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 6EC6DC433FE for ; Tue, 10 May 2022 18:13:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348814AbiEJSRc (ORCPT ); Tue, 10 May 2022 14:17:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348991AbiEJSQB (ORCPT ); Tue, 10 May 2022 14:16:01 -0400 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48B6D48E76; Tue, 10 May 2022 11:10:47 -0700 (PDT) Received: by mail-pf1-x42b.google.com with SMTP id bo5so15591586pfb.4; Tue, 10 May 2022 11:10:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=NxitTfSKesnnva4llqspEEmH1JhQn8Yta6nGnZ+J5WY=; b=E1t4DfqR5lOpRtgjzpMuYOACkMtYGWCtsmn6b+l80lYiPm4y99wFweIdHuSEA6iqh5 m12L00jUGX3nwKYailyCKKMmkSDavY3+QTooUO3w34tL5zSoILl9Ix+N5a4U3L9Pg72v 8hzPT8TArXiny5qpPCEM/DzqQFMVXW/VT3wG1dd1OnRAvb+wxxvasD1AevPTYcK9HDBZ BH4lrG1n9kONQ3AoTmjlS/sQwlLa7GMVrQxZdFFegxHaPpIjm+A9FRQtRhl6vPePwEbm mtPW/cqAr3yglubYMgbTGw/hKjdrN2G3DySdkeQHxDYiex1F13LeqMzluQn573GYwv3F BbbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=NxitTfSKesnnva4llqspEEmH1JhQn8Yta6nGnZ+J5WY=; b=OtrTiFRvp+Yk+Xr9292ggDpHjhI4qIFf1upJcJuthXdxwbuLdTLeNJMR6iO2txOBfP 9i2QCocW7UqahsQUmFZIr/GsPG3+W1Ege2BSOFulbdyY+K966SI0ql7kc3Mbu2LUzXzf ck7O6A4XTCyVmqOJKZXE6L1YCXKq2llOWcFQy3dvYzSMiUzCkUr2sYnvkdNF3DK/Qtnd ULp39BMHinKKMUwC6RPC88W6tKWAroAZMZJ3UcvjIGGCXfs43dYH/VVaaoYgmv5Xa7Pr l4iUMPFGj1XA1pAeY5rgt0sl9sLV2Y4UE/lg2LvUfZ0YbM4xX6vDu5atBSsDFZM74BdD V8cQ== X-Gm-Message-State: AOAM5331tQyKbFAd9IYcPBpg1F59p+oNDnN7EFzsZLEi/BrtvXCtcz/O 1Kpo1lxkTBWvM6yEeg8ivbnJJHLdg47gxi40lyQ= X-Google-Smtp-Source: ABdhPJxAAG9qIczR0J4LIkXo822fcHu4YrI6RMm9dcwY50p31FqMcWiUMufc4c3dp6Q5Pv/3f6gK7zX+CrubStqosko= X-Received: by 2002:a63:8343:0:b0:3c6:b375:9584 with SMTP id h64-20020a638343000000b003c6b3759584mr9717554pge.546.1652206246513; Tue, 10 May 2022 11:10:46 -0700 (PDT) MIME-Version: 1.0 References: <20220506142148.GA24802@asgard.redhat.com> In-Reply-To: <20220506142148.GA24802@asgard.redhat.com> From: Alexei Starovoitov Date: Tue, 10 May 2022 11:10:35 -0700 Message-ID: Subject: Re: [PATCH bpf] bpf_trace: bail out from bpf_kprobe_multi_link_attach when in compat To: Eugene Syromiatnikov Cc: Jiri Olsa , Masami Hiramatsu , Steven Rostedt , Ingo Molnar , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Network Development , bpf , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 6, 2022 at 7:22 AM Eugene Syromiatnikov wrote: > > Since bpf_kprobe_multi_link_attach doesn't support 32-bit kernels > for whatever reason, Jiri, why did you add this restriction? > having it enabled for compat processes on 64-bit > kernels makes even less sense due to discrepances in the type sizes > that it does not handle. I don't follow this logic. bpf progs are always 64-bit. Even when user space is 32-bit. Jiri's check is for the kernel. > Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link") > Signed-off-by: Eugene Syromiatnikov > --- > kernel/trace/bpf_trace.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index d8553f4..9560af6 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -2410,7 +2410,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > int err; > > /* no support for 32bit archs yet */ > - if (sizeof(u64) != sizeof(void *)) > + if (sizeof(u64) != sizeof(void *) || in_compat_syscall()) > return -EOPNOTSUPP; > > if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI) > -- > 2.1.4 >