From: Leonid Yegoshin <[email protected]> There is a potential race when probing the TLB in TLBL/M/S exception handlers for a matching entry. Between the time we hit a TLBL/S/M exception and the time we get to execute the TLBP instruction, the HTW may have killed the TLB entry we are interested in hence the TLB probe may fail. However, in the existing handlers, we never checked the status of the TLBP (ie check the result in the C0/Index register). We fix this by adding such a check when the core implements the HTW. If we couldn't find a matching entry, we return back and try again.
Cc: <[email protected]> # v3.17+ Signed-off-by: Leonid Yegoshin <[email protected]> Signed-off-by: Markos Chandras <[email protected]> --- arch/mips/mm/tlbex.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c index 7994368f96c4..3978a3d81366 100644 --- a/arch/mips/mm/tlbex.c +++ b/arch/mips/mm/tlbex.c @@ -1872,8 +1872,16 @@ build_r4000_tlbchange_handler_head(u32 **p, struct uasm_label **l, uasm_l_smp_pgtable_change(l, *p); #endif iPTE_LW(p, wr.r1, wr.r2); /* get even pte */ - if (!m4kc_tlbp_war()) + if (!m4kc_tlbp_war()) { build_tlb_probe_entry(p); + if (cpu_has_htw) { + /* race condition happens, leaving */ + uasm_i_ehb(p); + uasm_i_mfc0(p, wr.r3, C0_INDEX); + uasm_il_bltz(p, r, wr.r3, label_leave); + uasm_i_nop(p); + } + } return wr; } -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
