Re: [RFC PATCH] perf/kvm: Guest Symbol Resolution for powerpc

On 6/15/15 8:50 PM, Hemant Kumar wrote:

+/*
+ * Get the instruction pointer from the tracepoint data
+ */
+u64 arch__get_ip(struct perf_evsel *evsel, struct perf_sample *data)
+{
+	u64 tp_ip = data->ip;
+	int trap;
+
+	if (!strcmp(KVMPPC_EXIT, evsel->name)) {
+		trap = raw_field_value(evsel->tp_format, "trap", data->raw_data);
+
+		if (trap == HV_DECREMENTER)
+			tp_ip = raw_field_value(evsel->tp_format, "pc",
+						data->raw_data);
+	}
+	return tp_ip;
+}

You can tie a handler to an event; see builtin-trace.c for example 
(evsel->handler = handler). Then have the sample handler call it (e.g, 
see trace__process_sample). Then you don't have to check event names on 
each pass like this and just do event based processing.

+
+/*
+ * Get the HV and PR bits and accordingly, determine the cpumode
+ */
+u8 arch__get_cpumode(union perf_event *event, struct perf_evsel *evsel,
+		     struct perf_sample *data)
+{
+	unsigned long hv, pr, msr;
+	u8 cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;
+
+	if (strcmp(KVMPPC_EXIT, evsel->name))
+		goto ret;
+
+	if (data->raw_data)
+		msr = raw_field_value(evsel->tp_format, "msr", data->raw_data);
+	else
+		goto ret;
+
+	hv = msr & ((long unsigned)1 << (PPC_MAX - HV_BIT));
+	pr = msr & ((long unsigned)1 << (PPC_MAX - PR_BIT));
+
+	if (!hv && pr)
+		cpumode = PERF_RECORD_MISC_GUEST_USER;
+	else
+		cpumode = PERF_RECORD_MISC_GUEST_KERNEL;
+ret:
+	return cpumode;
+}

Why isn't that set properly kernel side when the sample is generated?

David