Commit 3090ffb5 authored by Stephane Eranian's avatar Stephane Eranian Committed by Arnaldo Carvalho de Melo
Browse files

perf: Disable PERF_RECORD_MMAP2 support 



For now, we disable the extended MMAP record support (MMAP2).

We have identified cases where it would not report the correct mapping
information, clone(VM_CLONE) but with separate pids.  We will revisit
the support once we find a solution for this case.

The patch changes the kernel to return EINVAL if attr->mmap2 is set. The
patch also modifies the perf tool to use regular PERF_RECORD_MMAP for
synthetic events and it also prevents the tool from requesting
attr->mmap2 mode because the kernel would reject it.

The support will be revisited once the kenrel interface is updated.

In V2, we reduce the patch to the strict minimum.

In V3, we avoid calling perf_event_open() with mmap2 set because we know
it will fail and require fallback retry.

Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131017173215.GA8820@quad


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 3b16ff89

kernel/events/core.c

+4 −0
Original line number Diff line number Diff line
@@ -6767,6 +6767,10 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, 
	if (ret)

		return -EFAULT;



	/* disabled for now */

	if (attr->mmap2)

		return -EINVAL;



	if (attr->__reserved_1)

		return -EINVAL;

tools/perf/util/event.c

+13 −17
Original line number Diff line number Diff line
@@ -187,7 +187,7 @@ static int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
		return -1;

	}



	event->header.type = PERF_RECORD_MMAP2;

	event->header.type = PERF_RECORD_MMAP;

	/*

	 * Just like the kernel, see __perf_event_mmap in kernel/perf_event.c

	 */
@@ -198,7 +198,6 @@ static int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
		char prot[5];

		char execname[PATH_MAX];

		char anonstr[] = "//anon";

		unsigned int ino;

		size_t size;

		ssize_t n;
@@ -209,13 +208,10 @@ static int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
		strcpy(execname, "");



		/* 00400000-0040c000 r-xp 00000000 fd:01 41038  /bin/cat */

		n = sscanf(bf, "%"PRIx64"-%"PRIx64" %s %"PRIx64" %x:%x %u %s\n",

		       &event->mmap2.start, &event->mmap2.len, prot,

		       &event->mmap2.pgoff, &event->mmap2.maj,

		       &event->mmap2.min,

		       &ino, execname);



		event->mmap2.ino = (u64)ino;

		n = sscanf(bf, "%"PRIx64"-%"PRIx64" %s %"PRIx64" %*x:%*x %*u %s\n",

		       &event->mmap.start, &event->mmap.len, prot,

		       &event->mmap.pgoff,

		       execname);



		if (n != 8)

			continue;
@@ -227,15 +223,15 @@ static int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
			strcpy(execname, anonstr);



		size = strlen(execname) + 1;

		memcpy(event->mmap2.filename, execname, size);

		memcpy(event->mmap.filename, execname, size);

		size = PERF_ALIGN(size, sizeof(u64));

		event->mmap2.len -= event->mmap.start;

		event->mmap2.header.size = (sizeof(event->mmap2) -

					(sizeof(event->mmap2.filename) - size));

		memset(event->mmap2.filename + size, 0, machine->id_hdr_size);

		event->mmap2.header.size += machine->id_hdr_size;

		event->mmap2.pid = tgid;

		event->mmap2.tid = pid;

		event->mmap.len -= event->mmap.start;

		event->mmap.header.size = (sizeof(event->mmap) -

					(sizeof(event->mmap.filename) - size));

		memset(event->mmap.filename + size, 0, machine->id_hdr_size);

		event->mmap.header.size += machine->id_hdr_size;

		event->mmap.pid = tgid;

		event->mmap.tid = pid;



		if (process(tool, event, &synth_sample, machine) != 0) {

			rc = -1;

tools/perf/util/evsel.c

+0 −1
Original line number Diff line number Diff line
@@ -678,7 +678,6 @@ void perf_evsel__config(struct perf_evsel *evsel, 
		attr->sample_type	|= PERF_SAMPLE_WEIGHT;



	attr->mmap  = track;

	attr->mmap2 = track && !perf_missing_features.mmap2;

	attr->comm  = track;



	/*

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