[RFC] [PATCH v3] trace: Add trace any kernel object

From: Jeff Xie
Date: Thu Oct 28 2021 - 05:27:46 EST

Introduce a method based on function tracer and kprobe/uprobe/trace_event/
to trace any object in the linux kernel.

Usage:
When using kprobe/uprobe/trace_event/ we can use a new trigger(objtrace)
to set object and trigger object trace.

For example:

For the function bio_add_page, we can trace the first argument:

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

[root@JeffXie ]# cd /sys/kernel/debug/tracing/
[root@JeffXie tracing]# echo 'p bio_add_page arg1=$arg1' > kprobe_events
[root@JeffXie tracing]# cd events/kprobes/p_bio_add_page_0/
[root@JeffXie p_bio_add_page_0]# echo 'objtrace:arg1:1 if comm == "cat"' > ./trigger
[root@JeffXie p_bio_add_page_0]# cat /test.txt
[root@JeffXie p_bio_add_page_0]# cd /sys/kernel/debug/tracing/
[root@JeffXie tracing]# cat ./trace
# tracer: nop
#
# entries-in-buffer/entries-written: 81/81 #P:4
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
cat-122 [001] ..... 111.193997: bio_add_page <-ext4_mpage_readpages object:0xffff888102a4b900
cat-122 [001] ..... 111.193998: __bio_try_merge_page <-bio_add_page object:0xffff888102a4b900
cat-122 [001] ..... 111.193998: __bio_add_page <-bio_add_page object:0xffff888102a4b900
cat-122 [001] ..... 111.193998: submit_bio <-ext4_mpage_readpages object:0xffff888102a4b900
cat-122 [001] ..... 111.193998: submit_bio_noacct <-ext4_mpage_readpages object:0xffff888102a4b900
cat-122 [001] ..... 111.193999: __submit_bio <-submit_bio_noacct object:0xffff888102a4b900
cat-122 [001] ..... 111.193999: submit_bio_checks <-__submit_bio object:0xffff888102a4b900
cat-122 [001] ..... 111.193999: __cond_resched <-submit_bio_checks object:0xffff888102a4b900
cat-122 [001] ..... 111.193999: rcu_all_qs <-__cond_resched object:0xffff888102a4b900
cat-122 [001] ..... 111.194000: should_fail_bio <-submit_bio_checks object:0xffff888102a4b900
cat-122 [001] ..... 111.194001: blk_mq_submit_bio <-__submit_bio object:0xffff888102a4b900
cat-122 [001] ..... 111.194001: blk_attempt_plug_merge <-blk_mq_submit_bio object:0xffff888102a4b900
cat-122 [001] ..... 111.194001: __blk_mq_sched_bio_merge <-blk_mq_submit_bio object:0xffff888102a4b900
cat-122 [001] ..... 111.194002: __blk_mq_alloc_request <-blk_mq_submit_bio object:0xffff888102a4b900
cat-122 [001] ..... 111.194002: blk_mq_get_tag <-__blk_mq_alloc_request object:0xffff888102a4b900
cat-122 [001] ..... 111.194003: blk_account_io_start <-blk_mq_submit_bio object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194212: bio_advance <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194213: bio_endio <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194213: mpage_end_io <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194213: __read_end_io <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194218: bio_put <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194218: bio_free <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194218: bio_free <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194218: bvec_free <-bio_free object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194219: mempool_free <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194219: mempool_free <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194219: mempool_free_slab <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194219: mempool_free_slab <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194219: kmem_cache_free <-blk_update_request object:0xffff888102a4b900
<idle>-0 [001] d.... 111.194219: kmem_cache_free <-blk_update_request object:0xffff888102a4b900

Signed-off-by: Jeff Xie <xiehuan09@xxxxxxxxx>
---
Currently only showing all the code I have, But I think that there are main three tasks
to be completed next:

1. Masami suggested:

<snip>
objfilter:add:arg1

and the exit event

objfilter:del:arg1

then user will only see the trace between the entrance and exit events.
</snip>

Actually, I don’t have a good idea to implement it now ;-)
Looking for related existing code logic.

2. Steven suggested:
<snip>
For example:

obj = arg1 + 0x64
if (copy_from_kernel_nofault(&val, arg1 + 0x64, sizeof(val)))
// faulted
return;

Now val has the content of __bi_cnt and we can print that!
</snip>

We need to implement a more complex parsing and also record the size of a arg
or other related members.it may change the way I record the object.


3. Update trigger documentation

https://lore.kernel.org/lkml/20211026225234.549ec8e9eb59f1fd1671edbc@xxxxxxxxxx/T/#t

I'm very happy to work with you all, and got a lot of knowledge from your help.

At present, I am the only person writing code using the free time, I usually need to do
other work about linux and take care of a three-month-old boy. unlike a group, the progress
of submitting patches may be slower.

include/linux/ftrace.h | 16 +
include/linux/trace_events.h | 1 +
kernel/trace/Kconfig | 7 +
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 | 553 ++++++++++++++++++++++++++++
kernel/trace/trace_output.c | 40 ++
9 files changed, 644 insertions(+)
create mode 100644 kernel/trace/trace_object.c

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 832e65f06754..37cbf154c2f8 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1078,4 +1078,20 @@ unsigned long arch_syscall_addr(int nr);

#endif /* CONFIG_FTRACE_SYSCALLS */

+struct trace_event_file;
+
+#ifdef CONFIG_TRACE_OBJECT
+int init_trace_object(void);
+int exit_trace_object(void);
+void set_trace_object(void *obj);
+void record_trace_object(struct trace_event_file *trace_file,
+ struct pt_regs *regs);
+#else
+static inline int init_trace_object(void) { return 0; }
+static inline int exit_trace_object(void) { return 0; }
+static inline void set_trace_object(void *obj) { }
+static inline void record_trace_object(struct trace_event_file *trace_file,
+ struct pt_regs *regs) { }
+#endif /* CONFIG_TRACE_OBJECT */
+
#endif /* _LINUX_FTRACE_H */
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..d302a0f085f9 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -237,6 +237,13 @@ config FUNCTION_PROFILER

If in doubt, say N.

+config TRACE_OBJECT
+ bool "Trace kernel object"
+ depends on FUNCTION_TRACER
+ default y
+ help
+ This help kernel developer to trace any kernel object.
+
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..c10d8fb913db
--- /dev/null
+++ b/kernel/trace/trace_object.c
@@ -0,0 +1,553 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace any object
+ * Copyright (C) 2021 Jeff Xie <xiehuan09@xxxxxxxxx>
+ */
+
+#define pr_fmt(fmt) "trace_object: " fmt
+
+#include <linux/workqueue.h>
+#include "trace_output.h"
+
+static struct work_struct obj_refill_work;
+static DEFINE_PER_CPU(atomic_t, trace_object_event_disable);
+static DEFINE_RAW_SPINLOCK(object_spin_lock);
+static struct trace_event_file event_trace_file;
+static LIST_HEAD(obj_head);
+static const int max_args_num = 6;
+static atomic_t trace_object_ref;
+
+struct obj_pool {
+ void **obj;
+ int min_nr;
+ int curr_nr;
+};
+
+static struct obj_pool obj_pool;
+static int init_obj_num = 1024;
+static int reserved_obj_num = 100;
+
+static int object_exist(void *obj)
+{
+ int i, used, ret = false;
+
+ if (!obj)
+ goto out;
+
+ used = obj_pool.min_nr - obj_pool.curr_nr;
+ if (!used)
+ goto out;
+
+ for (i = 0; i < used; i++) {
+ if (obj_pool.obj[obj_pool.curr_nr + i] == obj) {
+ ret = true;
+ goto out;
+ }
+ }
+out:
+ return ret;
+}
+
+static int object_empty(void)
+{
+ int ret;
+
+ ret = obj_pool.curr_nr == obj_pool.min_nr;
+
+ return ret;
+}
+
+static void **remove_object_element(void)
+{
+ void **obj = &obj_pool.obj[--obj_pool.curr_nr];
+ BUG_ON(obj_pool.curr_nr < 0);
+
+ return obj;
+}
+
+static void add_object_element(void *obj)
+{
+ BUG_ON(obj_pool.curr_nr >= obj_pool.min_nr);
+ obj_pool.obj[obj_pool.curr_nr++] = obj;
+}
+
+void set_trace_object(void *obj)
+{
+ unsigned long flags;
+ void **new_obj;
+
+ if (in_nmi())
+ return;
+
+ if (!obj)
+ return;
+
+ raw_spin_lock_irqsave(&object_spin_lock, flags);
+
+ if (object_exist(obj))
+ goto out;
+
+ if (obj_pool.curr_nr == 0) {
+ raw_spin_unlock_irqrestore(&object_spin_lock, flags);
+ trace_printk("object_pool is full, can't trace object:0x%px\n", obj);
+ return;
+ }
+
+ new_obj = remove_object_element();
+ *new_obj = obj;
+ if (obj_pool.curr_nr == reserved_obj_num) {
+ raw_spin_unlock_irqrestore(&object_spin_lock, flags);
+ schedule_work(&obj_refill_work);
+ return;
+ }
+out:
+ raw_spin_unlock_irqrestore(&object_spin_lock, flags);
+}
+
+static void object_pool_exit(void)
+{
+ obj_pool.min_nr = 0;
+ obj_pool.curr_nr = 0;
+ kfree(obj_pool.obj);
+ obj_pool.obj = NULL;
+}
+
+static void obj_refill_fn(struct work_struct *refill_work)
+{
+ void **new_obj_element;
+ unsigned long flags;
+ int new_min_nr, new_curr_nr;
+ int used_nr;
+
+ new_min_nr = obj_pool.min_nr * 2;
+ new_obj_element = kmalloc_array(new_min_nr, sizeof(void *), GFP_KERNEL);
+
+ if (!new_obj_element)
+ return;
+
+ raw_spin_lock_irqsave(&object_spin_lock, flags);
+
+ used_nr = obj_pool.min_nr - obj_pool.curr_nr;
+ new_curr_nr = new_min_nr - used_nr;
+ memcpy(new_obj_element + new_curr_nr, obj_pool.obj + obj_pool.curr_nr,
+ used_nr * sizeof(void *));
+
+ kfree(obj_pool.obj);
+ obj_pool.obj = new_obj_element;
+ obj_pool.curr_nr = new_curr_nr;
+ obj_pool.min_nr = new_min_nr;
+
+ raw_spin_unlock_irqrestore(&object_spin_lock, flags);
+}
+
+static int init_object_pool(void)
+{
+ int ret = 0;
+ int i;
+
+ obj_pool.obj = kmalloc_array(init_obj_num, sizeof(void *), GFP_KERNEL);
+ if (!obj_pool.obj) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ obj_pool.min_nr = init_obj_num;
+
+ for (i = 0; i < init_obj_num; i++)
+ add_object_element(obj_pool.obj[i]);
+
+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, (char *)rec + field->offset, field->size);
+ 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;
+}
+
+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 *trigger = NULL;
+ char *arg;
+ char *number;
+ int ret;
+
+ ret = -EINVAL;
+ if (!param)
+ goto out;
+
+ /* separate the trigger from the filter (a:n [if filter]) */
+ trigger = strsep(&param, " \t");
+ if (!trigger)
+ goto out;
+ if (param) {
+ param = skip_spaces(param);
+ if (!*param)
+ param = NULL;
+ }
+
+ 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;
+}
+
+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;
+
+ INIT_WORK(&obj_refill_work, obj_refill_fn);
+ 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;
+}
+
+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;
+ }
+ object_pool_exit();
+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