Messages in this thread | | | Date | Wed, 04 Nov 2015 10:41:53 -0800 | From | "Shi, Yang" <> | Subject | Re: [PATCH] arm64: bpf: fix div-by-zero case |
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On 11/4/2015 10:25 AM, Z Lim wrote: > On Wed, Nov 4, 2015 at 10:21 AM, Shi, Yang <yang.shi@linaro.org> wrote: >> On 11/3/2015 11:04 PM, Xi Wang wrote: >>> >>> On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim <zlim.lnx@gmail.com> 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 >>> >>
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