On Fri, 5 Aug 2016 14:33:53 +0900
Naohiro Aota <naohiro.a...@hgst.com> wrote:
> Perf-probe detects a variable's type and use the detected type to add new
> probe. Then, kprobes prints its variable in hexadecimal format if the
> variable is unsigned and prints in decimal if it is signed.
>
> We sometimes want to see unsigned variable in decimal format (e.g.
> sector_t or size_t). In that case, we need to investigate variable's
> size manually to specify just signedness.
>
> This patch add signedness casting support. By specifying "s" or "u" as a
> type, perf-probe will investigate variable size as usual and use
> the specified signedness.
OK, I could understand what the patch does from code. Please add an
example, and update tools/perf/Documentation/perf-probe.txt too.
Thank you,
>
> Signed-off-by: Naohiro Aota <naohiro.a...@hgst.com>
> ---
> tools/perf/util/probe-finder.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index f2d9ff0..5c290c6 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -297,10 +297,13 @@ static int convert_variable_type(Dwarf_Die *vr_die,
> char sbuf[STRERR_BUFSIZE];
> int bsize, boffs, total;
> int ret;
> + char sign;
>
> /* TODO: check all types */
> - if (cast && strcmp(cast, "string") != 0) {
> + if (cast && strcmp(cast, "string") != 0 &&
> + strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
> /* Non string type is OK */
> + /* and respect signedness cast */
> tvar->type = strdup(cast);
> return (tvar->type == NULL) ? -ENOMEM : 0;
> }
> @@ -361,6 +364,13 @@ static int convert_variable_type(Dwarf_Die *vr_die,
> return (tvar->type == NULL) ? -ENOMEM : 0;
> }
>
> + if (cast && (strcmp(cast, "u") == 0))
> + sign = 'u';
> + else if (cast && (strcmp(cast, "s") == 0))
> + sign = 's';
> + else
> + sign = die_is_signed_type(&type) ? 's' : 'u';
> +
> ret = dwarf_bytesize(&type);
> if (ret <= 0)
> /* No size ... try to use default type */
> @@ -373,8 +383,7 @@ static int convert_variable_type(Dwarf_Die *vr_die,
> dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
> ret = MAX_BASIC_TYPE_BITS;
> }
> - ret = snprintf(buf, 16, "%c%d",
> - die_is_signed_type(&type) ? 's' : 'u', ret);
> + ret = snprintf(buf, 16, "%c%d", sign, ret);
>
> formatted:
> if (ret < 0 || ret >= 16) {
> --
> 2.7.3
>
--
Masami Hiramatsu <mhira...@kernel.org>
