From patchwork Tue Jan 17 04:40:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13104167 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 7C8AFC678D8 for ; Tue, 17 Jan 2023 04:41:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235425AbjAQElQ (ORCPT ); Mon, 16 Jan 2023 23:41:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59392 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235385AbjAQElL (ORCPT ); Mon, 16 Jan 2023 23:41:11 -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 A5DA223102; Mon, 16 Jan 2023 20:41:04 -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 5BD5FB80DFA; Tue, 17 Jan 2023 04:41:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1365EC433D2; Tue, 17 Jan 2023 04:41:02 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1pHdmP-001rsA-0I; Mon, 16 Jan 2023 23:41:01 -0500 Message-ID: <20230117044100.962605301@goodmis.org> User-Agent: quilt/0.66 Date: Mon, 16 Jan 2023 23:40:12 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Ross Zwisler Subject: [PATCH 2/5] tracing: Allow stacktraces to be saved as histogram variables References: <20230117044010.838685230@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org 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=pid:st=stacktrace" > 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. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_hist.c | 35 +++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index fcaf226b7744..5cc7873983ee 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 = field->name; } else if (field->flags & HIST_FIELD_FL_TIMESTAMP) field_name = "common_timestamp"; + else if (field->flags & HIST_FIELD_FL_STACKTRACE) + field_name = "stacktrace"; else if (field->flags & HIST_FIELD_FL_HITCOUNT) field_name = "hitcount"; @@ -1980,6 +1982,10 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data, if (flags & HIST_FIELD_FL_STACKTRACE) { hist_field->fn_num = HIST_FIELD_FN_NOP; + hist_field->size = HIST_STACKTRACE_SIZE; + hist_field->type = kstrdup_const("unsigned long[]", GFP_KERNEL); + if (!hist_field->type) + goto free; goto out; } @@ -2349,6 +2355,8 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file, hist_data->enable_timestamps = true; if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS) hist_data->attrs->ts_in_usecs = true; + } else if (strcmp(field_name, "stacktrace") == 0) { + *flags |= HIST_FIELD_FL_STACKTRACE; } else if (strcmp(field_name, "common_cpu") == 0) *flags |= HIST_FIELD_FL_CPU; else if (strcmp(field_name, "hitcount") == 0) @@ -3822,7 +3830,8 @@ static void save_field_var(struct hist_trigger_data *hist_data, { hist_data->field_vars[hist_data->n_field_vars++] = field_var; - 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_STACKTRACE)) hist_data->n_field_var_str++; } @@ -4101,7 +4110,8 @@ static int action_create(struct hist_trigger_data *hist_data, } hist_data->save_vars[hist_data->n_save_vars++] = 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); } @@ -4349,7 +4359,8 @@ 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]); - 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 = hist_data->n_var_str++; return ret; @@ -5090,7 +5101,8 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data, if (hist_field->flags & HIST_FIELD_FL_VAR) { var_idx = hist_field->var.idx; - 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; @@ -5103,9 +5115,18 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data, str = elt_data->field_var_str[idx]; val_str = (char *)(uintptr_t)hist_val; - size = min(hist_field->size, STR_VAR_LEN_MAX); - strscpy(str, val_str, size); - + if (hist_field->flags & HIST_FIELD_FL_STRING) { + size = min(hist_field->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size); + } else { + int e; + + e = stack_trace_save((void *)str, + HIST_STACKTRACE_DEPTH, + HIST_STACKTRACE_SKIP); + if (e < HIST_STACKTRACE_DEPTH - 1) + ((unsigned long *)str)[e] = 0; + } hist_val = (u64)(uintptr_t)str; } tracing_map_set_var(elt, var_idx, hist_val);