Re: [PATCH] perf report: Support caller callchain order when using DWARF unwinder.

[Arnaldo Carvalho de Melo <acme@kernel.org>]

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 <milian.wolff@kdab.com>

Jiri,

	Can you please take a look at this?

- Arnaldo
 
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> ---
>  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);
>  	}
>  
>  	return ret;
> -- 
> 2.6.0
> 
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