From patchwork Fri Jun 14 23:08:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 1116307 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=kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45QbrD1ylxz9s4Y for ; Sat, 15 Jun 2019 09:08:28 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726693AbfFNXI0 convert rfc822-to-8bit (ORCPT ); Fri, 14 Jun 2019 19:08:26 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:57116 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726262AbfFNXI0 (ORCPT ); Fri, 14 Jun 2019 19:08:26 -0400 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5EN4CFh005678 for ; Fri, 14 Jun 2019 16:08:25 -0700 Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2t4ds0shtp-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Fri, 14 Jun 2019 16:08:24 -0700 Received: from mx-out.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Fri, 14 Jun 2019 16:08:23 -0700 Received: by devbig007.ftw2.facebook.com (Postfix, from userid 572438) id 971A5760C5E; Fri, 14 Jun 2019 16:08:21 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: CC: , , , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf] bpf, x64: fix stack layout of JITed bpf code Date: Fri, 14 Jun 2019 16:08:21 -0700 Message-ID: <20190614230821.3146272-1-ast@kernel.org> X-Mailer: git-send-email 2.20.0 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-14_09:, , signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=621 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906140182 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Since commit 177366bf7ceb the %rbp stopped pointing to %rbp of the previous stack frame. That broke frame pointer based stack unwinding. This commit is a partial revert of it. Note that the location of tail_call_cnt is fixed, since the verifier enforces MAX_BPF_STACK stack size for programs with tail calls. Fixes: 177366bf7ceb ("bpf: change x86 JITed program stack layout") Signed-off-by: Alexei Starovoitov --- arch/x86/net/bpf_jit_comp.c | 74 +++++++++++-------------------------- 1 file changed, 21 insertions(+), 53 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index afabf597c855..d88bc0935886 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -190,9 +190,7 @@ struct jit_context { #define BPF_MAX_INSN_SIZE 128 #define BPF_INSN_SAFETY 64 -#define AUX_STACK_SPACE 40 /* Space for RBX, R13, R14, R15, tailcnt */ - -#define PROLOGUE_SIZE 37 +#define PROLOGUE_SIZE 20 /* * Emit x86-64 prologue code for BPF program and check its size. @@ -203,44 +201,19 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf) u8 *prog = *pprog; int cnt = 0; - /* push rbp */ - EMIT1(0x55); - - /* mov rbp,rsp */ - EMIT3(0x48, 0x89, 0xE5); - - /* sub rsp, rounded_stack_depth + AUX_STACK_SPACE */ - EMIT3_off32(0x48, 0x81, 0xEC, - round_up(stack_depth, 8) + AUX_STACK_SPACE); - - /* sub rbp, AUX_STACK_SPACE */ - EMIT4(0x48, 0x83, 0xED, AUX_STACK_SPACE); - - /* mov qword ptr [rbp+0],rbx */ - EMIT4(0x48, 0x89, 0x5D, 0); - /* mov qword ptr [rbp+8],r13 */ - EMIT4(0x4C, 0x89, 0x6D, 8); - /* mov qword ptr [rbp+16],r14 */ - EMIT4(0x4C, 0x89, 0x75, 16); - /* mov qword ptr [rbp+24],r15 */ - EMIT4(0x4C, 0x89, 0x7D, 24); - + EMIT1(0x55); /* push rbp */ + EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ + /* sub rsp, rounded_stack_depth */ + EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8)); + EMIT1(0x53); /* push rbx */ + EMIT2(0x41, 0x55); /* push r13 */ + EMIT2(0x41, 0x56); /* push r14 */ + EMIT2(0x41, 0x57); /* push r15 */ if (!ebpf_from_cbpf) { - /* - * Clear the tail call counter (tail_call_cnt): for eBPF tail - * calls we need to reset the counter to 0. It's done in two - * instructions, resetting RAX register to 0, and moving it - * to the counter location. - */ - - /* xor eax, eax */ - EMIT2(0x31, 0xc0); - /* mov qword ptr [rbp+32], rax */ - EMIT4(0x48, 0x89, 0x45, 32); - + /* zero init tail_call_cnt */ + EMIT2(0x6a, 0x00); BUILD_BUG_ON(cnt != PROLOGUE_SIZE); } - *pprog = prog; } @@ -285,13 +258,13 @@ static void emit_bpf_tail_call(u8 **pprog) * if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; */ - EMIT2_off32(0x8B, 0x85, 36); /* mov eax, dword ptr [rbp + 36] */ + EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */ EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */ #define OFFSET2 (30 + RETPOLINE_RAX_BPF_JIT_SIZE) EMIT2(X86_JA, OFFSET2); /* ja out */ label2 = cnt; EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ - EMIT2_off32(0x89, 0x85, 36); /* mov dword ptr [rbp + 36], eax */ + EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ /* prog = array->ptrs[index]; */ EMIT4_off32(0x48, 0x8B, 0x84, 0xD6, /* mov rax, [rsi + rdx * 8 + offsetof(...)] */ @@ -1040,19 +1013,14 @@ xadd: if (is_imm8(insn->off)) seen_exit = true; /* Update cleanup_addr */ ctx->cleanup_addr = proglen; - /* mov rbx, qword ptr [rbp+0] */ - EMIT4(0x48, 0x8B, 0x5D, 0); - /* mov r13, qword ptr [rbp+8] */ - EMIT4(0x4C, 0x8B, 0x6D, 8); - /* mov r14, qword ptr [rbp+16] */ - EMIT4(0x4C, 0x8B, 0x75, 16); - /* mov r15, qword ptr [rbp+24] */ - EMIT4(0x4C, 0x8B, 0x7D, 24); - - /* add rbp, AUX_STACK_SPACE */ - EMIT4(0x48, 0x83, 0xC5, AUX_STACK_SPACE); - EMIT1(0xC9); /* leave */ - EMIT1(0xC3); /* ret */ + if (!bpf_prog_was_classic(bpf_prog)) + EMIT1(0x5B); /* get rid of tail_call_cnt */ + EMIT2(0x41, 0x5F); /* pop r15 */ + EMIT2(0x41, 0x5E); /* pop r14 */ + EMIT2(0x41, 0x5D); /* pop r13 */ + EMIT1(0x5B); /* pop rbx */ + EMIT1(0xC9); /* leave */ + EMIT1(0xC3); /* ret */ break; default: