Re: [PATCH v12 1/4] trace: Add trace any kernel object

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Tue,  7 Jun 2022 00:09:40 +0800
Jeff Xie <xiehuan09@gmail.com> wrote:

> Introduce objtrace trigger to get the call flow by tracing any kernel
> object in the function parameter.
> 
> The objtrace trigger makes a list of the target object address from
> the given event parameter, and records all kernel function calls
> which has the object address in its parameter.
> 
> Syntax:
> 	objtrace:add:obj[:count][if <filter>]
> 
> Usage:
> 	# echo 'p bio_add_page arg1=$arg1' > kprobe_events
> 	# cd events/kprobes/p_bio_add_page_0
> 	# echo 'objtrace:add:arg1:1 if comm == "cat"' > ./trigger
> 	# cat /test.txt
> 

This looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thank you,

> Signed-off-by: Jeff Xie <xiehuan09@gmail.com>
> ---
>  include/linux/trace_events.h        |   1 +
>  kernel/trace/Kconfig                |  10 +
>  kernel/trace/Makefile               |   1 +
>  kernel/trace/trace.c                |  11 +
>  kernel/trace/trace.h                |  21 ++
>  kernel/trace/trace_entries.h        |  17 ++
>  kernel/trace/trace_events_trigger.c |   5 +-
>  kernel/trace/trace_object.c         | 450 ++++++++++++++++++++++++++++
>  kernel/trace/trace_output.c         |  40 +++
>  9 files changed, 554 insertions(+), 2 deletions(-)
>  create mode 100644 kernel/trace/trace_object.c
> 
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index e6e95a9f07a5..f3645166b724 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -693,6 +693,7 @@ enum event_trigger_type {
>  	ETT_EVENT_HIST		= (1 << 4),
>  	ETT_HIST_ENABLE		= (1 << 5),
>  	ETT_EVENT_EPROBE	= (1 << 6),
> +	ETT_TRACE_OBJECT	= (1 << 7),
>  };
>  
>  extern int filter_match_preds(struct event_filter *filter, void *rec);
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 2c43e327a619..30c34d43dc3f 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -276,6 +276,16 @@ config FUNCTION_PROFILER
>  
>  	  If in doubt, say N.
>  
> +config TRACE_OBJECT
> +	bool "Trace kernel object in function parameter"
> +	depends on FUNCTION_TRACER
> +	depends on HAVE_FUNCTION_ARG_ACCESS_API
> +	select TRACING
> +	default y
> +	help
> +	 You can trace the kernel object in the kernel function parameter.
> +	 The kernel object is dynamically specified via event trigger.
> +
>  config STACK_TRACER
>  	bool "Trace max stack"
>  	depends on HAVE_FUNCTION_TRACER
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index 0d261774d6f3..90ecc3c6c9d5 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -71,6 +71,7 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += trace_functions_graph.o
>  obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
>  obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
>  obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += fgraph.o
> +obj-$(CONFIG_TRACE_OBJECT) += trace_object.o
>  ifeq ($(CONFIG_BLOCK),y)
>  obj-$(CONFIG_EVENT_TRACING) += blktrace.o
>  endif
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index f400800bc910..7074ad8bc1a0 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -5627,6 +5627,9 @@ static const char readme_msg[] =
>  	"\t            enable_hist:<system>:<event>\n"
>  	"\t            disable_hist:<system>:<event>\n"
>  #endif
> +#ifdef CONFIG_TRACE_OBJECT
> +	"\t            objtrace:add:obj[:count][if <filter>]\n"
> +#endif
>  #ifdef CONFIG_STACKTRACE
>  	"\t\t    stacktrace\n"
>  #endif
> @@ -9272,6 +9275,9 @@ static struct trace_array *trace_array_create(const char *name)
>  	if (ftrace_allocate_ftrace_ops(tr) < 0)
>  		goto out_free_tr;
>  
> +	if (allocate_objtrace_data(tr) < 0)
> +		goto out_free_tr;
> +
>  	ftrace_init_trace_array(tr);
>  
>  	init_trace_flags_index(tr);
> @@ -9291,6 +9297,7 @@ static struct trace_array *trace_array_create(const char *name)
>  
>   out_free_tr:
>  	ftrace_free_ftrace_ops(tr);
> +	free_objtrace_data(tr);
>  	free_trace_buffers(tr);
>  	free_cpumask_var(tr->tracing_cpumask);
>  	kfree(tr->name);
> @@ -9384,6 +9391,7 @@ static int __remove_instance(struct trace_array *tr)
>  	event_trace_del_tracer(tr);
>  	ftrace_clear_pids(tr);
>  	ftrace_destroy_function_files(tr);
> +	free_objtrace_data(tr);
>  	tracefs_remove(tr->dir);
>  	free_percpu(tr->last_func_repeats);
>  	free_trace_buffers(tr);
> @@ -10118,6 +10126,9 @@ __init static int tracer_alloc_buffers(void)
>  		goto out_free_savedcmd;
>  	}
>  
> +	if (allocate_objtrace_data(&global_trace))
> +		goto out_free_savedcmd;
> +
>  	if (global_trace.buffer_disabled)
>  		tracing_off();
>  
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index ff816fb41e48..18220b659555 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -54,6 +54,7 @@ enum trace_type {
>  	TRACE_TIMERLAT,
>  	TRACE_RAW_DATA,
>  	TRACE_FUNC_REPEATS,
> +	TRACE_OBJECT,
>  
>  	__TRACE_LAST_TYPE,
>  };
> @@ -363,6 +364,9 @@ struct trace_array {
>  	cpumask_var_t		tracing_cpumask; /* only trace on set CPUs */
>  	int			ref;
>  	int			trace_ref;
> +#ifdef CONFIG_TRACE_OBJECT
> +	struct objtrace_data	*obj_data;
> +#endif
>  #ifdef CONFIG_FUNCTION_TRACER
>  	struct ftrace_ops	*ops;
>  	struct trace_pid_list	__rcu *function_pids;
> @@ -471,6 +475,7 @@ extern void __ftrace_bad_type(void);
>  			  TRACE_GRAPH_RET);		\
>  		IF_ASSIGN(var, ent, struct func_repeats_entry,		\
>  			  TRACE_FUNC_REPEATS);				\
> +		IF_ASSIGN(var, ent, struct trace_object_entry, TRACE_OBJECT);\
>  		__ftrace_bad_type();					\
>  	} while (0)
>  
> @@ -1536,6 +1541,16 @@ static inline int register_trigger_hist_cmd(void) { return 0; }
>  static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
>  #endif
>  
> +#ifdef CONFIG_TRACE_OBJECT
> +extern int register_trigger_object_cmd(void);
> +extern int allocate_objtrace_data(struct trace_array *tr);
> +extern void free_objtrace_data(struct trace_array *tr);
> +#else
> +static inline int register_trigger_object_cmd(void) { return 0; }
> +static inline int allocate_objtrace_data(struct trace_array *tr) { return 0; }
> +static inline void free_objtrace_data(struct trace_array *tr) { };
> +#endif
> +
>  extern int register_trigger_cmds(void);
>  extern void clear_event_triggers(struct trace_array *tr);
>  
> @@ -1611,6 +1626,12 @@ extern bool event_trigger_check_remove(const char *glob);
>  extern bool event_trigger_empty_param(const char *param);
>  extern int event_trigger_separate_filter(char *param_and_filter, char **param,
>  					 char **filter, bool param_required);
> +extern int register_trigger(char *glob,
> +			struct event_trigger_data *data,
> +			struct trace_event_file *file);
> +extern void unregister_trigger(char *glob,
> +			struct event_trigger_data *test,
> +			struct trace_event_file *file);
>  extern struct event_trigger_data *
>  event_trigger_alloc(struct event_command *cmd_ops,
>  		    char *cmd,
> diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
> index cd41e863b51c..bb120d9498a9 100644
> --- a/kernel/trace/trace_entries.h
> +++ b/kernel/trace/trace_entries.h
> @@ -401,3 +401,20 @@ FTRACE_ENTRY(timerlat, timerlat_entry,
>  		 __entry->context,
>  		 __entry->timer_latency)
>  );
> +
> +/*
> + * trace object entry:
> + */
> +FTRACE_ENTRY(object, trace_object_entry,
> +
> +	TRACE_OBJECT,
> +
> +	F_STRUCT(
> +		__field(	unsigned long,		ip		)
> +		__field(	unsigned long,		parent_ip	)
> +		__field(	unsigned long,		object		)
> +	),
> +
> +	F_printk(" %ps <-- %ps object:%lx\n",
> +		 (void *)__entry->ip, (void *)__entry->parent_ip, __entry->object)
> +);
> diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
> index cb866c3141af..8bad4eb3b997 100644
> --- a/kernel/trace/trace_events_trigger.c
> +++ b/kernel/trace/trace_events_trigger.c
> @@ -560,7 +560,7 @@ void update_cond_flag(struct trace_event_file *file)
>   *
>   * Return: 0 on success, errno otherwise
>   */
> -static int register_trigger(char *glob,
> +int register_trigger(char *glob,
>  			    struct event_trigger_data *data,
>  			    struct trace_event_file *file)
>  {
> @@ -605,7 +605,7 @@ static int register_trigger(char *glob,
>   * Usually used directly as the @unreg method in event command
>   * implementations.
>   */
> -static void unregister_trigger(char *glob,
> +void unregister_trigger(char *glob,
>  			       struct event_trigger_data *test,
>  			       struct trace_event_file *file)
>  {
> @@ -1976,6 +1976,7 @@ __init int register_trigger_cmds(void)
>  	register_trigger_enable_disable_cmds();
>  	register_trigger_hist_enable_disable_cmds();
>  	register_trigger_hist_cmd();
> +	register_trigger_object_cmd();
>  
>  	return 0;
>  }
> diff --git a/kernel/trace/trace_object.c b/kernel/trace/trace_object.c
> new file mode 100644
> index 000000000000..19ec4b1c0186
> --- /dev/null
> +++ b/kernel/trace/trace_object.c
> @@ -0,0 +1,450 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * trace the kernel object in the kernel function parameter
> + * Copyright (C) 2021 Jeff Xie <xiehuan09@gmail.com>
> + */
> +
> +#define pr_fmt(fmt) "trace_object: " fmt
> +
> +#include "trace_output.h"
> +
> +#define MAX_TRACED_OBJECT 5
> +#define OBJTRACE_CMD_LEN  16
> +#define OBJTRACE_CMD_ADD "add"
> +static LIST_HEAD(obj_data_head);
> +static const int max_args_num = 6;
> +static void exit_trace_object(struct trace_array *tr);
> +static int init_trace_object(struct trace_array *tr);
> +
> +struct object_instance {
> +	void *obj;
> +	struct trace_array *tr;
> +};
> +
> +/* objtrace private data */
> +struct objtrace_trigger_data {
> +	struct ftrace_event_field *field;
> +	char objtrace_cmd[OBJTRACE_CMD_LEN];
> +	struct trace_array *tr;
> +};
> +
> +/* objtrace data with fops and objtrace_instances */
> +struct objtrace_data {
> +	struct list_head head;
> +	struct trace_array *tr;
> +	struct ftrace_ops fops;
> +	int num_traced_obj;
> +	struct object_instance traced_obj[MAX_TRACED_OBJECT];
> +	raw_spinlock_t obj_data_lock;
> +};
> +
> +static struct objtrace_data *get_obj_data(struct trace_array *tr)
> +{
> +	struct objtrace_data *obj_data = NULL;
> +
> +	list_for_each_entry(obj_data, &obj_data_head, head) {
> +		if (obj_data->tr == tr)
> +			break;
> +	}
> +	return obj_data;
> +}
> +
> +static bool object_exist(void *obj, struct trace_array *tr)
> +{
> +	int i, max;
> +	struct objtrace_data *obj_data;
> +
> +	obj_data = get_obj_data(tr);
> +	if (!obj_data)
> +		return false;
> +
> +	max = READ_ONCE(obj_data->num_traced_obj);
> +	smp_rmb();
> +	for (i = 0; i < max; i++) {
> +		if (obj_data->traced_obj[i].obj == obj)
> +			return true;
> +	}
> +	return false;
> +}
> +
> +static bool object_empty(struct trace_array *tr)
> +{
> +	struct objtrace_data *obj_data;
> +
> +	obj_data = get_obj_data(tr);
> +	if (!obj_data)
> +		return false;
> +
> +	return !READ_ONCE(obj_data->num_traced_obj);
> +}
> +
> +static void set_trace_object(void *obj, struct trace_array *tr)
> +{
> +	unsigned long flags;
> +	struct object_instance *obj_ins;
> +	struct objtrace_data *obj_data;
> +
> +	if (in_nmi())
> +		return;
> +
> +	if (!obj && object_exist(obj, tr))
> +		return;
> +
> +	obj_data = get_obj_data(tr);
> +	if (!obj_data)
> +		return;
> +
> +	/* only this place has write operations */
> +	raw_spin_lock_irqsave(&obj_data->obj_data_lock, flags);
> +	if (READ_ONCE(obj_data->num_traced_obj) == MAX_TRACED_OBJECT) {
> +		trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_,
> +				"object_pool is full, can't trace object:0x%px\n", obj);
> +		goto out;
> +	}
> +	obj_ins = &obj_data->traced_obj[READ_ONCE(obj_data->num_traced_obj)];
> +	obj_ins->obj = obj;
> +	obj_ins->tr = tr;
> +	/* make sure the num_traced_obj update always appears after traced_obj update */
> +	smp_wmb();
> +	obj_data->num_traced_obj++;
> +out:
> +	raw_spin_unlock_irqrestore(&obj_data->obj_data_lock, flags);
> +}
> +
> +static void submit_trace_object(unsigned long ip, unsigned long parent_ip,
> +				 unsigned long object, struct trace_array *tr)
> +{
> +
> +	struct trace_buffer *buffer = tr->array_buffer.buffer;
> +	struct ring_buffer_event *event;
> +	struct trace_object_entry *entry;
> +	unsigned int trace_ctx = 0;
> +
> +	trace_ctx = tracing_gen_ctx();
> +	event = trace_buffer_lock_reserve(buffer, TRACE_OBJECT,
> +			sizeof(*entry), trace_ctx);
> +	if (!event)
> +		return;
> +	entry   = ring_buffer_event_data(event);
> +	entry->ip                       = ip;
> +	entry->parent_ip                = parent_ip;
> +	entry->object			= object;
> +
> +	trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
> +}
> +
> +static void
> +trace_object_events_call(unsigned long ip, unsigned long parent_ip,
> +		struct ftrace_ops *op, struct ftrace_regs *fregs)
> +{
> +	struct pt_regs *pt_regs = ftrace_get_regs(fregs);
> +	struct trace_array *tr = op->private;
> +	struct trace_array_cpu *data;
> +	unsigned long obj;
> +	long disabled;
> +	int cpu, n;
> +
> +	preempt_disable_notrace();
> +
> +	cpu = raw_smp_processor_id();
> +	data = per_cpu_ptr(tr->array_buffer.data, cpu);
> +	disabled = atomic_inc_return(&data->disabled);
> +	if (likely(disabled == 1)) {
> +		if (object_empty(tr))
> +			goto out;
> +		for (n = 0; n < max_args_num; n++) {
> +			obj = regs_get_kernel_argument(pt_regs, n);
> +			if (object_exist((void *)obj, tr))
> +				submit_trace_object(ip, parent_ip, obj, tr);
> +		/* The parameters of a function may match multiple objects */
> +		}
> +	}
> +out:
> +	atomic_dec(&data->disabled);
> +	preempt_enable_notrace();
> +}
> +
> +static void
> +trace_object_trigger(struct event_trigger_data *data,
> +		   struct trace_buffer *buffer,  void *rec,
> +		   struct ring_buffer_event *event)
> +{
> +	struct objtrace_trigger_data *obj_data = data->private_data;
> +	struct trace_array *tr = obj_data->tr;
> +	struct ftrace_event_field *field;
> +	void *obj = NULL;
> +
> +	field = obj_data->field;
> +	memcpy(&obj, rec + field->offset, sizeof(obj));
> +	set_trace_object(obj, tr);
> +}
> +
> +static void
> +trace_object_trigger_free(struct event_trigger_data *data)
> +{
> +	struct objtrace_trigger_data *obj_data = data->private_data;
> +
> +	if (WARN_ON_ONCE(data->ref <= 0))
> +		return;
> +
> +	data->ref--;
> +	if (!data->ref) {
> +		exit_trace_object(obj_data->tr);
> +		kfree(data->private_data);
> +		trigger_data_free(data);
> +	}
> +}
> +
> +static void
> +trace_object_count_trigger(struct event_trigger_data *data,
> +			 struct trace_buffer *buffer, void *rec,
> +			 struct ring_buffer_event *event)
> +{
> +	if (!data->count)
> +		return;
> +
> +	if (data->count != -1)
> +		(data->count)--;
> +
> +	trace_object_trigger(data, buffer, rec, event);
> +}
> +
> +static int
> +event_trigger_print(const char *name, struct seq_file *m,
> +		void *data, char *filter_str, void *objtrace_data)
> +{
> +	long count = (long)data;
> +	struct objtrace_trigger_data *obj_data = objtrace_data;
> +
> +	seq_puts(m, name);
> +
> +	seq_printf(m, ":%s", obj_data->objtrace_cmd);
> +	seq_printf(m, ":%s", obj_data->field->name);
> +
> +	if (count == -1)
> +		seq_puts(m, ":unlimited");
> +	else
> +		seq_printf(m, ":count=%ld", count);
> +
> +	if (filter_str)
> +		seq_printf(m, " if %s\n", filter_str);
> +	else
> +		seq_putc(m, '\n');
> +
> +	return 0;
> +}
> +
> +static int event_object_trigger_init(struct event_trigger_data *data)
> +{
> +	struct objtrace_trigger_data *obj_data = data->private_data;
> +	int ret;
> +
> +	if (!data->ref) {
> +		ret = init_trace_object(obj_data->tr);
> +		if (ret)
> +			return ret;
> +	}
> +	data->ref++;
> +	return 0;
> +}
> +
> +static int
> +trace_object_trigger_print(struct seq_file *m, struct event_trigger_data *data)
> +{
> +	return event_trigger_print("objtrace", m, (void *)data->count,
> +				   data->filter_str, data->private_data);
> +}
> +
> +static struct event_trigger_ops objecttrace_trigger_ops = {
> +	.trigger		= trace_object_trigger,
> +	.print			= trace_object_trigger_print,
> +	.init			= event_object_trigger_init,
> +	.free			= trace_object_trigger_free,
> +};
> +
> +static struct event_trigger_ops objecttrace_count_trigger_ops = {
> +	.trigger		= trace_object_count_trigger,
> +	.print			= trace_object_trigger_print,
> +	.init			= event_object_trigger_init,
> +	.free			= trace_object_trigger_free,
> +};
> +
> +static struct event_trigger_ops *
> +objecttrace_get_trigger_ops(char *cmd, char *param)
> +{
> +	return param ? &objecttrace_count_trigger_ops : &objecttrace_trigger_ops;
> +}
> +
> +static bool field_exist(struct trace_event_file *file,
> +			struct event_command *cmd_ops,
> +			const char *field_name)
> +{
> +	struct event_trigger_data *data;
> +	struct objtrace_trigger_data *obj_data;
> +
> +	lockdep_assert_held(&event_mutex);
> +
> +	list_for_each_entry(data, &file->triggers, list) {
> +		if (data->cmd_ops->trigger_type == cmd_ops->trigger_type) {
> +			obj_data = data->private_data;
> +			if (!strcmp(obj_data->field->name, field_name))
> +				return true;
> +		}
> +	}
> +
> +	return false;
> +}
> +
> +static int
> +event_object_trigger_parse(struct event_command *cmd_ops,
> +		       struct trace_event_file *file,
> +		       char *glob, char *cmd, char *param_and_filter)
> +{
> +	struct event_trigger_data *trigger_data;
> +	struct objtrace_trigger_data *obj_data;
> +	struct ftrace_event_field *field;
> +	char *objtrace_cmd, *arg;
> +	char *param, *filter;
> +	int ret;
> +	bool remove;
> +
> +	remove = event_trigger_check_remove(glob);
> +
> +	/*
> +	 * separate the param and the filter:
> +	 * objtrace:add:OBJ[:COUNT] [if filter]
> +	 */
> +	ret = event_trigger_separate_filter(param_and_filter, &param, &filter, true);
> +	if (ret)
> +		return ret;
> +
> +	objtrace_cmd = strsep(&param, ":");
> +	if (!objtrace_cmd || strcmp(objtrace_cmd, OBJTRACE_CMD_ADD)) {
> +		pr_err("error objtrace command\n");
> +		return -EINVAL;
> +	}
> +
> +	arg = strsep(&param, ":");
> +	if (!arg)
> +		return -EINVAL;
> +
> +	field = trace_find_event_field(file->event_call, arg);
> +	if (!field)
> +		return -EINVAL;
> +
> +	if (field->size != sizeof(void *)) {
> +		pr_err("the size of the %s should be:%zu\n", field->name, sizeof(void *));
> +		return -EINVAL;
> +	}
> +
> +	if (remove && !field_exist(file, cmd_ops, field->name))
> +		return -ENOENT;
> +
> +	obj_data = kzalloc(sizeof(*obj_data), GFP_KERNEL);
> +	if (!obj_data)
> +		return -ENOMEM;
> +
> +	obj_data->field = field;
> +	obj_data->tr = file->tr;
> +	snprintf(obj_data->objtrace_cmd, OBJTRACE_CMD_LEN, objtrace_cmd);
> +
> +	trigger_data = event_trigger_alloc(cmd_ops, cmd, param, obj_data);
> +	if (!trigger_data) {
> +		kfree(obj_data);
> +		return -ENOMEM;
> +	}
> +	if (remove) {
> +		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
> +		kfree(obj_data);
> +		kfree(trigger_data);
> +		return 0;
> +	}
> +
> +	ret = event_trigger_parse_num(param, trigger_data);
> +	if (ret)
> +		goto out_free;
> +
> +	ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
> +	if (ret < 0)
> +		goto out_free;
> +
> +	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
> +	if (ret)
> +		goto out_free;
> +
> +	return ret;
> +
> + out_free:
> +	event_trigger_reset_filter(cmd_ops, trigger_data);
> +	kfree(obj_data);
> +	kfree(trigger_data);
> +	return ret;
> +}
> +
> +static struct event_command trigger_object_cmd = {
> +	.name			= "objtrace",
> +	.trigger_type		= ETT_TRACE_OBJECT,
> +	.flags			= EVENT_CMD_FL_NEEDS_REC,
> +	.parse			= event_object_trigger_parse,
> +	.reg			= register_trigger,
> +	.unreg			= unregister_trigger,
> +	.get_trigger_ops	= objecttrace_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
> +};
> +
> +__init int register_trigger_object_cmd(void)
> +{
> +	int ret;
> +
> +	ret = register_event_command(&trigger_object_cmd);
> +	WARN_ON(ret < 0);
> +
> +	return ret;
> +}
> +
> +int allocate_objtrace_data(struct trace_array *tr)
> +{
> +	struct objtrace_data *obj_data;
> +	struct ftrace_ops *fops;
> +
> +	obj_data = kzalloc(sizeof(*obj_data), GFP_KERNEL);
> +	if (!obj_data)
> +		return -ENOMEM;
> +
> +	raw_spin_lock_init(&obj_data->obj_data_lock);
> +	obj_data->tr = tr;
> +	fops = &obj_data->fops;
> +	fops->func = trace_object_events_call;
> +	fops->flags = FTRACE_OPS_FL_SAVE_REGS;
> +	fops->private = tr;
> +	list_add(&obj_data->head, &obj_data_head);
> +
> +	tr->obj_data = obj_data;
> +
> +	return 0;
> +}
> +
> +static int init_trace_object(struct trace_array *tr)
> +{
> +	int ret;
> +
> +	ret = register_ftrace_function(&tr->obj_data->fops);
> +	WARN_ON(ret < 0);
> +
> +	return ret;
> +}
> +
> +void free_objtrace_data(struct trace_array *tr)
> +{
> +	kfree(tr->obj_data);
> +	tr->obj_data = NULL;
> +}
> +
> +static void exit_trace_object(struct trace_array *tr)
> +{
> +	struct objtrace_data *obj_data = tr->obj_data;
> +
> +	obj_data->num_traced_obj = 0;
> +	WARN_ONCE(unregister_ftrace_function(&obj_data->fops),
> +			"can't unregister ftrace for trace object\n");
> +}
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index 67f47ea27921..34ff7b4dc521 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -1551,6 +1551,45 @@ static struct trace_event trace_func_repeats_event = {
>  	.funcs		= &trace_func_repeats_funcs,
>  };
>  
> +/* TRACE_OBJECT */
> +static enum print_line_t trace_object_print(struct trace_iterator *iter, int flags,
> +					struct trace_event *event)
> +{
> +	struct trace_object_entry *field;
> +	struct trace_seq *s = &iter->seq;
> +
> +	trace_assign_type(field, iter->ent);
> +	print_fn_trace(s, field->ip, field->parent_ip, flags);
> +	trace_seq_printf(s, " object:0x%lx", field->object);
> +	trace_seq_putc(s, '\n');
> +
> +	return trace_handle_return(s);
> +}
> +
> +static enum print_line_t trace_object_raw(struct trace_iterator *iter, int flags,
> +				      struct trace_event *event)
> +{
> +	struct trace_object_entry *field;
> +
> +	trace_assign_type(field, iter->ent);
> +
> +	trace_seq_printf(&iter->seq, "%lx %lx\n",
> +			 field->ip,
> +			 field->parent_ip);
> +
> +	return trace_handle_return(&iter->seq);
> +}
> +
> +static struct trace_event_functions trace_object_funcs = {
> +	.trace		= trace_object_print,
> +	.raw		= trace_object_raw,
> +};
> +
> +static struct trace_event trace_object_event = {
> +	.type		= TRACE_OBJECT,
> +	.funcs		= &trace_object_funcs,
> +};
> +
>  static struct trace_event *events[] __initdata = {
>  	&trace_fn_event,
>  	&trace_ctx_event,
> @@ -1565,6 +1604,7 @@ static struct trace_event *events[] __initdata = {
>  	&trace_timerlat_event,
>  	&trace_raw_data_event,
>  	&trace_func_repeats_event,
> +	&trace_object_event,
>  	NULL
>  };
>  
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>