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author | David S. Miller <davem@davemloft.net> | 2019-06-17 19:48:13 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2019-06-17 20:20:36 -0700 |
commit | 13091aa30535b719e269f20a7bc34002bf5afae5 (patch) | |
tree | bd17956c3ce606a119fadbd43bfa1c0c10006984 /arch/powerpc/include/asm/book3s/64/pgtable.h | |
parent | Merge branch 'UDP-GSO-audit-tests' (diff) | |
parent | Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs (diff) | |
download | linux-dev-13091aa30535b719e269f20a7bc34002bf5afae5.tar.xz linux-dev-13091aa30535b719e269f20a7bc34002bf5afae5.zip |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Honestly all the conflicts were simple overlapping changes,
nothing really interesting to report.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/pgtable.h')
-rw-r--r-- | arch/powerpc/include/asm/book3s/64/pgtable.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 7dede2e34b70..ccf00a8b98c6 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -876,6 +876,23 @@ static inline int pmd_present(pmd_t pmd) return false; } +static inline int pmd_is_serializing(pmd_t pmd) +{ + /* + * If the pmd is undergoing a split, the _PAGE_PRESENT bit is clear + * and _PAGE_INVALID is set (see pmd_present, pmdp_invalidate). + * + * This condition may also occur when flushing a pmd while flushing + * it (see ptep_modify_prot_start), so callers must ensure this + * case is fine as well. + */ + if ((pmd_raw(pmd) & cpu_to_be64(_PAGE_PRESENT | _PAGE_INVALID)) == + cpu_to_be64(_PAGE_INVALID)) + return true; + + return false; +} + static inline int pmd_bad(pmd_t pmd) { if (radix_enabled()) @@ -1092,6 +1109,19 @@ static inline int pmd_protnone(pmd_t pmd) #define pmd_access_permitted pmd_access_permitted static inline bool pmd_access_permitted(pmd_t pmd, bool write) { + /* + * pmdp_invalidate sets this combination (which is not caught by + * !pte_present() check in pte_access_permitted), to prevent + * lock-free lookups, as part of the serialize_against_pte_lookup() + * synchronisation. + * + * This also catches the case where the PTE's hardware PRESENT bit is + * cleared while TLB is flushed, which is suboptimal but should not + * be frequent. + */ + if (pmd_is_serializing(pmd)) + return false; + return pte_access_permitted(pmd_pte(pmd), write); } |