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 D45E247F5F for ; Sat, 6 Apr 2024 17:57:41 +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=1712426263; cv=none; b=Dk+VYpSMJvlrGS14UqR+WTbvwzUDtGuqYNVjAyX0VmEqYDH5r3J0KpFxtvR3p8ryxlKahMDNZre9OT/w9g7OzFVXkPmLZK/uDu+gKsuh8REIX6MRCAhN1PO5g01e7bJNOVQU8hhYH31kd527pcgEbgLkMiW4Tcx+4TTIbMineNE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712426263; c=relaxed/simple; bh=QCupe60Wi+dfmZCvC412Qmcmr7ZevvaEiPxSMLn4g/4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KjnBWHwDsIhJnK2Wbdd6ut1uQEZ3uGLCkddTYUjKhTa/G/w+3uvWQ+nejdOIYdJuKXiTUCNlCZbm1Hbv3Z2vsOtLeGFyYZDmYilDOo+h0gYs5l6jL/2wjw1EEJUi55CRAgSz1+qpeteFi7bIhV38OjUwgCjZbf/1of12p81XfiY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=ZU7db6c2; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="ZU7db6c2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712426260; 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=GReCWnFPjN08AjP0bPCM7WpKp2nC3psJcp83CUkmhh4=; b=ZU7db6c2wxXLUqXySolHAyrxiuTISTCiCoCIOFU1BQiurxy6TjFjvdxA0JPQ0ioBuSgZWH YfDcOVh70GBLbHQmaeK0xqcZOFHz/aOMukbOWJq4oyIqLnjMuA0v/WDb78EwUVO+izg1In e/ji7HO6TdkrdhL87deYv8un4/gBBwU= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-135-1Cg6l7qIPZ2PwNbQHHUDpg-1; Sat, 06 Apr 2024 13:57:34 -0400 X-MC-Unique: 1Cg6l7qIPZ2PwNbQHHUDpg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 32BB53C0F69A; Sat, 6 Apr 2024 17:57:33 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.136]) by smtp.corp.redhat.com (Postfix) with SMTP id F1667100F4D8; Sat, 6 Apr 2024 17:57:28 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sat, 6 Apr 2024 19:56:08 +0200 (CEST) Date: Sat, 6 Apr 2024 19:55:59 +0200 From: Oleg Nesterov To: Masami Hiramatsu Cc: Jiri Olsa , Andrii Nakryiko , Steven Rostedt , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Song Liu , Yonghong Song , John Fastabend , Peter Zijlstra , Thomas Gleixner , "Borislav Petkov (AMD)" , x86@kernel.org, linux-api@vger.kernel.org Subject: Re: [PATCHv2 1/3] uprobe: Add uretprobe syscall to speed up return probe Message-ID: <20240406175558.GC3060@redhat.com> References: <20240403230937.c3bd47ee47c102cd89713ee8@kernel.org> <20240404095829.ec5db177f29cd29e849169fa@kernel.org> <20240405005405.9bcbe5072d2f32967501edb3@kernel.org> <20240404161108.GG7153@redhat.com> <20240405102203.825c4a2e9d1c2be5b2bffe96@kernel.org> <20240405110230.GA22839@redhat.com> <20240406120536.57374198f3f45e809d7e4efa@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: <20240406120536.57374198f3f45e809d7e4efa@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 On 04/06, Masami Hiramatsu wrote: > > On Fri, 5 Apr 2024 13:02:30 +0200 > Oleg Nesterov wrote: > > > With or without this patch userpace can also do > > > > foo() { <-- retprobe1 > > bar() { > > jump to xol_area > > } > > } > > > > handle_trampoline() will handle retprobe1. > > This is OK because the execution path has been changed to trampoline, Agreed, in this case the misuse is more clear. But please see below. > but the above will continue running bar() after sys_uretprobe(). ... and most probably crash > > sigreturn() can be "improved" too. Say, it could validate sigcontext->ip > > and return -EINVAL if this addr is not valid. But why? > > Because sigreturn() never returns, but sys_uretprobe() will return. You mean, sys_uretprobe() returns to the next insn after syscall. Almost certainly yes, but this is not necessarily true. If one of consumers changes regs->sp sys_uretprobe() "returns" to another location, just like sys_rt_sigreturn(). That said. Masami, it is not that I am trying to prove that you are "wrong" ;) No. I see your points even if I am biased, I understand that my objections are not 100% "fair". I am just trying to explain why, rightly or not, I care much less about the abuse of sys_uretprobe(). Thanks! Oleg.