From nobody Sun Sep 14 08:39:12 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8AD8C54EAA for ; Wed, 25 Jan 2023 17:14:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236163AbjAYRON (ORCPT ); Wed, 25 Jan 2023 12:14:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235591AbjAYRNy (ORCPT ); Wed, 25 Jan 2023 12:13:54 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0470CC03 for ; Wed, 25 Jan 2023 09:13:43 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 77069B81A22 for ; Wed, 25 Jan 2023 17:13:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20BA0C4339C; Wed, 25 Jan 2023 17:13:41 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1pKjL9-004NsR-2B; Wed, 25 Jan 2023 12:13:39 -0500 Message-ID: <20230125171339.487333765@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 25 Jan 2023 12:12:58 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Tom Zanussi , Ross Zwisler , Ching-lin Yu Subject: [for-next][PATCH 06/12] tracing: Allow stacktraces to be saved as histogram variables References: <20230125171252.431857411@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" Allow to save stacktraces into a histogram variable. This will be used by synthetic events to allow a stacktrace from one event to be passed and displayed by another event. The special keyword "stacktrace" is to be used to trigger a stack trace for the event that the histogram trigger is attached to. echo 'hist:keys=3Dpid:st=3Dstacktrace" > events/sched/sched_waking/trigger Currently nothing can get access to the "$st" variable above that contains the stack trace, but that will soon change. Link: https://lkml.kernel.org/r/20230117152235.856323729@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Tom Zanussi Cc: Ross Zwisler Cc: Ching-lin Yu Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_hist.c | 52 ++++++++++++++++++++++++++------ 1 file changed, 42 insertions(+), 10 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_h= ist.c index 5edbf6b1da3f..f8f67e17898a 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1360,6 +1360,8 @@ static const char *hist_field_name(struct hist_field = *field, field_name =3D field->name; } else if (field->flags & HIST_FIELD_FL_TIMESTAMP) field_name =3D "common_timestamp"; + else if (field->flags & HIST_FIELD_FL_STACKTRACE) + field_name =3D "stacktrace"; else if (field->flags & HIST_FIELD_FL_HITCOUNT) field_name =3D "hitcount"; =20 @@ -1980,6 +1982,10 @@ static struct hist_field *create_hist_field(struct h= ist_trigger_data *hist_data, =20 if (flags & HIST_FIELD_FL_STACKTRACE) { hist_field->fn_num =3D HIST_FIELD_FN_NOP; + hist_field->size =3D HIST_STACKTRACE_SIZE; + hist_field->type =3D kstrdup_const("unsigned long[]", GFP_KERNEL); + if (!hist_field->type) + goto free; goto out; } =20 @@ -2351,6 +2357,8 @@ parse_field(struct hist_trigger_data *hist_data, stru= ct trace_event_file *file, hist_data->enable_timestamps =3D true; if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS) hist_data->attrs->ts_in_usecs =3D true; + } else if (strcmp(field_name, "stacktrace") =3D=3D 0) { + *flags |=3D HIST_FIELD_FL_STACKTRACE; } else if (strcmp(field_name, "common_cpu") =3D=3D 0) *flags |=3D HIST_FIELD_FL_CPU; else if (strcmp(field_name, "hitcount") =3D=3D 0) @@ -3119,13 +3127,24 @@ static inline void __update_field_vars(struct traci= ng_map_elt *elt, var_val =3D hist_fn_call(val, elt, buffer, rbe, rec); var_idx =3D var->var.idx; =20 - if (val->flags & HIST_FIELD_FL_STRING) { + if (val->flags & (HIST_FIELD_FL_STRING | + HIST_FIELD_FL_STACKTRACE)) { char *str =3D elt_data->field_var_str[j++]; char *val_str =3D (char *)(uintptr_t)var_val; unsigned int size; =20 - size =3D min(val->size, STR_VAR_LEN_MAX); - strscpy(str, val_str, size); + if (val->flags & HIST_FIELD_FL_STRING) { + size =3D min(val->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size); + } else { + int e; + + e =3D stack_trace_save((void *)str, + HIST_STACKTRACE_DEPTH, + HIST_STACKTRACE_SKIP); + if (e < HIST_STACKTRACE_DEPTH - 1) + ((unsigned long *)str)[e] =3D 0; + } var_val =3D (u64)(uintptr_t)str; } tracing_map_set_var(elt, var_idx, var_val); @@ -3824,7 +3843,8 @@ static void save_field_var(struct hist_trigger_data *= hist_data, { hist_data->field_vars[hist_data->n_field_vars++] =3D field_var; =20 - if (field_var->val->flags & HIST_FIELD_FL_STRING) + /* Stack traces are saved in the string storage too */ + if (field_var->val->flags & (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTR= ACE)) hist_data->n_field_var_str++; } =20 @@ -4103,7 +4123,8 @@ static int action_create(struct hist_trigger_data *hi= st_data, } =20 hist_data->save_vars[hist_data->n_save_vars++] =3D field_var; - if (field_var->val->flags & HIST_FIELD_FL_STRING) + if (field_var->val->flags & + (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) hist_data->n_save_var_str++; kfree(param); } @@ -4351,7 +4372,8 @@ static int create_var_field(struct hist_trigger_data = *hist_data, if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME) update_var_execname(hist_data->fields[val_idx]); =20 - if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING) + if (!ret && hist_data->fields[val_idx]->flags & + (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) hist_data->fields[val_idx]->var_str_idx =3D hist_data->n_var_str++; =20 return ret; @@ -5092,7 +5114,8 @@ static void hist_trigger_elt_update(struct hist_trigg= er_data *hist_data, if (hist_field->flags & HIST_FIELD_FL_VAR) { var_idx =3D hist_field->var.idx; =20 - if (hist_field->flags & HIST_FIELD_FL_STRING) { + if (hist_field->flags & + (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) { unsigned int str_start, var_str_idx, idx; char *str, *val_str; unsigned int size; @@ -5105,9 +5128,18 @@ static void hist_trigger_elt_update(struct hist_trig= ger_data *hist_data, str =3D elt_data->field_var_str[idx]; val_str =3D (char *)(uintptr_t)hist_val; =20 - size =3D min(hist_field->size, STR_VAR_LEN_MAX); - strscpy(str, val_str, size); - + if (hist_field->flags & HIST_FIELD_FL_STRING) { + size =3D min(hist_field->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size); + } else { + int e; + + e =3D stack_trace_save((void *)str, + HIST_STACKTRACE_DEPTH, + HIST_STACKTRACE_SKIP); + if (e < HIST_STACKTRACE_DEPTH - 1) + ((unsigned long *)str)[e] =3D 0; + } hist_val =3D (u64)(uintptr_t)str; } tracing_map_set_var(elt, var_idx, hist_val); --=20 2.39.0