From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBB6734B1B9; Wed, 22 Oct 2025 15:38:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761147496; cv=none; b=dOxEOFpfT8tu6Yt5X7DkHppYXG36gW2daHAWn2EByoja22FoJ0z5Un5ozMxphFuRObjAy/D74q5w5yaoCY/PD+w/RWTw0SdyuGd2QNqmKFTgNr+YjS29j+iy7MyqtCZ8rd5Cmr8ciV4Lb0oteGz0ZnQ/5RSFKC5OwEtjqzWRmEs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761147496; c=relaxed/simple; bh=5j3VT4KbSbX3c/BR4MZ9uVywTdekrN/AOdAmM6O2aew=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=DzvMnBfGrue3f8Zvv6HP4te6jkEPChXva0tIwU2QKYkkPQl6DGfbfqtW6ba0+3wwvswEHvcOSKG7RgcZqJllVqpbhSXOv0jCfebxYzM7miTUKwTawo34yEWQdt9CV3wKcL6ZSw9vwOvOrtb/XbsCh/zBbTMC5PpdmypnuDEmRew= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vMg9BSYN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vMg9BSYN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D29D6C4CEF5; Wed, 22 Oct 2025 15:38:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761147495; bh=5j3VT4KbSbX3c/BR4MZ9uVywTdekrN/AOdAmM6O2aew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vMg9BSYN2/xNd1NB2O35nlZOiUKGC3V0NTHE0nJggna/uwMALGS+GIFJFYzMX0xX4 YgBgoGjasV9BRmYoSblhaP0lsP97EKl0qYulUw94Quy+x9ikm9M79ICmFf08ZHwg+r U2ITffkpWaVNVSmDQXufTSuTWqqW6gEcz3UjppVhe/O8l42OvpHRg50OUN4c5ASZt0 kzV+ZaNXOzmg4L2s+OaDKEctAvtSqLNDYbrX7R6WVINUvNkp1r2XR38foPckR70lxN InYJh+zAqY2Tl9M03YIEAzhH1b2zi2+/B+iDyE2ysrxVch9fxlaDx5DvAn4wPSxaQd ixfBBk3euuvxQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v5 2/2] tracing: Add an option to show symbols in _text+offset for function profiler Date: Thu, 23 Oct 2025 00:38:11 +0900 Message-ID: <176114749146.315239.7968358300215825393.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <176114747153.315239.6863821259073466010.stgit@devnote2> References: <176114747153.315239.6863821259073466010.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit From: Masami Hiramatsu (Google) Function profiler shows the hit count of each function using its symbol name. However, there are some same-name local symbols, which we can not distinguish. To solve this issue, this introduces an option to show the symbols in "_text+OFFSET" format. This can avoid exposing the random shift of KASLR. The functions in modules are shown as "MODNAME+OFFSET" where the offset is from ".text". E.g. for the kernel text symbols, specify vmlinux and the output to addr2line, you can find the actual function and source info; $ addr2line -fie vmlinux _text+3078208 __balance_callbacks kernel/sched/core.c:5064 for modules, specify the module file and .text+OFFSET; $ addr2line -fie samples/trace_events/trace-events-sample.ko .text+8224 do_simple_thread_func samples/trace_events/trace-events-sample.c:23 Suggested-by: Steven Rostedt (Google) Signed-off-by: Masami Hiramatsu (Google) --- Changes in v5: - Update dummy flag according to new macros. Changes in v2: - Define a dummy TRACE_ITER_PROF_TEXT_OFFSET if CONFIG_FUNCTION_PROFILER=n. --- kernel/trace/ftrace.c | 26 +++++++++++++++++++++++++- kernel/trace/trace.c | 5 +++-- kernel/trace/trace.h | 11 ++++++++++- 3 files changed, 38 insertions(+), 4 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 00b76d450a89..a9ea2795506a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -534,7 +534,9 @@ static int function_stat_headers(struct seq_file *m) static int function_stat_show(struct seq_file *m, void *v) { + struct trace_array *tr = trace_get_global_array(); struct ftrace_profile *rec = v; + const char *refsymbol = NULL; char str[KSYM_SYMBOL_LEN]; #ifdef CONFIG_FUNCTION_GRAPH_TRACER static struct trace_seq s; @@ -554,7 +556,29 @@ static int function_stat_show(struct seq_file *m, void *v) return 0; #endif - kallsyms_lookup(rec->ip, NULL, NULL, NULL, str); + if (tr->trace_flags & TRACE_ITER(PROF_TEXT_OFFSET)) { + long offset; + + if (core_kernel_text(rec->ip)) { + refsymbol = "_text"; + offset = rec->ip - (unsigned long)_text; + } else { + struct module *mod; + + guard(rcu)(); + mod = __module_text_address(rec->ip); + if (mod) { + refsymbol = mod->name; + /* Calculate offset from module's text entry address. */ + offset = rec->ip - (unsigned long)mod->mem[MOD_TEXT].base; + } + } + if (refsymbol) + snprintf(str, sizeof(str), " %s%+ld", refsymbol, offset); + } + if (!refsymbol) + kallsyms_lookup(rec->ip, NULL, NULL, NULL, str); + seq_printf(m, " %-30.30s %10lu", str, rec->counter); #ifdef CONFIG_FUNCTION_GRAPH_TRACER diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index bc7d56e8b920..08b9abc90182 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -522,7 +522,8 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export); /* trace_options that are only supported by global_trace */ #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER(PRINTK) | \ - TRACE_ITER(PRINTK_MSGONLY) | TRACE_ITER(RECORD_CMD)) + TRACE_ITER(PRINTK_MSGONLY) | TRACE_ITER(RECORD_CMD) | \ + TRACE_ITER(PROF_TEXT_OFFSET)) /* trace_flags that are default zero for instances */ #define ZEROED_TRACE_FLAGS \ @@ -11106,7 +11107,7 @@ __init static int tracer_alloc_buffers(void) #ifdef CONFIG_FUNCTION_TRACER /* Used to set module cached ftrace filtering at boot up */ -__init struct trace_array *trace_get_global_array(void) +struct trace_array *trace_get_global_array(void) { return &global_trace; } diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 50b4c06e37f0..49992026801d 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1353,6 +1353,14 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf, # define STACK_FLAGS #endif +#ifdef CONFIG_FUNCTION_PROFILER +# define PROFILER_FLAGS \ + C(PROF_TEXT_OFFSET, "prof-text-offset"), +#else +# define PROFILER_FLAGS +# define TRACE_ITER_PROF_TEXT_OFFSET_BIT -1 +#endif + /* * trace_iterator_flags is an enumeration that defines bit * positions into trace_flags that controls the output. @@ -1391,7 +1399,8 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf, FUNCTION_FLAGS \ FGRAPH_FLAGS \ STACK_FLAGS \ - BRANCH_FLAGS + BRANCH_FLAGS \ + PROFILER_FLAGS /* * By defining C, we can make TRACE_FLAGS a list of bit names