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 77872C001DC for ; Thu, 27 Jul 2023 15:39:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232996AbjG0PjR (ORCPT ); Thu, 27 Jul 2023 11:39:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232997AbjG0PjR (ORCPT ); Thu, 27 Jul 2023 11:39:17 -0400 Received: from mail-lj1-x233.google.com (mail-lj1-x233.google.com [IPv6:2a00:1450:4864:20::233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 901FF2122; Thu, 27 Jul 2023 08:39:15 -0700 (PDT) Received: by mail-lj1-x233.google.com with SMTP id 38308e7fff4ca-2b95d5ee18dso16825151fa.1; Thu, 27 Jul 2023 08:39:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690472354; x=1691077154; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=e+lkkF+CLVMT4BhNE7E5cz+wEvXfUMd8e9OamCGK4HU=; b=F6j8OCqcwyXUBtmVT65R8NJsFMHmPiWy6i9WOipPq1JUReuJwpp7aO5NpFmwsAR2Bj CJsCu4ELCKvHF6Buf+HIqoBv1aHEZRzFmiYnY12OVJWMAQc3pKkjRFzkCEydeheZhyt7 655vh5dN+OSj6B90HrfVerPLGyIkLsuB8bRpc0VZ5MY8eoS1SY8BMK97RksKA/3jqBB2 HvFMgnXzruA7ExqfCWlPjGThQW7hoVWSqFEyAjlpmwWQVZ63nTxXDARLt03BdH+hNbsH 0uva1GVN1nm8Q5p97DFv+VhppdMZWgwz8cu8qnpoOLrSaxRMW6Rf6LxY/aSTEelVvfHP rNCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690472354; x=1691077154; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=e+lkkF+CLVMT4BhNE7E5cz+wEvXfUMd8e9OamCGK4HU=; b=f3rjp5b04tu9ncrFt5+SZ843ydDSIPEgxjuQrNUM7DCuK6vpyJrNKoGlKBuOlfdO88 LfGAIt8rrlM4dVpqXg5py6Nwm/AFeP00L7jJVSP532KFHYkBP2CTXk53Q07tySJjmQ1l VcYY+Hp51yibnIpYr5u5JpveyY9I9X9UHN82JKI+pIVVy5iAl2XFRVY4w2syPG4hl1+K kgTSBnx0BKtu46yOAEOY1EdyUVn9JvwStt/hFAz1yrX/NqCvOJx+/p9diV0e1CaRc31A AVN2Rnqf34YOfoNi+wIoPZ1ECGH/auOg31DkZYn5jeVJoh5vYEKT9yoXZojWNwEjWPTj YAXQ== X-Gm-Message-State: ABy/qLbq0md90o4yKFYLCl5feGLeuIHLIpPebBuEPUEYntZrXQZug8ur l1jxU3dB821RCG4kYU+y3syRKpnzmYVnlgEi+YDerJ1e X-Google-Smtp-Source: APBJJlHA2LryZdAFZw27OCE9QuUIMumteqO47AfYJLgL+VdWfhBqstNeXHkJEEr8D5zw7EBJt//GSIIFwIGvSWZJgLs= X-Received: by 2002:a2e:9842:0:b0:2b6:cf31:5e81 with SMTP id e2-20020a2e9842000000b002b6cf315e81mr2080102ljj.20.1690472353501; Thu, 27 Jul 2023 08:39:13 -0700 (PDT) MIME-Version: 1.0 References: <169037639315.607919.2613476171148037242.stgit@devnote2> <169037642351.607919.10234149030120807556.stgit@devnote2> In-Reply-To: <169037642351.607919.10234149030120807556.stgit@devnote2> From: Alexei Starovoitov Date: Thu, 27 Jul 2023 08:39:02 -0700 Message-ID: Subject: Re: [PATCH v3 3/9] bpf/btf: Add a function to search a member of a struct/union To: "Masami Hiramatsu (Google)" Cc: linux-trace-kernel@vger.kernel.org, LKML , Steven Rostedt , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Wed, Jul 26, 2023 at 6:00=E2=80=AFAM Masami Hiramatsu (Google) wrote: > > From: Masami Hiramatsu (Google) > > Add btf_find_struct_member() API to search a member of a given data struc= ture > or union from the member's name. > > Signed-off-by: Masami Hiramatsu (Google) > Reviewed-by: Alan Maguire > --- > Changes in v3: > - Remove simple input check. > - Fix unneeded IS_ERR_OR_NULL() check for btf_type_by_id(). > - Move the code next to btf_get_func_param(). > - Use for_each_member() macro instead of for-loop. > - Use btf_type_skip_modifiers() instead of btf_type_by_id(). > --- > include/linux/btf.h | 3 +++ > kernel/bpf/btf.c | 35 +++++++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+) > > diff --git a/include/linux/btf.h b/include/linux/btf.h > index 20e3a07eef8f..4b10d57ceee0 100644 > --- a/include/linux/btf.h > +++ b/include/linux/btf.h > @@ -226,6 +226,9 @@ const struct btf_type *btf_find_func_proto(const char= *func_name, > struct btf **btf_p); > const struct btf_param *btf_get_func_param(const struct btf_type *func_p= roto, > s32 *nr); > +const struct btf_member *btf_find_struct_member(struct btf *btf, > + const struct btf_type *ty= pe, > + const char *member_name); > > #define for_each_member(i, struct_type, member) \ > for (i =3D 0, member =3D btf_type_member(struct_type); \ > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index f7b25c615269..5258870030fc 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -958,6 +958,41 @@ const struct btf_param *btf_get_func_param(const str= uct btf_type *func_proto, s3 > return NULL; > } > > +/* > + * Find a member of data structure/union by name and return it. > + * Return NULL if not found, or -EINVAL if parameter is invalid. > + */ > +const struct btf_member *btf_find_struct_member(struct btf *btf, > + const struct btf_type *ty= pe, > + const char *member_name) > +{ > + const struct btf_member *member, *ret; > + const char *name; > + int i; > + > + if (!btf_type_is_struct(type)) > + return ERR_PTR(-EINVAL); > + > + for_each_member(i, type, member) { > + if (!member->name_off) { > + /* unnamed member: dig deeper */ > + type =3D btf_type_skip_modifiers(btf, member->typ= e, NULL); > + if (type) { > + ret =3D btf_find_struct_member(btf, type, > + member_name)= ; Unbounded recursion in the kernel? Ouch. That might cause issues. Please convert it to a loop. It doesn't have to be recursive. > + if (!IS_ERR_OR_NULL(ret)) > + return ret; > + } > + } else { > + name =3D btf_name_by_offset(btf, member->name_off= ); > + if (name && !strcmp(member_name, name)) > + return member; > + } > + } > + > + return NULL; > +} > + > #define BTF_SHOW_MAX_ITER 10 > > #define BTF_KIND_BIT(kind) (1ULL << kind) >