• Markos Chandras's avatar
    MIPS: HTW: Prevent accidental HTW start due to nested htw_{start, stop} · ed4cbc81
    Markos Chandras authored
    activate_mm() and switch_mm() call get_new_mmu_context() which in turn
    can enable the HTW before the entryhi is changed with the new ASID.
    Since the latter will enable the HTW in local_flush_tlb_all(),
    then there is a small timing window where the HTW is running with the
    new ASID but with an old pgd since the TLBMISS_HANDLER_SETUP_PGD
    hasn't assigned a new one yet. In order to prevent that, we introduce a
    simple htw counter to avoid starting HTW accidentally due to nested
    htw_{start,stop}() sequences. Moreover, since various IPI calls can
    enforce TLB flushing operations on a different core, such an operation
    may interrupt another htw_{stop,start} in progress leading inconsistent
    updates of the htw_seq variable. In order to avoid that, we disable the
    interrupts whenever we update that variable.
    Signed-off-by: default avatarMarkos Chandras <markos.chandras@imgtec.com>
    Cc: <stable@vger.kernel.org> # 3.17+
    Cc: linux-mips@linux-mips.org
    Patchwork: https://patchwork.linux-mips.org/patch/9118/Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
    ed4cbc81
pgtable.h 15.6 KB