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Date: Fri, 24 May 2019 17:36:54 +0100
From: Jiong Wang <jiong.wang@...ronome.com>
To: Björn Töpel <bjorn.topel@...il.com>
Cc: Jiong Wang <jiong.wang@...ronome.com>,
Alexei Starovoitov <alexei.starovoitov@...il.com>,
Daniel Borkmann <daniel@...earbox.net>,
bpf <bpf@...r.kernel.org>, Netdev <netdev@...r.kernel.org>,
oss-drivers@...ronome.com, David Miller <davem@...emloft.net>,
paul.burton@...s.com, udknight@...il.com, zlim.lnx@...il.com,
illusionist.neo@...il.com, naveen.n.rao@...ux.ibm.com,
sandipan@...ux.ibm.com, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com,
Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: Re: [PATCH v8 bpf-next 15/16] riscv: bpf: eliminate zero extension code-gen
Björn Töpel writes:
> On Fri, 24 May 2019 at 13:36, Jiong Wang <jiong.wang@...ronome.com> wrote:
>>
>> Cc: Björn Töpel <bjorn.topel@...il.com>
>> Acked-by: Björn Töpel <bjorn.topel@...il.com>
>> Tested-by: Björn Töpel <bjorn.topel@...il.com>
>> Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
>> ---
>> arch/riscv/net/bpf_jit_comp.c | 43 ++++++++++++++++++++++++++++++-------------
>> 1 file changed, 30 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
>> index 80b12aa..c4c836e 100644
>> --- a/arch/riscv/net/bpf_jit_comp.c
>> +++ b/arch/riscv/net/bpf_jit_comp.c
>> @@ -731,6 +731,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> {
>> bool is64 = BPF_CLASS(insn->code) == BPF_ALU64 ||
>> BPF_CLASS(insn->code) == BPF_JMP;
>> + struct bpf_prog_aux *aux = ctx->prog->aux;
>> int rvoff, i = insn - ctx->prog->insnsi;
>> u8 rd = -1, rs = -1, code = insn->code;
>> s16 off = insn->off;
>> @@ -742,8 +743,13 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> /* dst = src */
>> case BPF_ALU | BPF_MOV | BPF_X:
>> case BPF_ALU64 | BPF_MOV | BPF_X:
>> + if (imm == 1) {
>> + /* Special mov32 for zext */
>> + emit_zext_32(rd, ctx);
>> + break;
>> + }
>
> Hmm, missing is64 check here (fall-through for 64-bit movs)?
(re-send because of bouncing back)
FOR BPF_X form, when imm == 1, it is a special mov32 constructed by
verifier, it can only be BPF_ALU, not BPF_ALU64. And it is used for
instructing JIT back-end to do unconditional zero extension.
Please see patch 3 description for the explanation.
Thanks.
Regards,
Jiong
>
> Björn
>
>> emit(is64 ? rv_addi(rd, rs, 0) : rv_addiw(rd, rs, 0), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>>
>> @@ -771,19 +777,19 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> case BPF_ALU | BPF_MUL | BPF_X:
>> case BPF_ALU64 | BPF_MUL | BPF_X:
>> emit(is64 ? rv_mul(rd, rd, rs) : rv_mulw(rd, rd, rs), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_DIV | BPF_X:
>> case BPF_ALU64 | BPF_DIV | BPF_X:
>> emit(is64 ? rv_divu(rd, rd, rs) : rv_divuw(rd, rd, rs), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_MOD | BPF_X:
>> case BPF_ALU64 | BPF_MOD | BPF_X:
>> emit(is64 ? rv_remu(rd, rd, rs) : rv_remuw(rd, rd, rs), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_LSH | BPF_X:
>> @@ -867,7 +873,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> case BPF_ALU | BPF_MOV | BPF_K:
>> case BPF_ALU64 | BPF_MOV | BPF_K:
>> emit_imm(rd, imm, ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>>
>> @@ -882,7 +888,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit(is64 ? rv_add(rd, rd, RV_REG_T1) :
>> rv_addw(rd, rd, RV_REG_T1), ctx);
>> }
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_SUB | BPF_K:
>> @@ -895,7 +901,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit(is64 ? rv_sub(rd, rd, RV_REG_T1) :
>> rv_subw(rd, rd, RV_REG_T1), ctx);
>> }
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_AND | BPF_K:
>> @@ -906,7 +912,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, imm, ctx);
>> emit(rv_and(rd, rd, RV_REG_T1), ctx);
>> }
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_OR | BPF_K:
>> @@ -917,7 +923,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, imm, ctx);
>> emit(rv_or(rd, rd, RV_REG_T1), ctx);
>> }
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_XOR | BPF_K:
>> @@ -928,7 +934,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, imm, ctx);
>> emit(rv_xor(rd, rd, RV_REG_T1), ctx);
>> }
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_MUL | BPF_K:
>> @@ -936,7 +942,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, imm, ctx);
>> emit(is64 ? rv_mul(rd, rd, RV_REG_T1) :
>> rv_mulw(rd, rd, RV_REG_T1), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_DIV | BPF_K:
>> @@ -944,7 +950,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, imm, ctx);
>> emit(is64 ? rv_divu(rd, rd, RV_REG_T1) :
>> rv_divuw(rd, rd, RV_REG_T1), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_MOD | BPF_K:
>> @@ -952,7 +958,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, imm, ctx);
>> emit(is64 ? rv_remu(rd, rd, RV_REG_T1) :
>> rv_remuw(rd, rd, RV_REG_T1), ctx);
>> - if (!is64)
>> + if (!is64 && !aux->verifier_zext)
>> emit_zext_32(rd, ctx);
>> break;
>> case BPF_ALU | BPF_LSH | BPF_K:
>> @@ -1239,6 +1245,8 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, off, ctx);
>> emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
>> emit(rv_lbu(rd, 0, RV_REG_T1), ctx);
>> + if (insn_is_zext(&insn[1]))
>> + return 1;
>> break;
>> case BPF_LDX | BPF_MEM | BPF_H:
>> if (is_12b_int(off)) {
>> @@ -1249,6 +1257,8 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, off, ctx);
>> emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
>> emit(rv_lhu(rd, 0, RV_REG_T1), ctx);
>> + if (insn_is_zext(&insn[1]))
>> + return 1;
>> break;
>> case BPF_LDX | BPF_MEM | BPF_W:
>> if (is_12b_int(off)) {
>> @@ -1259,6 +1269,8 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>> emit_imm(RV_REG_T1, off, ctx);
>> emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
>> emit(rv_lwu(rd, 0, RV_REG_T1), ctx);
>> + if (insn_is_zext(&insn[1]))
>> + return 1;
>> break;
>> case BPF_LDX | BPF_MEM | BPF_DW:
>> if (is_12b_int(off)) {
>> @@ -1503,6 +1515,11 @@ static void bpf_flush_icache(void *start, void *end)
>> flush_icache_range((unsigned long)start, (unsigned long)end);
>> }
>>
>> +bool bpf_jit_needs_zext(void)
>> +{
>> + return true;
>> +}
>> +
>> struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
>> {
>> bool tmp_blinded = false, extra_pass = false;
>> --
>> 2.7.4
>>
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