diff options
| author | Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> | 2019-09-18 17:53:28 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-09-19 14:24:59 +0300 |
| commit | d9101bfa6adc831bda8836c4d774820553c14942 (patch) | |
| tree | 6ecb08a936eaf1af85eae2027ea0446407e53e07 | |
| parent | 7c1bb6bbf75d8ca5ec878627d3170effcaf54f27 (diff) | |
| download | linux-d9101bfa6adc831bda8836c4d774820553c14942.tar.xz | |
powerpc/mm/mce: Keep irqs disabled during lockless page table walk
__find_linux_mm_pte() returns a page table entry pointer after walking
the page table without holding locks. To make it safe against a THP
split and/or collapse, we disable interrupts around the lockless page
table walk. However we need to keep interrupts disabled as long as we
use the page table entry pointer that is returned.
Fix addr_to_pfn() to do that.
Fixes: ba41e1e1ccb9 ("powerpc/mce: Hookup derror (load/store) UE errors")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
[mpe: Rearrange code slightly and tweak change log wording]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190918145328.28602-1-aneesh.kumar@linux.ibm.com
| -rw-r--r-- | arch/powerpc/kernel/mce_power.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c index 356e7b99f661..1cbf7f1a4e3d 100644 --- a/arch/powerpc/kernel/mce_power.c +++ b/arch/powerpc/kernel/mce_power.c @@ -29,7 +29,7 @@ unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long addr) { pte_t *ptep; unsigned int shift; - unsigned long flags; + unsigned long pfn, flags; struct mm_struct *mm; if (user_mode(regs)) @@ -39,18 +39,22 @@ unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long addr) local_irq_save(flags); ptep = __find_linux_pte(mm->pgd, addr, NULL, &shift); - local_irq_restore(flags); - if (!ptep || pte_special(*ptep)) - return ULONG_MAX; + if (!ptep || pte_special(*ptep)) { + pfn = ULONG_MAX; + goto out; + } - if (shift > PAGE_SHIFT) { + if (shift <= PAGE_SHIFT) + pfn = pte_pfn(*ptep); + else { unsigned long rpnmask = (1ul << shift) - PAGE_SIZE; - - return pte_pfn(__pte(pte_val(*ptep) | (addr & rpnmask))); + pfn = pte_pfn(__pte(pte_val(*ptep) | (addr & rpnmask))); } - return pte_pfn(*ptep); +out: + local_irq_restore(flags); + return pfn; } /* flush SLBs and reload */ |