1 files changed, 878 insertions, 0 deletions
diff --git a/tools/tracing/rtla/src/osnoise.c b/tools/tracing/rtla/src/osnoise.c
new file mode 100644
index 000000000000..5648f9252e58
--- /dev/null
+++ b/tools/tracing/rtla/src/osnoise.c
@@ -0,0 +1,878 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <[email protected]>
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+#include "osnoise.h"
+#include "utils.h"
+
+/*
+ * osnoise_get_cpus - return the original "osnoise/cpus" content
+ *
+ * It also saves the value to be restored.
+ */
+char *osnoise_get_cpus(struct osnoise_context *context)
+{
+	if (context->curr_cpus)
+		return context->curr_cpus;
+
+	if (context->orig_cpus)
+		return context->orig_cpus;
+
+	context->orig_cpus = tracefs_instance_file_read(NULL, "osnoise/cpus", NULL);
+
+	/*
+	 * The error value (NULL) is the same for tracefs_instance_file_read()
+	 * and this functions, so:
+	 */
+	return context->orig_cpus;
+}
+
+/*
+ * osnoise_set_cpus - configure osnoise to run on *cpus
+ *
+ * "osnoise/cpus" file is used to set the cpus in which osnoise/timerlat
+ * will run. This function opens this file, saves the current value,
+ * and set the cpus passed as argument.
+ */
+int osnoise_set_cpus(struct osnoise_context *context, char *cpus)
+{
+	char *orig_cpus = osnoise_get_cpus(context);
+	char buffer[1024];
+	int retval;
+
+	if (!orig_cpus)
+		return -1;
+
+	context->curr_cpus = strdup(cpus);
+	if (!context->curr_cpus)
+		return -1;
+
+	snprintf(buffer, 1024, "%s\n", cpus);
+
+	debug_msg("setting cpus to %s from %s", cpus, context->orig_cpus);
+
+	retval = tracefs_instance_file_write(NULL, "osnoise/cpus", buffer);
+	if (retval < 0) {
+		free(context->curr_cpus);
+		context->curr_cpus = NULL;
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_cpus - restore the original "osnoise/cpus"
+ *
+ * osnoise_set_cpus() saves the original data for the "osnoise/cpus"
+ * file. This function restore the original config it was previously
+ * modified.
+ */
+void osnoise_restore_cpus(struct osnoise_context *context)
+{
+	int retval;
+
+	if (!context->orig_cpus)
+		return;
+
+	if (!context->curr_cpus)
+		return;
+
+	/* nothing to do? */
+	if (!strcmp(context->orig_cpus, context->curr_cpus))
+		goto out_done;
+
+	debug_msg("restoring cpus to %s", context->orig_cpus);
+
+	retval = tracefs_instance_file_write(NULL, "osnoise/cpus", context->orig_cpus);
+	if (retval < 0)
+		err_msg("could not restore original osnoise cpus\n");
+
+out_done:
+	free(context->curr_cpus);
+	context->curr_cpus = NULL;
+}
+
+/*
+ * osnoise_put_cpus - restore cpus config and cleanup data
+ */
+void osnoise_put_cpus(struct osnoise_context *context)
+{
+	osnoise_restore_cpus(context);
+
+	if (!context->orig_cpus)
+		return;
+
+	free(context->orig_cpus);
+	context->orig_cpus = NULL;
+}
+
+/*
+ * osnoise_read_ll_config - read a long long value from a config
+ *
+ * returns -1 on error.
+ */
+static long long osnoise_read_ll_config(char *rel_path)
+{
+	long long retval;
+	char *buffer;
+
+	buffer = tracefs_instance_file_read(NULL, rel_path, NULL);
+	if (!buffer)
+		return -1;
+
+	/* get_llong_from_str returns -1 on error */
+	retval = get_llong_from_str(buffer);
+
+	debug_msg("reading %s returned %lld\n", rel_path, retval);
+
+	free(buffer);
+
+	return retval;
+}
+
+/*
+ * osnoise_write_ll_config - write a long long value to a config in rel_path
+ *
+ * returns -1 on error.
+ */
+static long long osnoise_write_ll_config(char *rel_path, long long value)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	long long retval;
+
+	snprintf(buffer, sizeof(buffer), "%lld\n", value);
+
+	debug_msg("setting %s to %lld\n", rel_path, value);
+
+	retval = tracefs_instance_file_write(NULL, rel_path, buffer);
+	return retval;
+}
+
+/*
+ * osnoise_get_runtime - return the original "osnoise/runtime_us" value
+ *
+ * It also saves the value to be restored.
+ */
+unsigned long long osnoise_get_runtime(struct osnoise_context *context)
+{
+	long long runtime_us;
+
+	if (context->runtime_us != OSNOISE_TIME_INIT_VAL)
+		return context->runtime_us;
+
+	if (context->orig_runtime_us != OSNOISE_TIME_INIT_VAL)
+		return context->orig_runtime_us;
+
+	runtime_us = osnoise_read_ll_config("osnoise/runtime_us");
+	if (runtime_us < 0)
+		goto out_err;
+
+	context->orig_runtime_us = runtime_us;
+	return runtime_us;
+
+out_err:
+	return OSNOISE_TIME_INIT_VAL;
+}
+
+/*
+ * osnoise_get_period - return the original "osnoise/period_us" value
+ *
+ * It also saves the value to be restored.
+ */
+unsigned long long osnoise_get_period(struct osnoise_context *context)
+{
+	long long period_us;
+
+	if (context->period_us != OSNOISE_TIME_INIT_VAL)
+		return context->period_us;
+
+	if (context->orig_period_us != OSNOISE_TIME_INIT_VAL)
+		return context->orig_period_us;
+
+	period_us = osnoise_read_ll_config("osnoise/period_us");
+	if (period_us < 0)
+		goto out_err;
+
+	context->orig_period_us = period_us;
+	return period_us;
+
+out_err:
+	return OSNOISE_TIME_INIT_VAL;
+}
+
+static int __osnoise_write_runtime(struct osnoise_context *context,
+				   unsigned long long runtime)
+{
+	int retval;
+
+	if (context->orig_runtime_us == OSNOISE_TIME_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("osnoise/runtime_us", runtime);
+	if (retval < 0)
+		return -1;
+
+	context->runtime_us = runtime;
+	return 0;
+}
+
+static int __osnoise_write_period(struct osnoise_context *context,
+				  unsigned long long period)
+{
+	int retval;
+
+	if (context->orig_period_us == OSNOISE_TIME_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("osnoise/period_us", period);
+	if (retval < 0)
+		return -1;
+
+	context->period_us = period;
+	return 0;
+}
+
+/*
+ * osnoise_set_runtime_period - set osnoise runtime and period
+ *
+ * Osnoise's runtime and period are related as runtime <= period.
+ * Thus, this function saves the original values, and then tries
+ * to set the runtime and period if they are != 0.
+ */
+int osnoise_set_runtime_period(struct osnoise_context *context,
+			       unsigned long long runtime,
+			       unsigned long long period)
+{
+	unsigned long long curr_runtime_us;
+	unsigned long long curr_period_us;
+	int retval;
+
+	if (!period && !runtime)
+		return 0;
+
+	curr_runtime_us = osnoise_get_runtime(context);
+	curr_period_us = osnoise_get_period(context);
+
+	/* error getting any value? */
+	if (curr_period_us == OSNOISE_TIME_INIT_VAL || curr_runtime_us == OSNOISE_TIME_INIT_VAL)
+		return -1;
+
+	if (!period) {
+		if (runtime > curr_period_us)
+			return -1;
+		return __osnoise_write_runtime(context, runtime);
+	} else if (!runtime) {
+		if (period < curr_runtime_us)
+			return -1;
+		return __osnoise_write_period(context, period);
+	}
+
+	if (runtime > curr_period_us) {
+		retval = __osnoise_write_period(context, period);
+		if (retval)
+			return -1;
+		retval = __osnoise_write_runtime(context, runtime);
+		if (retval)
+			return -1;
+	} else {
+		retval = __osnoise_write_runtime(context, runtime);
+		if (retval)
+			return -1;
+		retval = __osnoise_write_period(context, period);
+		if (retval)
+			return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_runtime_period - restore the original runtime and period
+ */
+void osnoise_restore_runtime_period(struct osnoise_context *context)
+{
+	unsigned long long orig_runtime = context->orig_runtime_us;
+	unsigned long long orig_period = context->orig_period_us;
+	unsigned long long curr_runtime = context->runtime_us;
+	unsigned long long curr_period = context->period_us;
+	int retval;
+
+	if ((orig_runtime == OSNOISE_TIME_INIT_VAL) && (orig_period == OSNOISE_TIME_INIT_VAL))
+		return;
+
+	if ((orig_period == curr_period) && (orig_runtime == curr_runtime))
+		goto out_done;
+
+	retval = osnoise_set_runtime_period(context, orig_runtime, orig_period);
+	if (retval)
+		err_msg("Could not restore original osnoise runtime/period\n");
+
+out_done:
+	context->runtime_us = OSNOISE_TIME_INIT_VAL;
+	context->period_us = OSNOISE_TIME_INIT_VAL;
+}
+
+/*
+ * osnoise_put_runtime_period - restore original values and cleanup data
+ */
+void osnoise_put_runtime_period(struct osnoise_context *context)
+{
+	osnoise_restore_runtime_period(context);
+
+	if (context->orig_runtime_us != OSNOISE_TIME_INIT_VAL)
+		context->orig_runtime_us = OSNOISE_TIME_INIT_VAL;
+
+	if (context->orig_period_us != OSNOISE_TIME_INIT_VAL)
+		context->orig_period_us = OSNOISE_TIME_INIT_VAL;
+}
+
+/*
+ * osnoise_get_timerlat_period_us - read and save the original "timerlat_period_us"
+ */
+static long long
+osnoise_get_timerlat_period_us(struct osnoise_context *context)
+{
+	long long timerlat_period_us;
+
+	if (context->timerlat_period_us != OSNOISE_TIME_INIT_VAL)
+		return context->timerlat_period_us;
+
+	if (context->orig_timerlat_period_us != OSNOISE_TIME_INIT_VAL)
+		return context->orig_timerlat_period_us;
+
+	timerlat_period_us = osnoise_read_ll_config("osnoise/timerlat_period_us");
+	if (timerlat_period_us < 0)
+		goto out_err;
+
+	context->orig_timerlat_period_us = timerlat_period_us;
+	return timerlat_period_us;
+
+out_err:
+	return OSNOISE_TIME_INIT_VAL;
+}
+
+/*
+ * osnoise_set_timerlat_period_us - set "timerlat_period_us"
+ */
+int osnoise_set_timerlat_period_us(struct osnoise_context *context, long long timerlat_period_us)
+{
+	long long curr_timerlat_period_us = osnoise_get_timerlat_period_us(context);
+	int retval;
+
+	if (curr_timerlat_period_us == OSNOISE_TIME_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("osnoise/timerlat_period_us", timerlat_period_us);
+	if (retval < 0)
+		return -1;
+
+	context->timerlat_period_us = timerlat_period_us;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_timerlat_period_us - restore "timerlat_period_us"
+ */
+void osnoise_restore_timerlat_period_us(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_timerlat_period_us == OSNOISE_TIME_INIT_VAL)
+		return;
+
+	if (context->orig_timerlat_period_us == context->timerlat_period_us)
+		goto out_done;
+
+	retval = osnoise_write_ll_config("osnoise/timerlat_period_us", context->orig_timerlat_period_us);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise timerlat_period_us\n");
+
+out_done:
+	context->timerlat_period_us = OSNOISE_TIME_INIT_VAL;
+}
+
+/*
+ * osnoise_put_timerlat_period_us - restore original values and cleanup data
+ */
+void osnoise_put_timerlat_period_us(struct osnoise_context *context)
+{
+	osnoise_restore_timerlat_period_us(context);
+
+	if (context->orig_timerlat_period_us == OSNOISE_TIME_INIT_VAL)
+		return;
+
+	context->orig_timerlat_period_us = OSNOISE_TIME_INIT_VAL;
+}
+
+/*
+ * osnoise_get_stop_us - read and save the original "stop_tracing_us"
+ */
+static long long
+osnoise_get_stop_us(struct osnoise_context *context)
+{
+	long long stop_us;
+
+	if (context->stop_us != OSNOISE_OPTION_INIT_VAL)
+		return context->stop_us;
+
+	if (context->orig_stop_us != OSNOISE_OPTION_INIT_VAL)
+		return context->orig_stop_us;
+
+	stop_us = osnoise_read_ll_config("osnoise/stop_tracing_us");
+	if (stop_us < 0)
+		goto out_err;
+
+	context->orig_stop_us = stop_us;
+	return stop_us;
+
+out_err:
+	return OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_set_stop_us - set "stop_tracing_us"
+ */
+int osnoise_set_stop_us(struct osnoise_context *context, long long stop_us)
+{
+	long long curr_stop_us = osnoise_get_stop_us(context);
+	int retval;
+
+	if (curr_stop_us == OSNOISE_OPTION_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("osnoise/stop_tracing_us", stop_us);
+	if (retval < 0)
+		return -1;
+
+	context->stop_us = stop_us;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_stop_us - restore the original "stop_tracing_us"
+ */
+void osnoise_restore_stop_us(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_stop_us == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	if (context->orig_stop_us == context->stop_us)
+		goto out_done;
+
+	retval = osnoise_write_ll_config("osnoise/stop_tracing_us", context->orig_stop_us);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise stop_us\n");
+
+out_done:
+	context->stop_us = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_put_stop_us - restore original values and cleanup data
+ */
+void osnoise_put_stop_us(struct osnoise_context *context)
+{
+	osnoise_restore_stop_us(context);
+
+	if (context->orig_stop_us == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	context->orig_stop_us = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_get_stop_total_us - read and save the original "stop_tracing_total_us"
+ */
+static long long
+osnoise_get_stop_total_us(struct osnoise_context *context)
+{
+	long long stop_total_us;
+
+	if (context->stop_total_us != OSNOISE_OPTION_INIT_VAL)
+		return context->stop_total_us;
+
+	if (context->orig_stop_total_us != OSNOISE_OPTION_INIT_VAL)
+		return context->orig_stop_total_us;
+
+	stop_total_us = osnoise_read_ll_config("osnoise/stop_tracing_total_us");
+	if (stop_total_us < 0)
+		goto out_err;
+
+	context->orig_stop_total_us = stop_total_us;
+	return stop_total_us;
+
+out_err:
+	return OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_set_stop_total_us - set "stop_tracing_total_us"
+ */
+int osnoise_set_stop_total_us(struct osnoise_context *context, long long stop_total_us)
+{
+	long long curr_stop_total_us = osnoise_get_stop_total_us(context);
+	int retval;
+
+	if (curr_stop_total_us == OSNOISE_OPTION_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("osnoise/stop_tracing_total_us", stop_total_us);
+	if (retval < 0)
+		return -1;
+
+	context->stop_total_us = stop_total_us;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_stop_total_us - restore the original "stop_tracing_total_us"
+ */
+void osnoise_restore_stop_total_us(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_stop_total_us == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	if (context->orig_stop_total_us == context->stop_total_us)
+		goto out_done;
+
+	retval = osnoise_write_ll_config("osnoise/stop_tracing_total_us",
+			context->orig_stop_total_us);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise stop_total_us\n");
+
+out_done:
+	context->stop_total_us = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_put_stop_total_us - restore original values and cleanup data
+ */
+void osnoise_put_stop_total_us(struct osnoise_context *context)
+{
+	osnoise_restore_stop_total_us(context);
+
+	if (context->orig_stop_total_us == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	context->orig_stop_total_us = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_get_print_stack - read and save the original "print_stack"
+ */
+static long long
+osnoise_get_print_stack(struct osnoise_context *context)
+{
+	long long print_stack;
+
+	if (context->print_stack != OSNOISE_OPTION_INIT_VAL)
+		return context->print_stack;
+
+	if (context->orig_print_stack != OSNOISE_OPTION_INIT_VAL)
+		return context->orig_print_stack;
+
+	print_stack = osnoise_read_ll_config("osnoise/print_stack");
+	if (print_stack < 0)
+		goto out_err;
+
+	context->orig_print_stack = print_stack;
+	return print_stack;
+
+out_err:
+	return OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_set_print_stack - set "print_stack"
+ */
+int osnoise_set_print_stack(struct osnoise_context *context, long long print_stack)
+{
+	long long curr_print_stack = osnoise_get_print_stack(context);
+	int retval;
+
+	if (curr_print_stack == OSNOISE_OPTION_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("osnoise/print_stack", print_stack);
+	if (retval < 0)
+		return -1;
+
+	context->print_stack = print_stack;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_print_stack - restore the original "print_stack"
+ */
+void osnoise_restore_print_stack(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_print_stack == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	if (context->orig_print_stack == context->print_stack)
+		goto out_done;
+
+	retval = osnoise_write_ll_config("osnoise/print_stack", context->orig_print_stack);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise print_stack\n");
+
+out_done:
+	context->print_stack = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_put_print_stack - restore original values and cleanup data
+ */
+void osnoise_put_print_stack(struct osnoise_context *context)
+{
+	osnoise_restore_print_stack(context);
+
+	if (context->orig_print_stack == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	context->orig_print_stack = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * enable_osnoise - enable osnoise tracer in the trace_instance
+ */
+int enable_osnoise(struct trace_instance *trace)
+{
+	return enable_tracer_by_name(trace->inst, "osnoise");
+}
+
+/*
+ * enable_timerlat - enable timerlat tracer in the trace_instance
+ */
+int enable_timerlat(struct trace_instance *trace)
+{
+	return enable_tracer_by_name(trace->inst, "timerlat");
+}
+
+enum {
+	FLAG_CONTEXT_NEWLY_CREATED	= (1 << 0),
+	FLAG_CONTEXT_DELETED		= (1 << 1),
+};
+
+/*
+ * osnoise_get_context - increase the usage of a context and return it
+ */
+int osnoise_get_context(struct osnoise_context *context)
+{
+	int ret;
+
+	if (context->flags & FLAG_CONTEXT_DELETED) {
+		ret = -1;
+	} else {
+		context->ref++;
+		ret = 0;
+	}
+
+	return ret;
+}
+
+/*
+ * osnoise_context_alloc - alloc an osnoise_context
+ *
+ * The osnoise context contains the information of the "osnoise/" configs.
+ * It is used to set and restore the config.
+ */
+struct osnoise_context *osnoise_context_alloc(void)
+{
+	struct osnoise_context *context;
+
+	context = calloc(1, sizeof(*context));
+	if (!context)
+		return NULL;
+
+	context->orig_stop_us		= OSNOISE_OPTION_INIT_VAL;
+	context->stop_us		= OSNOISE_OPTION_INIT_VAL;
+
+	context->orig_stop_total_us	= OSNOISE_OPTION_INIT_VAL;
+	context->stop_total_us		= OSNOISE_OPTION_INIT_VAL;
+
+	context->orig_print_stack	= OSNOISE_OPTION_INIT_VAL;
+	context->print_stack		= OSNOISE_OPTION_INIT_VAL;
+
+	osnoise_get_context(context);
+
+	return context;
+}
+
+/*
+ * osnoise_put_context - put the osnoise_put_context
+ *
+ * If there is no other user for the context, the original data
+ * is restored.
+ */
+void osnoise_put_context(struct osnoise_context *context)
+{
+	if (--context->ref < 1)
+		context->flags |= FLAG_CONTEXT_DELETED;
+
+	if (!(context->flags & FLAG_CONTEXT_DELETED))
+		return;
+
+	osnoise_put_cpus(context);
+	osnoise_put_runtime_period(context);
+	osnoise_put_stop_us(context);
+	osnoise_put_stop_total_us(context);
+	osnoise_put_timerlat_period_us(context);
+	osnoise_put_print_stack(context);
+
+	free(context);
+}
+
+/*
+ * osnoise_destroy_tool - disable trace, restore configs and free data
+ */
+void osnoise_destroy_tool(struct osnoise_tool *top)
+{
+	if (!top)
+		return;
+
+	trace_instance_destroy(&top->trace);
+
+	if (top->context)
+		osnoise_put_context(top->context);
+
+	free(top);
+}
+
+/*
+ * osnoise_init_tool - init an osnoise tool
+ *
+ * It allocs data, create a context to store data and
+ * creates a new trace instance for the tool.
+ */
+struct osnoise_tool *osnoise_init_tool(char *tool_name)
+{
+	struct osnoise_tool *top;
+	int retval;
+
+	top = calloc(1, sizeof(*top));
+	if (!top)
+		return NULL;
+
+	top->context = osnoise_context_alloc();
+	if (!top->context)
+		goto out_err;
+
+	retval = trace_instance_init(&top->trace, tool_name);
+	if (retval)
+		goto out_err;
+
+	return top;
+out_err:
+	osnoise_destroy_tool(top);
+	return NULL;
+}
+
+/*
+ * osnoise_init_trace_tool - init a tracer instance to trace osnoise events
+ */
+struct osnoise_tool *osnoise_init_trace_tool(char *tracer)
+{
+	struct osnoise_tool *trace;
+	int retval;
+
+	trace = osnoise_init_tool("osnoise_trace");
+	if (!trace)
+		return NULL;
+
+	retval = tracefs_event_enable(trace->trace.inst, "osnoise", NULL);
+	if (retval < 0 && !errno) {
+		err_msg("Could not find osnoise events\n");
+		goto out_err;
+	}
+
+	retval = enable_tracer_by_name(trace->trace.inst, tracer);
+	if (retval) {
+		err_msg("Could not enable osnoiser tracer for tracing\n");
+		goto out_err;
+	}
+
+	return trace;
+out_err:
+	osnoise_destroy_tool(trace);
+	return NULL;
+}
+
+static void osnoise_usage(void)
+{
+	int i;
+
+	static const char *msg[] = {
+		"",
+		"osnoise version " VERSION,
+		"",
+		"  usage: [rtla] osnoise [MODE] ...",
+		"",
+		"  modes:",
+		"     top   - prints the summary from osnoise tracer",
+		"     hist  - prints a histogram of osnoise samples",
+		"",
+		"if no MODE is given, the top mode is called, passing the arguments",
+		NULL,
+	};
+
+	for (i = 0; msg[i]; i++)
+		fprintf(stderr, "%s\n", msg[i]);
+	exit(1);
+}
+
+int osnoise_main(int argc, char *argv[])
+{
+	if (argc == 0)
+		goto usage;
+
+	/*
+	 * if osnoise was called without any argument, run the
+	 * default cmdline.
+	 */
+	if (argc == 1) {
+		osnoise_top_main(argc, argv);
+		exit(0);
+	}
+
+	if ((strcmp(argv[1], "-h") == 0) || (strcmp(argv[1], "--help") == 0)) {
+		osnoise_usage();
+		exit(0);
+	} else if (strncmp(argv[1], "-", 1) == 0) {
+		/* the user skipped the tool, call the default one */
+		osnoise_top_main(argc, argv);
+		exit(0);
+	} else if (strcmp(argv[1], "top") == 0) {
+		osnoise_top_main(argc-1, &argv[1]);
+		exit(0);
+	} else if (strcmp(argv[1], "hist") == 0) {
+		osnoise_hist_main(argc-1, &argv[1]);
+		exit(0);
+	}
+
+usage:
+	osnoise_usage();
+	exit(1);
+}