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=-6.6 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,URIBL_BLOCKED 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 EFC45C31E4B for ; Fri, 14 Jun 2019 21:09:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BCD5421473 for ; Fri, 14 Jun 2019 21:09:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JZgmpSN5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726046AbfFNVJj (ORCPT ); Fri, 14 Jun 2019 17:09:39 -0400 Received: from mail-lf1-f67.google.com ([209.85.167.67]:38794 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725808AbfFNVJj (ORCPT ); Fri, 14 Jun 2019 17:09:39 -0400 Received: by mail-lf1-f67.google.com with SMTP id b11so2631637lfa.5; Fri, 14 Jun 2019 14:09:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=v+qcQqKKiwG5w/oU+IdQmrJep2NZINj+7oHHR2xuPAs=; b=JZgmpSN5yYfkYncJcrElvwgj4OEKjnzhrx8Y+npBWHEEuKFlCyctIyLRfaU938eSkm ydMtdUPeeOfgQQURVMKfqK5NKTdU7LHNx1zVxE2GWcRDWX37vp7FI5rGwoLG8xJTfTDx LBxaxJUIE3LoGGZv72sycp+bIzdufJ0YNeriF14LBX3Jcvv1KWD8c99rc3pewjd+sta/ ItdO9veSuvCL165PQEk67A/nFrfZQvVm/yVCR/or0MYXrg3B1JbsmUqYESQ6Tl0JvrJd CeffGRnQXnZAnccg16IAk4p0kQ19Q9mil9ZnsQqxy4XPWGAn/1N1/v8xaJbtOpF4zM+1 UJgw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=v+qcQqKKiwG5w/oU+IdQmrJep2NZINj+7oHHR2xuPAs=; b=bNY2PgJVMhTvF3mlxEnxx1n7zaVtFom7gvuQBGRZq5GuahRbkhBdXJwMk1VN9azAac ClmMpOL0oack2D8treazh7zztGKFWb+cXkHMU7P+6dVOtr7lHtb4FdR2Q6iy/T1gSV3b cKwD6xpnQFJZXIRPdeNu0DvsnoQ9+E5xMKxwfS0tBoWtQY+bf2defC8ukS0cegRMGZ2R xnIOx0LaFuK8jVDq4L98mB04i6KVFeIOqBRPLNm7rTzcFV1lvqFRAtlysXd3O8eAflkn M5L5hKAzWqMKfH5/MtMSB/Jw2zgc0+/bbYohvT0TFy4FkpGi8RjHZxiXmYUVkm61WL3A ll2w== X-Gm-Message-State: APjAAAW6ML8TawHMIjDCgTYO3cuf1lTFn0l2SZD/BI7XvnN35+iPTi0k 9v/udD1VtBJnE/PBjI2OsZQ3nZx/+M+cRszshm0= X-Google-Smtp-Source: APXvYqwq3u11dKxHDI2QG+IVfwb5B8nZjpa6KleNqVDZBV7nlRkSDMvzbqX2F0p7SNA9c9JGRz7K0eBuO85AA8OMvew= X-Received: by 2002:a19:dc45:: with SMTP id f5mr19270731lfj.162.1560546576551; Fri, 14 Jun 2019 14:09:36 -0700 (PDT) MIME-Version: 1.0 References: <20190614205841.s4utbpurntpr6aiq@ast-mbp.dhcp.thefacebook.com> <20190614210745.kwiqm5pkgabruzuj@treble> In-Reply-To: <20190614210745.kwiqm5pkgabruzuj@treble> From: Alexei Starovoitov Date: Fri, 14 Jun 2019 14:09:25 -0700 Message-ID: Subject: Re: [PATCH v2 2/5] objtool: Fix ORC unwinding in non-JIT BPF generated code To: Josh Poimboeuf Cc: X86 ML , Alexei Starovoitov , LKML , Daniel Borkmann , Network Development , bpf , Peter Zijlstra , Song Liu , Kairui Song , Steven Rostedt , David Laight , Thomas Gleixner , Borislav Petkov , Ingo Molnar Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Jun 14, 2019 at 2:07 PM Josh Poimboeuf wrote: > > On Fri, Jun 14, 2019 at 01:58:42PM -0700, Alexei Starovoitov wrote: > > 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." ? > > No, the point is that it's a generic feature which can also be used any > non-BPF code which might also have a jump table. and you're proposing to name all such jump tables in the kernel as static foo jump_table[] ?