[RFC][PATCH v5 2/4] trace/objtrace: get the value of the object

From: Jeff Xie
Date: Sat Nov 13 2021 - 07:08:04 EST

Signed-off-by: Jeff Xie <xiehuan09@xxxxxxxxx>
---
kernel/trace/trace_entries.h | 5 +-
kernel/trace/trace_object.c | 121 +++++++++++++++++++++++++++++------
kernel/trace/trace_output.c | 6 +-
3 files changed, 107 insertions(+), 25 deletions(-)

diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index bb120d9498a9..2407c45a568c 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -413,8 +413,9 @@ FTRACE_ENTRY(object, trace_object_entry,
__field( unsigned long, ip )
__field( unsigned long, parent_ip )
__field( unsigned long, object )
+ __field( unsigned long, value )
),

- F_printk(" %ps <-- %ps object:%lx\n",
- (void *)__entry->ip, (void *)__entry->parent_ip, __entry->object)
+ F_printk(" %ps <-- %ps object:%lx value:%lx\n", (void *)__entry->ip,
+ (void *)__entry->parent_ip, __entry->object, __entry->value)
);
diff --git a/kernel/trace/trace_object.c b/kernel/trace/trace_object.c
index 69465c2ffb7e..14993f7d0e5a 100644
--- a/kernel/trace/trace_object.c
+++ b/kernel/trace/trace_object.c
@@ -11,14 +11,25 @@

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 objtrace_trigger_data {
+ struct ftrace_event_field *field;
+ long offset;
+ int type_size;
+};
+
+struct objtrace_fetch_type {
+ char *name;
+ int type_size;
+};
+
struct object_instance {
void *object;
+ int obj_type_size;
struct freelist_node freelist;
};

@@ -59,8 +70,7 @@ static bool object_empty(void)
return ret;
}

-
-static void set_trace_object(void *obj)
+static void set_trace_object(void *obj, int type_size)
{
struct freelist_node *fn;
struct object_instance *ins;
@@ -79,6 +89,7 @@ static void set_trace_object(void *obj)

ins = container_of(fn, struct object_instance, freelist);
ins->object = obj;
+ ins->obj_type_size = type_size;

freelist_add(&ins->freelist, &obj_pool->customer_freelist);
atomic_inc(&obj_pool->nobject);
@@ -135,7 +146,7 @@ static int init_object_pool(void)
}

static void submit_trace_object(unsigned long ip, unsigned long parent_ip,
- unsigned long object)
+ unsigned long object, unsigned long value)
{

struct trace_buffer *buffer;
@@ -152,6 +163,7 @@ static void submit_trace_object(unsigned long ip, unsigned long parent_ip,
entry->ip = ip;
entry->parent_ip = parent_ip;
entry->object = object;
+ entry->value = value;

event_trigger_unlock_commit(&event_trace_file, buffer, event,
entry, pc);
@@ -161,10 +173,11 @@ 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;
+ struct freelist_node *node;
+ struct object_instance *inst;
+ unsigned long val = 0;
long disabled;
- int cpu, n;
+ int cpu;

preempt_disable_notrace();

@@ -177,10 +190,14 @@ trace_object_events_call(unsigned long ip, unsigned long parent_ip,
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);
+ node = obj_pool->customer_freelist.head;
+
+ while (node) {
+ inst = container_of(node, struct object_instance, freelist);
+ if (copy_from_kernel_nofault(&val, inst->object, inst->obj_type_size))
+ goto out;
+ submit_trace_object(ip, parent_ip, (unsigned long)inst->object, val);
+ node = node->next;
}

out:
@@ -198,12 +215,14 @@ 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 ftrace_event_field *field;
+ void *obj, *val = NULL;

- struct ftrace_event_field *field = data->private_data;
- void *obj = NULL;
-
- memcpy(&obj, rec + field->offset, sizeof(obj));
- set_trace_object(obj);
+ field = obj_data->field;
+ memcpy(&val, rec + field->offset, sizeof(val));
+ obj = val + obj_data->offset;
+ set_trace_object(obj, obj_data->type_size);
}

static void
@@ -350,6 +369,22 @@ static void unregister_object_trigger(char *glob, struct event_trigger_ops *ops,
}
}

+static const struct objtrace_fetch_type objtrace_fetch_types[] = {
+ {"u8", 1},
+ {"s8", 1},
+ {"x8", 1},
+ {"u16", 2},
+ {"s16", 2},
+ {"x16", 2},
+ {"u32", 4},
+ {"s32", 4},
+ {"x32", 4},
+ {"u64", 8},
+ {"s64", 8},
+ {"x64", 8},
+ {}
+};
+
static int
event_object_trigger_callback(struct event_command *cmd_ops,
struct trace_event_file *file,
@@ -357,13 +392,15 @@ event_object_trigger_callback(struct event_command *cmd_ops,
{
struct event_trigger_data *trigger_data;
struct event_trigger_ops *trigger_ops;
+ struct objtrace_trigger_data *obj_data;
struct trace_event_call *call;
struct ftrace_event_field *field;
char *objtrace_cmd;
+ long offset = 0;
char *trigger = NULL;
- char *arg;
+ char *arg, *type, *tr, *tr_end;
char *number;
- int ret;
+ int ret, i, type_size = 0;

ret = -EINVAL;
if (!param)
@@ -386,6 +423,38 @@ event_object_trigger_callback(struct event_command *cmd_ops,
arg = strsep(&trigger, ":");
if (!arg)
goto out;
+
+ tr = strchr(arg, '(');
+ /* now force to get the value of the val. */
+ if (!tr)
+ goto out;
+ tr_end = strchr(tr, ')');
+ if (!tr_end)
+ goto out;
+ *tr++ = '\0';
+ *tr_end = '\0';
+ ret = kstrtol(arg, 0, &offset);
+ if (ret)
+ goto out;
+ arg = tr;
+ ret = -EINVAL;
+ if (!trigger)
+ goto out;
+
+ type = strsep(&trigger, ":");
+ if (!type)
+ goto out;
+ for (i = 0; objtrace_fetch_types[i].name; i++) {
+ if (strcmp(objtrace_fetch_types[i].name, type) == 0) {
+ type_size = objtrace_fetch_types[i].type_size;
+ break;
+ }
+ }
+
+ if (type_size == 0)
+ goto out;
+
+
call = file->event_call;
field = trace_find_event_field(call, arg);
if (!field)
@@ -394,19 +463,30 @@ event_object_trigger_callback(struct event_command *cmd_ops,
trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);

ret = -ENOMEM;
+ obj_data = kzalloc(sizeof(*obj_data), GFP_KERNEL);
+ if (!obj_data)
+ goto out;
+
+ obj_data->field = field;
+ obj_data->offset = offset;
+ obj_data->type_size = type_size;
+
trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
- if (!trigger_data)
+ if (!trigger_data) {
+ kfree(obj_data);
goto out;
+ }

trigger_data->count = -1;
trigger_data->ops = trigger_ops;
trigger_data->cmd_ops = cmd_ops;
- trigger_data->private_data = field;
+ trigger_data->private_data = obj_data;
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(obj_data);
kfree(trigger_data);
ret = 0;
goto out;
@@ -461,6 +541,7 @@ event_object_trigger_callback(struct event_command *cmd_ops,
out_free:
if (cmd_ops->set_filter)
cmd_ops->set_filter(NULL, trigger_data, NULL);
+ kfree(obj_data);
kfree(trigger_data);
goto out;
}
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 76ca560af693..c8c427c23127 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1562,6 +1562,7 @@ static enum print_line_t trace_object_print(struct trace_iterator *iter, int fla
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_printf(s, " value:0x%lx", field->value);
trace_seq_putc(s, '\n');

return trace_handle_return(s);
@@ -1574,9 +1575,8 @@ static enum print_line_t trace_object_raw(struct trace_iterator *iter, int flags

trace_assign_type(field, iter->ent);

- trace_seq_printf(&iter->seq, "%lx %lx\n",
- field->ip,
- field->parent_ip);
+ trace_seq_printf(&iter->seq, "%lx %lx %lx %lx\n", field->ip,
+ field->parent_ip, field->object, field->value);

return trace_handle_return(&iter->seq);
}
--
2.25.1