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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 9FE18C31E5D for ; Mon, 17 Jun 2019 14:57:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 827632084A for ; Mon, 17 Jun 2019 14:57:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728279AbfFQO5c convert rfc822-to-8bit (ORCPT ); Mon, 17 Jun 2019 10:57:32 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:32197 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726215AbfFQO5b (ORCPT ); Mon, 17 Jun 2019 10:57:31 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-190-hVB7mw-INdG5k3bducDmrQ-1; Mon, 17 Jun 2019 15:57:27 +0100 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b::d117) by AcuMS.aculab.com (fd9f:af1c:a25b::d117) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 17 Jun 2019 15:57:26 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 17 Jun 2019 15:57:26 +0100 From: David Laight To: 'Alexei Starovoitov' , 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 , "Thomas Gleixner" , Borislav Petkov , Ingo Molnar Subject: RE: [PATCH v2 2/5] objtool: Fix ORC unwinding in non-JIT BPF generated code Thread-Topic: [PATCH v2 2/5] objtool: Fix ORC unwinding in non-JIT BPF generated code Thread-Index: AQHVIvP1MMjmbNr75kSp44+RDLqGVaaf832A Date: Mon, 17 Jun 2019 14:57:26 +0000 Message-ID: <28948180f13343b3b7b1f58878cebe3e@AcuMS.aculab.com> References: <20190614205841.s4utbpurntpr6aiq@ast-mbp.dhcp.thefacebook.com> In-Reply-To: <20190614205841.s4utbpurntpr6aiq@ast-mbp.dhcp.thefacebook.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: hVB7mw-INdG5k3bducDmrQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Alexei Starovoitov > Sent: 14 June 2019 21:59 > > 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." ? If external code might need to process such symbols then jump_table_bpf_interpreter would (probably) make the symbols easier to locate. Oh, and blue is a good colour :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)