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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 18755C742BA for ; Fri, 12 Jul 2019 12:28:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E14142171F for ; Fri, 12 Jul 2019 12:28:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562934487; bh=OEUtpqy8TaVlC4ATZK6ZIDpbuemkRobvqkRMAEHHcho=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CxV3iiKZsSiNIqPB35fU0tOwAVX6XtxvSXTM9Ek+IH7z8BMQYGf8Vxc8AN6UoFFdR ssJVsMpZgm2Ii3m+/svMruY0x8byIhKoAejk3gXqKkXouln97i7QHXjjCxXL6hC/Xw f3WXtS3phyyOm6fHZo2VTOBXufD2XPln5H67/T2s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728179AbfGLM2D (ORCPT ); Fri, 12 Jul 2019 08:28:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:41364 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728280AbfGLM2C (ORCPT ); Fri, 12 Jul 2019 08:28:02 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2B38B208E4; Fri, 12 Jul 2019 12:28:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562934481; bh=OEUtpqy8TaVlC4ATZK6ZIDpbuemkRobvqkRMAEHHcho=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aKyvu595hlt6IDeSvhvhkedumA75T7ep6SyWFJHq73ckcyxFdA1XQhLY9zW0yCIX1 p5+z2PnIPint6SUvD951OCNOWi5xVPOAZqK5aWHjpEWbXlbOcnSfL9B/Rnz+0BB8Og b3xIw7k8wMKHJMDJ+cavjH/9CP0Ar6jR6EIUB6eE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexei Starovoitov , Sasha Levin Subject: [PATCH 5.1 067/138] bpf, x64: fix stack layout of JITed bpf code Date: Fri, 12 Jul 2019 14:18:51 +0200 Message-Id: <20190712121631.241175596@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190712121628.731888964@linuxfoundation.org> References: <20190712121628.731888964@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit fe8d9571dc50232b569242fac7ea6332a654f186 ] 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 Signed-off-by: Sasha Levin --- 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: -- 2.20.1