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authorSandipan Das <sandipan@linux.ibm.com>2018-06-11 12:40:49 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-06-25 16:59:35 +0200
commit143c99f6ac6812d23254e80844d6e34be897d3e1 (patch)
treeaa3ecdc5bf721f3e55f01f0c43a10a92ba6870cd
parentperf test session topology: Fix test on s390 (diff)
downloadlinux-143c99f6ac6812d23254e80844d6e34be897d3e1.tar.xz
linux-143c99f6ac6812d23254e80844d6e34be897d3e1.zip
perf report powerpc: Fix crash if callchain is empty
For some cases, the callchain provided by the kernel may be empty. So, the callchain ip filtering code will cause a crash if we do not check whether the struct ip_callchain pointer is NULL before accessing any members. This can be observed on a powerpc64le system running Fedora 27 as shown below. # perf record -b -e cycles:u ls Before: # perf report --branch-history perf: Segmentation fault -------- backtrace -------- perf[0x1027615c] linux-vdso64.so.1(__kernel_sigtramp_rt64+0x0)[0x7fff856304d8] perf(arch_skip_callchain_idx+0x44)[0x10257c58] perf[0x1017f2e4] perf(thread__resolve_callchain+0x124)[0x1017ff5c] perf(sample__resolve_callchain+0xf0)[0x10172788] ... After: # perf report --branch-history Samples: 25 of event 'cycles:u', Event count (approx.): 2306870 Overhead Source:Line Symbol Shared Object + 11.60% _init+35736 [.] _init ls + 9.84% strcoll_l.c:137 [.] __strcoll_l libc-2.26.so + 9.16% memcpy.S:175 [.] __memcpy_power7 libc-2.26.so + 9.01% gconv_charset.h:54 [.] _nl_find_locale libc-2.26.so + 8.87% dl-addr.c:52 [.] _dl_addr libc-2.26.so + 8.83% _init+236 [.] _init ls ... Reported-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20180611104049.11048-1-sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r--tools/perf/arch/powerpc/util/skip-callchain-idx.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
index 3598b8b75d27..ef5d59a5742e 100644
--- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
+++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
@@ -243,7 +243,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
u64 ip;
u64 skip_slot = -1;
- if (chain->nr < 3)
+ if (!chain || chain->nr < 3)
return skip_slot;
ip = chain->ips[2];