Messages in this thread | | | Date | Tue, 8 Oct 2019 08:34:20 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] perf/kprobe: maxactive for fd-based kprobe (pmu perf_kprobe) |
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Hi,
On Mon, 7 Oct 2019 15:31:11 -0700 Song Liu <songliubraving@fb.com> wrote:
> Enable specifying maxactive for fd based kretprobe. This will be useful > for tracing tools like bcc and bpftrace. [1] discussed the need of this > in bpftrace. Use highest highest 12 bit (bit 52-63) to allow maximal > maxactive of 4095. > > [1] https://github.com/iovisor/bpftrace/issues/835
From the view point of trace_kprobe, this looks good to me.
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Thank you,
> > Signed-off-by: Song Liu <songliubraving@fb.com> > Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> > Cc: Masami Hiramatsu <mhiramat@kernel.org> > Cc: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > include/linux/trace_events.h | 3 ++- > kernel/events/core.c | 20 ++++++++++++++++---- > kernel/trace/trace_event_perf.c | 5 +++-- > kernel/trace/trace_kprobe.c | 4 ++-- > kernel/trace/trace_probe.h | 2 +- > 5 files changed, 24 insertions(+), 10 deletions(-) > > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h > index 30a8cdcfd4a4..706d515d2b5e 100644 > --- a/include/linux/trace_events.h > +++ b/include/linux/trace_events.h > @@ -581,7 +581,8 @@ 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 int perf_kprobe_init(struct perf_event *event, bool is_retprobe, > + int max_active); > extern void perf_kprobe_destroy(struct perf_event *event); > extern int bpf_get_kprobe_info(const struct perf_event *event, > u32 *fd_type, const char **symbol, > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 3f0cb82e4fbc..f1b16cda5a9b 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -8772,24 +8772,34 @@ static struct pmu perf_tracepoint = { > * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe > * if not set, create kprobe/uprobe > * > - * The following values specify a reference counter (or semaphore in the > - * terminology of tools like dtrace, systemtap, etc.) Userspace Statically > - * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset. > + * PERF_UPROBE_REF_CTR_OFFSET_* specify a reference counter (or semaphore > + * in the terminology of tools like dtrace, systemtap, etc.) Userspace > + * Statically Defined Tracepoints (USDT). Currently, we use 40 bit for the > + * offset. > * > * PERF_UPROBE_REF_CTR_OFFSET_BITS # of bits in config as th offset > * PERF_UPROBE_REF_CTR_OFFSET_SHIFT # of bits to shift left > + * > + * PERF_KPROBE_MAX_ACTIVE_* defines max_active for kretprobe. > + * KRETPROBE_MAXACTIVE_MAX is 4096. We allow 4095 here to save a bit. > */ > enum perf_probe_config { > PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0, /* [k,u]retprobe */ > PERF_UPROBE_REF_CTR_OFFSET_BITS = 32, > PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS, > + PERF_KPROBE_MAX_ACTIVE_BITS = 12, > + PERF_KPROBE_MAX_ACTIVE_SHIFT = 64 - PERF_KPROBE_MAX_ACTIVE_BITS, > }; > > PMU_FORMAT_ATTR(retprobe, "config:0"); > #endif > > #ifdef CONFIG_KPROBE_EVENTS > +/* KRETPROBE_MAXACTIVE_MAX is 4096, only allow 4095 here to save a bit */ > +PMU_FORMAT_ATTR(max_active, "config:52-63"); > + > static struct attribute *kprobe_attrs[] = { > + &format_attr_max_active.attr, > &format_attr_retprobe.attr, > NULL, > }; > @@ -8820,6 +8830,7 @@ static int perf_kprobe_event_init(struct perf_event *event) > { > int err; > bool is_retprobe; > + int max_active; > > if (event->attr.type != perf_kprobe.type) > return -ENOENT; > @@ -8834,7 +8845,8 @@ static int perf_kprobe_event_init(struct perf_event *event) > return -EOPNOTSUPP; > > is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE; > - err = perf_kprobe_init(event, is_retprobe); > + max_active = event->attr.config >> PERF_KPROBE_MAX_ACTIVE_SHIFT; > + err = perf_kprobe_init(event, is_retprobe, max_active); > if (err) > return err; > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c > index 0892e38ed6fb..da6744ac7bc9 100644 > --- a/kernel/trace/trace_event_perf.c > +++ b/kernel/trace/trace_event_perf.c > @@ -240,7 +240,8 @@ void perf_trace_destroy(struct perf_event *p_event) > } > > #ifdef CONFIG_KPROBE_EVENTS > -int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe) > +int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe, > + int max_active) > { > int ret; > char *func = NULL; > @@ -266,7 +267,7 @@ int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe) > > tp_event = create_local_trace_kprobe( > func, (void *)(unsigned long)(p_event->attr.kprobe_addr), > - p_event->attr.probe_offset, is_retprobe); > + p_event->attr.probe_offset, is_retprobe, max_active); > if (IS_ERR(tp_event)) { > ret = PTR_ERR(tp_event); > goto out; > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 324ffbea3556..12088a76e7da 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -1556,7 +1556,7 @@ static int unregister_kprobe_event(struct trace_kprobe *tk) > /* 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) > + bool is_return, int max_active) > { > struct trace_kprobe *tk; > int ret; > @@ -1570,7 +1570,7 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs, > event = func ? func : "DUMMY_EVENT"; > > tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func, > - offs, 0 /* maxactive */, 0 /* nargs */, > + offs, max_active, 0 /* nargs */, > is_return); > > if (IS_ERR(tk)) { > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h > index 4ee703728aec..b4368c652749 100644 > --- a/kernel/trace/trace_probe.h > +++ b/kernel/trace/trace_probe.h > @@ -373,7 +373,7 @@ extern int traceprobe_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); > + bool is_return, int max_active); > extern void destroy_local_trace_kprobe(struct trace_event_call *event_call); > > extern struct trace_event_call * > -- > 2.17.1 >
-- Masami Hiramatsu <mhiramat@kernel.org>
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