF_EVENTS select HAVE_DEBUG_BUGVERBOSE + select HAVE_GENERIC_GUP select ARCH_HAVE_CUSTOM_GPIO_H select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A) select ARCH_HAS_GCOV_PROFILE_ALL @@ -64,6 +65,7 @@ config SUPERH config SUPERH32 def_bool "$(ARCH)" = "sh" select ARCH_32BIT_OFF_T + select GUP_GET_PTE_LOW_HIGH if X2TLB select HAVE_KPROBES select HAVE_KRETPROBES select HAVE_IOREMAP_PROT if MMU && !X2TLB --- a/arch/sh/mm/gup.c +++ /dev/null @@ -1,277 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * Lockless get_user_pages_fast for SuperH - * - * Copyright (C) 2009 - 2010 Paul Mundt - * - * Cloned from the x86 and PowerPC versions, by: - * - * Copyright (C) 2008 Nick Piggin - * Copyright (C) 2008 Novell Inc. - */ -#include <linux/sched.h> -#include <linux/mm.h> -#include <linux/vmstat.h> -#include <linux/highmem.h> -#include <asm/pgtable.h> - -static inline pte_t gup_get_pte(pte_t *ptep) -{ -#ifndef CONFIG_X2TLB - return READ_ONCE(*ptep); -#else - /* - * With get_user_pages_fast, we walk down the pagetables without - * taking any locks. For this we would like to load the pointers - * atomically, but that is not possible with 64-bit PTEs. What - * we do have is the guarantee that a pte will only either go - * from not present to present, or present to not present or both - * -- it will not switch to a completely different present page - * without a TLB flush in between; something that we are blocking - * by holding interrupts off. - * - * Setting ptes from not present to present goes: - * ptep->pte_high = h; - * smp_wmb(); - * ptep->pte_low = l; - * - * And present to not present goes: - * ptep->pte_low = 0; - * smp_wmb(); - * ptep->pte_high = 0; - * - * We must ensure here that the load of pte_low sees l iff pte_high - * sees h. We load pte_high *after* loading pte_low, which ensures we - * don't see an older value of pte_high. *Then* we recheck pte_low, - * which ensures that we haven't picked up a changed pte high. We might - * have got rubbish values from pte_low and pte_high, but we are - * guaranteed that pte_low will not have the present bit set *unless* - * it is 'l'. And get_user_pages_fast only operates on present ptes, so - * we're safe. - * - * gup_get_pte should not be used or copied outside gup.c without being - * very careful -- it does not atomically load the pte or anything that - * is likely to be useful for you. - */ - pte_t pte; - -retry: - pte.pte_low = ptep->pte_low; - smp_rmb(); - pte.pte_high = ptep->pte_high; - smp_rmb(); - if (unlikely(pte.pte_low != ptep->pte_low)) - goto retry; - - return pte; -#endif -} - -/* - * 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) -{ - u64 mask, result; - pte_t *ptep; - -#ifdef CONFIG_X2TLB - result = _PAGE_PRESENT | _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ); - if (write) - result |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE); -#elif defined(CONFIG_SUPERH64) - result = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ; - if (write) - result |= _PAGE_WRITE; -#else - result = _PAGE_PRESENT | _PAGE_USER; - if (write) - result |= _PAGE_RW; -#endif - - mask = result | _PAGE_SPECIAL; - - ptep = pte_offset_map(&pmd, addr); - do { - pte_t pte = gup_get_pte(ptep); - struct page *page; - - if ((pte_val(pte) & mask) != result) { - pte_unmap(ptep); - return 0; - } - VM_BUG_ON(!pfn_valid(pte_pfn(pte))); - page = pte_page(pte); - get_page(page); - __flush_anon_page(page, addr); - flush_dcache_page(page); - pages[*nr] = page; - (*nr)++; - - } while (ptep++, addr += PAGE_SIZE, addr != end); - pte_unmap(ptep - 1); - - 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 (!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; -} - -/* - * 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; - unsigned long flags; - pgd_t *pgdp; - int nr = 0; - - start &= PAGE_MASK; - addr = start; - len = (unsigned long) nr_pages << PAGE_SHIFT; - end = start + len; - if (unlikely(!access_ok((void __user *)start, len))) - return 0; - - /* - * This doesn't prevent pagetable teardown, but does prevent - * the pagetables and pages from being freed. - */ - 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; -} - -/** - * get_user_pages_fast() - pin user pages in memory - * @start: starting user address - * @nr_pages: number of pages from start to pin - * @gup_flags: flags modifying pin behaviour - * @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, - 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; - - start &= PAGE_MASK; - addr = start; - len = (unsigned long) nr_pages << PAGE_SHIFT; - - end = start + len; - if (end < start) - goto slow_irqon; - - 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(); -slow_irqon: - /* 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; - } -} --- a/arch/sh/mm/Makefile~sh-use-the-generic-get_user_pages_fast-code +++ a/arch/sh/mm/Makefile @@ -17,7 +17,7 @@ cacheops-$(CONFIG_CPU_SHX3) += cache-sh obj-y += $(cacheops-y) mmu-y := nommu.o extable_32.o -mmu-$(CONFIG_MMU) := extable_$(BITS).o fault.o gup.o ioremap.o kmap.o \ +mmu-$(CONFIG_MMU) := extable_$(BITS).o fault.o ioremap.o kmap.o \ pgtable.o tlbex_$(BITS).o tlbflush_$(BITS).o obj-y += $(mmu-y) _
