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perf/core: Implement the 'perf_kprobe' PMU

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A new PMU type, perf_kprobe is added. Based on attr from perf_event_open(),
perf_kprobe creates a kprobe (or kretprobe) for the perf_event. This
kprobe is private to this perf_event, and thus not added to global
lists, and not available in tracefs.

Two functions, create_local_trace_kprobe() and
destroy_local_trace_kprobe()  are added to created and destroy these
local trace_kprobe.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Cc: <daniel@iogearbox.net>
Cc: <davem@davemloft.net>
Cc: <kernel-team@fb.com>
Cc: <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171206224518.3598254-6-songliubraving@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Song Liu 2017-12-06 14:45:15 -08:00 committed by Ingo Molnar
parent 0d8dd67be0
commit e12f03d703
5 changed files with 250 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/trace_events.h
View File

@ -533,6 +533,10 @@ extern int perf_trace_init(struct perf_event *event);
extern void perf_trace_destroy(struct perf_event *event);
extern int perf_trace_add(struct perf_event *event, int flags);
extern void perf_trace_del(struct perf_event *event, int flags);
#ifdef CONFIG_KPROBE_EVENTS
extern int perf_kprobe_init(struct perf_event *event, bool is_retprobe);
extern void perf_kprobe_destroy(struct perf_event *event);
#endif
extern int ftrace_profile_set_filter(struct perf_event *event, int event_id,
char *filter_str);
extern void ftrace_profile_free_filter(struct perf_event *event);

142
kernel/events/core.c
View File

@ -7992,9 +7992,77 @@ static struct pmu perf_tracepoint = {
.read = perf_swevent_read,
};
#ifdef CONFIG_KPROBE_EVENTS
/*
* Flags in config, used by dynamic PMU kprobe and uprobe
* The flags should match following PMU_FORMAT_ATTR().
*
* PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
* if not set, create kprobe/uprobe
*/
enum perf_probe_config {
PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0, /* [k,u]retprobe */
};
PMU_FORMAT_ATTR(retprobe, "config:0");
static struct attribute *probe_attrs[] = {
&format_attr_retprobe.attr,
NULL,
};
static struct attribute_group probe_format_group = {
.name = "format",
.attrs = probe_attrs,
};
static const struct attribute_group *probe_attr_groups[] = {
&probe_format_group,
NULL,
};
static int perf_kprobe_event_init(struct perf_event *event);
static struct pmu perf_kprobe = {
.task_ctx_nr = perf_sw_context,
.event_init = perf_kprobe_event_init,
.add = perf_trace_add,
.del = perf_trace_del,
.start = perf_swevent_start,
.stop = perf_swevent_stop,
.read = perf_swevent_read,
.attr_groups = probe_attr_groups,
};
static int perf_kprobe_event_init(struct perf_event *event)
{
int err;
bool is_retprobe;
if (event->attr.type != perf_kprobe.type)
return -ENOENT;
/*
* no branch sampling for probe events
*/
if (has_branch_stack(event))
return -EOPNOTSUPP;
is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
err = perf_kprobe_init(event, is_retprobe);
if (err)
return err;
event->destroy = perf_kprobe_destroy;
return 0;
}
#endif /* CONFIG_KPROBE_EVENTS */
static inline void perf_tp_register(void)
{
perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
#ifdef CONFIG_KPROBE_EVENTS
perf_pmu_register(&perf_kprobe, "kprobe", -1);
#endif
}
static void perf_event_free_filter(struct perf_event *event)
@ -8071,13 +8139,28 @@ static void perf_event_free_bpf_handler(struct perf_event *event)
}
#endif
/*
* returns true if the event is a tracepoint, or a kprobe/upprobe created
* with perf_event_open()
*/
static inline bool perf_event_is_tracing(struct perf_event *event)
{
if (event->pmu == &perf_tracepoint)
return true;
#ifdef CONFIG_KPROBE_EVENTS
if (event->pmu == &perf_kprobe)
return true;
#endif
return false;
}
static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
{
bool is_kprobe, is_tracepoint, is_syscall_tp;
struct bpf_prog *prog;
int ret;
if (event->attr.type != PERF_TYPE_TRACEPOINT)
if (!perf_event_is_tracing(event))
return perf_event_set_bpf_handler(event, prog_fd);
is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;
@ -8116,7 +8199,7 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
static void perf_event_free_bpf_prog(struct perf_event *event)
{
if (event->attr.type != PERF_TYPE_TRACEPOINT) {
if (!perf_event_is_tracing(event)) {
perf_event_free_bpf_handler(event);
return;
}
@ -8535,47 +8618,36 @@ fail_clear_files:
return ret;
}
static int
perf_tracepoint_set_filter(struct perf_event *event, char *filter_str)
{
struct perf_event_context *ctx = event->ctx;
int ret;
/*
* Beware, here be dragons!!
*
* the tracepoint muck will deadlock against ctx->mutex, but the tracepoint
* stuff does not actually need it. So temporarily drop ctx->mutex. As per
* perf_event_ctx_lock() we already have a reference on ctx.
*
* This can result in event getting moved to a different ctx, but that
* does not affect the tracepoint state.
*/
mutex_unlock(&ctx->mutex);
ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
mutex_lock(&ctx->mutex);
return ret;
}
static int perf_event_set_filter(struct perf_event *event, void __user *arg)
{
char *filter_str;
int ret = -EINVAL;
if ((event->attr.type != PERF_TYPE_TRACEPOINT ||
!IS_ENABLED(CONFIG_EVENT_TRACING)) &&
!has_addr_filter(event))
return -EINVAL;
char *filter_str;
filter_str = strndup_user(arg, PAGE_SIZE);
if (IS_ERR(filter_str))
return PTR_ERR(filter_str);
if (IS_ENABLED(CONFIG_EVENT_TRACING) &&
event->attr.type == PERF_TYPE_TRACEPOINT)
ret = perf_tracepoint_set_filter(event, filter_str);
else if (has_addr_filter(event))
#ifdef CONFIG_EVENT_TRACING
if (perf_event_is_tracing(event)) {
struct perf_event_context *ctx = event->ctx;
/*
* Beware, here be dragons!!
*
* the tracepoint muck will deadlock against ctx->mutex, but
* the tracepoint stuff does not actually need it. So
* temporarily drop ctx->mutex. As per perf_event_ctx_lock() we
* already have a reference on ctx.
*
* This can result in event getting moved to a different ctx,
* but that does not affect the tracepoint state.
*/
mutex_unlock(&ctx->mutex);
ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
mutex_lock(&ctx->mutex);
} else
#endif
if (has_addr_filter(event))
ret = perf_event_set_addr_filter(event, filter_str);
kfree(filter_str);

49
kernel/trace/trace_event_perf.c
View File

@ -8,6 +8,7 @@
#include <linux/module.h>
#include <linux/kprobes.h>
#include "trace.h"
#include "trace_probe.h"
static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
@ -237,6 +238,54 @@ void perf_trace_destroy(struct perf_event *p_event)
mutex_unlock(&event_mutex);
}
#ifdef CONFIG_KPROBE_EVENTS
int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
{
int ret;
char *func = NULL;
struct trace_event_call *tp_event;
if (p_event->attr.kprobe_func) {
func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
if (!func)
return -ENOMEM;
ret = strncpy_from_user(
func, u64_to_user_ptr(p_event->attr.kprobe_func),
KSYM_NAME_LEN);
if (ret < 0)
goto out;
if (func[0] == '\0') {
kfree(func);
func = NULL;
}
}
tp_event = create_local_trace_kprobe(
func, (void *)(unsigned long)(p_event->attr.kprobe_addr),
p_event->attr.probe_offset, is_retprobe);
if (IS_ERR(tp_event)) {
ret = PTR_ERR(tp_event);
goto out;
}
ret = perf_trace_event_init(tp_event, p_event);
if (ret)
destroy_local_trace_kprobe(tp_event);
out:
kfree(func);
return ret;
}
void perf_kprobe_destroy(struct perf_event *p_event)
{
perf_trace_event_close(p_event);
perf_trace_event_unreg(p_event);
destroy_local_trace_kprobe(p_event->tp_event);
}
#endif /* CONFIG_KPROBE_EVENTS */
int perf_trace_add(struct perf_event *p_event, int flags)
{
struct trace_event_call *tp_event = p_event->tp_event;

91
kernel/trace/trace_kprobe.c
View File

@ -438,6 +438,14 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
disable_kprobe(&tk->rp.kp);
wait = 1;
}
/*
* if tk is not added to any list, it must be a local trace_kprobe
* created with perf_event_open. We don't need to wait for these
* trace_kprobes
*/
if (list_empty(&tk->list))
wait = 0;
out:
if (wait) {
/*
@ -1313,12 +1321,9 @@ static struct trace_event_functions kprobe_funcs = {
.trace = print_kprobe_event
};
static int register_kprobe_event(struct trace_kprobe *tk)
static inline void init_trace_event_call(struct trace_kprobe *tk,
struct trace_event_call *call)
{
struct trace_event_call *call = &tk->tp.call;
int ret;
/* Initialize trace_event_call */
INIT_LIST_HEAD(&call->class->fields);
if (trace_kprobe_is_return(tk)) {
call->event.funcs = &kretprobe_funcs;
@ -1327,6 +1332,19 @@ static int register_kprobe_event(struct trace_kprobe *tk)
call->event.funcs = &kprobe_funcs;
call->class->define_fields = kprobe_event_define_fields;
}
call->flags = TRACE_EVENT_FL_KPROBE;
call->class->reg = kprobe_register;
call->data = tk;
}
static int register_kprobe_event(struct trace_kprobe *tk)
{
struct trace_event_call *call = &tk->tp.call;
int ret = 0;
init_trace_event_call(tk, call);
if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
return -ENOMEM;
ret = register_trace_event(&call->event);
@ -1334,9 +1352,6 @@ static int register_kprobe_event(struct trace_kprobe *tk)
kfree(call->print_fmt);
return -ENODEV;
}
call->flags = TRACE_EVENT_FL_KPROBE;
call->class->reg = kprobe_register;
call->data = tk;
ret = trace_add_event_call(call);
if (ret) {
pr_info("Failed to register kprobe event: %s\n",
@ -1358,6 +1373,66 @@ static int unregister_kprobe_event(struct trace_kprobe *tk)
return ret;
}
#ifdef CONFIG_PERF_EVENTS
/* create a trace_kprobe, but don't add it to global lists */
struct trace_event_call *
create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
bool is_return)
{
struct trace_kprobe *tk;
int ret;
char *event;
/*
* local trace_kprobes are not added to probe_list, so they are never
* searched in find_trace_kprobe(). Therefore, there is no concern of
* duplicated name here.
*/
event = func ? func : "DUMMY_EVENT";
tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
offs, 0 /* maxactive */, 0 /* nargs */,
is_return);
if (IS_ERR(tk)) {
pr_info("Failed to allocate trace_probe.(%d)\n",
(int)PTR_ERR(tk));
return ERR_CAST(tk);
}
init_trace_event_call(tk, &tk->tp.call);
if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
ret = -ENOMEM;
goto error;
}
ret = __register_trace_kprobe(tk);
if (ret < 0)
goto error;
return &tk->tp.call;
error:
free_trace_kprobe(tk);
return ERR_PTR(ret);
}
void destroy_local_trace_kprobe(struct trace_event_call *event_call)
{
struct trace_kprobe *tk;
tk = container_of(event_call, struct trace_kprobe, tp.call);
if (trace_probe_is_enabled(&tk->tp)) {
WARN_ON(1);
return;
}
__unregister_trace_kprobe(tk);
free_trace_kprobe(tk);
}
#endif /* CONFIG_PERF_EVENTS */
/* Make a tracefs interface for controlling probe points */
static __init int init_kprobe_trace(void)
{

7
kernel/trace/trace_probe.h
View File

@ -404,3 +404,10 @@ store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
}
extern int set_print_fmt(struct trace_probe *tp, bool is_return);
#ifdef CONFIG_PERF_EVENTS
extern struct trace_event_call *
create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
bool is_return);
extern void destroy_local_trace_kprobe(struct trace_event_call *event_call);
#endif