On 12/01/2016 03:18 AM, Andrew Jones wrote:
> On Wed, Nov 30, 2016 at 11:16:41PM -0600, Wei Huang wrote:
>> From: Christopher Covington <cov@xxxxxxxxxxxxxx>
>>
>> Ensure that reads of the PMCCNTR_EL0 are monotonically increasing,
>> even for the smallest delta of two subsequent reads.
>>
>> Signed-off-by: Christopher Covington <cov@xxxxxxxxxxxxxx>
>> Signed-off-by: Wei Huang <wei@xxxxxxxxxx>
>> Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
>> ---
>> arm/pmu.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 94 insertions(+)
>>
>> diff --git a/arm/pmu.c b/arm/pmu.c
>> index 1fe2b1a..3566a27 100644
>> --- a/arm/pmu.c
>> +++ b/arm/pmu.c
>> @@ -16,6 +16,9 @@
>> #include "asm/barrier.h"
>> #include "asm/processor.h"
>>
>> +#define PMU_PMCR_E (1 << 0)
>> +#define PMU_PMCR_C (1 << 2)
>> +#define PMU_PMCR_LC (1 << 6)
>> #define PMU_PMCR_N_SHIFT 11
>> #define PMU_PMCR_N_MASK 0x1f
>> #define PMU_PMCR_ID_SHIFT 16
>> @@ -23,10 +26,57 @@
>> #define PMU_PMCR_IMP_SHIFT 24
>> #define PMU_PMCR_IMP_MASK 0xff
>>
>> +#define ID_DFR0_PERFMON_SHIFT 24
>> +#define ID_DFR0_PERFMON_MASK 0xf
>> +
>> +#define PMU_CYCLE_IDX 31
>> +
>> +#define NR_SAMPLES 10
>> +
>> +static unsigned int pmu_version;
>> #if defined(__arm__)
>> DEFINE_GET_SYSREG32(pmcr, 0, c9, c12, 0)
>> +DEFINE_SET_SYSREG32(pmcr, 0, c9, c12, 0)
>> +DEFINE_GET_SYSREG32(id_dfr0, 0, c0, c1, 2)
>> +DEFINE_SET_SYSREG32(pmselr, 0, c9, c12, 5)
>> +DEFINE_SET_SYSREG32(pmxevtyper, 0, c9, c13, 1)
>> +DEFINE_GET_SYSREG32(pmccntr32, 0, c9, c13, 0)
>> +DEFINE_SET_SYSREG32(pmccntr32, 0, c9, c13, 0)
>> +DEFINE_GET_SYSREG64(pmccntr64, 0, c9)
>> +DEFINE_SET_SYSREG64(pmccntr64, 0, c9)
>> +DEFINE_SET_SYSREG32(pmcntenset, 0, c9, c12, 1)
>
> Seeing how we get lots of redundant looking lines, I think instead
> of defining DEFINE_SET/GET_SYSREG32/64, we should instead have
>
> DEFINE_SYSREG32/64 ... creates both get_<reg> and set_<reg>
> DEFINE_SYSREG32/64_RO ... creates just get_<reg>
Don't like the naming. I think we can create a new macro, named
DEFINE_GET_SET_SYSREG32/64. I know it is boring, but readers should get
the idea easily.
>
>> +
>> +static inline uint64_t get_pmccntr(void)
>> +{
>> + if (pmu_version == 0x3)
>> + return get_pmccntr64();
>> + else
>> + return get_pmccntr32();
>> +}
>> +
>> +static inline void set_pmccntr(uint64_t value)
>> +{
>> + if (pmu_version == 0x3)
>> + set_pmccntr64(value);
>> + else
>> + set_pmccntr32(value & 0xffffffff);
>> +}
>
> So the two accessors above are exceptional, which is why we don't
> use SYSREG for them. These can have uint64_t for there external
> interface. We can't require 'unsigned long' or 'unsigned long long'
>
>> +
>> +/* PMCCFILTR is an obsolete name for PMXEVTYPER31 in ARMv7 */
>> +static inline void set_pmccfiltr(uint32_t value)
>> +{
>> + set_pmselr(PMU_CYCLE_IDX);
>> + set_pmxevtyper(value);
>> + isb();
>> +}
>> #elif defined(__aarch64__)
>> DEFINE_GET_SYSREG32(pmcr, el0)
>> +DEFINE_SET_SYSREG32(pmcr, el0)
>> +DEFINE_GET_SYSREG32(id_dfr0, el1)
>> +DEFINE_GET_SYSREG64(pmccntr, el0);
>> +DEFINE_SET_SYSREG64(pmccntr, el0);
>> +DEFINE_SET_SYSREG32(pmcntenset, el0);
>> +DEFINE_SET_SYSREG32(pmccfiltr, el0);
>> #endif
>>
>> /*
>> @@ -52,11 +102,55 @@ static bool check_pmcr(void)
>> return ((pmcr >> PMU_PMCR_IMP_SHIFT) & PMU_PMCR_IMP_MASK) != 0;
>> }
>>
>> +/*
>> + * Ensure that the cycle counter progresses between back-to-back reads.
>> + */
>> +static bool check_cycles_increase(void)
>> +{
>> + bool success = true;
>> +
>> + /* init before event access, this test only cares about cycle count */
>> + set_pmcntenset(1 << PMU_CYCLE_IDX);
>> + set_pmccfiltr(0); /* count cycles in EL0, EL1, but not EL2 */
>> + set_pmccntr(0);
>> +
>> + set_pmcr(get_pmcr() | PMU_PMCR_LC | PMU_PMCR_C | PMU_PMCR_E);
>> +
>> + for (int i = 0; i < NR_SAMPLES; i++) {
>> + uint64_t a, b;
>> +
>> + a = get_pmccntr();
>> + b = get_pmccntr();
>> +
>> + if (a >= b) {
>> + printf("Read %"PRId64" then %"PRId64".\n", a, b);
>> + success = false;
>> + break;
>> + }
>> + }
>> +
>> + set_pmcr(get_pmcr() & ~PMU_PMCR_E);
>> +
>> + return success;
>> +}
>> +
>> +void pmu_init(void)
>> +{
>> + uint32_t dfr0;
>> +
>> + /* probe pmu version */
>> + dfr0 = get_id_dfr0();
>> + pmu_version = (dfr0 >> ID_DFR0_PERFMON_SHIFT) & ID_DFR0_PERFMON_MASK;
>> + report_info("PMU version: %d", pmu_version);
>> +}
>> +
>> int main(void)
>> {
>> report_prefix_push("pmu");
>>
>> + pmu_init();
>> report("Control register", check_pmcr());
>> + report("Monotonically increasing cycle count", check_cycles_increase());
>>
>> return report_summary();
>> }
>> --
>> 1.8.3.1
>>
>>
>
> drew
>
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