Messages in this thread | | | Date | Fri, 13 Nov 2020 13:29:35 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH 03/24] perf: Add build id data in mmap2 event |
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Hi Jiri,
On Mon, Nov 09, 2020 at 10:53:54PM +0100, Jiri Olsa wrote: > Adding support to carry build id data in mmap2 event. > > The build id data replaces maj/min/ino/ino_generation > fields, whichc are also used to identify map's binary, > so it's ok to replace them with build id data: > > union { > struct { > u32 maj; > u32 min; > u64 ino; > u64 ino_generation; > }; > struct { > u8 build_id[20]; > u8 build_id_size; > u8 __reserved_1; > u16 __reserved_2; > }; > }; > > Replaced maj/min/ino/ino_generation fields give us size > of 24 bytes. We use 20 bytes for build id data, 1 byte > for size and rest is unused. > > There's new misc bit for mmap2 to signal there's build > id data in it: > > #define PERF_RECORD_MISC_BUILD_ID (1 << 14) > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- [SNIP] > diff --git a/kernel/events/core.c b/kernel/events/core.c > index da467e1dd49a..808473b6ce85 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -51,6 +51,7 @@ > #include <linux/proc_ns.h> > #include <linux/mount.h> > #include <linux/min_heap.h> > +#include <linux/buildid.h> > > #include "internal.h" > > @@ -395,6 +396,7 @@ static atomic_t nr_ksymbol_events __read_mostly; > static atomic_t nr_bpf_events __read_mostly; > static atomic_t nr_cgroup_events __read_mostly; > static atomic_t nr_text_poke_events __read_mostly; > +static atomic_t nr_build_id_events __read_mostly; > > static LIST_HEAD(pmus); > static DEFINE_MUTEX(pmus_lock); > @@ -4672,6 +4674,8 @@ static void unaccount_event(struct perf_event *event) > dec = true; > if (event->attr.mmap || event->attr.mmap_data) > atomic_dec(&nr_mmap_events); > + if (event->attr.build_id) > + atomic_dec(&nr_build_id_events); > if (event->attr.comm) > atomic_dec(&nr_comm_events); > if (event->attr.namespaces) > @@ -7942,6 +7946,8 @@ struct perf_mmap_event { > u64 ino; > u64 ino_generation; > u32 prot, flags; > + u8 build_id[BUILD_ID_SIZE]; > + u32 build_id_size; > > struct { > struct perf_event_header header; > @@ -7997,13 +8003,23 @@ static void perf_event_mmap_output(struct perf_event *event, > mmap_event->event_id.pid = perf_event_pid(event, current); > mmap_event->event_id.tid = perf_event_tid(event, current); > > + if (event->attr.mmap2 && event->attr.build_id) > + mmap_event->event_id.header.misc |= PERF_RECORD_MISC_BUILD_ID; > + > perf_output_put(&handle, mmap_event->event_id); > > if (event->attr.mmap2) { > - perf_output_put(&handle, mmap_event->maj); > - perf_output_put(&handle, mmap_event->min); > - perf_output_put(&handle, mmap_event->ino); > - perf_output_put(&handle, mmap_event->ino_generation); > + if (event->attr.build_id) { > + u8 size[4] = { (u8) mmap_event->build_id_size, 0, 0, 0 }; > + > + __output_copy(&handle, mmap_event->build_id, BUILD_ID_SIZE); > + __output_copy(&handle, size, 4); > + } else { > + perf_output_put(&handle, mmap_event->maj); > + perf_output_put(&handle, mmap_event->min); > + perf_output_put(&handle, mmap_event->ino); > + perf_output_put(&handle, mmap_event->ino_generation); > + } > perf_output_put(&handle, mmap_event->prot); > perf_output_put(&handle, mmap_event->flags); > } > @@ -8132,6 +8148,11 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) > > mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size; > > + if (atomic_read(&nr_build_id_events)) { > + build_id_parse_size(vma, mmap_event->build_id, > + &mmap_event->build_id_size);
This can fail, right? Then we need to fallback to use dev/ino..
Thanks, Namhyung
> + } > + > perf_iterate_sb(perf_event_mmap_output, > mmap_event, > NULL); > @@ -11069,6 +11090,8 @@ static void account_event(struct perf_event *event) > inc = true; > if (event->attr.mmap || event->attr.mmap_data) > atomic_inc(&nr_mmap_events); > + if (event->attr.build_id) > + atomic_inc(&nr_build_id_events); > if (event->attr.comm) > atomic_inc(&nr_comm_events); > if (event->attr.namespaces) > -- > 2.26.2 >
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