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[PATCH 10/12] perf evlist: Only open events on CPUs an evsel permits

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From: Mark Rutland <mark.rutland@arm.com>

In systems with heterogeneous CPU PMUs, it's possible for each evsel to
cover a distinct set of CPUs, and hence the cpu_map associated with each
evsel may have a distinct idx<->id mapping. Any of these may be distinct
from the evlist's cpu map.

Events can be tied to the same fd so long as they use the same per-cpu
ringbuffer (i.e. so long as they are on the same CPU). To acquire the
correct FDs, we must compare the Linux logical IDs rather than the evsel
or evlist indices.

This path adds logic to perf_evlist__mmap_per_evsel to handle this,
translating IDs as required. As PMUs may cover a subset of CPUs from the
evlist, we skip the CPUs a PMU cannot handle.

Without this patch, perf record may try to mmap erroneous FDs on
heterogeneous systems, and will bail out early rather than running the
workload.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1473330112-28528-7-git-send-email-mark.rutland@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/evlist.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 097b3ed77fdd..ea34c5a32c11 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1032,16 +1032,18 @@ perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
 }
 
 static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
-				       struct mmap_params *mp, int cpu,
+				       struct mmap_params *mp, int cpu_idx,
 				       int thread, int *_output, int *_output_backward)
 {
 	struct perf_evsel *evsel;
 	int revent;
+	int evlist_cpu = cpu_map__cpu(evlist->cpus, cpu_idx);
 
 	evlist__for_each_entry(evlist, evsel) {
 		struct perf_mmap *maps = evlist->mmap;
 		int *output = _output;
 		int fd;
+		int cpu;
 
 		if (evsel->attr.write_backward) {
 			output = _output_backward;
@@ -1060,6 +1062,10 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 		if (evsel->system_wide && thread)
 			continue;
 
+		cpu = cpu_map__idx(evsel->cpus, evlist_cpu);
+		if (cpu == -1)
+			continue;
+
 		fd = FD(evsel, cpu, thread);
 
 		if (*output == -1) {
-- 
2.7.4

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[GIT PULL 00/12] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 07/12] tools lib api fs: Add hugetlbfs filesystem detector Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 02/12] perf top: Remove old kernel-only symbol filter Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 06/12] perf tools: Recognize hugetlb mapping as anon mapping Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 11/12] perf pmu: Support alternative sysfs cpumask Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 12/12] perf powerpc: Fix build-test failure Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 08/12] perf record: Mark MAP_HUGETLB when synthesizing mmap events Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 04/12] perf test vmlinux: Remove dead symbol_filter_t code Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 10/12] perf evlist: Only open events on CPUs an evsel permits Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  [PATCH 03/12] perf machine: Remove machine->symbol_filter and friends Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-09-08 22:50 +0200
  Re: [GIT PULL 00/12] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2016-09-09 07:50 +0200

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