From nobody Thu Oct 2 07:43:31 2025 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 D26D22522BE; Fri, 19 Sep 2025 05:55:54 +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=1758261355; cv=none; b=dB+wc+82ninj4SOzUl65bwQSXWkq+Tn0KAR3uDzZr5Hn8AeyijPbTFRHxJCw05qJyDK6c9ZFtu4TIy30CKjchhnZeGXlfWMp6u9OMqPK+lcrnxKev/zSjQNn/wEhUzEC0RwQw1U2UoYBD/bhWkYq6eHpjjLRXNduruoaZlQZdYc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758261355; c=relaxed/simple; bh=fn2LTaeB7nmbRxugxeZG6nhXPDtiqg7HUccKWZc+oZI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=SK1/3VIcgVePtcz3v+l+St7UcA39jC5SyJjnqvOOZelJ7oWhLGPnvt5ex+8sxKh65AVabvI04vBT4lqdafsCg1CCBElani+pXgI++fG+pREdJK28eVjVILE4RSnK2MkVoavmye343nWRsW32pOe2nwAIcWJgx678teC+3nvuYPw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UP6W36si; 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="UP6W36si" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB283C4CEF0; Fri, 19 Sep 2025 05:55:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758261354; bh=fn2LTaeB7nmbRxugxeZG6nhXPDtiqg7HUccKWZc+oZI=; h=From:To:Cc:Subject:Date:From; b=UP6W36si3ug6giUmM3i4niYCh2tXKVWIYS9y/iIMkTkw9waIFEbmpCXU73ST69vtT 06S970dwx0vhudb+mQO7ztJ1sB8iszjnGmDX9AjUo+BUfkFE8Yq1dRwaGLdGJCqqs4 MbVvJXCAQiX7CNJbaET6J24nsEaiBUuW9mZ2a2bKyp3oLJ+MZ/LVNrBFyWuen0PYzO kVGW7sSAn5OXt7QpJaf2DR01NdtZaJz3DL4oFb1KvbH2uf00FyvUGoKWY2Va8JdKIf p8b7jI/Was7FW6t1wiVVXQ3MZLjJYfxseopvYyf434aiA2CZcGmcv28s+zZoWXVr4L uD+5Q9RweiEFg== 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] tracing: Add an option to show symbols in _text+offset for function profiler Date: Fri, 19 Sep 2025 14:55:50 +0900 Message-ID: <175826135058.101165.7219957344129610147.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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) --- kernel/trace/ftrace.c | 26 +++++++++++++++++++++++++- kernel/trace/trace.c | 5 +++-- kernel/trace/trace.h | 10 +++++++++- 3 files changed, 37 insertions(+), 4 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index a69067367c29..c759cc392fbe 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -534,7 +534,9 @@ static int function_stat_headers(struct seq_file *m) =20 static int function_stat_show(struct seq_file *m, void *v) { + struct trace_array *tr =3D trace_get_global_array(); struct ftrace_profile *rec =3D v; + const char *refsymbol =3D 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 =20 - 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 =3D "_text"; + offset =3D rec->ip - (unsigned long)_text; + } else { + struct module *mod; + + guard(rcu)(); + mod =3D __module_text_address(rec->ip); + if (mod) { + refsymbol =3D mod->name; + /* Calculate offset from module's text entry address. */ + offset =3D 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); =20 #ifdef CONFIG_FUNCTION_GRAPH_TRACER diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b3c94fbaf002..bd82b28b8d2b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -522,7 +522,8 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export); =20 /* 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) =20 /* trace_flags that are default zero for instances */ #define ZEROED_TRACE_FLAGS \ @@ -11115,7 +11116,7 @@ __init static int tracer_alloc_buffers(void) =20 #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 5f4bed5842f9..f698aac73b14 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1359,6 +1359,13 @@ extern int trace_get_user(struct trace_parser *parse= r, const char __user *ubuf, # define STACK_FLAGS #endif =20 +#ifdef CONFIG_FUNCTION_PROFILER +# define PROFILER_FLAGS \ + C(PROF_TEXT_OFFSET, "prof-text-offset"), +#else +# define PROFILER_FLAGS +#endif + /* * trace_iterator_flags is an enumeration that defines bit * positions into trace_flags that controls the output. @@ -1397,7 +1404,8 @@ 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 =20 /* * By defining C, we can make TRACE_FLAGS a list of bit names