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Message-ID: <CAEr6+ECgyf00BMY1=GfXmxqtUoTFYpXScWHdBbAtkYHY4NRAdw@mail.gmail.com>
Date:   Sun, 26 Jun 2022 01:10:39 +0800
From:   Jeff Xie <xiehuan09@...il.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>, mingo@...hat.com,
        Tom Zanussi <zanussi@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v12 1/4] trace: Add trace any kernel object

Hi Masami,

On Sat, Jun 25, 2022 at 11:59 PM Masami Hiramatsu <mhiramat@...nel.org> wrote:
>
> On Tue,  7 Jun 2022 00:09:40 +0800
> Jeff Xie <xiehuan09@...il.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@...nel.org>

Thank you  for your strong support, my technical level is limited,
Thank you for your continuous support ;-)

> Thank you,
>
> > 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.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@...il.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@...nel.org>

Thanks,
JeffXie

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