From patchwork Thu Jun 13 13:20:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josh Poimboeuf X-Patchwork-Id: 1115165 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45PnQc24xhz9sPp for ; Fri, 14 Jun 2019 01:16:56 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388612AbfFMPQw (ORCPT ); Thu, 13 Jun 2019 11:16:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35560 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732203AbfFMNXo (ORCPT ); Thu, 13 Jun 2019 09:23:44 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CE355300145F; Thu, 13 Jun 2019 13:23:39 +0000 (UTC) Received: from treble.redhat.com (ovpn-121-232.rdu2.redhat.com [10.10.121.232]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2C7A3541F0; Thu, 13 Jun 2019 13:23:35 +0000 (UTC) From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org, bpf@vger.kernel.org, Peter Zijlstra , Song Liu , Kairui Song Subject: [PATCH 2/9] objtool: Fix ORC unwinding in non-JIT BPF generated code Date: Thu, 13 Jun 2019 08:20:59 -0500 Message-Id: <99c22bbd79e72855f4bc9049981602d537a54e70.1560431531.git.jpoimboe@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Thu, 13 Jun 2019 13:23:44 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 --- 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." + struct alternative { struct list_head list; struct instruction *insn; @@ -997,6 +999,7 @@ static struct rela *find_switch_table(struct objtool_file *file, struct instruction *orig_insn = insn; struct section *rodata_sec; unsigned long table_offset; + struct symbol *sym; /* * Backward search using the @first_jump_src links, these help avoid @@ -1035,9 +1038,18 @@ static struct rela *find_switch_table(struct objtool_file *file, /* * Make sure the .rodata address isn't associated with a - * symbol. gcc jump tables are anonymous data. + * symbol. GCC jump tables are anonymous data. + * + * Also support C jump tables which are in the same format as + * switch jump tables. Each jump table should be a static + * local const array named "jump_table" for objtool to + * recognize it. Note: GCC will add a numbered suffix to the + * ELF symbol name, like "jump_table.12345", which it does for + * all static local variables. */ - if (find_symbol_containing(rodata_sec, table_offset)) + sym = find_symbol_containing(rodata_sec, table_offset); + if (sym && strncmp(sym->name, JUMP_TABLE_SYM_PREFIX, + strlen(JUMP_TABLE_SYM_PREFIX))) continue; rodata_rela = find_rela_by_dest(rodata_sec, table_offset);