diff options
author | Steven Price <steven.price@arm.com> | 2019-12-05 13:24:49 +1100 |
---|---|---|
committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2019-12-05 13:24:49 +1100 |
commit | aa04c7bd3b7bbea2061b73e871bcb86cba728156 (patch) | |
tree | c3dd9c39dc6db61f368ce68c022870899c4f7674 | |
parent | 2743a8a5cb29b23e04c2eab25d00588440c0d5f7 (diff) |
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.
[steven.price@arm.com: v15]
Link: http://lkml.kernel.org/r/20191101140942.51554-13-steven.price@arm.com
[steven.price@arm.com: fix boot crash]
Link: http://lkml.kernel.org/r/20191028135910.33253-13-steven.price@arm.com
Cc: Zong Li <zong.li@sifive.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Shiraz Hashim <shashim@codeaurora.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
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: Dave Jiang <dave.jiang@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: James Hogan <jhogan@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@sifive.com>
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: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r-- | include/linux/pagewalk.h | 5 | ||||
-rw-r--r-- | mm/pagewalk.c | 44 |
2 files changed, 41 insertions, 8 deletions
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index 06790f23957f..2c9725bdcf1f 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -59,6 +59,7 @@ struct mm_walk_ops { * @ops: operation to call during the walk * @mm: mm_struct representing the target process of page table walk * @vma: vma currently walked (NULL if walking outside vmas) + * @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) @@ -67,12 +68,16 @@ struct mm_walk { const struct mm_walk_ops *ops; struct mm_struct *mm; struct vm_area_struct *vma; + 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 c089786e7a7f..efa464cf079b 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) @@ -62,9 +62,14 @@ again: if (!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; + } else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) { + continue; + } + err = walk_pte_range(pmd, addr, next, walk); if (err) break; @@ -85,7 +90,7 @@ 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) @@ -99,9 +104,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, break; } - split_huge_pud(walk->vma, pud, addr); - if (pud_none(*pud)) - goto again; + if (walk->vma) { + split_huge_pud(walk->vma, pud, addr); + if (pud_none(*pud)) + goto again; + } else if (pud_leaf(*pud) || !pud_present(*pud)) { + continue; + } if (ops->pmd_entry || ops->pte_entry) err = walk_pmd_range(pud, addr, next, walk); @@ -374,6 +383,25 @@ 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) { |