From mboxrd@z Thu Jan 1 00:00:00 1970 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CEBCC433FE for ; Fri, 22 Oct 2021 20:50:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4291C61208 for ; Fri, 22 Oct 2021 20:50:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234790AbhJVUw2 (ORCPT ); Fri, 22 Oct 2021 16:52:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:40634 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234433AbhJVUvD (ORCPT ); Fri, 22 Oct 2021 16:51:03 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1DF88613A2; Fri, 22 Oct 2021 20:48:45 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.95) (envelope-from ) id 1me1T2-000QTZ-8H; Fri, 22 Oct 2021 16:48:44 -0400 Message-ID: <20211022204844.089918832@goodmis.org> User-Agent: quilt/0.66 Date: Fri, 22 Oct 2021 16:48:28 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Tom Zanussi , Arnd Bergmann Subject: [for-next][PATCH 32/40] tracing: use %ps format string to print symbols References: <20211022204756.099054287@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann clang started warning about excessive stack usage in hist_trigger_print_key() kernel/trace/trace_events_hist.c:4723:13: error: stack frame size (1336) exceeds limit (1024) in function 'hist_trigger_print_key' [-Werror,-Wframe-larger-than] The problem is that there are two 512-byte arrays on the stack if hist_trigger_stacktrace_print() gets inlined. I don't think this has changed in the past five years, but something probably changed the inlining decisions made by the compiler, so the problem is now made more obvious. Rather than printing the symbol names into separate buffers, it seems we can simply use the special %ps format string modifier to print the pointers symbolically and get rid of both buffers. Marking hist_trigger_stacktrace_print() would be a simpler way of avoiding the warning, but that would not address the excessive stack usage. Link: https://lkml.kernel.org/r/20211019153337.294790-1-arnd@kernel.org Fixes: 69a0200c2e25 ("tracing: Add hist trigger support for stacktraces as keys") Link: https://lore.kernel.org/all/20211015095704.49a99859@gandalf.local.home/ Reviewed-by: Tom Zanussi Tested-by: Tom Zanussi Signed-off-by: Arnd Bergmann Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_hist.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index a6061a69aa84..b64aed538628 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4706,7 +4706,6 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, unsigned long *stacktrace_entries, unsigned int max_entries) { - char str[KSYM_SYMBOL_LEN]; unsigned int spaces = 8; unsigned int i; @@ -4715,8 +4714,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, return; seq_printf(m, "%*c", 1 + spaces, ' '); - sprint_symbol(str, stacktrace_entries[i]); - seq_printf(m, "%s\n", str); + seq_printf(m, "%pS\n", (void*)stacktrace_entries[i]); } } @@ -4726,7 +4724,6 @@ static void hist_trigger_print_key(struct seq_file *m, struct tracing_map_elt *elt) { struct hist_field *key_field; - char str[KSYM_SYMBOL_LEN]; bool multiline = false; const char *field_name; unsigned int i; @@ -4747,14 +4744,12 @@ static void hist_trigger_print_key(struct seq_file *m, seq_printf(m, "%s: %llx", field_name, uval); } else if (key_field->flags & HIST_FIELD_FL_SYM) { uval = *(u64 *)(key + key_field->offset); - sprint_symbol_no_offset(str, uval); - seq_printf(m, "%s: [%llx] %-45s", field_name, - uval, str); + seq_printf(m, "%s: [%llx] %-45ps", field_name, + uval, (void *)(uintptr_t)uval); } else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) { uval = *(u64 *)(key + key_field->offset); - sprint_symbol(str, uval); - seq_printf(m, "%s: [%llx] %-55s", field_name, - uval, str); + seq_printf(m, "%s: [%llx] %-55pS", field_name, + uval, (void *)(uintptr_t)uval); } else if (key_field->flags & HIST_FIELD_FL_EXECNAME) { struct hist_elt_data *elt_data = elt->private_data; char *comm; -- 2.33.0