Commit 88a16a13 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

perf: Add build id data in mmap2 event 



Adding support to carry build id data in mmap2 event.

The build id data replaces maj/min/ino/ino_generation
fields, which 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_size;
                  u8        __reserved_1;
                  u16       __reserved_2;
                  u8        build_id[20];
          };
  };

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_MMAP_BUILD_ID   (1 << 14)

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210114134044.1418404-4-jolsa@kernel.org
parent 921f88fc

include/uapi/linux/perf_event.h

+37 −5
Original line number Diff line number Diff line
@@ -386,7 +386,8 @@ struct perf_event_attr { 
				aux_output     :  1, /* generate AUX records instead of events */

				cgroup         :  1, /* include cgroup events */

				text_poke      :  1, /* include text poke events */

				__reserved_1   : 30;

				build_id       :  1, /* use build id in mmap2 events */

				__reserved_1   : 29;



	union {

		__u32		wakeup_events;	  /* wakeup every n events */
@@ -659,6 +660,22 @@ struct perf_event_mmap_page { 
	__u64	aux_size;

};



/*

 * The current state of perf_event_header::misc bits usage:

 * ('|' used bit, '-' unused bit)

 *

 *  012         CDEF

 *  |||---------||||

 *

 *  Where:

 *    0-2     CPUMODE_MASK

 *

 *    C       PROC_MAP_PARSE_TIMEOUT

 *    D       MMAP_DATA / COMM_EXEC / FORK_EXEC / SWITCH_OUT

 *    E       MMAP_BUILD_ID / EXACT_IP / SCHED_OUT_PREEMPT

 *    F       (reserved)

 */



#define PERF_RECORD_MISC_CPUMODE_MASK		(7 << 0)

#define PERF_RECORD_MISC_CPUMODE_UNKNOWN	(0 << 0)

#define PERF_RECORD_MISC_KERNEL			(1 << 0)
@@ -690,6 +707,7 @@ struct perf_event_mmap_page { 
 *

 *   PERF_RECORD_MISC_EXACT_IP           - PERF_RECORD_SAMPLE of precise events

 *   PERF_RECORD_MISC_SWITCH_OUT_PREEMPT - PERF_RECORD_SWITCH* events

 *   PERF_RECORD_MISC_MMAP_BUILD_ID      - PERF_RECORD_MMAP2 event

 *

 *

 * PERF_RECORD_MISC_EXACT_IP:
@@ -699,9 +717,13 @@ struct perf_event_mmap_page { 
 *

 * PERF_RECORD_MISC_SWITCH_OUT_PREEMPT:

 *   Indicates that thread was preempted in TASK_RUNNING state.

 *

 * PERF_RECORD_MISC_MMAP_BUILD_ID:

 *   Indicates that mmap2 event carries build id data.

 */

#define PERF_RECORD_MISC_EXACT_IP		(1 << 14)

#define PERF_RECORD_MISC_SWITCH_OUT_PREEMPT	(1 << 14)

#define PERF_RECORD_MISC_MMAP_BUILD_ID		(1 << 14)

/*

 * Reserve the last bit to indicate some extended misc field

 */
@@ -915,10 +937,20 @@ enum perf_event_type { 
	 *	u64				addr;

	 *	u64				len;

	 *	u64				pgoff;

	 *	union {

	 *		struct {

	 *			u32		maj;

	 *			u32		min;

	 *			u64		ino;

	 *			u64		ino_generation;

	 *		};

	 *		struct {

	 *			u8		build_id_size;

	 *			u8		__reserved_1;

	 *			u16		__reserved_2;

	 *			u8		build_id[20];

	 *		};

	 *	};

	 *	u32				prot, flags;

	 *	char				filename[];

	 * 	struct sample_id		sample_id;

kernel/events/core.c

+28 −4
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
#include <linux/min_heap.h>

#include <linux/highmem.h>

#include <linux/pgtable.h>

#include <linux/buildid.h>



#include "internal.h"
@@ -397,6 +398,7 @@ 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);
@@ -4673,6 +4675,8 @@ 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)
@@ -8046,6 +8050,8 @@ struct perf_mmap_event { 
	u64			ino;

	u64			ino_generation;

	u32			prot, flags;

	u8			build_id[BUILD_ID_SIZE_MAX];

	u32			build_id_size;



	struct {

		struct perf_event_header	header;
@@ -8077,6 +8083,7 @@ static void perf_event_mmap_output(struct perf_event *event, 
	struct perf_sample_data sample;

	int size = mmap_event->event_id.header.size;

	u32 type = mmap_event->event_id.header.type;

	bool use_build_id;

	int ret;



	if (!perf_event_mmap_match(event, data))
@@ -8101,13 +8108,25 @@ 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);



	use_build_id = event->attr.build_id && mmap_event->build_id_size;



	if (event->attr.mmap2 && use_build_id)

		mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;



	perf_output_put(&handle, mmap_event->event_id);



	if (event->attr.mmap2) {

		if (use_build_id) {

			u8 size[4] = { (u8) mmap_event->build_id_size, 0, 0, 0 };



			__output_copy(&handle, size, 4);

			__output_copy(&handle, mmap_event->build_id, BUILD_ID_SIZE_MAX);

		} 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);

	}
@@ -8236,6 +8255,9 @@ 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(vma, mmap_event->build_id, &mmap_event->build_id_size);



	perf_iterate_sb(perf_event_mmap_output,

		       mmap_event,

		       NULL);
@@ -11172,6 +11194,8 @@ 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)