On Sun, Oct 04, 2015 at 05:38:17PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sun, Oct 04, 2015 at 05:16:37PM +0200, Milian Wolff escreveu:
> > We cannot reverse the order of the libunwind stepper. To workaround
> > this, we store the IPs in a temporary stack buffer and then walk
> > this buffer in reverse order when callchain_param.order is set to
> > ORDER_CALLER.
> >
> > Signed-off-by: Milian Wolff <[email protected]>
>
> Jiri,
>
> Can you please take a look at this?
>
> - Arnaldo
>
> > Cc: Arnaldo Carvalho de Melo <[email protected]>
> > ---
> > tools/perf/util/unwind-libunwind.c | 21 +++++++++++++++++----
> > 1 file changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/unwind-libunwind.c
> > b/tools/perf/util/unwind-libunwind.c
> > index 4c00507..bf631f1 100644
> > --- a/tools/perf/util/unwind-libunwind.c
> > +++ b/tools/perf/util/unwind-libunwind.c
> > @@ -621,11 +621,24 @@ static int get_entries(struct unwind_info *ui,
> > unwind_entry_cb_t cb,
> > if (ret)
> > display_error(ret);
> >
> > - while (!ret && (unw_step(&c) > 0) && max_stack--) {
> > - unw_word_t ip;
> > + if (callchain_param.order == ORDER_CALLEE) {
> > + while (!ret && (unw_step(&c) > 0) && max_stack--) {
> > + unw_word_t ip;
> >
> > - unw_get_reg(&c, UNW_REG_IP, &ip);
> > - ret = ip ? entry(ip, ui->thread, cb, arg) : 0;
> > + unw_get_reg(&c, UNW_REG_IP, &ip);
> > + ret = ip ? entry(ip, ui->thread, cb, arg) : 0;
> > + }
> > + } else {
> > + unw_word_t ips[max_stack];
> > + int i = 0;
> > +
> > + while ((unw_step(&c) > 0) && i < max_stack) {
> > + unw_get_reg(&c, UNW_REG_IP, &ips[i]);
> > + ++i;
> > + }
> > + max_stack = i;
> > + for (i = max_stack - 1; i >= 0; --i)
> > + entry(ips[i], ui->thread, cb, arg);
there's no check for return value of entry callback
also I wonder would it be better to store into ips[] within
the single loop all the time, and iterate throught it after
forward/backward based on the callchain_param.order
please check attached patch, totaly untested, probably leaking some index ;-)
any chance this could be done also for util/unwind-libdw.c ?
thanks,
jirka
---
diff --git a/tools/perf/util/unwind-libunwind.c
b/tools/perf/util/unwind-libunwind.c
index 4c00507ee3fd..f91433f868f9 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -609,9 +609,10 @@ void unwind__finish_access(struct thread *thread)
static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
void *arg, int max_stack)
{
+ unw_word_t ips[max_stack];
unw_addr_space_t addr_space;
unw_cursor_t c;
- int ret;
+ int ret, i = 0;
addr_space = thread__priv(ui->thread);
if (addr_space == NULL)
@@ -621,11 +622,19 @@ static int get_entries(struct unwind_info *ui,
unwind_entry_cb_t cb,
if (ret)
display_error(ret);
- while (!ret && (unw_step(&c) > 0) && max_stack--) {
- unw_word_t ip;
+ while ((unw_step(&c) > 0) && i < max_stack) {
+ unw_get_reg(&c, UNW_REG_IP, &ips[i]);
+ ++i;
+ }
+
+ max_stack = i;
+
+ for (i = 0; i < max_stack && !ret; i++) {
+ int j = i;
- unw_get_reg(&c, UNW_REG_IP, &ip);
- ret = ip ? entry(ip, ui->thread, cb, arg) : 0;
+ if (callchain_param.order == ORDER_CALLER)
+ j = max_stack - i - 1;
+ ret = entry(ips[j], ui->thread, cb, arg);
}
return ret;
--
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