diff options
author | Dave Hansen <dave.hansen@linux.intel.com> | 2016-02-12 21:02:18 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2016-02-18 08:32:44 (GMT) |
commit | 1874f6895c92d991ccf85edcc55a0d9dd552d71c (patch) | |
tree | d0abdaa8d71abc9850fdbf8c8fa39696a6501e10 /arch/x86/mm | |
parent | d4925e00d59698a201231cf99dce47d8b922bb34 (diff) | |
download | linux-1874f6895c92d991ccf85edcc55a0d9dd552d71c.tar.xz |
x86/mm/gup: Simplify get_user_pages() PTE bit handling
The current get_user_pages() code is a wee bit more complicated
than it needs to be for pte bit checking. Currently, it establishes
a mask of required pte _PAGE_* bits and ensures that the pte it
goes after has all those bits.
This consolidates the three identical copies of this code.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210218.3A2D4045@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm')
-rw-r--r-- | arch/x86/mm/gup.c | 38 |
1 files changed, 22 insertions, 16 deletions
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index ce5e454..2f0a329 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -75,6 +75,24 @@ static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages) } /* + * 'pteval' can come from a pte, pmd or pud. We only check + * _PAGE_PRESENT, _PAGE_USER, and _PAGE_RW in here which are the + * same value on all 3 types. + */ +static inline int pte_allows_gup(unsigned long pteval, int write) +{ + unsigned long need_pte_bits = _PAGE_PRESENT|_PAGE_USER; + + if (write) + need_pte_bits |= _PAGE_RW; + + if ((pteval & need_pte_bits) != need_pte_bits) + return 0; + + return 1; +} + +/* * The performance critical leaf functions are made noinline otherwise gcc * inlines everything into a single function which results in too much * register pressure. @@ -83,14 +101,9 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { struct dev_pagemap *pgmap = NULL; - unsigned long mask; int nr_start = *nr; pte_t *ptep; - mask = _PAGE_PRESENT|_PAGE_USER; - if (write) - mask |= _PAGE_RW; - ptep = pte_offset_map(&pmd, addr); do { pte_t pte = gup_get_pte(ptep); @@ -110,7 +123,8 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr, pte_unmap(ptep); return 0; } - } else if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) { + } else if (!pte_allows_gup(pte_val(pte), write) || + pte_special(pte)) { pte_unmap(ptep); return 0; } @@ -164,14 +178,10 @@ static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr, static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { - unsigned long mask; struct page *head, *page; int refs; - mask = _PAGE_PRESENT|_PAGE_USER; - if (write) - mask |= _PAGE_RW; - if ((pmd_flags(pmd) & mask) != mask) + if (!pte_allows_gup(pmd_val(pmd), write)) return 0; VM_BUG_ON(!pfn_valid(pmd_pfn(pmd))); @@ -231,14 +241,10 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, static noinline int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { - unsigned long mask; struct page *head, *page; int refs; - mask = _PAGE_PRESENT|_PAGE_USER; - if (write) - mask |= _PAGE_RW; - if ((pud_flags(pud) & mask) != mask) + if (!pte_allows_gup(pud_val(pud), write)) return 0; /* hugepages are never "special" */ VM_BUG_ON(pud_flags(pud) & _PAGE_SPECIAL); |