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author | 2020-02-03 17:35:54 -0800 | |
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committer | 2020-02-04 03:05:25 +0000 | |
commit | fbf56346b855872db45af7c1274180f9d91f46cd (patch) | |
tree | 30a520c91c81e5a33ee997cae81316ab00776bd7 /mm/pagewalk.c | |
parent | mm: pagewalk: allow walking without vma (diff) | |
download | linux-fbf56346b855872db45af7c1274180f9d91f46cd.tar.gz linux-fbf56346b855872db45af7c1274180f9d91f46cd.tar.bz2 linux-fbf56346b855872db45af7c1274180f9d91f46cd.zip |
mm: pagewalk: don't lock PTEs for walk_page_range_novma()
walk_page_range_novma() can be used to walk page tables or the kernel or
for firmware. These page tables may contain entries that are not backed
by a struct page and so it isn't (in general) possible to take the PTE
lock for the pte_entry() callback. So update walk_pte_range() to only
take the lock when no_vma==false by splitting out the inner loop to a
separate function and add a comment explaining the difference to
walk_page_range_novma().
Link: http://lkml.kernel.org/r/20191218162402.45610-14-steven.price@arm.com
Signed-off-by: Steven Price <steven.price@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/pagewalk.c')
-rw-r--r-- | mm/pagewalk.c | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/mm/pagewalk.c b/mm/pagewalk.c index d5773465f6da..4b5ee92ba079 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -4,15 +4,12 @@ #include <linux/sched.h> #include <linux/hugetlb.h> -static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, - struct mm_walk *walk) +static int walk_pte_range_inner(pte_t *pte, unsigned long addr, + unsigned long end, struct mm_walk *walk) { - pte_t *pte; - int err = 0; const struct mm_walk_ops *ops = walk->ops; - spinlock_t *ptl; + int err = 0; - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (;;) { err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); if (err) @@ -22,8 +19,26 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, break; pte++; } + return err; +} + +static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + pte_t *pte; + int err = 0; + spinlock_t *ptl; + + if (walk->no_vma) { + pte = pte_offset_map(pmd, addr); + err = walk_pte_range_inner(pte, addr, end, walk); + pte_unmap(pte); + } else { + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + err = walk_pte_range_inner(pte, addr, end, walk); + pte_unmap_unlock(pte, ptl); + } - pte_unmap_unlock(pte, ptl); return err; } @@ -394,6 +409,12 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, return err; } +/* + * Similar to walk_page_range() but can walk any page tables even if they are + * not backed by VMAs. Because 'unusual' entries may be walked this function + * will also not lock the PTEs for the pte_entry() callback. This is useful for + * walking the kernel pages tables or page tables for firmware. + */ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private) |