diff options
author | Steven Price <steven.price@arm.com> | 2020-02-03 17:35:50 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-02-04 03:05:25 +0000 |
commit | 488ae6a2b933cb538b5d91b1c0a3420188d28771 (patch) | |
tree | b8701a4e809d670e4503cc646fafd23156801ad0 | |
parent | 3afc423632a194d7d6afef34e4bb98f804cd071d (diff) | |
download | linux-488ae6a2b933cb538b5d91b1c0a3420188d28771.tar.bz2 |
mm: pagewalk: allow walking without vma
Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range for
vma(VM_PFNMAP)", page_table_walk() will report any kernel area as a hole,
because it lacks a vma.
This means each arch has re-implemented page table walking when needed,
for example in the per-arch ptdump walker.
Remove the requirement to have a vma in the generic code and add a new
function walk_page_range_novma() which ignores the VMAs and simply walks
the page tables.
Link: http://lkml.kernel.org/r/20191218162402.45610-13-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>
-rw-r--r-- | include/linux/pagewalk.h | 5 | ||||
-rw-r--r-- | mm/pagewalk.c | 40 |
2 files changed, 37 insertions, 8 deletions
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index aa6a0b63964e..d5d07f7a9c14 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -73,6 +73,7 @@ enum page_walk_action { * @mm: mm_struct representing the target process of page table walk * @vma: vma currently walked (NULL if walking outside vmas) * @action: next action to perform (see enum page_walk_action) + * @no_vma: walk ignoring vmas (vma will always be NULL) * @private: private data for callbacks' usage * * (see the comment on walk_page_range() for more details) @@ -82,12 +83,16 @@ struct mm_walk { struct mm_struct *mm; struct vm_area_struct *vma; enum page_walk_action action; + bool no_vma; void *private; }; int walk_page_range(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private); +int walk_page_range_novma(struct mm_struct *mm, unsigned long start, + unsigned long end, const struct mm_walk_ops *ops, + void *private); int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private); int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, diff --git a/mm/pagewalk.c b/mm/pagewalk.c index 690af44609e2..d5773465f6da 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -39,7 +39,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, do { again: next = pmd_addr_end(addr, end); - if (pmd_none(*pmd) || !walk->vma) { + if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) { if (ops->pte_hole) err = ops->pte_hole(addr, next, walk); if (err) @@ -65,13 +65,16 @@ again: * Check this here so we only break down trans_huge * pages when we _need_ to */ - if (walk->action == ACTION_CONTINUE || + if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) || + walk->action == ACTION_CONTINUE || !(ops->pte_entry)) continue; - split_huge_pmd(walk->vma, pmd, addr); - if (pmd_trans_unstable(pmd)) - goto again; + if (walk->vma) { + split_huge_pmd(walk->vma, pmd, addr); + if (pmd_trans_unstable(pmd)) + goto again; + } err = walk_pte_range(pmd, addr, next, walk); if (err) @@ -93,7 +96,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, do { again: next = pud_addr_end(addr, end); - if (pud_none(*pud) || !walk->vma) { + if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) { if (ops->pte_hole) err = ops->pte_hole(addr, next, walk); if (err) @@ -111,11 +114,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, if (walk->action == ACTION_AGAIN) goto again; - if (walk->action == ACTION_CONTINUE || + if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) || + walk->action == ACTION_CONTINUE || !(ops->pmd_entry || ops->pte_entry)) continue; - split_huge_pud(walk->vma, pud, addr); + if (walk->vma) + split_huge_pud(walk->vma, pud, addr); if (pud_none(*pud)) goto again; @@ -389,6 +394,25 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, return err; } +int walk_page_range_novma(struct mm_struct *mm, unsigned long start, + unsigned long end, const struct mm_walk_ops *ops, + void *private) +{ + struct mm_walk walk = { + .ops = ops, + .mm = mm, + .private = private, + .no_vma = true + }; + + if (start >= end || !walk.mm) + return -EINVAL; + + lockdep_assert_held(&walk.mm->mmap_sem); + + return __walk_page_range(start, end, &walk); +} + int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private) { |