On Sun, Dec 08, 2013 at 10:46:13AM -0700, David Ahern wrote: > ping.. Jiri, any thoughts on this?
oops, missed that.. sry > > On 12/1/13, 5:01 PM, David Ahern wrote: > >The dwarf option for callstacks is getting stuck on the unwind and showing > >repeated frames. For example, > > > >qemu-system-x86 13759 [001] 287663.084957: syscalls:sys_enter_futex: uaddr: > >0x7f770a958700, op: 0x00000081, val: 0x00000001, utime: 0x7f75ea > > 7f7705fd23ea __lll_unlock_wake (/lib64/libpthread-2.14.90.so) > > 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) > > 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) > > 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) > > 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) > > 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) > > ... I wonder this is us or libunwind bug (or cfi code) ;-) looks like you can reproduce..? are you using the latest libunwind? > > (Last frame repeats 126 times) > > > >Catch that the same frame is hit multiple times and break out of the loop. > > > >With this patch: > > > >qemu-system-x86 13759 [001] 287663.084967: syscalls:sys_exit_futex: 0x1 > > 7f7705fd23ea __lll_unlock_wake (/lib64/libpthread-2.14.90.so) > > 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) > > > >Signed-off-by: David Ahern <[email protected]> > >Cc: Jiri Olsa <[email protected]> > >--- > > tools/perf/util/unwind.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > >diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c > >index 0efd5393de85..817ffc1f3a00 100644 > >--- a/tools/perf/util/unwind.c > >+++ b/tools/perf/util/unwind.c > >@@ -563,6 +563,7 @@ static int get_entries(struct unwind_info *ui, > >unwind_entry_cb_t cb, > > { > > unw_addr_space_t addr_space; > > unw_cursor_t c; > >+ unw_word_t prev_ip = 0; > > int ret; > > > > addr_space = unw_create_addr_space(&accessors, 0); > >@@ -579,6 +580,10 @@ static int get_entries(struct unwind_info *ui, > >unwind_entry_cb_t cb, > > unw_word_t ip; > > > > unw_get_reg(&c, UNW_REG_IP, &ip); > >+ if (ip == prev_ip) > >+ break; > >+ prev_ip = ip; hum, how about recursion? how about some counter and break after some insane value and maybe display some warning.. qemu-system-x86 13759 [001] 287663.084967: syscalls:sys_exit_futex: 0x1 7f7705fd23ea __lll_unlock_wake (/lib64/libpthread-2.14.90.so) 7f7705fcf045 _L_unlock_649 (/lib64/libpthread-2.14.90.so) warning: unwind broken jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
