diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 25a0fcfa7a5da4f9fee9b6e5c277bd87136e2592..75326d8ab1af392c9077dac329e44c26badc6c94 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -814,6 +814,15 @@ config GCOV_PROFILE_FTRACE
Note that on a kernel compiled with this config, ftrace will
run significantly slower.
+config BOOTTIME_TRACING
+ bool "Boot-time Tracing support"
+ depends on BOOT_CONFIG && TRACING
+ default y
+ help
+ Enable developer to setup ftrace subsystem via supplemental
+ kernel cmdline at boot time for debugging (tracing) driver
+ initialization and boot process.
+
endif # FTRACE
endif # TRACING_SUPPORT
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 0e63db62225fc62fab61558cfefa2d3f5f0c9695..395e2db9c7428be8aa25af2bc541e07d0d821040 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -83,6 +83,7 @@ endif
obj-$(CONFIG_DYNAMIC_EVENTS) += trace_dynevent.o
obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
obj-$(CONFIG_UPROBE_EVENTS) += trace_uprobe.o
+obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o
obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index cb850d2c4bfac9c6a54fce02dbd0c59640ed9914..6c996d1b1687ffc611b000cfa6d47201db4cf7c9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -162,7 +162,7 @@ union trace_eval_map_item {
static union trace_eval_map_item *trace_eval_maps;
#endif /* CONFIG_TRACE_EVAL_MAP_FILE */
-static int tracing_set_tracer(struct trace_array *tr, const char *buf);
+int tracing_set_tracer(struct trace_array *tr, const char *buf);
static void ftrace_trace_userstack(struct trace_buffer *buffer,
unsigned long flags, int pc);
@@ -4747,7 +4747,7 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
return 0;
}
-static int trace_set_options(struct trace_array *tr, char *option)
+int trace_set_options(struct trace_array *tr, char *option)
{
char *cmp;
int neg = 0;
@@ -5647,8 +5647,8 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
return ret;
}
-static ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
- unsigned long size, int cpu_id)
+ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
+ unsigned long size, int cpu_id)
{
int ret = size;
@@ -5727,7 +5727,7 @@ static void add_tracer_options(struct trace_array *tr, struct tracer *t)
create_trace_option_files(tr, t);
}
-static int tracing_set_tracer(struct trace_array *tr, const char *buf)
+int tracing_set_tracer(struct trace_array *tr, const char *buf)
{
struct tracer *t;
#ifdef CONFIG_TRACER_MAX_TRACE
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
new file mode 100644
index 0000000000000000000000000000000000000000..4b41310184dff9ae098fde9e83faf3c73d3e9305
--- /dev/null
+++ b/kernel/trace/trace_boot.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace_boot.c
+ * Tracing kernel boot-time
+ */
+
+#define pr_fmt(fmt) "trace_boot: " fmt
+
+#include <linux/ftrace.h>
+#include <linux/init.h>
+#include <linux/bootconfig.h>
+
+#include "trace.h"
+
+#define MAX_BUF_LEN 256
+
+extern int trace_set_options(struct trace_array *tr, char *option);
+extern int tracing_set_tracer(struct trace_array *tr, const char *buf);
+extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
+ unsigned long size, int cpu_id);
+
+static void __init
+trace_boot_set_ftrace_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);
+ }
+}
+
+#ifdef CONFIG_EVENT_TRACING
+extern int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
+
+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);
+ }
+}
+#else
+#define trace_boot_enable_events(tr, node) do {} while (0)
+#endif
+
+static void __init
+trace_boot_enable_tracer(struct trace_array *tr, struct xbc_node *node)
+{
+ const char *p;
+
+ 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 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;
+
+ trace_boot_set_ftrace_options(tr, trace_node);
+ trace_boot_enable_events(tr, trace_node);
+ trace_boot_enable_tracer(tr, trace_node);
+
+ return 0;
+}
+
+fs_initcall(trace_boot_init);