From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BBC4E7262B; Mon, 13 Jul 2026 02:16:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783908989; cv=none; b=jWSxvvr7p2MIkFBo3AmyRSsxkOhn/9s/zJVJrmKS4JzXEfrqvSvIByPuXjgCvA+6M3o0CLkNrWTkGnwajSAJsgRZsgjhkZzskhoraO7MttyVqm5hB6jsYbt2mssV487GpwHB+bzsheulnGMue38L5DcBLDloer+fXodN/PEqnqw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783908989; c=relaxed/simple; bh=dGF7xPfKvWbgXDdOai1l5M80C/P3hvIHfMKdaVHUE6c=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=NNQjgslskxFOKFzRQwB5iQ1WNp1JyueAdVAsgmnfTif16yIi+u65Unkvj4ldmAqPC0IhkNaHyXFqEpmbrtQch4ktrPm77zKrRbCP2wFENE/9H/ZRz/Wp0xs6aH5bVxNObCR2+gR+ng2CUA0oEAQZynQ/odfO3tZ+R2DK/odImbc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jR3FcJwl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jR3FcJwl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7F3D1F000E9; Mon, 13 Jul 2026 02:16:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783908987; bh=br9FhVYJuPRVoM9lVCAAChWOr0wLAcBU1znUuGfC0yc=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=jR3FcJwlDRti3QVIqRaiPv4Zm+2+TGc1dcjjVxG/8zGXzm0KoYX90rnA4ZmX2GyEn adYWCj22e+XxSrBbiZlHg+V38A5Zbj3u3MW8oPoR7uXoO57O1UxHdc8j+y8a1/NCbP RzqvCKk7nyX3XMBMnjc8rrd9+YXJxju7a0C/HP4yYBSYOPxg5gI1BdfDONQsLvTplu +1hIfghtwvt7gpOMqS1RVUknFeYTcVKOJfxXasS9iC/lrFhKL0jqxIB4ikSatdxpuT QaGjuZAEQVwpOWv0EeqLd32dl6VKTHAtkdbV+vFpXLgPM5mhd4eMpc3KZkou5GTwGC QDIoT+tjgUDfA== Date: Mon, 13 Jul 2026 11:16:23 +0900 From: Masami Hiramatsu (Google) To: "Masami Hiramatsu (Google)" Cc: Steven Rostedt , Shuah Khan , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 4/5] tracing/probes: Extend max length of argument string Message-Id: <20260713111623.bae8f26476740a0467b03521@kernel.org> In-Reply-To: <178386880215.3174487.982264935084717241.stgit@devnote2> References: <178386876526.3174487.5142283230157728964.stgit@devnote2> <178386880215.3174487.982264935084717241.stgit@devnote2> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 13 Jul 2026 00:06:42 +0900 "Masami Hiramatsu (Google)" wrote: > From: Masami Hiramatsu > > To support BTF argument parsing (such as accessing fields within nested > structures via typecasting), the maximum argument string length needs > to be extended. Extend MAX_ARGSTR_LEN from 63 to 256. > > Since MAX_ARGSTR_LEN was previously reused to format command heads in > trace_*probe_match_command_head() functions, introduce a dedicated > MAX_COMMON_HEAD_LEN (63) macro for matching command heads and switch > these functions to use the new macro. > > Assisted-by: Antigravity:gemini-3.5-flash > Signed-off-by: Masami Hiramatsu (Google) Sashiko asked to extend other macros, > Does this code also need to increase MAX_BTF_ARGS_LEN and MAX_DENTRY_ARGS_LEN? I don't agree this. MAX_BTF_ARGS_LEN is only for expanding "$args" into each parameter names. The other arguments are kept on the same memory. MAX_DENTRY_ARGS_LEN is already 256, so I think if that is too long, it should be rejected. (But MAX_ARGSTR_LEN should be 255.) BTW, both macro names are a bit complicated because those are just buffer size, not max length of something. Thank you, > --- > kernel/trace/trace_fprobe.c | 2 +- > kernel/trace/trace_kprobe.c | 2 +- > kernel/trace/trace_probe.h | 3 ++- > kernel/trace/trace_uprobe.c | 2 +- > .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 2 +- > .../ftrace/test.d/dynevent/tprobe_syntax_errors.tc | 2 +- > .../ftrace/test.d/kprobe/kprobe_syntax_errors.tc | 2 +- > 7 files changed, 8 insertions(+), 7 deletions(-) > > diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c > index 536781cd4c47..5638a90e61cc 100644 > --- a/kernel/trace/trace_fprobe.c > +++ b/kernel/trace/trace_fprobe.c > @@ -238,7 +238,7 @@ static bool trace_fprobe_is_busy(struct dyn_event *ev) > static bool trace_fprobe_match_command_head(struct trace_fprobe *tf, > int argc, const char **argv) > { > - char buf[MAX_ARGSTR_LEN + 1]; > + char buf[MAX_COMMON_HEAD_LEN + 1]; > > if (!argc) > return true; > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index cfa807d8e760..cc24e992732c 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -149,7 +149,7 @@ static bool trace_kprobe_is_busy(struct dyn_event *ev) > static bool trace_kprobe_match_command_head(struct trace_kprobe *tk, > int argc, const char **argv) > { > - char buf[MAX_ARGSTR_LEN + 1]; > + char buf[MAX_COMMON_HEAD_LEN + 1]; > > if (!argc) > return true; > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h > index e64e323244a5..e6aee800a7d9 100644 > --- a/kernel/trace/trace_probe.h > +++ b/kernel/trace/trace_probe.h > @@ -32,7 +32,8 @@ > #include "trace_output.h" > > #define MAX_TRACE_ARGS 128 > -#define MAX_ARGSTR_LEN 63 > +#define MAX_ARGSTR_LEN 256 > +#define MAX_COMMON_HEAD_LEN 63 > #define MAX_ARRAY_LEN 64 > #define MAX_ARG_NAME_LEN 32 > #define MAX_BTF_ARGS_LEN 128 > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c > index b2e264a4b96c..67bd8fd91e3e 100644 > --- a/kernel/trace/trace_uprobe.c > +++ b/kernel/trace/trace_uprobe.c > @@ -281,7 +281,7 @@ static bool trace_uprobe_is_busy(struct dyn_event *ev) > static bool trace_uprobe_match_command_head(struct trace_uprobe *tu, > int argc, const char **argv) > { > - char buf[MAX_ARGSTR_LEN + 1]; > + char buf[MAX_COMMON_HEAD_LEN + 1]; > int len; > > if (!argc) > diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc > index e9d7e6919c7f..984ab94df213 100644 > --- a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc > +++ b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc > @@ -75,7 +75,7 @@ check_error 'f vfs_read ^arg123456789012345678901234567890=@11' # ARG_NAME_TOO_L > check_error 'f vfs_read ^=@11' # NO_ARG_NAME > check_error 'f vfs_read ^var.1=@11' # BAD_ARG_NAME > check_error 'f vfs_read var1=@11 ^var1=@12' # USED_ARG_NAME > -check_error 'f vfs_read ^+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(@1234))))))' # ARG_TOO_LONG > +check_error 'f vfs_read ^+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(@1234))))))))))))))))))))))))))' # ARG_TOO_LONG > check_error 'f vfs_read arg1=^' # NO_ARG_BODY > > > diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/tprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/tprobe_syntax_errors.tc > index ffe8ffef4027..2d0905b2c8b7 100644 > --- a/tools/testing/selftests/ftrace/test.d/dynevent/tprobe_syntax_errors.tc > +++ b/tools/testing/selftests/ftrace/test.d/dynevent/tprobe_syntax_errors.tc > @@ -61,7 +61,7 @@ check_error 't kfree ^arg123456789012345678901234567890=@11' # ARG_NAME_TOO_LOG > check_error 't kfree ^=@11' # NO_ARG_NAME > check_error 't kfree ^var.1=@11' # BAD_ARG_NAME > check_error 't kfree var1=@11 ^var1=@12' # USED_ARG_NAME > -check_error 't kfree ^+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(@1234))))))' # ARG_TOO_LONG > +check_error 't kfree ^+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(@1234))))))))))))))))))))))))))' # ARG_TOO_LONG > check_error 't kfree arg1=^' # NO_ARG_BODY > > > diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc > index 21ce8414459f..d28f63b7e8a9 100644 > --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc > +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc > @@ -71,7 +71,7 @@ check_error 'p vfs_read ^arg123456789012345678901234567890=@11' # ARG_NAME_TOO_L > check_error 'p vfs_read ^=@11' # NO_ARG_NAME > check_error 'p vfs_read ^var.1=@11' # BAD_ARG_NAME > check_error 'p vfs_read var1=@11 ^var1=@12' # USED_ARG_NAME > -check_error 'p vfs_read ^+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(@1234))))))' # ARG_TOO_LONG > +check_error 'p vfs_read ^+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(+1234567(@1234))))))))))))))))))))))))))' # ARG_TOO_LONG > check_error 'p vfs_read arg1=^' # NO_ARG_BODY > > # instruction boundary check is valid on x86 (at this moment) > -- Masami Hiramatsu (Google)