Commit 9c5b9d3d authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

tracing/boot: Add boot-time tracing 

Setup tracing options via extra boot config in addition to kernel
command line.

This adds following commands support. These are applied to
the global trace instance.

 - ftrace.options = OPT1[,OPT2...]
   Enable given ftrace options.

 - ftrace.trace_clock = CLOCK
   Set given CLOCK to ftrace's trace_clock.

 - ftrace.buffer_size = SIZE
   Configure ftrace buffer size to SIZE. You can use "KB" or "MB"
   for that SIZE.

 - ftrace.events = EVENT[, EVENT2...]
   Enable given events on boot. You can use a wild card in EVENT.

 - ftrace.tracer = TRACER
   Set TRACER to current tracer on boot. (e.g. function)

Note that this is NOT replacing the kernel parameters, because
this boot config based setting is later than that. If you want to
trace earlier boot events, you still need kernel parameters.

Link: http://lkml.kernel.org/r/157867237723.17873.17494943526320587488.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 48ac9488

kernel/trace/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -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

kernel/trace/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

kernel/trace/trace.c

+5 −5
Original line number Diff line number Diff line
@@ -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;
@@ -5647,7 +5647,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, 
	return ret;

}



static ssize_t tracing_resize_ring_buffer(struct trace_array *tr,

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

kernel/trace/trace_boot.c

0 → 100644
+113 −0
Original line number Diff line number Diff line 
// 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);

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