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 57921C43334 for ; Fri, 8 Jul 2022 11:28:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237949AbiGHL23 (ORCPT ); Fri, 8 Jul 2022 07:28:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237934AbiGHL22 (ORCPT ); Fri, 8 Jul 2022 07:28:28 -0400 Received: from mail-ed1-x52c.google.com (mail-ed1-x52c.google.com [IPv6:2a00:1450:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF595390 for ; Fri, 8 Jul 2022 04:28:27 -0700 (PDT) Received: by mail-ed1-x52c.google.com with SMTP id eq6so26477477edb.6 for ; Fri, 08 Jul 2022 04:28:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=qfcra8dp/WqcWbHWPJN9873xIFza9RyRRhiMmAwAopU=; b=Fn+9vBmaTdOB/l+GFW5srXibpo3G4tscy6sdd9lfYos5V+X9Hj/ovlHItf+vj7Rmp8 DnEOZfAVga1rEGujbDhoIyI85byHCfjjHdRbZXEzXDqW5wAMUyic3lbO70gmvjgQEw6I 0g27Plns2f0CZhcvbLyz9CbY0+5+4NpvLCmAfOvCmcx+IADaSgBg9eZeGzfqY8rZ9l6V y3fwlQyl44auutMzMwW8kEyODmPcXec1+xreGf/ycML6qVEhFFNUW0vTbtxHvFwlNlhW eZf4/0SYin6zPyhpeCmHRtYIsXNXLX8QAaJQqgfetsvW2JEDYQO9WOmObmLijSH+eHSo BVmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=qfcra8dp/WqcWbHWPJN9873xIFza9RyRRhiMmAwAopU=; b=j6d0WmxXU688w/K5+B5m3XU8NEdL1CiEZwhgiP+P0OMYWa3Qx178+2O2p6mad4l+20 8NQ5BHA4M4vQKwmmtmayvjZMbMD6HmRIB+vs/dlNwXvv0igrPDHXUjtAREqkh3eJ3m8I L91D8uZG2aIGrAau4h9yXNOMjCrFp7ODrbtE6WTXwDWcT/xIvKBdDwwzegaNbdNHeXU5 GdpXjs9u/arktnaG/zzyRYhUCbwZre6DA2QQ0KvQIrrIEeUe3Gsga54pFTMWKIdWgCAf bI2BgWI/Rfc6JPEZtTjw9fWQh2EkSLBO71MD33399eh1KI2+08djEMbzjxiTqxJlhALZ G40w== X-Gm-Message-State: AJIora/SYJxFhtuewqSCCTv3K+HBQd0Q0ZF9TMJeITjhBA066iLqDS3O LwXS0ScF5YB8GQL67+mhxxs= X-Google-Smtp-Source: AGRyM1uYPdap8y6kRkdqzFyhmtuDTk9mtL7krNzC9dXyelZzmAelYZOP7PEHymbwA+uEm2s0vz8aZQ== X-Received: by 2002:aa7:db09:0:b0:43a:7353:94a6 with SMTP id t9-20020aa7db09000000b0043a735394a6mr4139425eds.191.1657279706245; Fri, 08 Jul 2022 04:28:26 -0700 (PDT) Received: from krava ([151.14.22.253]) by smtp.gmail.com with ESMTPSA id lc3-20020a170906f90300b00705976bcd01sm20113322ejb.206.2022.07.08.04.28.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Jul 2022 04:28:25 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Fri, 8 Jul 2022 13:28:22 +0200 To: Andrii Nakryiko Cc: Alexei Starovoitov , Andrii Nakryiko , bpf , Alexei Starovoitov , Daniel Borkmann , Kernel Team , Ilya Leoshkevich , Kenta Tada , Hengqi Chen Subject: Re: [PATCH RFC bpf-next 2/3] libbpf: add ksyscall/kretsyscall sections support for syscall kprobes Message-ID: References: <20220707004118.298323-1-andrii@kernel.org> <20220707004118.298323-3-andrii@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Jul 07, 2022 at 12:10:30PM -0700, Andrii Nakryiko wrote: SNIP > > Maybe we should do the other way around ? > > cat /proc/kallsyms |grep sys_bpf > > > > and figure out the prefix from there? > > Then we won't need to do giant > > #if defined(__x86_64__) > > ... > > > > Unfortunately this won't work well due to compat and 32-bit APIs (and > bpf() syscall is particularly bad with also bpf_sys_bpf): > > $ sudo cat /proc/kallsyms| rg '_sys_bpf$' > ffffffff811cb100 t __sys_bpf > ffffffff811cd380 T bpf_sys_bpf > ffffffff811cd520 T __x64_sys_bpf > ffffffff811cd540 T __ia32_sys_bpf > ffffffff8256fce0 r __ksymtab_bpf_sys_bpf > ffffffff8259b5a2 r __kstrtabns_bpf_sys_bpf > ffffffff8259bab9 r __kstrtab_bpf_sys_bpf > ffffffff83abc400 t _eil_addr___ia32_sys_bpf > ffffffff83abc410 t _eil_addr___x64_sys_bpf > > $ sudo cat /proc/kallsyms| rg '_sys_mmap$' > ffffffff81024480 T __x64_sys_mmap > ffffffff810244c0 T __ia32_sys_mmap > ffffffff83abae30 t _eil_addr___ia32_sys_mmap > ffffffff83abae40 t _eil_addr___x64_sys_mmap > > We have similar arch-specific switches in few other places (USDT and > lib path detection, for example), so it's not a new precedent (for > better or worse). > > > > /proc/kallsyms has world read permissions: > > proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); > > unlike available_filter_functions. > > > > Also tracefs might be mounted in a different dir than > > /sys/kernel/tracing/ > > like > > /sys/kernel/debug/tracing/ > > Yeah, good point, was trying to avoid parsing more expensive kallsyms, > but given it's done once, it might not be a big deal. we could get that also from BTF? jirka