From b57aa7bdc3b4f16b216bd854e86431146729a640 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 22 Aug 2022 14:23:52 +0100 Subject: target/arm: Ignore PMCR.D when PMCR.LC is set The architecture requires that if PMCR.LC is set (for a 64-bit cycle counter) then PMCR.D (which enables the clock divider so the counter ticks every 64 cycles rather than every cycle) should be ignored. We were always honouring PMCR.D; fix the bug so we correctly ignore it in this situation. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-Id: <20220822132358.3524971-5-peter.maydell@linaro.org> Signed-off-by: Richard Henderson --- target/arm/helper.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'target') diff --git a/target/arm/helper.c b/target/arm/helper.c index a348c74..f1b20de 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -1172,6 +1172,17 @@ static void pmu_update_irq(CPUARMState *env) (env->cp15.c9_pminten & env->cp15.c9_pmovsr)); } +static bool pmccntr_clockdiv_enabled(CPUARMState *env) +{ + /* + * Return true if the clock divider is enabled and the cycle counter + * is supposed to tick only once every 64 clock cycles. This is + * controlled by PMCR.D, but if PMCR.LC is set to enable the long + * (64-bit) cycle counter PMCR.D has no effect. + */ + return (env->cp15.c9_pmcr & (PMCRD | PMCRLC)) == PMCRD; +} + /* * Ensure c15_ccnt is the guest-visible count so that operations such as * enabling/disabling the counter or filtering, modifying the count itself, @@ -1184,8 +1195,7 @@ static void pmccntr_op_start(CPUARMState *env) if (pmu_counter_enabled(env, 31)) { uint64_t eff_cycles = cycles; - if (env->cp15.c9_pmcr & PMCRD) { - /* Increment once every 64 processor clock cycles */ + if (pmccntr_clockdiv_enabled(env)) { eff_cycles /= 64; } @@ -1228,8 +1238,7 @@ static void pmccntr_op_finish(CPUARMState *env) #endif uint64_t prev_cycles = env->cp15.c15_ccnt_delta; - if (env->cp15.c9_pmcr & PMCRD) { - /* Increment once every 64 processor clock cycles */ + if (pmccntr_clockdiv_enabled(env)) { prev_cycles /= 64; } env->cp15.c15_ccnt_delta = prev_cycles - env->cp15.c15_ccnt; -- cgit v1.1