diff mbox series

[PATCHv3,bpf-next,2/9] bpf: Add missed value to kprobe_multi link info

Message ID 20230920213145.1941596-3-jolsa@kernel.org (mailing list archive)
State Accepted
Commit e2b2cd592adbd303bcc02451d32fedd511000fb0
Delegated to: BPF
Headers show
Series bpf: Add missed stats for kprobes | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3092 this patch: 3092
netdev/cc_maintainers warning 6 maintainers not CCed: rostedt@goodmis.org martin.lau@linux.dev kpsingh@kernel.org yonghong.song@linux.dev mhiramat@kernel.org linux-trace-kernel@vger.kernel.org
netdev/build_clang success Errors and warnings before: 1531 this patch: 1531
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 3185 this patch: 3185
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 21 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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Commit Message

Jiri Olsa Sept. 20, 2023, 9:31 p.m. UTC 
Add missed value to kprobe_multi link info to hold the stats of missed
kprobe_multi probe.

The missed counter gets incremented when fprobe fails the recursion
check or there's no rethook available for return probe. In either
case the attached bpf program is not executed.

Acked-by: Hou Tao <houtao1@huawei.com>
Reviewed-and-tested-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/uapi/linux/bpf.h       | 1 +
 kernel/trace/bpf_trace.c       | 1 +
 tools/include/uapi/linux/bpf.h | 1 +
 3 files changed, 3 insertions(+)

Comments

Song Liu Sept. 21, 2023, 6:52 p.m. UTC | #1 
On Wed, Sep 20, 2023 at 2:32 PM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Add missed value to kprobe_multi link info to hold the stats of missed
> kprobe_multi probe.
>
> The missed counter gets incremented when fprobe fails the recursion
> check or there's no rethook available for return probe. In either
> case the attached bpf program is not executed.
>
> Acked-by: Hou Tao <houtao1@huawei.com>
> Reviewed-and-tested-by: Song Liu <song@kernel.org>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  include/uapi/linux/bpf.h       | 1 +
>  kernel/trace/bpf_trace.c       | 1 +
>  tools/include/uapi/linux/bpf.h | 1 +
>  3 files changed, 3 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 73b155e52204..e5216420ec73 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -6530,6 +6530,7 @@ struct bpf_link_info {
>                         __aligned_u64 addrs;
>                         __u32 count; /* in/out: kprobe_multi function count */
>                         __u32 flags;
> +                       __u64 missed;

This does not make bpf_link_info bigger. So if we use newer user space
on older kernel, the user space cannot tell whether missed == 0 or the
kernel doesn't support "missed". Right?

Thanks,
Song

>                 } kprobe_multi;
>                 struct {
>                         __u32 type; /* enum bpf_perf_event_type */
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 279a3d370812..aec52938c703 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2614,6 +2614,7 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
>         kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
>         info->kprobe_multi.count = kmulti_link->cnt;
>         info->kprobe_multi.flags = kmulti_link->flags;
> +       info->kprobe_multi.missed = kmulti_link->fp.nmissed;
>
>         if (!uaddrs)
>                 return 0;
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 73b155e52204..e5216420ec73 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -6530,6 +6530,7 @@ struct bpf_link_info {
>                         __aligned_u64 addrs;
>                         __u32 count; /* in/out: kprobe_multi function count */
>                         __u32 flags;
> +                       __u64 missed;
>                 } kprobe_multi;
>                 struct {
>                         __u32 type; /* enum bpf_perf_event_type */
> --
> 2.41.0
>
>
Jiri Olsa Sept. 23, 2023, 8:21 a.m. UTC | #2 
On Thu, Sep 21, 2023 at 11:52:16AM -0700, Song Liu wrote:
> On Wed, Sep 20, 2023 at 2:32 PM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Add missed value to kprobe_multi link info to hold the stats of missed
> > kprobe_multi probe.
> >
> > The missed counter gets incremented when fprobe fails the recursion
> > check or there's no rethook available for return probe. In either
> > case the attached bpf program is not executed.
> >
> > Acked-by: Hou Tao <houtao1@huawei.com>
> > Reviewed-and-tested-by: Song Liu <song@kernel.org>
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> >  include/uapi/linux/bpf.h       | 1 +
> >  kernel/trace/bpf_trace.c       | 1 +
> >  tools/include/uapi/linux/bpf.h | 1 +
> >  3 files changed, 3 insertions(+)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 73b155e52204..e5216420ec73 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -6530,6 +6530,7 @@ struct bpf_link_info {
> >                         __aligned_u64 addrs;
> >                         __u32 count; /* in/out: kprobe_multi function count */
> >                         __u32 flags;
> > +                       __u64 missed;
> 
> This does not make bpf_link_info bigger. So if we use newer user space
> on older kernel, the user space cannot tell whether missed == 0 or the
> kernel doesn't support "missed". Right?

hum, I think that's right.. but I think that would be the case
even if it did make bpf_link_info bigger, because we'd need to
pass zeroed value in 'missed' field and it'd not be changed by
older kernel

user space could maybe check if there's 'missed field in
bpf_link_info.perf_event.kprobe.missed ?

jirka

> 
> Thanks,
> Song
> 
> >                 } kprobe_multi;
> >                 struct {
> >                         __u32 type; /* enum bpf_perf_event_type */
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 279a3d370812..aec52938c703 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -2614,6 +2614,7 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
> >         kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
> >         info->kprobe_multi.count = kmulti_link->cnt;
> >         info->kprobe_multi.flags = kmulti_link->flags;
> > +       info->kprobe_multi.missed = kmulti_link->fp.nmissed;
> >
> >         if (!uaddrs)
> >                 return 0;
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index 73b155e52204..e5216420ec73 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -6530,6 +6530,7 @@ struct bpf_link_info {
> >                         __aligned_u64 addrs;
> >                         __u32 count; /* in/out: kprobe_multi function count */
> >                         __u32 flags;
> > +                       __u64 missed;
> >                 } kprobe_multi;
> >                 struct {
> >                         __u32 type; /* enum bpf_perf_event_type */
> > --
> > 2.41.0
> >
> >
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 73b155e52204..e5216420ec73 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6530,6 +6530,7 @@  struct bpf_link_info {
 			__aligned_u64 addrs;
 			__u32 count; /* in/out: kprobe_multi function count */
 			__u32 flags;
+			__u64 missed;
 		} kprobe_multi;
 		struct {
 			__u32 type; /* enum bpf_perf_event_type */
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 279a3d370812..aec52938c703 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2614,6 +2614,7 @@  static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 	kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
 	info->kprobe_multi.count = kmulti_link->cnt;
 	info->kprobe_multi.flags = kmulti_link->flags;
+	info->kprobe_multi.missed = kmulti_link->fp.nmissed;
 
 	if (!uaddrs)
 		return 0;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 73b155e52204..e5216420ec73 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6530,6 +6530,7 @@  struct bpf_link_info {
 			__aligned_u64 addrs;
 			__u32 count; /* in/out: kprobe_multi function count */
 			__u32 flags;
+			__u64 missed;
 		} kprobe_multi;
 		struct {
 			__u32 type; /* enum bpf_perf_event_type */