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;
kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN);
ret = kprobe_event_gen_cmd_start(&cmd, event, NULL);
if (ret)
return ret;
xbc_node_for_each_array_value(node, "probes", anode, val) {
ret = kprobe_event_add_field(&cmd, val);
if (ret)
return ret;
}
ret = kprobe_event_gen_cmd_end(&cmd);
if (ret)
pr_err("Failed to add probe: %s\n", buf);
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_HIST_TRIGGERS
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);