trace: Add trace any kernel object

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(objfilter)
to set object and tigger 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 'objfilter:arg1 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@gmail.com>

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 */

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);

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

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

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)
 
@@ -1950,6 +1952,11 @@ struct trace_min_max_param {
 	u64		*max;
 };
 
+struct object_trigger_param {
+	struct pt_regs *regs;
+	int param;
+};
+
 #define U64_STR_SIZE		24	/* 20 digits max */
 
 extern const struct file_operations trace_min_max_fops;

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)
+);

kernel/trace/trace_events_trigger.c

@@ -756,12 +756,36 @@ int set_trigger_filter(char *filter_str,
 	struct event_filter *filter = NULL, *tmp;
 	int ret = -EINVAL;
 	char *s;
+	unsigned long param;
+	struct object_trigger_param *obj_param;
+	int len;
 
 	if (!filter_str) /* clear the current filter */
 		goto assign;
 
 	s = strsep(&filter_str, " \t");
 
+	if (data->cmd_ops->trigger_type == ETT_TRACE_OBJECT) {
+		obj_param = data->private_data;
+		len = str_has_prefix(s, "arg");
+		if (!len)
+			goto out;
+		ret = kstrtoul(s + len, 10, &param);
+		if (ret || param == 0)
+			goto out;
+		obj_param = kmalloc(sizeof(*obj_param), GFP_KERNEL);
+		if (!obj_param) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		data->private_data = obj_param;
+		obj_param->param = param;
+		init_trace_object();
+	}
+	if (!strlen(s) || !filter_str)
+		goto out;
+
+	s = strsep(&filter_str, " \t");
 	if (!strlen(s) || strcmp(s, "if") != 0)
 		goto out;
 
@@ -1679,6 +1703,103 @@ static __init int register_trigger_traceon_traceoff_cmds(void)
 	return ret;
 }
 
+#ifdef CONFIG_TRACE_OBJECT
+
+static void
+trace_object_trigger(struct event_trigger_data *data,
+		   struct trace_buffer *buffer,  void *rec,
+		   struct ring_buffer_event *event)
+{
+
+	struct object_trigger_param *obj_param = data->private_data;
+	unsigned long param;
+
+	param = regs_get_kernel_argument(obj_param->regs, obj_param->param - 1);
+	set_trace_object((void *)param);
+}
+
+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) {
+		exit_trace_object();
+		trigger_data_free(data);
+		kfree(data->private_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
+trace_object_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+			 struct event_trigger_data *data)
+{
+	return event_trigger_print("objfilter", 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_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_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 struct event_command trigger_object_cmd = {
+	.name			= "objfilter",
+	.trigger_type		= ETT_TRACE_OBJECT,
+	.flags			= EVENT_CMD_FL_NEEDS_REC,
+	.func			= event_trigger_callback,
+	.reg			= register_trigger,
+	.unreg			= unregister_trigger,
+	.get_trigger_ops	= objecttrace_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static __init int register_trigger_object_cmd(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_object_cmd);
+	WARN_ON(ret < 0);
+
+	return ret;
+}
+
+#else
+static __init int register_trigger_object_cmd(void) { return 0; }
+#endif
+
 __init int register_trigger_cmds(void)
 {
 	register_trigger_traceon_traceoff_cmds();
@@ -1687,6 +1808,7 @@ __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;
 }

kernel/trace/trace_kprobe.c

@@ -1380,6 +1380,7 @@ __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
 
 	WARN_ON(call != trace_file->event_call);
 
+	record_trace_object(trace_file, regs);
 	if (trace_trigger_soft_disabled(trace_file))
 		return;