On Wed, 3 Feb 2021 10:25:07 +0800
Jianlin Lv <jianlin...@arm.com> wrote:
> if dwarf_offdie() return NULL, the continue statement forces the next
> iteration of the loop without update variable off. It will cause an
> endless loop in the process of traversing the compilation unit.
> So added exception protection for loop CUs.
Good catch!
>
> Signed-off-by: Jianlin Lv <jianlin...@arm.com>
> ---
> tools/perf/util/probe-finder.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 76dd349aa48d..887bffb1cc58 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -1156,7 +1156,7 @@ static int debuginfo__find_probe_location(struct
> debuginfo *dbg,
> Dwarf_Die *diep;
> int ret = 0;
>
> - off = 0;
> + noff = 0;
> pf->lcache = intlist__new(NULL);
> if (!pf->lcache)
> return -ENOMEM;
> @@ -1184,7 +1184,7 @@ static int debuginfo__find_probe_location(struct
> debuginfo *dbg,
> }
>
> /* Loop on CUs (Compilation Unit) */
> - while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
> + while (!dwarf_nextcu(dbg->dbg, off = noff, &noff, &cuhl, NULL, NULL,
> NULL)) {
I don't like to update variable in function argument,
I would rather like below code;
> /* Get the DIE(Debugging Information Entry) of this CU */
> diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
if (!diep) {
+ off = noff;
continue;
}
Or, "goto next;" and
> @@ -1208,7 +1208,6 @@ static int debuginfo__find_probe_location(struct
> debuginfo *dbg,
> if (ret < 0)
> break;
> }
next:
> - off = noff;
> }
>
> found:
> @@ -1919,7 +1918,7 @@ int debuginfo__find_line_range(struct debuginfo *dbg,
> struct line_range *lr)
> {
> struct line_finder lf = {.lr = lr, .found = 0};
> int ret = 0;
> - Dwarf_Off off = 0, noff;
> + Dwarf_Off off = 0, noff = 0;
> size_t cuhl;
> Dwarf_Die *diep;
> const char *comp_dir;
> @@ -1943,6 +1942,7 @@ int debuginfo__find_line_range(struct debuginfo *dbg,
> struct line_range *lr)
>
> /* Loop on CUs (Compilation Unit) */
> while (!lf.found && ret >= 0) {
> + off = noff;
Here too.
Can you update it?
Thank you,
> if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
> NULL, NULL, NULL) != 0)
> break;
> @@ -1967,7 +1967,6 @@ int debuginfo__find_line_range(struct debuginfo *dbg,
> struct line_range *lr)
> ret = find_line_range_by_line(NULL, &lf);
> }
> }
> - off = noff;
> }
>
> found:
> --
> 2.25.1
>
--
Masami Hiramatsu <mhira...@kernel.org>
