From mboxrd@z Thu Jan 1 00:00:00 1970 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 ED7A8C43217 for ; Tue, 15 Nov 2022 03:04:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236982AbiKODED (ORCPT ); Mon, 14 Nov 2022 22:04:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237555AbiKODDN (ORCPT ); Mon, 14 Nov 2022 22:03:13 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A08810B6 for ; Mon, 14 Nov 2022 19:02:19 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id x11-20020a056a000bcb00b0056c6ec11eefso7090729pfu.14 for ; Mon, 14 Nov 2022 19:02:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=a5AIkCTUh38LdhgjcqmXMopWX95gOLvjqlIhAbQ6HyA=; b=ZwvO7zet084WHw2NNbL2nH/2JhepQmESb/xkbKDrZhFD7rXiVClnYJnNz2HPlkFqu9 Ry+yzF0yZ8oiV7/OJEQazrwgilIw6a7C3V6GeatC+nPUohEmxF7rcFqep8BVmsZ4zkdl qIG4GOhaL3WMrLDYlnxvKEIY5Ylaxa6JSxZOOzAiFjFY3/b1+tjCPqlMaoLb2+zbfmLh 3eXcY6OTSJHXwqYPdiE1zqOsrpaMF2Hpq9pgIVOlpSKWdIYvsKQB0/Z+svvx1rsMcFN1 AVfAGx4kLB4T3kV4jIyy3345Y0VqRwtwiSAEWOShlAMxnRJs8FuZfe7+g8Td1QxXybYd YbKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=a5AIkCTUh38LdhgjcqmXMopWX95gOLvjqlIhAbQ6HyA=; b=xKzc6RpfjyIT/5wZseRcbtcK3xu0hr4ndYe5kASB7as7aCQTDH39YhrM6uRyGTglSN E5yk1h0KlpXG+JFOFIoiIhrO0UlZ5Qb/MO9knbyZvburOiXKqfJxgruDPJhZ3PbjOOpZ 0ZxGSL1ynVEM6t6oGXjHFWsh5RTQ3VdLLqRujcFgGcM1R84dL+RCWyvd64/FqyzE5AwN t+KAcc2IQv0YeG4YXg8Sz8NiuKJ+uGeZ2CEl7TvlMGCfTrZr/C/1YrNwmNqosTFKWNYt sNMpmyBxnAFqE4vmyt5OOxSLFSMrhADoe987/J0tosrlGIUYNJvV7tuS+qXmdZslhg7n cEoQ== X-Gm-Message-State: ANoB5pkMBoteXGzqsmDkSKbPAs0YO6EFdXcIac4txZ7czisxjStnkQG+ jPGKgulhd+y8wOMMOVGwEyz7qaBbdOilQyGvho+G+OteIM9GkYz2YV/kPbHVAUb7Khj2eZN9NcO sF+ZU0Gr7vdyAcmlKk0Avrd/oYW2ZMnhqd5lUSI0ZnKBKrIqs7A== X-Google-Smtp-Source: AA0mqf5ShA3hCnfBoDvhrowJbJznEs4r+D7gQF9n9YYWRe0n8Vk+I8CK63wpuPvFahtMYEOmePixyTA= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a62:6283:0:b0:56e:989d:7410 with SMTP id w125-20020a626283000000b0056e989d7410mr16594601pfb.1.1668481339043; Mon, 14 Nov 2022 19:02:19 -0800 (PST) Date: Mon, 14 Nov 2022 19:02:03 -0800 In-Reply-To: <20221115030210.3159213-1-sdf@google.com> Mime-Version: 1.0 References: <20221115030210.3159213-1-sdf@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221115030210.3159213-5-sdf@google.com> Subject: [PATCH bpf-next 04/11] bpf: Implement hidden BPF_PUSH64 and BPF_POP64 instructions From: Stanislav Fomichev To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, Zi Shen Lim Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Implemented for: - x86_64 jit (tested) - arm64 jit (untested) Interpreter is not implemented because push/pop are currently used only with xdp kfunc and jit is required to use kfuncs. Fundamentally: BPF_ST | BPF_STACK + src_reg == store into the stack BPF_LD | BPF_STACK + dst_reg == load from the stack off/imm are unused Updated disasm code to properly dump these new instructions: 31: (e2) push r1 32: (79) r5 = *(u64 *)(r1 +56) 33: (55) if r5 != 0x0 goto pc+2 34: (b7) r0 = 0 35: (05) goto pc+1 36: (79) r0 = *(u64 *)(r5 +32) 37: (e0) pop r1 Cc: Zi Shen Lim Suggested-by: Alexei Starovoitov Signed-off-by: Stanislav Fomichev --- arch/arm64/net/bpf_jit_comp.c | 8 ++++++++ arch/x86/net/bpf_jit_comp.c | 8 ++++++++ include/linux/filter.h | 23 +++++++++++++++++++++++ kernel/bpf/disasm.c | 6 ++++++ 4 files changed, 45 insertions(+) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 62f805f427b7..4c0e70e6572a 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1185,6 +1185,14 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, */ break; + /* kernel hidden stack operations */ + case BPF_ST | BPF_STACK: + emit(A64_PUSH(src, src, A64_SP), ctx); + break; + case BPF_LD | BPF_STACK: + emit(A64_POP(dst, dst, A64_SP), ctx); + break; + /* ST: *(size *)(dst + off) = imm */ case BPF_ST | BPF_MEM | BPF_W: case BPF_ST | BPF_MEM | BPF_H: diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index cec5195602bc..528bece87ca4 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1324,6 +1324,14 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image EMIT_LFENCE(); break; + /* kernel hidden stack operations */ + case BPF_ST | BPF_STACK: + EMIT1(add_1reg(0x50, src_reg)); /* pushq */ + break; + case BPF_LD | BPF_STACK: + EMIT1(add_1reg(0x58, dst_reg)); /* popq */ + break; + /* ST: *(u8*)(dst_reg + off) = imm */ case BPF_ST | BPF_MEM | BPF_B: if (is_ereg(dst_reg)) diff --git a/include/linux/filter.h b/include/linux/filter.h index efc42a6e3aed..42c61ec8f895 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -76,6 +76,9 @@ struct ctl_table_header; */ #define BPF_NOSPEC 0xc0 +/* unused opcode for kernel hidden stack operations */ +#define BPF_STACK 0xe0 + /* As per nm, we expose JITed images as text (code) section for * kallsyms. That way, tools like perf can find it to match * addresses. @@ -402,6 +405,26 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) .off = 0, \ .imm = 0 }) +/* Push SRC register value onto the stack */ + +#define BPF_PUSH64(SRC) \ + ((struct bpf_insn) { \ + .code = BPF_ST | BPF_STACK, \ + .dst_reg = 0, \ + .src_reg = SRC, \ + .off = 0, \ + .imm = 0 }) + +/* Pop stack value into DST register */ + +#define BPF_POP64(DST) \ + ((struct bpf_insn) { \ + .code = BPF_LD | BPF_STACK, \ + .dst_reg = DST, \ + .src_reg = 0, \ + .off = 0, \ + .imm = 0 }) + /* Internal classic blocks for direct assignment */ #define __BPF_STMT(CODE, K) \ diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c index 7b4afb7d96db..9cd22f3591de 100644 --- a/kernel/bpf/disasm.c +++ b/kernel/bpf/disasm.c @@ -214,6 +214,9 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs, insn->off, insn->imm); } else if (BPF_MODE(insn->code) == 0xc0 /* BPF_NOSPEC, no UAPI */) { verbose(cbs->private_data, "(%02x) nospec\n", insn->code); + } else if (BPF_MODE(insn->code) == 0xe0 /* BPF_STACK, no UAPI */) { + verbose(cbs->private_data, "(%02x) push r%d\n", + insn->code, insn->src_reg); } else { verbose(cbs->private_data, "BUG_st_%02x\n", insn->code); } @@ -254,6 +257,9 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs, insn->code, insn->dst_reg, __func_imm_name(cbs, insn, imm, tmp, sizeof(tmp))); + } else if (BPF_MODE(insn->code) == 0xe0 /* BPF_STACK, no UAPI */) { + verbose(cbs->private_data, "(%02x) pop r%d\n", + insn->code, insn->dst_reg); } else { verbose(cbs->private_data, "BUG_ld_%02x\n", insn->code); return; -- 2.38.1.431.g37b22c650d-goog