From patchwork Wed Jul 26 22:07:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13328632 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91601379A5 for ; Wed, 26 Jul 2023 22:31:47 +0000 (UTC) Received: from 66-220-155-178.mail-mxout.facebook.com (66-220-155-178.mail-mxout.facebook.com [66.220.155.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED36C1FFA for ; Wed, 26 Jul 2023 15:31:45 -0700 (PDT) Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 2403023B79C99; Wed, 26 Jul 2023 15:07:42 -0700 (PDT) From: Yonghong Song To: Alexei Starovoitov , Andrii Nakryiko , bpf@vger.kernel.org, Daniel Borkmann , Martin KaFai Lau Cc: David Faust , Fangrui Song , "Jose E . Marchesi" , kernel-team@fb.com, Eduard Zingerman Subject: [PATCH bpf-next v4 03/17] bpf: Handle sign-extenstin ctx member accesses Date: Wed, 26 Jul 2023 15:07:42 -0700 Message-Id: <20230726220742.1092332-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230726220726.1089817-1-yonghong.song@linux.dev> References: <20230726220726.1089817-1-yonghong.song@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,RDNS_DYNAMIC, SPF_HELO_PASS,SPF_SOFTFAIL,TVD_RCVD_IP,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net Currently, if user accesses a ctx member with signed types, the compiler will generate an unsigned load followed by necessary left and right shifts. With the introduction of sign-extension load, compiler may just emit a ldsx insn instead. Let us do a final movsx sign extension to the final unsigned ctx load result to satisfy original sign extension requirement. Acked-by: Eduard Zingerman Signed-off-by: Yonghong Song --- kernel/bpf/verifier.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2f3eebcd962f..7a6945be07e3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -17716,6 +17716,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) for (i = 0; i < insn_cnt; i++, insn++) { bpf_convert_ctx_access_t convert_ctx_access; + u8 mode; if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || insn->code == (BPF_LDX | BPF_MEM | BPF_H) || @@ -17797,6 +17798,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; size = BPF_LDST_BYTES(insn); + mode = BPF_MODE(insn->code); /* If the read access is a narrower load of the field, * convert to a 4/8-byte load, to minimum program type specific @@ -17856,6 +17858,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) (1ULL << size * 8) - 1); } } + if (mode == BPF_MEMSX) + insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X, + insn->dst_reg, insn->dst_reg, + size * 8, 0); new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog)