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 X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8598AC48BD6 for ; Thu, 27 Jun 2019 01:07:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 425A521726 for ; Thu, 27 Jun 2019 01:07:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726873AbfF0BHD (ORCPT ); Wed, 26 Jun 2019 21:07:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32852 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726373AbfF0BHD (ORCPT ); Wed, 26 Jun 2019 21:07:03 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 70C99308A963; Thu, 27 Jun 2019 01:07:01 +0000 (UTC) Received: from treble (ovpn-126-66.rdu2.redhat.com [10.10.126.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E21701001284; Thu, 27 Jun 2019 01:06:55 +0000 (UTC) Date: Wed, 26 Jun 2019 20:06:53 -0500 From: Josh Poimboeuf To: Alexei Starovoitov Cc: X86 ML , LKML , Peter Zijlstra , Song Liu , Kairui Song , Steven Rostedt , Thomas Gleixner , Borislav Petkov , Ingo Molnar Subject: Re: [PATCH v3 3/4] bpf: Fix ORC unwinding in non-JIT BPF code Message-ID: <20190627010653.yovvztgmimaywaz5@treble> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 27 Jun 2019 01:07:03 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 26, 2019 at 05:57:08PM -0700, Alexei Starovoitov wrote: > On Wed, Jun 26, 2019 at 5:36 PM Josh Poimboeuf wrote: > > > > Objtool previously ignored ___bpf_prog_run() because it didn't > > understand the jump table. This resulted in the ORC unwinder not being > > able to unwind through non-JIT BPF code. > > > > Now that objtool knows how to read jump tables, remove the whitelist and > > rename the variable to "jump_table" so objtool can recognize it. > > > > Fixes: d15d356887e7 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER") > > Reported-by: Song Liu > > Signed-off-by: Josh Poimboeuf > > --- > > kernel/bpf/core.c | 5 ++--- > > 1 file changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > > index 080e2bb644cc..ff66294882f8 100644 > > --- a/kernel/bpf/core.c > > +++ b/kernel/bpf/core.c > > @@ -1299,7 +1299,7 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) > > { > > #define BPF_INSN_2_LBL(x, y) [BPF_##x | BPF_##y] = &&x##_##y > > #define BPF_INSN_3_LBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = &&x##_##y##_##z > > - static const void *jumptable[256] = { > > + static const void *jump_table[256] = { > > [0 ... 255] = &&default_label, > > /* Now overwrite non-defaults ... */ > > BPF_INSN_MAP(BPF_INSN_2_LBL, BPF_INSN_3_LBL), > > @@ -1315,7 +1315,7 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) > > #define CONT_JMP ({ insn++; goto select_insn; }) > > > > select_insn: > > - goto *jumptable[insn->code]; > > + goto *jump_table[insn->code]; > > I thought we were clear that it is a nack? > Either live it alone or rename to something like jump_table_bpf_interpreter > or bpf_interpreter_jump_table. As I have said many times: The jump table detection is a generic objtool feature. It makes no sense to give a bpf-specific name to a generic objtool feature which can be used by other components. -- Josh