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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4368C433ED for ; Tue, 11 May 2021 23:34:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A401E6187E for ; Tue, 11 May 2021 23:34:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229970AbhEKXf0 (ORCPT ); Tue, 11 May 2021 19:35:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbhEKXfY (ORCPT ); Tue, 11 May 2021 19:35:24 -0400 Received: from mail-yb1-xb36.google.com (mail-yb1-xb36.google.com [IPv6:2607:f8b0:4864:20::b36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3923FC06174A for ; Tue, 11 May 2021 16:34:17 -0700 (PDT) Received: by mail-yb1-xb36.google.com with SMTP id y2so28481762ybq.13 for ; Tue, 11 May 2021 16:34:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nsXVvyWVcTliqHYVVLc+UKG6tcVtsZpjdubfjZ8XAUU=; b=FL7iq2KLOcL4gXyRnPyhv32J+E/LQ5ltIIr9+xrchJPSXQRLfva5PDF4Ue3lQDDwjn Y467TH+Vo4tVrLHprA7c1O7T4briZhfgCO3wthdV8Slk4UjSk9avrk+ohw2nlyKDPoNY 9Y0dOylVu92j+Mk0AmJcNUctaZJkqtDQtFAKB3AAiyQZSb8VZ1ulh0cszP+T13TNnv0K he23jtZwTQSlohFo7a0yTsdsI3J40KCCbp7IiWhPOCwhXZaqiIdrinvNzD5c4gl2iqfn 9KNJO6CIVDFym7AVtIdCJbqi5BBMCYiKPz5ZCLZrb0Kzp1KvFeRC+IqbwK0eBoSVPaT4 FD3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nsXVvyWVcTliqHYVVLc+UKG6tcVtsZpjdubfjZ8XAUU=; b=SBamSA0woxmT6qrpOn3Rl3na/oKQa5BJI3tmv6H61R5Ipfaz8cJmHEkFhv5VvA/2UO irevxssmN8oeI8pIkFan9rp8XdpaRedEP19YKgL/daOFjxPKYT9kdWMZTr6VEERYp6QH hmBZBkOA5/DUFhDdRVwexyiJPn0/L0zRbL+Sp44gk+jWjJXnl4bF1NWhjSjVrAoQOEOD OqfOG2Ob3yms+wb7PjGpQnm0uJQjiF3s9mx0XzTjPFRdNOj3Z3YwMKNahyf581uWQMFj D4vZr/u53r77ezg1uH+crhn3BOo5JZDMtmUBD4lBUyOsZYBAkGWrgxmeI8umewNt2Iwf VZBg== X-Gm-Message-State: AOAM531fkbqSTPfKyiLrrL6DsUsMvJLmMRQjUCBfP01EaDsyFaXXCThD ppl+pkwwIMDj242jLJ5J93RtOEkVhGGIgf3/NNU= X-Google-Smtp-Source: ABdhPJxy0IJ6kfP66R6PPSSKMq+cEV0PpaPfSDqS5+PGiolzUaO52GWHBUBX0cVcWQNJfdZWaM5K9OqQ63O6RkhA0Vo= X-Received: by 2002:a25:3357:: with SMTP id z84mr43482966ybz.260.1620776056585; Tue, 11 May 2021 16:34:16 -0700 (PDT) MIME-Version: 1.0 References: <20210508034837.64585-1-alexei.starovoitov@gmail.com> <20210508034837.64585-17-alexei.starovoitov@gmail.com> In-Reply-To: <20210508034837.64585-17-alexei.starovoitov@gmail.com> From: Andrii Nakryiko Date: Tue, 11 May 2021 16:34:05 -0700 Message-ID: Subject: Re: [PATCH v4 bpf-next 16/22] libbpf: Cleanup temp FDs when intermediate sys_bpf fails. To: Alexei Starovoitov Cc: "David S. Miller" , Daniel Borkmann , Andrii Nakryiko , john fastabend , bpf , Kernel Team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, May 7, 2021 at 8:49 PM Alexei Starovoitov wrote: > > From: Alexei Starovoitov > > Fix loader program to close temporary FDs when intermediate > sys_bpf command fails. > > Signed-off-by: Alexei Starovoitov > --- Looks good, but curious about 2 jumps vs 1 jump for cleanup Acked-by: Andrii Nakryiko > tools/lib/bpf/bpf_gen_internal.h | 1 + > tools/lib/bpf/gen_loader.c | 38 ++++++++++++++++++++++++++++---- > 2 files changed, 35 insertions(+), 4 deletions(-) > > diff --git a/tools/lib/bpf/bpf_gen_internal.h b/tools/lib/bpf/bpf_gen_internal.h > index f42a55efd559..da2c026a3f31 100644 > --- a/tools/lib/bpf/bpf_gen_internal.h > +++ b/tools/lib/bpf/bpf_gen_internal.h > @@ -15,6 +15,7 @@ struct bpf_gen { > void *data_cur; > void *insn_start; > void *insn_cur; > + size_t cleanup_label; > __u32 nr_progs; > __u32 nr_maps; > int log_level; > diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c > index 585c672cc53e..b1709421ba90 100644 > --- a/tools/lib/bpf/gen_loader.c > +++ b/tools/lib/bpf/gen_loader.c > @@ -97,8 +97,36 @@ static void bpf_gen__emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bp > > void bpf_gen__init(struct bpf_gen *gen, int log_level) > { > + size_t stack_sz = sizeof(struct loader_stack); > + int i; > + > gen->log_level = log_level; > + /* save ctx pointer into R6 */ > bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_6, BPF_REG_1)); > + > + /* bzero stack */ > + bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10)); > + bpf_gen__emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -stack_sz)); > + bpf_gen__emit(gen, BPF_MOV64_IMM(BPF_REG_2, stack_sz)); > + bpf_gen__emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0)); > + bpf_gen__emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel)); > + > + /* jump over cleanup code */ > + bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, > + /* size of cleanup code below */ > + (stack_sz / 4) * 3 + 2)); > + > + /* remember the label where all error branches will jump to */ > + gen->cleanup_label = gen->insn_cur - gen->insn_start; > + /* emit cleanup code: close all temp FDs */ > + for (i = 0; i < stack_sz; i+= 4) { nit: checkpatch complains about missing space before += > + bpf_gen__emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -stack_sz + i)); > + bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0, 1)); > + bpf_gen__emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close)); > + } > + /* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */ > + bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7)); > + bpf_gen__emit(gen, BPF_EXIT_INSN()); > } > > static int bpf_gen__add_data(struct bpf_gen *gen, const void *data, __u32 size) > @@ -179,10 +207,12 @@ static void bpf_gen__emit_sys_bpf(struct bpf_gen *gen, int cmd, int attr, int at > > static void bpf_gen__emit_check_err(struct bpf_gen *gen) > { > - bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 2)); > - bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7)); > - /* TODO: close intermediate FDs in case of error */ > - bpf_gen__emit(gen, BPF_EXIT_INSN()); > + /* R7 contains result of last sys_bpf command. > + * if (R7 < 0) goto cleanup; > + */ > + bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 1)); > + bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, > + -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1)); Just curious, why not a single BPF_JSLT straight to the cleanup label? > } > > /* reg1 and reg2 should not be R1 - R5. They can be R0, R6 - R10 */ > -- > 2.30.2 >