[PATCH v3 07/11] lib: sbi: Allow programmable counters to monitor cycle/instret events
Anup Patel
anup at brainfault.org
Wed Nov 3 03:55:36 PDT 2021
On Tue, Nov 2, 2021 at 8:40 PM Atish Patra <atish.patra at wdc.com> wrote:
>
> A platform may use programmable counters for cycle/instret events.
> The priv spec allows that provided that cycle/instret also report those
> events in addition to the programmable counters. We should allow that
> functionality in OpenSBI.
>
> Signed-off-by: Atish Patra <atish.patra at wdc.com>
Looks good to me.
Reviewed-by: Anup Patel <anup.patel at wdc.com>
Regards,
Anup
> ---
> include/sbi/sbi_pmu.h | 1 +
> lib/sbi/sbi_pmu.c | 59 +++++++++++++++++++++++++++++++------------
> 2 files changed, 44 insertions(+), 16 deletions(-)
>
> diff --git a/include/sbi/sbi_pmu.h b/include/sbi/sbi_pmu.h
> index b3010cc5c1ce..f0185566cd6d 100644
> --- a/include/sbi/sbi_pmu.h
> +++ b/include/sbi/sbi_pmu.h
> @@ -26,6 +26,7 @@
> #define SBI_PMU_FW_CTR_MAX 16
> #define SBI_PMU_HW_CTR_MAX 32
> #define SBI_PMU_CTR_MAX (SBI_PMU_HW_CTR_MAX + SBI_PMU_FW_CTR_MAX)
> +#define SBI_PMU_FIXED_CTR_MASK 0x07
>
> /** Initialize PMU */
> int sbi_pmu_init(struct sbi_scratch *scratch, bool cold_boot);
> diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
> index b7bd120a6f68..9d97014eed88 100644
> --- a/lib/sbi/sbi_pmu.c
> +++ b/lib/sbi/sbi_pmu.c
> @@ -175,9 +175,7 @@ static int pmu_add_hw_event_map(u32 eidx_start, u32 eidx_end, u32 cmap,
> struct sbi_pmu_hw_event *event = &hw_event_map[num_hw_events];
>
> /* The first two counters are reserved by priv spec */
> - if ((eidx_start == SBI_PMU_HW_CPU_CYCLES && cmap != 0x1) ||
> - (eidx_start == SBI_PMU_HW_INSTRUCTIONS && cmap != 0x4) ||
> - (eidx_start > SBI_PMU_HW_INSTRUCTIONS && (cmap & 0x07)))
> + if (eidx_start > SBI_PMU_HW_INSTRUCTIONS && (cmap & SBI_PMU_FIXED_CTR_MASK))
> return SBI_EDENIED;
>
> if (num_hw_events >= SBI_PMU_HW_EVENT_MAX - 1) {
> @@ -188,8 +186,6 @@ static int pmu_add_hw_event_map(u32 eidx_start, u32 eidx_end, u32 cmap,
>
> event->start_idx = eidx_start;
> event->end_idx = eidx_end;
> - event->counters = cmap;
> - event->select = select;
>
> /* Sanity check */
> for (i = 0; i < num_hw_events; i++) {
> @@ -199,11 +195,19 @@ static int pmu_add_hw_event_map(u32 eidx_start, u32 eidx_end, u32 cmap,
> else
> is_overlap = pmu_event_range_overlap(&hw_event_map[i], event);
> if (is_overlap)
> - return SBI_EINVALID_ADDR;
> + goto reset_event;
> }
> +
> + event->counters = cmap;
> + event->select = select;
> num_hw_events++;
>
> return 0;
> +
> +reset_event:
> + event->start_idx = 0;
> + event->end_idx = 0;
> + return SBI_EINVAL;
> }
>
> /**
> @@ -436,23 +440,37 @@ static int pmu_update_hw_mhpmevent(struct sbi_pmu_hw_event *hw_evt, int ctr_idx,
> return 0;
> }
>
> +static int pmu_ctr_find_fixed_fw(unsigned long evt_idx_code)
> +{
> + /* Non-programmables counters are enabled always. No need to do lookup */
> + if (evt_idx_code == SBI_PMU_HW_CPU_CYCLES)
> + return 0;
> + else if (evt_idx_code == SBI_PMU_HW_INSTRUCTIONS)
> + return 2;
> + else
> + return SBI_EINVAL;
> +}
> +
> static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned long flags,
> unsigned long event_idx, uint64_t data)
> {
> unsigned long ctr_mask;
> - int i, ret = 0, ctr_idx = SBI_ENOTSUPP;
> + int i, ret = 0, fixed_ctr, ctr_idx = SBI_ENOTSUPP;
> struct sbi_pmu_hw_event *temp;
> unsigned long mctr_inhbt = csr_read(CSR_MCOUNTINHIBIT);
> - int evt_idx_code = get_cidx_code(event_idx);
> + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> + bool sscof_present = sbi_hart_has_feature(scratch, SBI_HART_HAS_SSCOF);
>
> if (cbase > num_hw_ctrs)
> return SBI_EINVAL;
>
> - /* Non-programmables counters are enabled always. No need to do lookup */
> - if (evt_idx_code == SBI_PMU_HW_CPU_CYCLES)
> - return 0;
> - else if (evt_idx_code == SBI_PMU_HW_INSTRUCTIONS)
> - return 2;
> + /**
> + * If Sscof is present try to find the programmable counter for
> + * cycle/instret as well.
> + */
> + fixed_ctr = pmu_ctr_find_fixed_fw(event_idx);
> + if (fixed_ctr >= 0 && !sscof_present)
> + return fixed_ctr;
>
> for (i = 0; i < num_hw_events; i++) {
> temp = &hw_event_map[i];
> @@ -464,7 +482,8 @@ static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned lo
> if ((event_idx == SBI_PMU_EVENT_RAW_IDX) && temp->select != data)
> continue;
>
> - ctr_mask = temp->counters & (cmask << cbase);
> + /* Fixed counters should not be part of the search */
> + ctr_mask = temp->counters & (cmask << cbase) & (~SBI_PMU_FIXED_CTR_MASK);
> for_each_set_bit_from(cbase, &ctr_mask, SBI_PMU_HW_CTR_MAX) {
> if (__test_bit(cbase, &mctr_inhbt)) {
> ctr_idx = cbase;
> @@ -473,8 +492,16 @@ static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned lo
> }
> }
>
> - if (ctr_idx == SBI_ENOTSUPP)
> - return SBI_EFAIL;
> + if (ctr_idx == SBI_ENOTSUPP) {
> + /**
> + * We can't find any programmable counters for cycle/instret.
> + * Return the fixed counter as they are mandatory anyways.
> + */
> + if (fixed_ctr >= 0)
> + return fixed_ctr;
> + else
> + return SBI_EFAIL;
> + }
>
> ret = pmu_update_hw_mhpmevent(temp, ctr_idx, flags, event_idx, data);
>
> --
> 2.31.1
>
>
> --
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