alistair23-linux/kernel/trace/trace_boot.c

// SPDX-License-Identifier: GPL-2.0
/*
 * trace_boot.c
 * Tracing kernel boot-time
 */

#define pr_fmt(fmt)	"trace_boot: " fmt

#include <linux/bootconfig.h>
#include <linux/cpumask.h>
#include <linux/ftrace.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/trace.h>
#include <linux/trace_events.h>

#include "trace.h"

#define MAX_BUF_LEN 256

static void __init
trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node)
{
	struct xbc_node *anode;
	const char *p;
	char buf[MAX_BUF_LEN];
	unsigned long v = 0;

	/* Common ftrace options */
	xbc_node_for_each_array_value(node, "options", anode, p) {
		if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
			pr_err("String is too long: %s\n", p);
			continue;
		}

		if (trace_set_options(tr, buf) < 0)
			pr_err("Failed to set option: %s\n", buf);
	}

	p = xbc_node_find_value(node, "trace_clock", NULL);
	if (p && *p != '\0') {
		if (tracing_set_clock(tr, p) < 0)
			pr_err("Failed to set trace clock: %s\n", p);
	}

	p = xbc_node_find_value(node, "buffer_size", NULL);
	if (p && *p != '\0') {
		v = memparse(p, NULL);
		if (v < PAGE_SIZE)
			pr_err("Buffer size is too small: %s\n", p);
		if (tracing_resize_ring_buffer(tr, v, RING_BUFFER_ALL_CPUS) < 0)
			pr_err("Failed to resize trace buffer to %s\n", p);
	}

	p = xbc_node_find_value(node, "cpumask", NULL);
	if (p && *p != '\0') {
		cpumask_var_t new_mask;

		if (alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
			if (cpumask_parse(p, new_mask) < 0 ||
			    tracing_set_cpumask(tr, new_mask) < 0)
				pr_err("Failed to set new CPU mask %s\n", p);
			free_cpumask_var(new_mask);
		}
	}
}

#ifdef CONFIG_EVENT_TRACING
static void __init
trace_boot_enable_events(struct trace_array *tr, struct xbc_node *node)
{
	struct xbc_node *anode;
	char buf[MAX_BUF_LEN];
	const char *p;

	xbc_node_for_each_array_value(node, "events", anode, p) {
		if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
			pr_err("String is too long: %s\n", p);
			continue;
		}

		if (ftrace_set_clr_event(tr, buf, 1) < 0)
			pr_err("Failed to enable event: %s\n", p);
	}
}

#ifdef CONFIG_KPROBE_EVENTS
static int __init
trace_boot_add_kprobe_event(struct xbc_node *node, const char *event)
{
	struct dynevent_cmd cmd;
	struct xbc_node *anode;
	char buf[MAX_BUF_LEN];
	const char *val;
	int ret = 0;

	xbc_node_for_each_array_value(node, "probes", anode, val) {
		kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN);

		ret = kprobe_event_gen_cmd_start(&cmd, event, val);
		if (ret) {
			pr_err("Failed to generate probe: %s\n", buf);
			break;
		}

		ret = kprobe_event_gen_cmd_end(&cmd);
		if (ret) {
			pr_err("Failed to add probe: %s\n", buf);
			break;
		}
	}

	return ret;
}
#else
static inline int __init
trace_boot_add_kprobe_event(struct xbc_node *node, const char *event)
{
	pr_err("Kprobe event is not supported.\n");
	return -ENOTSUPP;
}
#endif

#ifdef CONFIG_SYNTH_EVENTS
static int __init
trace_boot_add_synth_event(struct xbc_node *node, const char *event)
{
	struct dynevent_cmd cmd;
	struct xbc_node *anode;
	char buf[MAX_BUF_LEN];
	const char *p;
	int ret;

	synth_event_cmd_init(&cmd, buf, MAX_BUF_LEN);

	ret = synth_event_gen_cmd_start(&cmd, event, NULL);
	if (ret)
		return ret;

	xbc_node_for_each_array_value(node, "fields", anode, p) {
		ret = synth_event_add_field_str(&cmd, p);
		if (ret)
			return ret;
	}

	ret = synth_event_gen_cmd_end(&cmd);
	if (ret < 0)
		pr_err("Failed to add synthetic event: %s\n", buf);

	return ret;
}
#else
static inline int __init
trace_boot_add_synth_event(struct xbc_node *node, const char *event)
{
	pr_err("Synthetic event is not supported.\n");
	return -ENOTSUPP;
}
#endif

static void __init
trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
			  struct xbc_node *enode)
{
	struct trace_event_file *file;
	struct xbc_node *anode;
	char buf[MAX_BUF_LEN];
	const char *p, *group, *event;

	group = xbc_node_get_data(gnode);
	event = xbc_node_get_data(enode);

	if (!strcmp(group, "kprobes"))
		if (trace_boot_add_kprobe_event(enode, event) < 0)
			return;
	if (!strcmp(group, "synthetic"))
		if (trace_boot_add_synth_event(enode, event) < 0)
			return;

	mutex_lock(&event_mutex);
	file = find_event_file(tr, group, event);
	if (!file) {
		pr_err("Failed to find event: %s:%s\n", group, event);
		goto out;
	}

	p = xbc_node_find_value(enode, "filter", NULL);
	if (p && *p != '\0') {
		if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
			pr_err("filter string is too long: %s\n", p);
		else if (apply_event_filter(file, buf) < 0)
			pr_err("Failed to apply filter: %s\n", buf);
	}

	xbc_node_for_each_array_value(enode, "actions", anode, p) {
		if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
			pr_err("action string is too long: %s\n", p);
		else if (trigger_process_regex(file, buf) < 0)
			pr_err("Failed to apply an action: %s\n", buf);
	}

	if (xbc_node_find_value(enode, "enable", NULL)) {
		if (trace_event_enable_disable(file, 1, 0) < 0)
			pr_err("Failed to enable event node: %s:%s\n",
				group, event);
	}
out:
	mutex_unlock(&event_mutex);
}

static void __init
trace_boot_init_events(struct trace_array *tr, struct xbc_node *node)
{
	struct xbc_node *gnode, *enode;

	node = xbc_node_find_child(node, "event");
	if (!node)
		return;
	/* per-event key starts with "event.GROUP.EVENT" */
	xbc_node_for_each_child(node, gnode)
		xbc_node_for_each_child(gnode, enode)
			trace_boot_init_one_event(tr, gnode, enode);
}
#else
#define trace_boot_enable_events(tr, node) do {} while (0)
#define trace_boot_init_events(tr, node) do {} while (0)
#endif

#ifdef CONFIG_DYNAMIC_FTRACE
static void __init
trace_boot_set_ftrace_filter(struct trace_array *tr, struct xbc_node *node)
{
	struct xbc_node *anode;
	const char *p;
	char *q;

	xbc_node_for_each_array_value(node, "ftrace.filters", anode, p) {
		q = kstrdup(p, GFP_KERNEL);
		if (!q)
			return;
		if (ftrace_set_filter(tr->ops, q, strlen(q), 0) < 0)
			pr_err("Failed to add %s to ftrace filter\n", p);
		else
			ftrace_filter_param = true;
		kfree(q);
	}
	xbc_node_for_each_array_value(node, "ftrace.notraces", anode, p) {
		q = kstrdup(p, GFP_KERNEL);
		if (!q)
			return;
		if (ftrace_set_notrace(tr->ops, q, strlen(q), 0) < 0)
			pr_err("Failed to add %s to ftrace filter\n", p);
		else
			ftrace_filter_param = true;
		kfree(q);
	}
}
#else
#define trace_boot_set_ftrace_filter(tr, node) do {} while (0)
#endif

static void __init
trace_boot_enable_tracer(struct trace_array *tr, struct xbc_node *node)
{
	const char *p;

	trace_boot_set_ftrace_filter(tr, node);

	p = xbc_node_find_value(node, "tracer", NULL);
	if (p && *p != '\0') {
		if (tracing_set_tracer(tr, p) < 0)
			pr_err("Failed to set given tracer: %s\n", p);
	}
}

static void __init
trace_boot_init_one_instance(struct trace_array *tr, struct xbc_node *node)
{
	trace_boot_set_instance_options(tr, node);
	trace_boot_init_events(tr, node);
	trace_boot_enable_events(tr, node);
	trace_boot_enable_tracer(tr, node);
}

static void __init
trace_boot_init_instances(struct xbc_node *node)
{
	struct xbc_node *inode;
	struct trace_array *tr;
	const char *p;

	node = xbc_node_find_child(node, "instance");
	if (!node)
		return;

	xbc_node_for_each_child(node, inode) {
		p = xbc_node_get_data(inode);
		if (!p || *p == '\0')
			continue;

		tr = trace_array_get_by_name(p);
		if (!tr) {
			pr_err("Failed to get trace instance %s\n", p);
			continue;
		}
		trace_boot_init_one_instance(tr, inode);
		trace_array_put(tr);
	}
}

static int __init trace_boot_init(void)
{
	struct xbc_node *trace_node;
	struct trace_array *tr;

	trace_node = xbc_find_node("ftrace");
	if (!trace_node)
		return 0;

	tr = top_trace_array();
	if (!tr)
		return 0;

	/* Global trace array is also one instance */
	trace_boot_init_one_instance(tr, trace_node);
	trace_boot_init_instances(trace_node);

	return 0;
}

fs_initcall(trace_boot_init);