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SubjectRe: [PATCH] perf script: Show binary offsets for userspace addr
On Tue, Oct 19, 2021 at 03:24:17PM +0800, Lexi Shao wrote:
> Show binary offsets for userspace addr with map in perf script output
> with callchain.
>
> In commit 19610184693c("perf script: Show virtual addresses instead of
> offsets"), the addr shown in perf script output with callchain is changed
> from binary offsets to virtual address to fix the incorrectness when
> displaying symbol offset.
>
> This is inconvenient in scenario that the binary is stripped and
> symbol cannot be resolved. If someone wants to further resolve symbols for
> specific binaries later, he would need an extra step to translate virtual
> address to binary offset with mapping information recorded in perf.data,
> which can be difficult for people not familiar with perf.
>
> This patch modifies function sample__fprintf_callchain to print binary
> offset for userspace addr with dsos, and virtual address otherwise. It
> does not affect symbol offset calculation so symoff remains correct.
>
> Before applying this patch:
> test 1512 78.711307: 533129 cycles:
> aaaae0da07f4 [unknown] (/tmp/test)
> aaaae0da0704 [unknown] (/tmp/test)
> ffffbe9f7ef4 __libc_start_main+0xe4 (/lib64/libc-2.31.so)
>
> After this patch:
> test 1519 111.330127: 406953 cycles:
> 7f4 [unknown] (/tmp/test)
> 704 [unknown] (/tmp/test)
> 20ef4 __libc_start_main+0xe4 (/lib64/libc-2.31.so)
>
> Fixes: 19610184693c("perf script: Show virtual addresses instead of offsets")
>
> Signed-off-by: Lexi Shao <shaolexi@huawei.com>

makes sense to me

Acked-/Tested-by Jiri Olsa <jolsa@redhat.com>

should we have a way to display these callchain detail in perf report output as well?

thanks,
jirka

> ---
> tools/perf/util/evsel_fprintf.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/evsel_fprintf.c b/tools/perf/util/evsel_fprintf.c
> index bfedd7b23521..8c2ea8001329 100644
> --- a/tools/perf/util/evsel_fprintf.c
> +++ b/tools/perf/util/evsel_fprintf.c
> @@ -11,6 +11,7 @@
> #include "strlist.h"
> #include "symbol.h"
> #include "srcline.h"
> +#include "dso.h"
>
> static int comma_fprintf(FILE *fp, bool *first, const char *fmt, ...)
> {
> @@ -144,12 +145,17 @@ int sample__fprintf_callchain(struct perf_sample *sample, int left_alignment,
> if (print_arrow && !first)
> printed += fprintf(fp, " <-");
>
> - if (print_ip)
> - printed += fprintf(fp, "%c%16" PRIx64, s, node->ip);
> -
> if (map)
> addr = map->map_ip(map, node->ip);
>
> + if (print_ip) {
> + /* Show binary offset for userspace addr */
> + if (map && !map->dso->kernel)
> + printed += fprintf(fp, "%c%16" PRIx64, s, addr);
> + else
> + printed += fprintf(fp, "%c%16" PRIx64, s, node->ip);
> + }
> +
> if (print_sym) {
> printed += fprintf(fp, " ");
> node_al.addr = addr;
> --
> 2.12.3
>

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