From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1ECE5C433EF for ; Mon, 25 Oct 2021 12:45:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F077860EE9 for ; Mon, 25 Oct 2021 12:45:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233243AbhJYMsK (ORCPT ); Mon, 25 Oct 2021 08:48:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233302AbhJYMsH (ORCPT ); Mon, 25 Oct 2021 08:48:07 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E320C061745; Mon, 25 Oct 2021 05:45:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=RIUrXxUV4UbEv2DGGHaNGcFcvRKSfANE71br1DygmXE=; b=kUsxMs1Z4n8b+0909nSn+49Any grB324UAZJIgSY8CEqFEGD9kDcJlSbAXEHEM5uF1VJfACLytS5tLr0AOW3iRjvNMzkzI4EkzcstfR +nFtDTfAKYaWhoHjLDm7S8ldi+sD8pS6e1DY/rZKvpXjLrZqT0/FNOiZ/vFWTU34FE/LrJ0+1yb/T of/8Eu0kWXkmohp69S/6d4RSNk+03UsI999j/TpKjxfDyZW/5dXeQFnqLpLs+VIg8PPDqNXoCV+aB Cn2AT1e+d447yMvQr2vnM+AET2VoTaVsfd7VVv4506Nki8Y58U29DajzAiA6IcccwvVXKCeEfJRHG Rh9XIiFQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mezJZ-00G7qw-94; Mon, 25 Oct 2021 12:43:12 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (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) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0556A3002AE; Mon, 25 Oct 2021 14:42:56 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E2B74212E25E6; Mon, 25 Oct 2021 14:42:55 +0200 (CEST) Date: Mon, 25 Oct 2021 14:42:55 +0200 From: Peter Zijlstra To: Maciej Fijalkowski Cc: Alexei Starovoitov , Josh Poimboeuf , X86 ML , Andrew Cooper , LKML , Nick Desaulniers , Daniel Borkmann , bpf , Andrii Nakryiko Subject: Re: [PATCH v2 14/14] bpf,x86: Respect X86_FEATURE_RETPOLINE* Message-ID: References: <20211021000502.ltn5o6ji6offwzeg@ast-mbp.dhcp.thefacebook.com> <20211021223719.GY174703@worktop.programming.kicks-ass.net> <20211021233852.gbkyl7wpunyyq4y5@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 25, 2021 at 03:44:24PM +0200, Maciej Fijalkowski wrote: > On Fri, Oct 22, 2021 at 08:22:35AM -0700, Alexei Starovoitov wrote: > > On Fri, Oct 22, 2021 at 4:33 AM Peter Zijlstra wrote: > > > > > > On Thu, Oct 21, 2021 at 04:42:12PM -0700, Alexei Starovoitov wrote: > > > > > > > Ahh. Right. It's potentially a different offset for every prog. > > > > Let's put it into struct jit_context then. > > > > > > Something like this... > > > > Yep. Looks nice and clean to me. > > > > > - poke->tailcall_bypass = image + (addr - poke_off - X86_PATCH_SIZE); > > > + poke->tailcall_bypass = ip + (prog - start); > > > poke->adj_off = X86_TAIL_CALL_OFFSET; > > > - poke->tailcall_target = image + (addr - X86_PATCH_SIZE); > > > + poke->tailcall_target = ip + ctx->tail_call_direct_label - X86_PATCH_SIZE; > > > > This part looks correct too, but this is Daniel's magic. > > He'll probably take a look next week when he comes back from PTO. > > I don't recall which test exercises this tailcall poking logic. > > It's only used with dynamic updates to prog_array. > > insmod test_bpf.ko and test_verifier won't go down this path. > > Please run ./test_progs -t tailcalls from tools/testing/selftests/bpf and > make sure that all of the tests are passing in there, especially the > tailcall_bpf2bpf* subset. Yeah, so nothing from that selftests crud wants to work for me; also I *really* dislike how vmtest.sh as found there tramples all over my source dir without asking. Note that even when eventually supplied with O=builddir (confusingly in front of it), it doesn't want to work and bails with lots of -ENOSPC warnings (I double checked, my disks are nowhere near full). (and this is after installing some horrendous python rst crap because clearly running a test needs to build documentation :/) I've spend hours on that, I'm not sinking more time into it. If you want me to run that crap, fix it first.