From da8a58b56c661681f9b2fd2fa59c6da3a5bac8d1 Mon Sep 17 00:00:00 2001 From: Jan Stancek Date: Fri, 17 Feb 2017 12:10:26 +0100 Subject: perf tools: Replace _SC_NPROCESSORS_CONF with max_present_cpu in cpu_topology_map There are 2 problems wrt. cpu_topology_map on systems with sparse CPUs: 1. offline/absent CPUs will have their socket_id and core_id set to -1 which triggers: "socket_id number is too big.You may need to upgrade the perf tool." 2. size of cpu_topology_map (perf_env.cpu[]) is allocated based on _SC_NPROCESSORS_CONF, but can be indexed with CPU ids going above. Users of perf_env.cpu[] are using CPU id as index. This can lead to read beyond what was allocated: ==19991== Invalid read of size 4 ==19991== at 0x490CEB: check_cpu_topology (topology.c:69) ==19991== by 0x490CEB: test_session_topology (topology.c:106) ... For example: _SC_NPROCESSORS_CONF == 16 available: 2 nodes (0-1) node 0 cpus: 0 6 8 10 16 22 24 26 node 0 size: 12004 MB node 0 free: 9470 MB node 1 cpus: 1 7 9 11 23 25 27 node 1 size: 12093 MB node 1 free: 9406 MB node distances: node 0 1 0: 10 20 1: 20 10 This patch changes HEADER_NRCPUS.nr_cpus_available from _SC_NPROCESSORS_CONF to max_present_cpu and updates any user of cpu_topology_map to iterate with nr_cpus_avail. As a consequence HEADER_CPU_TOPOLOGY core_id and socket_id lists get longer, but maintain compatibility with pre-patch state - index to cpu_topology_map is CPU id. perf test 36 -v 36: Session topology : --- start --- test child forked, pid 22211 templ file: /tmp/perf-test-gmdX5i CPU 0, core 0, socket 0 CPU 1, core 0, socket 1 CPU 6, core 10, socket 0 CPU 7, core 10, socket 1 CPU 8, core 1, socket 0 CPU 9, core 1, socket 1 CPU 10, core 9, socket 0 CPU 11, core 9, socket 1 CPU 16, core 0, socket 0 CPU 22, core 10, socket 0 CPU 23, core 10, socket 1 CPU 24, core 1, socket 0 CPU 25, core 1, socket 1 CPU 26, core 9, socket 0 CPU 27, core 9, socket 1 test child finished with 0 ---- end ---- Session topology: Ok Signed-off-by: Jan Stancek Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/d7c05c6445fca74a8442c2c73cfffd349c52c44f.1487146877.git.jstancek@redhat.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/env.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/perf/util/env.c') diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c index bb964e86b09d..075fc77286bf 100644 --- a/tools/perf/util/env.c +++ b/tools/perf/util/env.c @@ -66,7 +66,7 @@ int perf_env__read_cpu_topology_map(struct perf_env *env) return 0; if (env->nr_cpus_avail == 0) - env->nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF); + env->nr_cpus_avail = cpu__max_present_cpu(); nr_cpus = env->nr_cpus_avail; if (nr_cpus == -1) -- cgit v1.2.3