[PATCH] tools/perf: Fix addr location init during arch_skip_callchain_idx function

[Athira Rajeev]

perf record with callchain recording fails as below
in powerpc:

    ./perf record -a -gR sleep 10
    ./perf report
    perf: Segmentation fault

gdb trace points to thread__find_map

    0  0x00000000101df314 in atomic_cmpxchg (newval=1818846826, oldval=1818846827, v=0x1001a8f3) at /home/athira/linux/tools/include/asm-generic/atomic-gcc.h:70
    1  refcount_sub_and_test (i=1, r=0x1001a8f3) at /home/athira/linux/tools/include/linux/refcount.h:135
    2  refcount_dec_and_test (r=0x1001a8f3) at /home/athira/linux/tools/include/linux/refcount.h:148
    3  map__put (map=0x1001a8b3) at util/map.c:311
    4  0x000000001016842c in __map__zput (map=0x7fffffffa368) at util/map.h:190
    5  thread__find_map (thread=0x105b92f0, cpumode=<optimized out>, addr=13835058055283572736, al=al at entry=0x7fffffffa358) at util/event.c:582
    6  0x000000001016882c in thread__find_symbol (thread=<optimized out>, cpumode=<optimized out>, addr=<optimized out>, al=0x7fffffffa358) at util/event.c:656
    7  0x00000000102e12b4 in arch_skip_callchain_idx (thread=<optimized out>, chain=<optimized out>) at arch/powerpc/util/skip-callchain-idx.c:255
    8  0x00000000101d3bf4 in thread__resolve_callchain_sample (thread=0x105b92f0, cursor=0x1053d160, evsel=<optimized out>, sample=0x7fffffffa908, parent=0x7fffffffa778, root_al=0x7fffffffa710,
        max_stack=<optimized out>) at util/machine.c:2940
    9  0x00000000101cd210 in sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=<optimized out>, evsel=<optimized out>, al=<optimized out>, max_stack=<optimized out>)
        at util/callchain.c:1112
    10 0x000000001022a9d8 in hist_entry_iter__add (iter=0x7fffffffa750, al=0x7fffffffa710, max_stack_depth=<optimized out>, arg=0x7fffffffbbd0) at util/hist.c:1232
    11 0x0000000010056d98 in process_sample_event (tool=0x7fffffffbbd0, event=0x7ffff6223c38, sample=0x7fffffffa908, evsel=<optimized out>, machine=0x10524ef8) at builtin-report.c:332

Here arch_skip_callchain_idx calls thread__find_symbol and which
invokes thread__find_map with uninitialised "addr_location".
Snippet:

thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);

Recent change with commit 0dd5041c9a0ea ("perf addr_location:
Add init/exit/copy functions"), introduced "maps__zput" in the
function thread__find_map. This could result in segfault while
accessing uninitialised map from "struct addr_location". Fix this
by adding addr_location__init and addr_location__exit in
arch_skip_callchain_idx.

Fixes: 0dd5041c9a0ea ("perf addr_location: Add init/exit/copy functions")
Reported-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
---
 tools/perf/arch/powerpc/util/skip-callchain-idx.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
index b7223feec770..5f3edb3004d8 100644
--- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
+++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
@@ -250,6 +250,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
 	if (!chain || chain->nr < 3)
 		return skip_slot;
 
+	addr_location__init(&al);
 	ip = chain->ips[1];
 
 	thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
@@ -259,6 +260,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
 
 	if (!dso) {
 		pr_debug("%" PRIx64 " dso is NULL\n", ip);
+		addr_location__exit(&al);
 		return skip_slot;
 	}
 
@@ -279,5 +281,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
 		 */
 		skip_slot = 3;
 	}
+
+	addr_location__exit(&al);
 	return skip_slot;
 }
-- 
2.25.1