Re: [PATCH v5 03/22] drivers/perf: riscv: Read upper bits of a firmware counter

On Wed, Apr 03, 2024 at 01:04:32AM -0700, Atish Patra wrote:

SBI v2.0 introduced a explicit function to read the upper 32 bits for any firmware counter width that is longer than 32bits. This is only applicable for RV32 where firmware counter can be 64 bit.

Reviewed-by: Andrew Jones ajones@ventanamicro.com Acked-by: Palmer Dabbelt palmer@rivosinc.com Reviewed-by: Conor Dooley conor.dooley@microchip.com Reviewed-by: Anup Patel anup@brainfault.org Signed-off-by: Atish Patra atishp@rivosinc.com

---

drivers/perf/riscv_pmu_sbi.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c index 3e44d2fb8bf8..babf1b9a4dbe 100644 --- a/drivers/perf/riscv_pmu_sbi.c +++ b/drivers/perf/riscv_pmu_sbi.c @@ -57,6 +57,8 @@ asm volatile(ALTERNATIVE( \ PMU_FORMAT_ATTR(event, "config:0-47"); PMU_FORMAT_ATTR(firmware, "config:63"); +static bool sbi_v2_available;

static struct attribute *riscv_arch_formats_attr[] = { &format_attr_event.attr, &format_attr_firmware.attr, @@ -511,19 +513,29 @@ static u64 pmu_sbi_ctr_read(struct perf_event *event) struct hw_perf_event *hwc = &event->hw; int idx = hwc->idx; struct sbiret ret;

• union sbi_pmu_ctr_info info; u64 val = 0;

• union sbi_pmu_ctr_info info = pmu_ctr_list[idx];

if (pmu_sbi_is_fw_event(event)) { ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ, hwc->idx, 0, 0, 0, 0, 0);

• if (!ret.error)
  

• 	val = ret.value;
  

• if (ret.error)
  

• 	return 0;
  

• val = ret.value;
  

• if (IS_ENABLED(CONFIG_32BIT) && sbi_v2_available && info.width >= 32) {
  

• 	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ_HI,
  

• 			hwc->idx, 0, 0, 0, 0, 0);
  

• 	if (!ret.error)
  

• 		val |= ((u64)ret.value << 32);
  

• 	else
  

• 		WARN_ONCE(1, "Unable to read upper 32 bits of firmware counter error: %d\n",
  

• 			  sbi_err_map_linux_errno(ret.error));
  

I don't think we should use sbi_err_map_linux_errno() in this case since we don't have a 1:1 mapping of SBI errors to Linux errors and we don't propagate the error as a Linux error. For warnings, it's better to output the exact SBI error.

• }
  

  } else {

• info = pmu_ctr_list[idx];
  

  val = riscv_pmu_ctr_read_csr(info.csr); if (IS_ENABLED(CONFIG_32BIT))

• 	val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 31 | val;
  

• 	val |= ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32;
  

  }

return val; @@ -1135,6 +1147,9 @@ static int __init pmu_sbi_devinit(void) return 0; }

• if (sbi_spec_version >= sbi_mk_version(2, 0))

• sbi_v2_available = true;
  

• ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_RISCV_STARTING, "perf/riscv/pmu:starting", pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);

-- 2.34.1

Thanks, drew