| Message ID | 1446620204-4228-1-git-send-email-zlim.lnx@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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.
On 11/3/2015 10:56 PM, Zi Shen Lim wrote: > In the case of division by zero in a BPF program: > A = A / X; (X == 0) > the expected behavior is to terminate with return value 0. > > This is confirmed by the test case introduced in commit 86bf1721b226 > ("test_bpf: add tests checking that JIT/interpreter sets A and X to 0."). > > Reported-by: Shi, Yang <yang.shi@linaro.org> Thanks for coming up with the fix promptly. s/Shi, Yang/Yang Shi Tested with the latest 4.3 kernel. Tested-by: Yang Shi <yang.shi@linaro.org> Yang > CC: Xi Wang <xi.wang@gmail.com> > CC: Alexei Starovoitov <ast@plumgrid.com> > CC: Catalin Marinas <catalin.marinas@arm.com> > CC: linux-arm-kernel@lists.infradead.org > CC: linux-kernel@vger.kernel.org > Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") > Cc: <stable@vger.kernel.org> # 3.18+ > Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com> > --- > arch/arm64/net/bpf_jit.h | 3 ++- > arch/arm64/net/bpf_jit_comp.c | 37 +++++++++++++++++++++++++------------ > 2 files changed, 27 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h > index 98a26ce..aee5637 100644 > --- a/arch/arm64/net/bpf_jit.h > +++ b/arch/arm64/net/bpf_jit.h > @@ -1,7 +1,7 @@ > /* > * BPF JIT compiler for ARM64 > * > - * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com> > + * Copyright (C) 2014-2015 Zi Shen Lim <zlim.lnx@gmail.com> > * > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Public License version 2 as > @@ -35,6 +35,7 @@ > aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \ > AARCH64_INSN_BRANCH_COMP_##type) > #define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO) > +#define A64_CBNZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, NONZERO) > > /* Conditional branch (immediate) */ > #define A64_COND_BRANCH(cond, offset) \ > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index c047598..9ae6f23 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -1,7 +1,7 @@ > /* > * BPF JIT compiler for ARM64 > * > - * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com> > + * Copyright (C) 2014-2015 Zi Shen Lim <zlim.lnx@gmail.com> > * > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Public License version 2 as > @@ -225,6 +225,17 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) > u8 jmp_cond; > s32 jmp_offset; > > +#define check_imm(bits, imm) do { \ > + if ((((imm) > 0) && ((imm) >> (bits))) || \ > + (((imm) < 0) && (~(imm) >> (bits)))) { \ > + pr_info("[%2d] imm=%d(0x%x) out of range\n", \ > + i, imm, imm); \ > + return -EINVAL; \ > + } \ > +} while (0) > +#define check_imm19(imm) check_imm(19, imm) > +#define check_imm26(imm) check_imm(26, imm) > + > switch (code) { > /* dst = src */ > case BPF_ALU | BPF_MOV | BPF_X: > @@ -258,8 +269,21 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) > break; > 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: > ctx->tmp_used = 1; > @@ -393,17 +417,6 @@ emit_bswap_uxt: > emit(A64_ASR(is64, dst, dst, imm), ctx); > break; > > -#define check_imm(bits, imm) do { \ > - if ((((imm) > 0) && ((imm) >> (bits))) || \ > - (((imm) < 0) && (~(imm) >> (bits)))) { \ > - pr_info("[%2d] imm=%d(0x%x) out of range\n", \ > - i, imm, imm); \ > - return -EINVAL; \ > - } \ > -} while (0) > -#define check_imm19(imm) check_imm(19, imm) > -#define check_imm26(imm) check_imm(26, imm) > - > /* JUMP off */ > case BPF_JMP | BPF_JA: > jmp_offset = bpf2a64_offset(i + off, i, ctx); >
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. Agreed, and we may need add one more test cases in test_bpf module to cover MOD? Yang > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
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 :) > > Yang > >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >> >
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 >>> >>
On 11/04/2015 07:41 PM, Shi, Yang wrote: ... >>> 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. Looks good to me. Thanks, Daniel
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 98a26ce..aee5637 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com> + * Copyright (C) 2014-2015 Zi Shen Lim <zlim.lnx@gmail.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -35,6 +35,7 @@ aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \ AARCH64_INSN_BRANCH_COMP_##type) #define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO) +#define A64_CBNZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, NONZERO) /* Conditional branch (immediate) */ #define A64_COND_BRANCH(cond, offset) \ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c047598..9ae6f23 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com> + * Copyright (C) 2014-2015 Zi Shen Lim <zlim.lnx@gmail.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -225,6 +225,17 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 jmp_cond; s32 jmp_offset; +#define check_imm(bits, imm) do { \ + if ((((imm) > 0) && ((imm) >> (bits))) || \ + (((imm) < 0) && (~(imm) >> (bits)))) { \ + pr_info("[%2d] imm=%d(0x%x) out of range\n", \ + i, imm, imm); \ + return -EINVAL; \ + } \ +} while (0) +#define check_imm19(imm) check_imm(19, imm) +#define check_imm26(imm) check_imm(26, imm) + switch (code) { /* dst = src */ case BPF_ALU | BPF_MOV | BPF_X: @@ -258,8 +269,21 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) break; 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: ctx->tmp_used = 1; @@ -393,17 +417,6 @@ emit_bswap_uxt: emit(A64_ASR(is64, dst, dst, imm), ctx); break; -#define check_imm(bits, imm) do { \ - if ((((imm) > 0) && ((imm) >> (bits))) || \ - (((imm) < 0) && (~(imm) >> (bits)))) { \ - pr_info("[%2d] imm=%d(0x%x) out of range\n", \ - i, imm, imm); \ - return -EINVAL; \ - } \ -} while (0) -#define check_imm19(imm) check_imm(19, imm) -#define check_imm26(imm) check_imm(26, imm) - /* JUMP off */ case BPF_JMP | BPF_JA: jmp_offset = bpf2a64_offset(i + off, i, ctx);
In the case of division by zero in a BPF program: A = A / X; (X == 0) the expected behavior is to terminate with return value 0. This is confirmed by the test case introduced in commit 86bf1721b226 ("test_bpf: add tests checking that JIT/interpreter sets A and X to 0."). Reported-by: Shi, Yang <yang.shi@linaro.org> CC: Xi Wang <xi.wang@gmail.com> CC: Alexei Starovoitov <ast@plumgrid.com> CC: Catalin Marinas <catalin.marinas@arm.com> CC: linux-arm-kernel@lists.infradead.org CC: linux-kernel@vger.kernel.org Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Cc: <stable@vger.kernel.org> # 3.18+ Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com> --- arch/arm64/net/bpf_jit.h | 3 ++- arch/arm64/net/bpf_jit_comp.c | 37 +++++++++++++++++++++++++------------ 2 files changed, 27 insertions(+), 13 deletions(-)