Re: [PATCH 3/3] perf unwind-libunwind: Fix base address for .eh_frame

[Ian Rogers]

On Mon, Dec 11, 2023 at 11:05 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> The base address of a DSO mapping should start at the start of the file.
> Usually DSOs are mapped from the pgoff 0 so it doesn't matter when it
> uses the start of the map address.  But generated DSOs for JIT codes
> doesn't start from the 0 so it should subtract the offset to calculate
> the .eh_frame table offsets correctly.
>
> Fixes: dc2cf4ca866f ("perf unwind: Fix segbase for ld.lld linked objects")
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/util/unwind-libunwind-local.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/unwind-libunwind-local.c b/tools/perf/util/unwind-libunwind-local.c
> index c0641882fd2f..5e5c3395a499 100644
> --- a/tools/perf/util/unwind-libunwind-local.c
> +++ b/tools/perf/util/unwind-libunwind-local.c
> @@ -327,7 +327,7 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct unwind_info *ui,
>
>         maps__for_each_entry(thread__maps(ui->thread), map_node) {
>                 struct map *map = map_node->map;
> -               u64 start = map__start(map);
> +               u64 start = map__start(map) - map__pgoff(map);
>
>                 if (map__dso(map) == dso && start < base_addr)
>                         base_addr = start;
> --
> 2.43.0.472.g3155946c3a-goog
>