From: Markos Chandras Date: Mon, 26 Jan 2015 13:04:33 +0000 (+0000) Subject: MIPS: HTW: Prevent accidental HTW start due to nested htw_{start, stop} X-Git-Tag: fixes-v4.0-rc1~21^2~33 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed4cbc81addbc076b016c5b979fd1a02f0897f0a;p=pandora-kernel.git MIPS: HTW: Prevent accidental HTW start due to nested htw_{start, stop} 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: Markos Chandras Cc: # 3.17+ Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9118/ Signed-off-by: Ralf Baechle --- Reading git-diff-tree failed