There are various pmu tests that require an isb() between enabling
counting and the actual counting. This can lead to count registers
reporting less events than expected; the actual enabling happens after
some events have happened. For example, some missing isb()'s in the
pmu-sw-incr test lead to the following errors on bare-metal:
INFO: pmu: pmu-sw-incr: SW_INCR counter #0 has value 4294967280
PASS: pmu: pmu-sw-incr: PWSYNC does not increment if PMCR.E is unset
FAIL: pmu: pmu-sw-incr: counter #1 after + 100 SW_INCR
FAIL: pmu: pmu-sw-incr: counter #0 after + 100 SW_INCR
INFO: pmu: pmu-sw-incr: counter values after 100 SW_INCR #0=82 #1=98
PASS: pmu: pmu-sw-incr: overflow on counter #0 after 100 SW_INCR
SUMMARY: 4 tests, 2 unexpected failures
Add the missing isb()'s on all failing tests, plus some others that seem
required:
- after clearing the overflow signal in the IRQ handler to make spurious
interrupts less likely.
- after direct writes to PMSWINC_EL0 for software to read the correct
value for PMEVNCTR0_EL0 (from ARM DDI 0487H.a, page D13-5237).
Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
---
arm/pmu.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/arm/pmu.c b/arm/pmu.c
index 15c542a2..4c601b05 100644
--- a/arm/pmu.c
+++ b/arm/pmu.c
@@ -307,6 +307,7 @@ static void irq_handler(struct pt_regs *regs)
}
}
write_sysreg(ALL_SET, pmovsclr_el0);
+ isb();
} else {
pmu_stats.unexpected = true;
}
@@ -534,10 +535,12 @@ static void test_sw_incr(void)
write_sysreg_s(0x3, PMCNTENSET_EL0);
write_regn_el0(pmevcntr, 0, PRE_OVERFLOW);
+ isb();
for (i = 0; i < 100; i++)
write_sysreg(0x1, pmswinc_el0);
+ isb();
report_info("SW_INCR counter #0 has value %ld", read_regn_el0(pmevcntr, 0));
report(read_regn_el0(pmevcntr, 0) == PRE_OVERFLOW,
"PWSYNC does not increment if PMCR.E is unset");
@@ -547,10 +550,12 @@ static void test_sw_incr(void)
write_regn_el0(pmevcntr, 0, PRE_OVERFLOW);
write_sysreg_s(0x3, PMCNTENSET_EL0);
set_pmcr(pmu.pmcr_ro | PMU_PMCR_E);
+ isb();
for (i = 0; i < 100; i++)
write_sysreg(0x3, pmswinc_el0);
+ isb();
report(read_regn_el0(pmevcntr, 0) == 84, "counter #1 after + 100 SW_INCR");
report(read_regn_el0(pmevcntr, 1) == 100,
"counter #0 after + 100 SW_INCR");
@@ -618,9 +623,12 @@ static void test_chained_sw_incr(void)
write_regn_el0(pmevcntr, 0, PRE_OVERFLOW);
set_pmcr(pmu.pmcr_ro | PMU_PMCR_E);
+ isb();
+
for (i = 0; i < 100; i++)
write_sysreg(0x1, pmswinc_el0);
+ isb();
report(!read_sysreg(pmovsclr_el0) && (read_regn_el0(pmevcntr, 1) == 1),
"no overflow and chain counter incremented after 100 SW_INCR/CHAIN");
report_info("overflow=0x%lx, #0=%ld #1=%ld", read_sysreg(pmovsclr_el0),
@@ -634,9 +642,12 @@ static void test_chained_sw_incr(void)
write_regn_el0(pmevcntr, 1, ALL_SET);
write_sysreg_s(0x3, PMCNTENSET_EL0);
set_pmcr(pmu.pmcr_ro | PMU_PMCR_E);
+ isb();
+
for (i = 0; i < 100; i++)
write_sysreg(0x1, pmswinc_el0);
+ isb();
report((read_sysreg(pmovsclr_el0) == 0x2) &&
(read_regn_el0(pmevcntr, 1) == 0) &&
(read_regn_el0(pmevcntr, 0) == 84),
@@ -821,10 +832,14 @@ static void test_overflow_interrupt(void)
report(expect_interrupts(0), "no overflow interrupt after preset");
set_pmcr(pmu.pmcr_ro | PMU_PMCR_E);
+ isb();
+
for (i = 0; i < 100; i++)
write_sysreg(0x2, pmswinc_el0);
+ isb();
set_pmcr(pmu.pmcr_ro);
+ isb();
report(expect_interrupts(0), "no overflow interrupt after counting");
/* enable interrupts */
@@ -879,6 +894,7 @@ static bool check_cycles_increase(void)
set_pmccfiltr(0); /* count cycles in EL0, EL1, but not EL2 */
set_pmcr(get_pmcr() | PMU_PMCR_LC | PMU_PMCR_C | PMU_PMCR_E);
+ isb();
for (int i = 0; i < NR_SAMPLES; i++) {
uint64_t a, b;
@@ -894,6 +910,7 @@ static bool check_cycles_increase(void)
}
set_pmcr(get_pmcr() & ~PMU_PMCR_E);
+ isb();
return success;
}
--
2.37.1.559.g78731f0fdb-goog
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