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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable 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 D9D99C31E4B for ; Fri, 14 Jun 2019 20:59:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ACA4B2168B for ; Fri, 14 Jun 2019 20:59:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="t+C/+5N1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726435AbfFNU6q (ORCPT ); Fri, 14 Jun 2019 16:58:46 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:46451 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726028AbfFNU6p (ORCPT ); Fri, 14 Jun 2019 16:58:45 -0400 Received: by mail-pf1-f195.google.com with SMTP id 81so2102224pfy.13; Fri, 14 Jun 2019 13:58:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Xq4ZMKmqaYESp+y/yJJJP8yO0vJ9LIM89P2olkrziRk=; b=t+C/+5N1BeFF0+8rA+KyhTRzSjhvhsOZcJrTvQXMr5WlSBGoIt/6KaEULswU39rYbL jN6F1y5z7P0gOqPXmMrC0z5Fd+mFOPHkpOABh/6vWy10SoS9cpgo3nvRx6S6l3IYC7FZ Fwe+c2wfbO0ppAsuwkfV6/N9L85bqc/PlhBFEirifKfo07LrOjvTI5U06tYykJeZKR2T fTAV3dpF3nRcPGi9IK2cr5htjIWYV+nbOTYMzvTkN9I0aKSlr7JWFLiNogysBtpcTVXJ hmBLwzHOYPNKDw0zCIkJYwku/Gcdtqf7lYBSmuDcP9XV45MFiMUWLlTXd9+CWrJcUb7Q lX3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Xq4ZMKmqaYESp+y/yJJJP8yO0vJ9LIM89P2olkrziRk=; b=aRpMT8P1ptBFKjEGBdtx6kGezUPLuvBqXmpWn3DRqklDzDYTlloimQPc7eMXWNDh1O x/WkKbmxMY0ayG+9Yah36pXUGXepkiX0WNS0xDBpPo6k1QfbuJO5+rxvvzMqCFtdcXZZ DgiilVLHgIVdQCRI/hrRRtBOV1cY79mp6UquglpcMai0IMUCcP8gSs8QTGv3Ej+6mhmP Q90nZgjCQJON3MVeQcrc+sgC/o3s5dEJPnXVCmVoSSdObw/MnQ8U0zLkNqgiZIN2/rkU ktktPQO/LZsPRwVuj9BBnO5Z0BOXxLQnqY8DEWut+lK37l35fM9isXKLB18R6yEyYPRt LsKw== X-Gm-Message-State: APjAAAXgxLRUknPmdnKugvKzAfQp23D/IjGB++6dEKhsyqbR3E27+etr FRsMqB40JY2HvRqW+PZREJ4= X-Google-Smtp-Source: APXvYqyfietE6hYnW8A2nm9Oi7jLNJHkHCuwiYicck1X2QlqdRn7NU8fr62322sbEDeDmYSqFm8jqQ== X-Received: by 2002:a63:6142:: with SMTP id v63mr38145069pgb.309.1560545924079; Fri, 14 Jun 2019 13:58:44 -0700 (PDT) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:200::1:6345]) by smtp.gmail.com with ESMTPSA id l2sm3340105pgs.33.2019.06.14.13.58.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Jun 2019 13:58:43 -0700 (PDT) Date: Fri, 14 Jun 2019 13:58:42 -0700 From: Alexei Starovoitov To: Josh Poimboeuf Cc: x86@kernel.org, Alexei Starovoitov , linux-kernel@vger.kernel.org, Daniel Borkmann , netdev@vger.kernel.org, bpf@vger.kernel.org, Peter Zijlstra , Song Liu , Kairui Song , Steven Rostedt , David Laight , Thomas Gleixner , Borislav Petkov , Ingo Molnar Subject: Re: [PATCH v2 2/5] objtool: Fix ORC unwinding in non-JIT BPF generated code Message-ID: <20190614205841.s4utbpurntpr6aiq@ast-mbp.dhcp.thefacebook.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180223 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Jun 14, 2019 at 12:56:41PM -0500, Josh Poimboeuf wrote: > Objtool currently ignores ___bpf_prog_run() because it doesn't > understand the jump table. This results in the ORC unwinder not being > able to unwind through non-JIT BPF code. > > Luckily, the BPF jump table resembles a GCC switch jump table, which > objtool already knows how to read. > > Add generic support for reading any static local jump table array named > "jump_table", and rename the BPF variable accordingly, so objtool can > generate ORC data for ___bpf_prog_run(). > > Fixes: d15d356887e7 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER") > Reported-by: Song Liu > Signed-off-by: Josh Poimboeuf > Acked-by: Peter Zijlstra (Intel) > --- > kernel/bpf/core.c | 5 ++--- > tools/objtool/check.c | 16 ++++++++++++++-- > 2 files changed, 16 insertions(+), 5 deletions(-) > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 7c473f208a10..aa546ef7dbdc 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]; > > /* ALU */ > #define ALU(OPCODE, OP) \ > @@ -1558,7 +1558,6 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) > BUG_ON(1); > return 0; > } > -STACK_FRAME_NON_STANDARD(___bpf_prog_run); /* jump table */ > > #define PROG_NAME(stack_size) __bpf_prog_run##stack_size > #define DEFINE_BPF_PROG_RUN(stack_size) \ > diff --git a/tools/objtool/check.c b/tools/objtool/check.c > index 172f99195726..8341c2fff14f 100644 > --- a/tools/objtool/check.c > +++ b/tools/objtool/check.c > @@ -18,6 +18,8 @@ > > #define FAKE_JUMP_OFFSET -1 > > +#define JUMP_TABLE_SYM_PREFIX "jump_table." since external tool will be looking at it should it be named "bpf_jump_table." to avoid potential name conflicts? Or even more unique name? Like "bpf_interpreter_jump_table." ?