On Sun, Oct 17, 2021 at 08:05:46PM +0800, Leo Yan wrote:
[...]
To allow arm_spe_buffer_has_wrapped() to work properly, I think we need to clean up the top 8 bytes of the AUX buffer in Arm SPE driver when start the PMU event (please note, this change has an assumption that is meantioned in another email that suggests to remove redundant PERF_RECORD_AUX events so the function arm_spe_perf_aux_output_begin() is invoked only once when start PMU event, so we can use the top 8 bytes in AUX buffer to indicate trace is wrap around or not).
diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c index d44bcc29d99c..eb35f85d0efb 100644 --- a/drivers/perf/arm_spe_pmu.c +++ b/drivers/perf/arm_spe_pmu.c @@ -493,6 +493,16 @@ static void arm_spe_perf_aux_output_begin(struct perf_output_handle *handle, if (limit) limit |= BIT(SYS_PMBLIMITR_EL1_E_SHIFT);
/** Cleanup the top 8 bytes for snapshot mode; these 8 bytes are* used to indicate if trace data is wrap around if they are not* zero.*/if (buf->snapshot) {void *tail = buf->base + (buf->nr_pages << PAGE_SHIFT) - 8;memset(tail, 0x0, 8);
Here need to add below code for flushing data cache:
flush_dcache_range((unsigned long)tail, (unsigned long)tail+8);
Sorry for spamming.
Leo
}limit += (u64)buf->base; base = (u64)buf->base + PERF_IDX2OFF(handle->head, buf); write_sysreg_s(base, SYS_PMBPTR_EL1);