linux-kernel - [for-next][PATCH 21/24] tracing: Simplify printfing in seq_print

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20181221175658.872681406@goodmis.org>
Date:   Fri, 21 Dec 2018 12:56:39 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [for-next][PATCH 21/24] tracing: Simplify printfing in seq_print_sym

From: Rasmus Villemoes <linux@...musvillemoes.dk>

trace_seq_printf(..., "%s", ...) can be done with trace_seq_puts()
instead, avoiding printf overhead. In the second instance, the string
we're copying was just created from an snprintf() to a stack buffer, so
we might as well do that printf directly. This naturally leads to moving
the declaration of the str buffer inside the CONFIG_KALLSYMS guard,
which in turn will make gcc inline the function for !CONFIG_KALLSYMS (it
only has a single caller, but the huge stack frame seems to make gcc not
inline it for CONFIG_KALLSYMS).

Link: http://lkml.kernel.org/r/20181029223542.26175-4-linux@rasmusvillemoes.dk

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/trace_output.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index f06fb899b746..54373d93e251 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -341,8 +341,8 @@ static inline const char *kretprobed(const char *name)
 static void
 seq_print_sym(struct trace_seq *s, unsigned long address, bool offset)
 {
-	char str[KSYM_SYMBOL_LEN];
 #ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
 	const char *name;
 
 	if (offset)
@@ -352,12 +352,11 @@ seq_print_sym(struct trace_seq *s, unsigned long address, bool offset)
 	name = kretprobed(str);
 
 	if (name && strlen(name)) {
-		trace_seq_printf(s, "%s", name);
+		trace_seq_puts(s, name);
 		return;
 	}
 #endif
-	snprintf(str, KSYM_SYMBOL_LEN, "0x%08lx", address);
-	trace_seq_printf(s, "%s", str);
+	trace_seq_printf(s, "0x%08lx", address);
 }
 
 #ifndef CONFIG_64BIT
-- 
2.19.2