1 files changed, 87 insertions, 0 deletions
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index e67b5a7670f3..009061852808 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -392,6 +392,93 @@ struct machine *machines__find_guest(struct machines *machines, pid_t pid)
 	return machine;
 }
 
+/*
+ * A common case for KVM test programs is that the test program acts as the
+ * hypervisor, creating, running and destroying the virtual machine, and
+ * providing the guest object code from its own object code. In this case,
+ * the VM is not running an OS, but only the functions loaded into it by the
+ * hypervisor test program, and conveniently, loaded at the same virtual
+ * addresses.
+ *
+ * Normally to resolve addresses, MMAP events are needed to map addresses
+ * back to the object code and debug symbols for that object code.
+ *
+ * Currently, there is no way to get such mapping information from guests
+ * but, in the scenario described above, the guest has the same mappings
+ * as the hypervisor, so support for that scenario can be achieved.
+ *
+ * To support that, copy the host thread's maps to the guest thread's maps.
+ * Note, we do not discover the guest until we encounter a guest event,
+ * which works well because it is not until then that we know that the host
+ * thread's maps have been set up.
+ *
+ * This function returns the guest thread. Apart from keeping the data
+ * structures sane, using a thread belonging to the guest machine, instead
+ * of the host thread, allows it to have its own comm (refer
+ * thread__set_guest_comm()).
+ */
+static struct thread *findnew_guest_code(struct machine *machine,
+					 struct machine *host_machine,
+					 pid_t pid)
+{
+	struct thread *host_thread;
+	struct thread *thread;
+	int err;
+
+	if (!machine)
+		return NULL;
+
+	thread = machine__findnew_thread(machine, -1, pid);
+	if (!thread)
+		return NULL;
+
+	/* Assume maps are set up if there are any */
+	if (thread->maps->nr_maps)
+		return thread;
+
+	host_thread = machine__find_thread(host_machine, -1, pid);
+	if (!host_thread)
+		goto out_err;
+
+	thread__set_guest_comm(thread, pid);
+
+	/*
+	 * Guest code can be found in hypervisor process at the same address
+	 * so copy host maps.
+	 */
+	err = maps__clone(thread, host_thread->maps);
+	thread__put(host_thread);
+	if (err)
+		goto out_err;
+
+	return thread;
+
+out_err:
+	thread__zput(thread);
+	return NULL;
+}
+
+struct thread *machines__findnew_guest_code(struct machines *machines, pid_t pid)
+{
+	struct machine *host_machine = machines__find(machines, HOST_KERNEL_ID);
+	struct machine *machine = machines__findnew(machines, pid);
+
+	return findnew_guest_code(machine, host_machine, pid);
+}
+
+struct thread *machine__findnew_guest_code(struct machine *machine, pid_t pid)
+{
+	struct machines *machines = machine->machines;
+	struct machine *host_machine;
+
+	if (!machines)
+		return NULL;
+
+	host_machine = machines__find(machines, HOST_KERNEL_ID);
+
+	return findnew_guest_code(machine, host_machine, pid);
+}
+
 void machines__process_guests(struct machines *machines,
 			      machine__process_t process, void *data)
 {