Nicholas Piggin 33258a1db1 powerpc/64s: Fix THP PMD collapse serialisation ... Commit 1b2443a547 ("powerpc/book3s64: Avoid multiple endian conversion in pte helpers") changed the actual bitwise tests in pte_access_permitted by using pte_write() and pte_present() helpers rather than raw bitwise testing _PAGE_WRITE and _PAGE_PRESENT bits. The pte_present() change now returns true for PTEs which are !_PAGE_PRESENT and _PAGE_INVALID, which is the combination used by pmdp_invalidate() to synchronize access from lock-free lookups. pte_access_permitted() is used by pmd_access_permitted(), so allowing GUP lock free access to proceed with such PTEs breaks this synchronisation. This bug has been observed on a host using the hash page table MMU, with random crashes and corruption in guests, usually together with bad PMD messages in the host. Fix this by adding an explicit check in pmd_access_permitted(), and documenting the condition explicitly. The pte_write() change should be okay, and would prevent GUP from falling back to the slow path when encountering savedwrite PTEs, which matches what x86 (that does not implement savedwrite) does. Fixes: 1b2443a547 ("powerpc/book3s64: Avoid multiple endian conversion in pte helpers") Cc: stable@vger.kernel.org # v4.20+ Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>		2019-06-07 16:26:44 +10:00
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32	powerpc/32: make KVIRT_TOP dependent on FIXMAP_START	2019-05-03 01:20:26 +10:00
64	powerpc/64s: Fix THP PMD collapse serialisation	2019-06-07 16:26:44 +10:00
pgalloc.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
pgtable.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
tlbflush.h	powerpc: split asm/tlbflush.h	2018-07-30 22:48:21 +10:00