Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032767AbbKDSl7 (ORCPT ); Wed, 4 Nov 2015 13:41:59 -0500 Received: from mail-pa0-f45.google.com ([209.85.220.45]:35796 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030832AbbKDSl4 (ORCPT ); Wed, 4 Nov 2015 13:41:56 -0500 Message-ID: <563A5171.5070608@linaro.org> Date: Wed, 04 Nov 2015 10:41:53 -0800 From: "Shi, Yang" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Z Lim CC: Xi Wang , Catalin Marinas , stable@vger.kernel.org, LKML , "linux-arm-kernel@lists.infradead.org" , Alexei Starovoitov Subject: Re: [PATCH] arm64: bpf: fix div-by-zero case References: <1446620204-4228-1-git-send-email-zlim.lnx@gmail.com> <563A4C9A.7000002@linaro.org> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3060 Lines: 97 On 11/4/2015 10:25 AM, Z Lim wrote: > On Wed, Nov 4, 2015 at 10:21 AM, Shi, Yang wrote: >> On 11/3/2015 11:04 PM, Xi Wang wrote: >>> >>> On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim wrote: >>>> >>>> case BPF_ALU | BPF_DIV | BPF_X: >>>> case BPF_ALU64 | BPF_DIV | BPF_X: >>>> + { >>>> + const u8 r0 = bpf2a64[BPF_REG_0]; >>>> + >>>> + /* if (src == 0) return 0 */ >>>> + jmp_offset = 3; /* skip ahead to else path */ >>>> + check_imm19(jmp_offset); >>>> + emit(A64_CBNZ(is64, src, jmp_offset), ctx); >>>> + emit(A64_MOVZ(1, r0, 0, 0), ctx); >>>> + jmp_offset = epilogue_offset(ctx); >>>> + check_imm26(jmp_offset); >>>> + emit(A64_B(jmp_offset), ctx); >>>> + /* else */ >>>> emit(A64_UDIV(is64, dst, dst, src), ctx); >>>> break; >>>> + } >>>> case BPF_ALU | BPF_MOD | BPF_X: >>>> case BPF_ALU64 | BPF_MOD | BPF_X: >>> >>> >>> BPF_MOD might need the same fix. > > I'll post a fix for this case as well. > >> >> >> Agreed, and we may need add one more test cases in test_bpf module to cover >> MOD? > > Let me know if you have a test case ready :) Does the below change look like a valid test? + "MOD default X", + .u.insns = { + /* + * A = 0x42 + * A = A mod X ; this halt the filter execution if X is 0 + * ret 0x42 + */ + BPF_STMT(BPF_LD | BPF_IMM, 0x42), + BPF_STMT(BPF_ALU | BPF_MOD | BPF_X, 0), + BPF_STMT(BPF_RET | BPF_K, 0x42), + }, + CLASSIC | FLAG_NO_DATA, + {}, + { {0x1, 0x0 } }, + }, + { + "MOD default A", + .u.insns = { + /* + * A = A mod 1 + * ret A + */ + BPF_STMT(BPF_ALU | BPF_MOD | BPF_K, 0x1), + BPF_STMT(BPF_RET | BPF_A, 0x0), + }, + CLASSIC | FLAG_NO_DATA, + {}, + { {0x1, 0x0 } }, + }, My test result with it: test_bpf: #284 MOD default X jited:1 ret 66 != 0 FAIL (1 times) test_bpf: #285 MOD default A jited:1 102 PASS If it looks right, I will post a patch to add the test cases. Thanks, Yang > >> >> Yang >> >>> >>> _______________________________________________ >>> linux-arm-kernel mailing list >>> linux-arm-kernel@lists.infradead.org >>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >>> >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/