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Subject[PATCH] Prevent infinite loop if unwind fails
Date
Unwind may loop forever if sample is incomplete or bogus. Bound the number of
unw_step() that yield the same IP to prevent infinite loop.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
---
tools/perf/util/unwind.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c
index 958723b..bf45b6b 100644
--- a/tools/perf/util/unwind.c
+++ b/tools/perf/util/unwind.c
@@ -520,7 +520,8 @@ static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
{
unw_addr_space_t addr_space;
unw_cursor_t c;
- int ret;
+ unw_word_t prev_ip = 0;
+ int ret, rec = 0;

addr_space = unw_create_addr_space(&accessors, 0);
if (!addr_space) {
@@ -537,6 +538,11 @@ static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,

unw_get_reg(&c, UNW_REG_IP, &ip);
ret = entry(ip, ui->thread, ui->machine, cb, arg);
+ if (prev_ip != ip)
+ rec = 0;
+ if (++rec >= 100)
+ break;
+ prev_ip = ip;
}

unw_destroy_addr_space(addr_space);
--
1.8.1.2


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