Message-Id: <20211113120632.94754-1-xiehuan09@gmail.com>
Date:   Sat, 13 Nov 2021 20:06:29 +0800
From:   Jeff Xie <xiehuan09@...il.com>
To:     rostedt@...dmis.org
Cc:     mhiramat@...nel.org, mingo@...hat.com, zanussi@...nel.org,
        linux-kernel@...r.kernel.org, Jeff Xie <xiehuan09@...il.com>
Subject: [RFC][PATCH v5 1/4] trace: Add trace any kernel object

Introduce a method based on function tracer to trace any object and get
the value of the object dynamically. the object can be obtained from the
dynamic event (kprobe_event/uprobe_event) or the static event(tracepoint).

Usage:
When using the kprobe event, only need to set the objtrace(a new trigger),
we can get the value of the object. The object is from the setting of the 
kprobe event.

For example:
For the function bio_add_page():

int bio_add_page(struct bio *bio, struct page *page,
	unsigned int len, unsigned int offset)

Firstly, we can set the base of the object, thus the first string "arg1"
stands for the value of the first parameter of this function bio_add_gage(),

# echo 'p bio_add_page arg1=$arg1' >> ./kprobe_events

Secondly, we can get the value dynamically base the above object. 

find the offset of the bi_size in struct bio:
$ gdb vmlinux
(gdb) p &(((struct bio *)0)->bi_iter.bi_size)
$1 = (unsigned int *) 0x28

# echo 'objtrace:0x28(arg1):u32:1 if comm == "cat"' > ./events/kprobes/ \
	p_bio_add_page_0/trigger

The best way to use this is that we can set the entrance event and exit
event, for example, the following example is to set the read_papes as
the entrance event, and set the blk_account_io_start as the exit event.

# dd if=/dev/zero of=/test.txt bs=4k count=3
# cd /sys/kernel/debug/tracing/
# echo 0 > ./tracing_on
# echo 'p read_pages' >> ./kprobe_events
# echo 'p blk_account_io_start' >> ./kprobe_events
# echo 'traceon if comm == "cat"' > ./events/kprobes/p_read_pages_0/trigger
# echo 'traceoff if comm == "cat"' > ./events/kprobes/p_blk_account_io_start_0/trigger
# echo 'p bio_add_page arg1=$arg1' >> ./kprobe_events
# echo 'objtrace:0x28(arg1):u32:1 if comm == "cat"' > ./events/kprobes/p_bio_add_page_0/trigger

# du -sh /test.txt
12.0K   /test.txt

# cat  /test.txt > /dev/null
# cat ./trace

# tracer: nop
#
# entries-in-buffer/entries-written: 50/50   #P:1
#
#                                _-----=> irqs-off
#                               / _----=> need-resched
#                              | / _---=> hardirq/softirq
#                              || / _--=> preempt-depth
#                              ||| / _-=> migrate-disable
#                              |||| /     delay
#           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
#              | |         |   |||||     |         |
             cat-95      [000] .....     1.412065: _raw_spin_unlock_irqrestore <-event_triggers_call object:0xffff888108af6328 value:0x0
             cat-95      [000] .....     1.412066: __bio_try_merge_page <-bio_add_page object:0xffff888108af6328 value:0x0
             cat-95      [000] .....     1.412066: __bio_add_page <-bio_add_page object:0xffff888108af6328 value:0x0
             cat-95      [000] .....     1.412066: rcu_read_unlock_strict <-xa_load object:0xffff888108af6328 value:0x1000
             cat-95      [000] .....     1.412066: bio_add_page <-ext4_mpage_readpages object:0xffff888108af6328 value:0x1000
             cat-95      [000] .....     1.412066: kprobe_ftrace_handler <-ftrace_ops_list_func object:0xffff888108af6328 value:0x1000
             cat-95      [000] .....     1.412067: get_kprobe <-kprobe_ftrace_handler object:0xffff888108af6328 value:0x1000
             cat-95      [000] .....     1.412067: __bio_try_merge_page <-bio_add_page object:0xffff888108af6328 value:0x1000
             cat-95      [000] .....     1.412067: __bio_add_page <-bio_add_page object:0xffff888108af6328 value:0x1000
             cat-95      [000] .....     1.412067: rcu_read_unlock_strict <-xa_load object:0xffff888108af6328 value:0x2000
             cat-95      [000] .....     1.412067: bio_add_page <-ext4_mpage_readpages object:0xffff888108af6328 value:0x2000
             cat-95      [000] .....     1.412067: kprobe_ftrace_handler <-ftrace_ops_list_func object:0xffff888108af6328 value:0x2000
             cat-95      [000] .....     1.412067: get_kprobe <-kprobe_ftrace_handler object:0xffff888108af6328 value:0x2000
             cat-95      [000] .....     1.412067: __bio_try_merge_page <-bio_add_page object:0xffff888108af6328 value:0x2000
             cat-95      [000] .....     1.412068: submit_bio <-ext4_mpage_readpages object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: submit_bio_noacct <-ext4_mpage_readpages object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: __submit_bio <-submit_bio_noacct object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: blk_try_enter_queue <-__submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: rcu_read_unlock_strict <-blk_try_enter_queue object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: rcu_read_unlock_strict <-blk_try_enter_queue object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: submit_bio_checks <-__submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: __cond_resched <-submit_bio_checks object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: rcu_all_qs <-__cond_resched object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412068: should_fail_bio <-submit_bio_checks object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: create_task_io_context <-submit_bio_checks object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: kmem_cache_alloc_node <-create_task_io_context object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: should_failslab <-kmem_cache_alloc_node object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: _raw_spin_lock <-create_task_io_context object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: blk_mq_submit_bio <-__submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: __blk_queue_split <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: bvec_split_segs <-__blk_queue_split object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412069: blk_attempt_plug_merge <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: __blk_mq_sched_bio_merge <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: dd_bio_merge <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: _raw_spin_lock <-dd_bio_merge object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: blk_mq_sched_try_merge <-dd_bio_merge object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: elv_merge <-blk_mq_sched_try_merge object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: elv_rqhash_find <-elv_merge object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: dd_request_merge <-blk_mq_sched_try_merge object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: elv_rb_find <-dd_request_merge object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412070: __blk_mq_alloc_request <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: dd_limit_depth <-__blk_mq_alloc_request object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: blk_mq_get_tag <-__blk_mq_alloc_request object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: __blk_mq_get_tag <-blk_mq_get_tag object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: blk_mq_rq_ctx_init.isra.0 <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: ktime_get <-blk_mq_rq_ctx_init.isra.0 object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: dd_prepare_request <-blk_mq_rq_ctx_init.isra.0 object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: blk_account_io_start <-blk_mq_submit_bio object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: kprobe_ftrace_handler <-ftrace_ops_list_func object:0xffff888108af6328 value:0x3000
             cat-95      [000] .....     1.412071: get_kprobe <-kprobe_ftrace_handler object:0xffff888108af6328 value:0x3000

Signed-off-by: Jeff Xie <xiehuan09@...il.com>
---
 include/linux/trace_events.h        |   1 +
 kernel/trace/Kconfig                |  10 +
 kernel/trace/Makefile               |   1 +
 kernel/trace/trace.h                |   8 +
 kernel/trace/trace_entries.h        |  17 +
 kernel/trace/trace_events_trigger.c |   1 +
 kernel/trace/trace_object.c         | 532 ++++++++++++++++++++++++++++
 kernel/trace/trace_output.c         |  40 +++
 8 files changed, 610 insertions(+)
 create mode 100644 kernel/trace/trace_object.c

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 3e475eeb5a99..84b5c12c7f44 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -684,6 +684,7 @@ 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 420ff4bc67fd..f69761cbfaaa 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -237,6 +237,16 @@ 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 6de5d4d63165..6d9e78a488aa 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -66,6 +66,7 @@ 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.h b/kernel/trace/trace.h
index b7c0f8e160fb..d2508f977fe6 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -49,6 +49,7 @@ enum trace_type {
 	TRACE_TIMERLAT,
 	TRACE_RAW_DATA,
 	TRACE_FUNC_REPEATS,
+	TRACE_OBJECT,
 
 	__TRACE_LAST_TYPE,
 };
@@ -460,6 +461,7 @@ 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)
 
@@ -1510,6 +1512,12 @@ 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);
+#else
+static inline int register_trigger_object_cmd(void) { return 0; }
+#endif
+
 extern int register_trigger_cmds(void);
 extern void clear_event_triggers(struct trace_array *tr);
 
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 3d5c07239a2a..da2d871fa809 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -1687,6 +1687,7 @@ __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..69465c2ffb7e
--- /dev/null
+++ b/kernel/trace/trace_object.c
@@ -0,0 +1,532 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace any object
+ * Copyright (C) 2021 Jeff Xie <xiehuan09@...il.com>
+ */
+
+#define pr_fmt(fmt) "trace_object: " fmt
+
+#include "trace_output.h"
+#include <linux/freelist.h>
+
+static DEFINE_PER_CPU(atomic_t, trace_object_event_disable);
+static struct trace_event_file event_trace_file;
+static const int max_args_num = 6;
+static const int max_obj_pool = 10;
+static atomic_t trace_object_ref;
+static int exit_trace_object(void);
+static int init_trace_object(void);
+
+struct object_instance {
+	void *object;
+	struct freelist_node freelist;
+};
+
+struct obj_pool {
+	int maxactive;
+	atomic_t nobject;
+	struct freelist_head product_freelist;
+	struct freelist_head customer_freelist;
+};
+static struct obj_pool *obj_pool;
+
+static bool object_exist(void *obj)
+{
+	struct freelist_node *node;
+	struct object_instance *inst;
+	bool ret = false;
+
+	node = obj_pool->customer_freelist.head;
+
+	while (node) {
+		inst = container_of(node, struct object_instance, freelist);
+		if (inst->object == obj) {
+			ret = true;
+			goto out;
+		}
+		node = node->next;
+	}
+out:
+	return ret;
+}
+
+static bool object_empty(void)
+{
+	bool ret;
+
+	ret = atomic_read(&obj_pool->nobject) == 0;
+
+	return ret;
+}
+
+
+static void set_trace_object(void *obj)
+{
+	struct freelist_node *fn;
+	struct object_instance *ins;
+
+	if (!obj)
+		return;
+
+	if (object_exist(obj))
+		goto out;
+
+	fn = freelist_try_get(&obj_pool->product_freelist);
+	if (!fn) {
+		trace_printk("object_pool is full, can't trace object:0x%px\n", obj);
+		return;
+	}
+
+	ins = container_of(fn, struct object_instance, freelist);
+	ins->object = obj;
+
+	freelist_add(&ins->freelist, &obj_pool->customer_freelist);
+	atomic_inc(&obj_pool->nobject);
+
+out:
+	return;
+}
+
+static inline void free_objects(struct freelist_node *node)
+{
+
+	struct object_instance *inst;
+
+	while (node) {
+		inst = container_of(node, struct object_instance, freelist);
+		node = node->next;
+		kfree(inst);
+	}
+}
+
+static inline void free_object_pool(void)
+{
+	free_objects(obj_pool->product_freelist.head);
+	free_objects(obj_pool->customer_freelist.head);
+	kfree(obj_pool);
+}
+
+
+static int init_object_pool(void)
+{
+	struct object_instance *inst;
+	int i, ret = 0;
+
+	obj_pool = kzalloc(sizeof(*obj_pool), GFP_KERNEL);
+	if (!obj_pool) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	obj_pool->maxactive = max_obj_pool;
+	obj_pool->product_freelist.head = NULL;
+	obj_pool->customer_freelist.head = NULL;
+
+	for (i = 0; i < obj_pool->maxactive; i++) {
+		inst = kzalloc(sizeof(*inst), GFP_KERNEL);
+		if (!inst) {
+			free_object_pool();
+			ret = -ENOMEM;
+			goto out;
+		}
+		freelist_add(&inst->freelist, &obj_pool->product_freelist);
+	}
+out:
+	return ret;
+}
+
+static void submit_trace_object(unsigned long ip, unsigned long parent_ip,
+				 unsigned long object)
+{
+
+	struct trace_buffer *buffer;
+	struct ring_buffer_event *event;
+	struct trace_object_entry *entry;
+	int pc;
+
+	pc = preempt_count();
+	event = trace_event_buffer_lock_reserve(&buffer, &event_trace_file,
+			TRACE_OBJECT, sizeof(*entry), pc);
+	if (!event)
+		return;
+	entry   = ring_buffer_event_data(event);
+	entry->ip                       = ip;
+	entry->parent_ip                = parent_ip;
+	entry->object			= object;
+
+	event_trigger_unlock_commit(&event_trace_file, buffer, event,
+		entry, pc);
+}
+
+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);
+	unsigned long obj;
+	long disabled;
+	int cpu, n;
+
+	preempt_disable_notrace();
+
+	cpu = raw_smp_processor_id();
+	disabled = atomic_inc_return(&per_cpu(trace_object_event_disable, cpu));
+
+	if (disabled != 1)
+		goto out;
+
+	if (object_empty())
+		goto out;
+
+	for (n = 0; n < max_args_num; n++) {
+		obj = regs_get_kernel_argument(pt_regs, n);
+		if (object_exist((void *)obj))
+			submit_trace_object(ip, parent_ip, obj);
+	}
+
+out:
+	atomic_dec(&per_cpu(trace_object_event_disable, cpu));
+	preempt_enable_notrace();
+}
+
+static struct ftrace_ops trace_ops = {
+	.func  = trace_object_events_call,
+	.flags = FTRACE_OPS_FL_SAVE_REGS,
+};
+
+static void
+trace_object_trigger(struct event_trigger_data *data,
+		   struct trace_buffer *buffer,  void *rec,
+		   struct ring_buffer_event *event)
+{
+
+	struct ftrace_event_field *field = data->private_data;
+	void *obj = NULL;
+
+	memcpy(&obj, rec + field->offset, sizeof(obj));
+	set_trace_object(obj);
+}
+
+static void
+trace_object_trigger_free(struct event_trigger_ops *ops,
+		   struct event_trigger_data *data)
+{
+	if (WARN_ON_ONCE(data->ref <= 0))
+		return;
+
+	data->ref--;
+	if (!data->ref)
+		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_object_trigger_init(struct event_trigger_ops *ops,
+		       struct event_trigger_data *data)
+{
+	data->ref++;
+	return 0;
+}
+
+static int
+event_trigger_print(const char *name, struct seq_file *m,
+		    void *data, char *filter_str)
+{
+	long count = (long)data;
+
+	seq_puts(m, 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
+trace_object_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+			 struct event_trigger_data *data)
+{
+	return event_trigger_print("objtrace", m, (void *)data->count,
+				   data->filter_str);
+}
+
+
+static struct event_trigger_ops objecttrace_trigger_ops = {
+	.func			= 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 = {
+	.func			= 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 int register_object_trigger(char *glob, struct event_trigger_ops *ops,
+			    struct event_trigger_data *data,
+			    struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+	int ret = 0;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
+			ret = -EEXIST;
+			goto out;
+		}
+	}
+
+	if (data->ops->init) {
+		ret = data->ops->init(data->ops, data);
+		if (ret < 0)
+			goto out;
+	}
+
+	list_add_rcu(&data->list, &file->triggers);
+	ret++;
+
+	update_cond_flag(file);
+	if (trace_event_trigger_enable_disable(file, 1) < 0) {
+		list_del_rcu(&data->list);
+		update_cond_flag(file);
+		ret--;
+	}
+	init_trace_object();
+out:
+	return ret;
+}
+
+static void unregister_object_trigger(char *glob, struct event_trigger_ops *ops,
+			       struct event_trigger_data *test,
+			       struct trace_event_file *file)
+{
+	struct event_trigger_data *data;
+	bool unregistered = false;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(data, &file->triggers, list) {
+		if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
+			unregistered = true;
+			list_del_rcu(&data->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			break;
+		}
+	}
+
+	if (unregistered && data->ops->free) {
+		data->ops->free(data->ops, data);
+		exit_trace_object();
+	}
+}
+
+static int
+event_object_trigger_callback(struct event_command *cmd_ops,
+		       struct trace_event_file *file,
+		       char *glob, char *cmd, char *param)
+{
+	struct event_trigger_data *trigger_data;
+	struct event_trigger_ops *trigger_ops;
+	struct trace_event_call *call;
+	struct ftrace_event_field *field;
+	char *objtrace_cmd;
+	char *trigger = NULL;
+	char *arg;
+	char *number;
+	int ret;
+
+	ret = -EINVAL;
+	if (!param)
+		goto out;
+
+	/* separate the trigger from the filter (c:a:n [if filter]) */
+	trigger = strsep(&param, " \t");
+	if (!trigger)
+		goto out;
+	if (param) {
+		param = skip_spaces(param);
+		if (!*param)
+			param = NULL;
+	}
+
+	objtrace_cmd = strsep(&trigger, ":");
+	if (!objtrace_cmd || strcmp(objtrace_cmd, "add"))
+		goto out;
+
+	arg = strsep(&trigger, ":");
+	if (!arg)
+		goto out;
+	call = file->event_call;
+	field = trace_find_event_field(call, arg);
+	if (!field)
+		goto out;
+
+	trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
+
+	ret = -ENOMEM;
+	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
+	if (!trigger_data)
+		goto out;
+
+	trigger_data->count = -1;
+	trigger_data->ops = trigger_ops;
+	trigger_data->cmd_ops = cmd_ops;
+	trigger_data->private_data = field;
+	INIT_LIST_HEAD(&trigger_data->list);
+	INIT_LIST_HEAD(&trigger_data->named_list);
+
+	if (glob[0] == '!') {
+		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
+		kfree(trigger_data);
+		ret = 0;
+		goto out;
+	}
+
+	if (trigger) {
+		number = strsep(&trigger, ":");
+
+		ret = -EINVAL;
+		if (!strlen(number))
+			goto out_free;
+
+		/*
+		 * We use the callback data field (which is a pointer)
+		 * as our counter.
+		 */
+		ret = kstrtoul(number, 0, &trigger_data->count);
+		if (ret)
+			goto out_free;
+	}
+
+	if (!param) /* if param is non-empty, it's supposed to be a filter */
+		goto out_reg;
+
+	if (!cmd_ops->set_filter)
+		goto out_reg;
+
+	ret = cmd_ops->set_filter(param, trigger_data, file);
+	if (ret < 0)
+		goto out_free;
+
+ out_reg:
+	/* Up the trigger_data count to make sure reg doesn't free it on failure */
+	event_object_trigger_init(trigger_ops, trigger_data);
+	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
+	/*
+	 * The above returns on success the # of functions enabled,
+	 * but if it didn't find any functions it returns zero.
+	 * Consider no functions a failure too.
+	 */
+	if (!ret) {
+		cmd_ops->unreg(glob, trigger_ops, trigger_data, file);
+		ret = -ENOENT;
+	} else if (ret > 0)
+		ret = 0;
+
+	/* Down the counter of trigger_data or free it if not used anymore */
+	trace_object_trigger_free(trigger_ops, trigger_data);
+ out:
+	return ret;
+
+ out_free:
+	if (cmd_ops->set_filter)
+		cmd_ops->set_filter(NULL, trigger_data, NULL);
+	kfree(trigger_data);
+	goto out;
+}
+
+static struct event_command trigger_object_cmd = {
+	.name			= "objtrace",
+	.trigger_type		= ETT_TRACE_OBJECT,
+	.flags			= EVENT_CMD_FL_NEEDS_REC,
+	.func			= event_object_trigger_callback,
+	.reg			= register_object_trigger,
+	.unreg			= unregister_object_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;
+}
+
+static int init_trace_object(void)
+{
+	int ret;
+
+	if (atomic_inc_return(&trace_object_ref) != 1) {
+		ret = 0;
+		goto out;
+	}
+
+	ret = init_object_pool();
+	if (ret)
+		goto out;
+
+	event_trace_file.tr = top_trace_array();
+	if (WARN_ON(!event_trace_file.tr)) {
+		ret = -1;
+		goto out;
+	}
+	ret = register_ftrace_function(&trace_ops);
+out:
+	return ret;
+}
+
+static int exit_trace_object(void)
+{
+	int ret;
+
+	if (WARN_ON_ONCE(atomic_read(&trace_object_ref) <= 0))
+		goto out;
+
+	if (atomic_dec_return(&trace_object_ref) != 0) {
+		ret = 0;
+		goto out;
+	}
+
+	ret = unregister_ftrace_function(&trace_ops);
+	if (ret) {
+		pr_err("can't unregister ftrace for trace object\n");
+		goto out;
+	}
+	free_object_pool();
+out:
+	return ret;
+}
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index c2ca40e8595b..76ca560af693 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1552,6 +1552,45 @@ 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,
@@ -1566,6 +1605,7 @@ static struct trace_event *events[] __initdata = {
 	&trace_timerlat_event,
 	&trace_raw_data_event,
 	&trace_func_repeats_event,
+	&trace_object_event,
 	NULL
 };
 
-- 
2.25.1

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