From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 D796B2E5B19 for ; Mon, 8 Dec 2025 10:29:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765189770; cv=none; b=fvCCCyI/sSZnOrkZZfzw5wobyiixsVwo91PfW+vDa8MHqKx1qZoPcD6UZE6pG6QZx4ZNfPIJvC2HAxoU7RzahgdIcaXhzVFWhIrrM3Srcha8VN1Q2zlmHRiJhn0QPD25LspAQ05ZBrqDdmpac8JIVJnuxUbilnJQDiHvqO2hQks= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765189770; c=relaxed/simple; bh=Lai2720BhSwYhpwgkcvbksu2hyCojtOkg28bQeIJf4Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mL5PlY4IgIDDpqmzHTBEmvQwsMuoPJGWyuA3HIFvLQSfVVVOKIFIAButvRLKVL1olOhSp2VOM8pFZmicQhiguewwAK+0v43725JHnYgOHkznG1yOa7KB99DjqhixCdM+tKyF5/1Kv1NHM+a82A3IHzffACmnFtuUs102Fnp/Bhs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Rl6NRuOC; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Rl6NRuOC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1765189767; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Lai2720BhSwYhpwgkcvbksu2hyCojtOkg28bQeIJf4Q=; b=Rl6NRuOCx3epes229VYIwW9/dO/i+4C24SUDgkKDRQuyjWCTOLi5UEuQZBmBB996qTux2h v2VNRQEtbsfMnBVfmJp9VUn00Qlsa497+/LJqY+ly5Idib9JB/aen/qU3VgzrxXmennE3F uesgu7uTq0KCx1uh0/bzN9aqfqnsUZk= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-677-Puq_hxsiMPi3trjBsX9Jew-1; Mon, 08 Dec 2025 05:29:19 -0500 X-MC-Unique: Puq_hxsiMPi3trjBsX9Jew-1 X-Mimecast-MFC-AGG-ID: Puq_hxsiMPi3trjBsX9Jew_1765189757 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 049101956054; Mon, 8 Dec 2025 10:29:17 +0000 (UTC) Received: from fedora (unknown [10.45.224.91]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id E6D9F19560B0; Mon, 8 Dec 2025 10:29:10 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 8 Dec 2025 11:29:16 +0100 (CET) Date: Mon, 8 Dec 2025 11:29:09 +0100 From: Oleg Nesterov To: Masami Hiramatsu Cc: Jiri Olsa , Peter Zijlstra , Andrii Nakryiko , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Steven Rostedt , Ingo Molnar , David Laight Subject: Re: [RFC PATCH 0/8] uprobe/x86: Add support to optimize prologue Message-ID: References: <20251117124057.687384-1-jolsa@kernel.org> <20251208153056.3a4e9cd3511ccf00dc12e265@kernel.org> 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-Disposition: inline In-Reply-To: <20251208153056.3a4e9cd3511ccf00dc12e265@kernel.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On 12/08, Masami Hiramatsu wrote: > > On Mon, 24 Nov 2025 19:12:42 +0100 > Oleg Nesterov wrote: > > > On 11/17, Jiri Olsa wrote: > > > > > > There's an additional issue that single instruction replacement does > > > not have and it's the possibility of the user space code to jump in the > > > middle of those 5 bytes. I think it's unlikely to happen at the function > > > prologue, but uprobe could be placed anywhere. I'm not sure how to > > > mitigate this other than having some enable/disable switch or config > > > option, which is unfortunate. > > > > plus this breaks single-stepping... Although perhaps we don't really care. > > Yeah, and I think we can stop optimization if post_handler is set. Hmm, why? This doesn't depend on whether ->ret_handler is set or not... Oleg.