Messages in this thread | | | From | Jeff Xie <> | Date | Wed, 27 Apr 2022 23:50:26 +0800 | Subject | Re: [PATCH v9 1/4] trace: Add trace any kernel object |
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Hi Tom,
I have checked your patches:
https://lore.kernel.org/all/cover.1644010575.git.zanussi@kernel.org/
But I found that I can't use the generic function you implemented, I don't know if I understand correctly, when you are free, hope you can help to check it ;-) , thanks.
On Fri, Feb 4, 2022 at 11:57 AM Jeff Xie <xiehuan09@gmail.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=$arg1' > kprobe_events > # cd events/kprobes/p_bio_add_page_0 > # echo 'objtrace:add:arg1:1 if comm == "cat"' > ./trigger > # cat /test.txt > > Signed-off-by: Jeff Xie <xiehuan09@gmail.com> > --- > include/linux/trace_events.h | 1 + > kernel/trace/Kconfig | 10 + > kernel/trace/Makefile | 1 + > kernel/trace/trace.c | 3 + > kernel/trace/trace.h | 8 + > kernel/trace/trace_entries.h | 17 + > kernel/trace/trace_events_trigger.c | 1 + > kernel/trace/trace_object.c | 515 ++++++++++++++++++++++++++++ > kernel/trace/trace_output.c | 40 +++ > 9 files changed, 596 insertions(+) > create mode 100644 kernel/trace/trace_object.c > > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h > index 70c069aef02c..3ccdbc1d25dd 100644 > --- a/include/linux/trace_events.h > +++ b/include/linux/trace_events.h > @@ -685,6 +685,7 @@ enum event_trigger_type { > ETT_EVENT_HIST = (1 << 4), > ETT_HIST_ENABLE = (1 << 5), > ETT_EVENT_EPROBE = (1 << 6), > + ETT_TRACE_OBJECT = (1 << 7), > }; > > extern int filter_match_preds(struct event_filter *filter, void *rec); > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index a5eb5e7fd624..c51b7eb1508d 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -250,6 +250,16 @@ config FUNCTION_PROFILER > > If in doubt, say N. > > +config TRACE_OBJECT > + bool "Trace kernel object in function parameter" > + depends on FUNCTION_TRACER > + depends on HAVE_FUNCTION_ARG_ACCESS_API > + select TRACING > + default y > + help > + You can trace the kernel object in the kernel function parameter. > + The kernel object is dynamically specified via event trigger. > + > config STACK_TRACER > bool "Trace max stack" > depends on HAVE_FUNCTION_TRACER > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile > index bedc5caceec7..b924b8e55922 100644 > --- a/kernel/trace/Makefile > +++ b/kernel/trace/Makefile > @@ -67,6 +67,7 @@ obj-$(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 a734d5ae34c8..b4513c2bbd52 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -5605,6 +5605,9 @@ 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 > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 0f5e22238cd2..8b66515a36d5 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, > }; > @@ -472,6 +473,7 @@ 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) > > @@ -1537,6 +1539,12 @@ 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 d00fee705f9c..c3371a6902af 100644 > --- a/kernel/trace/trace_events_trigger.c > +++ b/kernel/trace/trace_events_trigger.c > @@ -2025,6 +2025,7 @@ __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..540e387c613a > --- /dev/null > +++ b/kernel/trace/trace_object.c > @@ -0,0 +1,515 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * trace the kernel object in the kernel function parameter > + * Copyright (C) 2021 Jeff Xie <xiehuan09@gmail.com> > + */ > + > +#define pr_fmt(fmt) "trace_object: " fmt > + > +#include "trace_output.h" > + > +#define MAX_TRACED_OBJECT 5 > +#define OBJTRACE_CMD_LEN 10 > +static DEFINE_PER_CPU(unsigned int, trace_object_event_disable); > +static DEFINE_RAW_SPINLOCK(trace_obj_lock); > +static struct trace_event_file event_trace_file; > +static const int max_args_num = 6; > +static atomic_t trace_object_ref; > +static atomic_t num_traced_obj; > +static int exit_trace_object(void); > +static int init_trace_object(void); > + > +static struct object_instance { > + void *obj; > +} traced_obj[MAX_TRACED_OBJECT]; > + > +/* objtrace private data */ > +struct objtrace_trigger_data { > + struct ftrace_event_field *field; > + char objtrace_cmd[OBJTRACE_CMD_LEN]; > +}; > + > +static bool object_exist(void *obj) > +{ > + int i, max; > + > + max = atomic_read(&num_traced_obj); > + smp_rmb(); > + for (i = 0; i < max; i++) { > + if (traced_obj[i].obj == obj) > + return true; > + } > + return false; > +} > + > +static bool object_empty(void) > +{ > + return !atomic_read(&num_traced_obj); > +} > + > +static void set_trace_object(void *obj) > +{ > + unsigned long flags; > + > + if (in_nmi()) > + return; > + > + if (!obj) > + return; > + > + if (object_exist(obj)) > + return; > + > + /* only this place has write operations */ > + raw_spin_lock_irqsave(&trace_obj_lock, flags); > + if (atomic_read(&num_traced_obj) == MAX_TRACED_OBJECT) { > + trace_printk("object_pool is full, can't trace object:0x%px\n", obj); > + goto out; > + } > + traced_obj[atomic_read(&num_traced_obj)].obj = obj; > + /* make sure the num_traced_obj update always appears after traced_obj update */ > + smp_wmb(); > + atomic_inc(&num_traced_obj); > +out: > + raw_spin_unlock_irqrestore(&trace_obj_lock, flags); > +} > + > +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; > + unsigned int disabled; > + int n; > + > + preempt_disable_notrace(); > + > + disabled = this_cpu_inc_return(trace_object_event_disable); > + 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); > + /* The parameters of a function may match multiple objects */ > + } > +out: > + this_cpu_dec(trace_object_event_disable); > + 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 objtrace_trigger_data *obj_data = data->private_data; > + struct ftrace_event_field *field; > + void *obj = NULL; > + > + field = obj_data->field; > + 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) { > + 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_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, 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 > +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, 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 int register_object_trigger(char *glob, > + 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; > +}
Can't replace the register_object_trigger() with register_trigger(), as there will be no place to invoke the init_trace_object(), maybe It will be better to add a callback in struct event_command, for example, cmd_ops->init()
> +static void unregister_object_trigger(char *glob, > + 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) { > + if (data->ops->free) > + data->ops->free(data->ops, data); > + exit_trace_object(); > + } > +} > +
Can't replace the unregister_object_trigger() with unregister_trigger(), as there will be no place to invoke the exit_trace_object().Maybe need to add a callback, for example cmd_ops->free().
> +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) > +{ > + 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; > + char *trigger = NULL; > + char *arg; > + char *number; > + int ret; > + bool remove = false; > + > + ret = -EINVAL; > + if (!param) > + goto out; > + > + /* separate the trigger from the filter (c:a:n [if filter]) */ > + trigger = strsep(¶m, " \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; > + > + if (field->size != sizeof(void *)) > + goto out; > + > + if (glob[0] == '!') > + remove = true; > + > + if (remove && !field_exist(file, cmd_ops, field->name)) > + goto out; > + 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; > + snprintf(obj_data->objtrace_cmd, OBJTRACE_CMD_LEN, objtrace_cmd); > + > + trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL); > + 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 = obj_data; > + INIT_LIST_HEAD(&trigger_data->list); > + INIT_LIST_HEAD(&trigger_data->named_list); > + > + if (remove) { > + cmd_ops->unreg(glob+1, trigger_data, file); > + kfree(obj_data); > + 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_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_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(obj_data); > + kfree(trigger_data); > + goto out; > +}
Can't replace the event_object_trigger_parse() with event_trigger_parse(). Because the event_object_trigger_parse() needs to parse more fields, for example need to parse objtrace_cmd("add" etc.,) and need to use other special private_data. Maybe It will have to use the event_object_trigger_parse().
> +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_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; > + } > + > + event_trace_file.tr = top_trace_array(); > + if (WARN_ON(!event_trace_file.tr)) { > + ret = -1; > + atomic_dec(&trace_object_ref); > + 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)) { > + ret = -1; > + 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; > + } > + atomic_set(&num_traced_obj, 0); > +out: > + return ret; > +} > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 8aa493d25c73..265428154638 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -1547,6 +1547,45 @@ 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, > @@ -1561,6 +1600,7 @@ static struct trace_event *events[] __initdata = { > &trace_timerlat_event, > &trace_raw_data_event, > &trace_func_repeats_event, > + &trace_object_event, > NULL > }; > > -- > 2.25.1 >
Thanks, JeffXie
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