From nobody Fri Sep 19 02:19:33 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE0D6C4167B for ; Wed, 30 Nov 2022 03:37:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232866AbiK3Dhd (ORCPT ); Tue, 29 Nov 2022 22:37:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232827AbiK3Dh2 (ORCPT ); Tue, 29 Nov 2022 22:37:28 -0500 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A276D73BBF; Tue, 29 Nov 2022 19:37:25 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4NMPz41THGz4f3mS4; Wed, 30 Nov 2022 11:37:20 +0800 (CST) Received: from localhost.localdomain (unknown [10.67.175.61]) by APP2 (Coremail) with SMTP id Syh0CgBHXrnyz4ZjLguABQ--.10963S2; Wed, 30 Nov 2022 11:37:22 +0800 (CST) From: Pu Lehui To: bpf@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Paul Walmsley , Palmer Dabbelt , Albert Ou , Pu Lehui , Pu Lehui Subject: [PATCH bpf] riscv, bpf: Emit fixed-length imm64 for BPF_PSEUDO_FUNC Date: Wed, 30 Nov 2022 11:38:06 +0800 Message-Id: <20221130033806.2967822-1-pulehui@huaweicloud.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: Syh0CgBHXrnyz4ZjLguABQ--.10963S2 X-Coremail-Antispam: 1UD129KBjvJXoW7CFy5AFyxuryDur4UCF1DAwb_yoW8tFy5pr WUKr4fCFZ2qr1S9rnxtr1rXr15CF40qFsIgry3Way5Ga12qrsF93WDKw4Yka98ZFy8Gr15 XFyUKF9xua4Dt3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvF14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4 xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5 MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I 0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrJr0_WFyUJwCI42IY6I8E87Iv67AK xVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvj fUF0eHDUUUU X-CM-SenderInfo: psxovxtxl6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Pu Lehui For BPF_PSEUDO_FUNC instruction, verifier will refill imm with correct addresses of bpf_calls and then run last pass of JIT. Since the emit_imm of RV64 is variable-length, which will emit appropriate length instructions accorroding to the imm, it may broke ctx->offset, and lead to unpredictable problem, such as inaccurate jump. So let's fix it with fixed-length imm64 insns. Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Signed-off-by: Pu Lehui --- arch/riscv/net/bpf_jit_comp64.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp6= 4.c index eb99df41fa33..f984d5fa014b 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -139,6 +139,30 @@ static bool in_auipc_jalr_range(s64 val) val < ((1L << 31) - (1L << 11)); } =20 +/* Emit fixed-length instructions for 32-bit imm */ +static void emit_fixed_imm32(u8 rd, s32 val, struct rv_jit_context *ctx) +{ + s32 upper =3D (val + (1U << 11)) >> 12; + s32 lower =3D ((val & 0xfff) << 20) >> 20; + + emit(rv_lui(rd, upper), ctx); + emit(rv_addi(rd, rd, lower), ctx); +} + +/* Emit fixed-length instructions for 64-bit imm */ +static void emit_fixed_imm64(u8 rd, s64 val, struct rv_jit_context *ctx) +{ + /* Compensation for sign-extension of rv_addi */ + s32 imm_hi =3D (val + (1U << 31)) >> 32; + s32 imm_lo =3D val; + + emit_fixed_imm32(rd, imm_hi, ctx); + emit_fixed_imm32(RV_REG_T1, imm_lo, ctx); + emit(rv_slli(rd, rd, 32), ctx); + emit(rv_add(rd, rd, RV_REG_T1), ctx); +} + +/* Emit variable-length instructions for 32-bit and 64-bit imm */ static void emit_imm(u8 rd, s64 val, struct rv_jit_context *ctx) { /* Note that the immediate from the add is sign-extended, @@ -1053,7 +1077,12 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, s= truct rv_jit_context *ctx, u64 imm64; =20 imm64 =3D (u64)insn1.imm << 32 | (u32)imm; - emit_imm(rd, imm64, ctx); + if (bpf_pseudo_func(insn)) + /* fixed-length insns for extra jit pass */ + emit_fixed_imm64(rd, imm64, ctx); + else + emit_imm(rd, imm64, ctx); + return 1; } =20 --=20 2.25.1