On Thu, Dec 01, 2016 at 11:36:55AM -0600, Wei Huang wrote:
>
>
> 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.
I don't like the looks of DEFINE_GET_SET_SYSREG32/64... But we don't
need the _RO version I proposed. Just DEFINE_SYSREG32/64, which makes
both get/set is fine. Unit tests shouldn't be restricted on attempting
to write r/o registers - they're testing precisely that type of thing,
and they shouldn't have to write their own set accessors to do it either.
>
> >
> >> +
> >> +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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