perf/core: Implement the 'perf_kprobe' PMU
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
Ingo Molnar
parent
0d8dd67be0
commit
e12f03d703
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@ -533,6 +533,10 @@ extern int perf_trace_init(struct perf_event *event);
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extern void perf_trace_destroy(struct perf_event *event);
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extern int perf_trace_add(struct perf_event *event, int flags);
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extern void perf_trace_del(struct perf_event *event, int flags);
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#ifdef CONFIG_KPROBE_EVENTS
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extern int perf_kprobe_init(struct perf_event *event, bool is_retprobe);
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extern void perf_kprobe_destroy(struct perf_event *event);
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#endif
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extern int ftrace_profile_set_filter(struct perf_event *event, int event_id,
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char *filter_str);
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extern void ftrace_profile_free_filter(struct perf_event *event);
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@ -7992,9 +7992,77 @@ static struct pmu perf_tracepoint = {
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.read = perf_swevent_read,
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};
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#ifdef CONFIG_KPROBE_EVENTS
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/*
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* Flags in config, used by dynamic PMU kprobe and uprobe
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* The flags should match following PMU_FORMAT_ATTR().
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*
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* PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
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* if not set, create kprobe/uprobe
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*/
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enum perf_probe_config {
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PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0, /* [k,u]retprobe */
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};
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PMU_FORMAT_ATTR(retprobe, "config:0");
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static struct attribute *probe_attrs[] = {
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&format_attr_retprobe.attr,
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NULL,
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};
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static struct attribute_group probe_format_group = {
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.name = "format",
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.attrs = probe_attrs,
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};
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static const struct attribute_group *probe_attr_groups[] = {
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&probe_format_group,
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NULL,
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};
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static int perf_kprobe_event_init(struct perf_event *event);
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static struct pmu perf_kprobe = {
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.task_ctx_nr = perf_sw_context,
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.event_init = perf_kprobe_event_init,
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.add = perf_trace_add,
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.del = perf_trace_del,
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.start = perf_swevent_start,
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.stop = perf_swevent_stop,
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.read = perf_swevent_read,
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.attr_groups = probe_attr_groups,
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};
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static int perf_kprobe_event_init(struct perf_event *event)
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{
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int err;
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bool is_retprobe;
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if (event->attr.type != perf_kprobe.type)
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return -ENOENT;
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/*
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* no branch sampling for probe events
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*/
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if (has_branch_stack(event))
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return -EOPNOTSUPP;
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is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
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err = perf_kprobe_init(event, is_retprobe);
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if (err)
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return err;
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event->destroy = perf_kprobe_destroy;
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return 0;
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}
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#endif /* CONFIG_KPROBE_EVENTS */
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static inline void perf_tp_register(void)
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{
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perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
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#ifdef CONFIG_KPROBE_EVENTS
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perf_pmu_register(&perf_kprobe, "kprobe", -1);
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#endif
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}
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static void perf_event_free_filter(struct perf_event *event)
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@ -8071,13 +8139,28 @@ static void perf_event_free_bpf_handler(struct perf_event *event)
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}
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#endif
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/*
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* returns true if the event is a tracepoint, or a kprobe/upprobe created
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* with perf_event_open()
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*/
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static inline bool perf_event_is_tracing(struct perf_event *event)
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{
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if (event->pmu == &perf_tracepoint)
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return true;
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#ifdef CONFIG_KPROBE_EVENTS
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if (event->pmu == &perf_kprobe)
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return true;
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#endif
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return false;
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}
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static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
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{
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bool is_kprobe, is_tracepoint, is_syscall_tp;
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struct bpf_prog *prog;
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int ret;
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if (event->attr.type != PERF_TYPE_TRACEPOINT)
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if (!perf_event_is_tracing(event))
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return perf_event_set_bpf_handler(event, prog_fd);
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is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;
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@ -8116,7 +8199,7 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
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static void perf_event_free_bpf_prog(struct perf_event *event)
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{
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if (event->attr.type != PERF_TYPE_TRACEPOINT) {
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if (!perf_event_is_tracing(event)) {
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perf_event_free_bpf_handler(event);
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return;
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}
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@ -8535,47 +8618,36 @@ fail_clear_files:
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return ret;
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}
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static int
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perf_tracepoint_set_filter(struct perf_event *event, char *filter_str)
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{
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struct perf_event_context *ctx = event->ctx;
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int ret;
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/*
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* Beware, here be dragons!!
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*
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* the tracepoint muck will deadlock against ctx->mutex, but the tracepoint
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* stuff does not actually need it. So temporarily drop ctx->mutex. As per
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* perf_event_ctx_lock() we already have a reference on ctx.
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*
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* This can result in event getting moved to a different ctx, but that
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* does not affect the tracepoint state.
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*/
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mutex_unlock(&ctx->mutex);
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ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
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mutex_lock(&ctx->mutex);
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return ret;
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}
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static int perf_event_set_filter(struct perf_event *event, void __user *arg)
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{
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char *filter_str;
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int ret = -EINVAL;
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if ((event->attr.type != PERF_TYPE_TRACEPOINT ||
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!IS_ENABLED(CONFIG_EVENT_TRACING)) &&
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!has_addr_filter(event))
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return -EINVAL;
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char *filter_str;
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filter_str = strndup_user(arg, PAGE_SIZE);
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if (IS_ERR(filter_str))
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return PTR_ERR(filter_str);
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if (IS_ENABLED(CONFIG_EVENT_TRACING) &&
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event->attr.type == PERF_TYPE_TRACEPOINT)
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ret = perf_tracepoint_set_filter(event, filter_str);
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else if (has_addr_filter(event))
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#ifdef CONFIG_EVENT_TRACING
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if (perf_event_is_tracing(event)) {
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struct perf_event_context *ctx = event->ctx;
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/*
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* Beware, here be dragons!!
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*
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* the tracepoint muck will deadlock against ctx->mutex, but
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* the tracepoint stuff does not actually need it. So
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* temporarily drop ctx->mutex. As per perf_event_ctx_lock() we
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* already have a reference on ctx.
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*
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* This can result in event getting moved to a different ctx,
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* but that does not affect the tracepoint state.
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*/
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mutex_unlock(&ctx->mutex);
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ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
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mutex_lock(&ctx->mutex);
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} else
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#endif
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if (has_addr_filter(event))
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ret = perf_event_set_addr_filter(event, filter_str);
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kfree(filter_str);
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@ -8,6 +8,7 @@
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#include <linux/module.h>
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#include <linux/kprobes.h>
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#include "trace.h"
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#include "trace_probe.h"
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static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
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@ -237,6 +238,54 @@ void perf_trace_destroy(struct perf_event *p_event)
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mutex_unlock(&event_mutex);
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}
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#ifdef CONFIG_KPROBE_EVENTS
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int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
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{
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int ret;
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char *func = NULL;
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struct trace_event_call *tp_event;
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if (p_event->attr.kprobe_func) {
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func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
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if (!func)
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return -ENOMEM;
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ret = strncpy_from_user(
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func, u64_to_user_ptr(p_event->attr.kprobe_func),
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KSYM_NAME_LEN);
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if (ret < 0)
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goto out;
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if (func[0] == '\0') {
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kfree(func);
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func = NULL;
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}
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}
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tp_event = create_local_trace_kprobe(
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func, (void *)(unsigned long)(p_event->attr.kprobe_addr),
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p_event->attr.probe_offset, is_retprobe);
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if (IS_ERR(tp_event)) {
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ret = PTR_ERR(tp_event);
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goto out;
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}
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ret = perf_trace_event_init(tp_event, p_event);
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if (ret)
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destroy_local_trace_kprobe(tp_event);
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out:
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kfree(func);
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return ret;
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}
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void perf_kprobe_destroy(struct perf_event *p_event)
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{
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perf_trace_event_close(p_event);
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perf_trace_event_unreg(p_event);
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destroy_local_trace_kprobe(p_event->tp_event);
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}
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#endif /* CONFIG_KPROBE_EVENTS */
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int perf_trace_add(struct perf_event *p_event, int flags)
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{
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struct trace_event_call *tp_event = p_event->tp_event;
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@ -438,6 +438,14 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
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disable_kprobe(&tk->rp.kp);
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wait = 1;
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}
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/*
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* if tk is not added to any list, it must be a local trace_kprobe
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* created with perf_event_open. We don't need to wait for these
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* trace_kprobes
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*/
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if (list_empty(&tk->list))
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wait = 0;
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out:
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if (wait) {
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/*
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@ -1313,12 +1321,9 @@ static struct trace_event_functions kprobe_funcs = {
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.trace = print_kprobe_event
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};
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static int register_kprobe_event(struct trace_kprobe *tk)
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static inline void init_trace_event_call(struct trace_kprobe *tk,
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struct trace_event_call *call)
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{
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struct trace_event_call *call = &tk->tp.call;
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int ret;
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/* Initialize trace_event_call */
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INIT_LIST_HEAD(&call->class->fields);
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if (trace_kprobe_is_return(tk)) {
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call->event.funcs = &kretprobe_funcs;
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@ -1327,6 +1332,19 @@ static int register_kprobe_event(struct trace_kprobe *tk)
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call->event.funcs = &kprobe_funcs;
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call->class->define_fields = kprobe_event_define_fields;
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}
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call->flags = TRACE_EVENT_FL_KPROBE;
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call->class->reg = kprobe_register;
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call->data = tk;
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}
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static int register_kprobe_event(struct trace_kprobe *tk)
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{
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struct trace_event_call *call = &tk->tp.call;
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int ret = 0;
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init_trace_event_call(tk, call);
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if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
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return -ENOMEM;
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ret = register_trace_event(&call->event);
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@ -1334,9 +1352,6 @@ static int register_kprobe_event(struct trace_kprobe *tk)
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kfree(call->print_fmt);
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return -ENODEV;
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}
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call->flags = TRACE_EVENT_FL_KPROBE;
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call->class->reg = kprobe_register;
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call->data = tk;
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ret = trace_add_event_call(call);
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if (ret) {
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pr_info("Failed to register kprobe event: %s\n",
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@ -1358,6 +1373,66 @@ static int unregister_kprobe_event(struct trace_kprobe *tk)
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return ret;
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}
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#ifdef CONFIG_PERF_EVENTS
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/* create a trace_kprobe, but don't add it to global lists */
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struct trace_event_call *
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create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
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bool is_return)
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{
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struct trace_kprobe *tk;
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int ret;
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char *event;
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/*
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* local trace_kprobes are not added to probe_list, so they are never
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* searched in find_trace_kprobe(). Therefore, there is no concern of
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* duplicated name here.
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*/
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event = func ? func : "DUMMY_EVENT";
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tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
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offs, 0 /* maxactive */, 0 /* nargs */,
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is_return);
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if (IS_ERR(tk)) {
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pr_info("Failed to allocate trace_probe.(%d)\n",
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(int)PTR_ERR(tk));
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return ERR_CAST(tk);
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}
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init_trace_event_call(tk, &tk->tp.call);
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if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
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ret = -ENOMEM;
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goto error;
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}
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ret = __register_trace_kprobe(tk);
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if (ret < 0)
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goto error;
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return &tk->tp.call;
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error:
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free_trace_kprobe(tk);
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return ERR_PTR(ret);
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}
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void destroy_local_trace_kprobe(struct trace_event_call *event_call)
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{
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struct trace_kprobe *tk;
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tk = container_of(event_call, struct trace_kprobe, tp.call);
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if (trace_probe_is_enabled(&tk->tp)) {
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WARN_ON(1);
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return;
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}
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__unregister_trace_kprobe(tk);
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free_trace_kprobe(tk);
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}
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#endif /* CONFIG_PERF_EVENTS */
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/* Make a tracefs interface for controlling probe points */
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static __init int init_kprobe_trace(void)
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{
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@ -404,3 +404,10 @@ store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
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}
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extern int set_print_fmt(struct trace_probe *tp, bool is_return);
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#ifdef CONFIG_PERF_EVENTS
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extern struct trace_event_call *
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create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
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bool is_return);
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extern void destroy_local_trace_kprobe(struct trace_event_call *event_call);
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#endif
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