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 14855446B8; Thu, 29 Feb 2024 07:13:24 +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=1709190805; cv=none; b=p6lmd6WfsVkv8V8EhFuiCZd4qyXAR9UR4exEcOJIS9OrB55CBMVN0Zd1KbczT3HszLEhG+os1jT604Q/naEdnncUtK6DZVVPkad5jsTjHyLFe+4ll5abluIfQXC/hfHYiTZza8l/OkKQAe0pVhqcEWuXE6phoR7pSPgtWxahpTc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709190805; c=relaxed/simple; bh=sTFRZabajf/krYk3PM4o4UwGsA4jCPH/kYX/YIBaFFQ=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=rrou+qyt/mZB5i6rY5HjB2GFYmu6UMU3/LcpUhAgwEd4c9Zu4+zUl8aykqOr0l00V2QjOaY1o5AISgPbM5x+zONjMpQMkG6puRABdnaUn6RCS1g77m8sWIoVMsmshvVR9GH24SpsNrEPe0V7V3VsvjdV2CwDpeazsjhwQbiiw2I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OUGlU738; 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="OUGlU738" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 98225C433F1; Thu, 29 Feb 2024 07:13:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709190804; bh=sTFRZabajf/krYk3PM4o4UwGsA4jCPH/kYX/YIBaFFQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OUGlU738hUpRVx01d84rqAhOzR10pyvcWXzBPl3tO/bB0Ve/kdCrehO4Nvx7CNknc zrpXNjLeKSA8R10DDUlU9Euuer0LPnly3RInbJbxAd3H7CTMDjQUXxjB6PzSbM64UQ 94U86xoToN7HwCt8P917HtYwhQdXb1ENvc6Dj5pdtv/I0KC2QZfhVqYj8HyVtbBHtI L40MwM5UeB/+WMvCHr3E7OZ7koK23UXGBLX/alScaAmG5kFCKjKboruwtYlov6xQOa diSK0jIl+0u04MeA5uel3UHKZA8Cz6573rDBfoiZcAj0nZlS/+zZKnm1jFzoJffcKA tw+pk4LjuB1yg== Date: Thu, 29 Feb 2024 16:13:20 +0900 From: Masami Hiramatsu (Google) To: Masami Hiramatsu (Google) Cc: Jiri Olsa , Steven Rostedt , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 0/7] tracing/probes: Support function parameter access from return probe Message-Id: <20240229161320.978190f42dcc1a521c192e7d@kernel.org> In-Reply-To: <20240229153855.6fe3fb454cf56eebc6ea9953@kernel.org> References: <170891987362.609861.6767830614537418260.stgit@devnote2> <20240229145139.a215085c44add62302463312@kernel.org> <20240229153855.6fe3fb454cf56eebc6ea9953@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 29 Feb 2024 15:38:55 +0900 Masami Hiramatsu (Google) wrote: > Hmm, this seems arch_rethook_trampoline caused the issue. > > And curiously, it depends on the number of stored data. > > OK: > /sys/kernel/tracing # echo 'f vfs_read%return $arg1 $arg2 $arg3' >> dynamic_events > /sys/kernel/tracing # echo 1 > events/fprobes/enable > > NG: > /sys/kernel/tracing # echo 'f vfs_read%return $arg1 $arg2 $arg3 $arg4' >> dynamic_events > /sys/kernel/tracing # echo 1 > events/fprobes/enable > > I also confirmed that on 'vfs_write' caused the same result. 3 arguments(24 bytes) is OK, > but 4 arguments (32bytes) is NG. And this may be the fprobe bug. kretprobe events doesn't show this issue. OK: /sys/kernel/tracing # echo 'r vfs_read $arg*' >> kprobe_events /sys/kernel/tracing # echo 1 > events/kprobes/enable But this is strange because both uses same rethook... Thank you, -- Masami Hiramatsu (Google)