From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f172.google.com (mail-oi1-f172.google.com [209.85.167.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 050A8C2ED for ; Thu, 4 Jul 2024 20:51:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720126273; cv=none; b=R9C2UudeH5y8S8N9w/jpLdpebYNH01pzPsJK+0Ln2FaPqlmZd1Cr2HIZXTakapCaBvugR3zYbmtpUwHwVkXNx+hiUvYEr304dfGNSkiuPa+xhc6IUq+ZTMtBnFaYXZMOIgZ9IwQfh0sDqCovySnYodoGhU+pRzpLLuY305aWEjI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720126273; c=relaxed/simple; bh=JSaf/nDb0s6xGvsoeMt5COMRWNoeH1JiLaKYcQ+ydJU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=uSfVlOSoa1MUGyPPC/2PDcOhsXNRrpoD1TVcY4YcWjI9NPIkhxoFK8fna5l4xHll0i4xRCq3yXXiRbzB3NHSqoL/HEMkn9AU/hlfhBHdDlx4mK7ZeMBa7O45uMWZlSAIlL8glR/GZ2dswc/nX/lzg6SN8HP4fG9+XZrLG3vA83o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=k8DGUv6M; arc=none smtp.client-ip=209.85.167.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="k8DGUv6M" Received: by mail-oi1-f172.google.com with SMTP id 5614622812f47-3d5666a4860so590383b6e.2 for ; Thu, 04 Jul 2024 13:51:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1720126271; x=1720731071; darn=vger.kernel.org; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:from:to:cc:subject :date:message-id:reply-to; bh=G0SjGj3ys0flTzVDf7zfKXKhRIXzc4MQs3jIg6g/3fI=; b=k8DGUv6MDypBdCgtGJrMxYHLodwMODQNMbQ22HJaQRybz4VYpabOZ6OsYaefWjJUb5 eBdPYZcenapUP+If1+qY/sbd6rVVjIpdzJINX/aTOgHsAuQ30oRRRmXxxvV0GsAvFIKI v9qwabJeYYbNTKBGyNYV1Ra+ANpr8NRrCJouxoVOc6dsyrPvZr7F9zlRv32FXHpShque zNdL0pOxEteG0nFPig9iv/WK7tuUs8F963qj3gegLOqd1kS4PD1FiwVhIGLNRSvJKubE s7Q8UbZdHBweMC9OgH6GcUTyAT4Lb3gIBTpUqWxCl3IZ+sECb3FQHj2WNEcE4poTK64o d4SA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720126271; x=1720731071; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=G0SjGj3ys0flTzVDf7zfKXKhRIXzc4MQs3jIg6g/3fI=; b=QQO9fkJPgxA9WAymm20qlX2umyGjbZI8TfJ9cs1brpWbf2kDYCKQKM9einUcG+TA/E yxr2Hz9nWIAGQZh1imSWAJX6UE4aYhI9orQVm+KbuY9MedjPQ5J5BcYyxlrsi2RbOG0B ei+M0Mdx2vtj2LWvckpHRvqRWP/xqIas2q6FkTjOa+CnK6GBmhBplP2k1JDqnRm5eV7v bixEDfF+C+iSFIVwwyGRls8f1NhEjz/2BdiO8iI7DuCB7zCGu7GElEXUxD2D9K6lmQdw bXdAc9ZCp1rW9FTwfwOd0mC64mqPxI8pREwE+0LCvPLuOMhR3EH9ouras1XlZ0B5tKOr zTkw== X-Forwarded-Encrypted: i=1; AJvYcCXNZIZofpjREUuTUy7SsAPOvl108HmFwRRMEN50TG9EY7UDbxt8r1LQm5mr2sAoC3DH7xy9RQ53wdU4NLzXCF4mUWRd X-Gm-Message-State: AOJu0YziHn2QjVTUPMKgLTiIZGilbaafThxWuUNPvU9aNbwszUZ2HOJZ h5+uP0gJhx/fQAiacv1E/yK3RixMjHIobLcQD5XiqOjD8vPNuFvI X-Google-Smtp-Source: AGHT+IF+yDoamCtKQa1xkLE1AEzGpi9io685TizdTMWXkQUHJM5dKAQg1qqa6MFE8szsSxO8KhrHuQ== X-Received: by 2002:a05:6808:238f:b0:3d5:1eba:10b5 with SMTP id 5614622812f47-3d914c51bacmr3243106b6e.12.1720126271001; Thu, 04 Jul 2024 13:51:11 -0700 (PDT) Received: from [192.168.0.31] ([38.34.87.7]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7084d7061a0sm12369848b3a.219.2024.07.04.13.51.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Jul 2024 13:51:10 -0700 (PDT) Message-ID: <11196cc77173e29588e93078bd74a9ae9d8463e5.camel@gmail.com> Subject: Re: [PATCH bpf-next 2/2] libbpf: fix BPF skeleton forward/backward compat handling From: Eduard Zingerman To: Andrii Nakryiko , bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@kernel.org Cc: kernel-team@meta.com, Mykyta Yatsenko Date: Thu, 04 Jul 2024 13:51:05 -0700 In-Reply-To: <20240704001527.754710-3-andrii@kernel.org> References: <20240704001527.754710-1-andrii@kernel.org> <20240704001527.754710-3-andrii@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4-0ubuntu2 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2024-07-03 at 17:15 -0700, Andrii Nakryiko wrote: > BPF skeleton was designed from day one to be extensible. Generated BPF > skeleton code specifies actual sizes of map/prog/variable skeletons for > that reason and libbpf is supposed to work with newer/older versions > correctly. >=20 > Unfortunately, it was missed that we implicitly embed hard-coded most > up-to-date (according to libbpf's version of libbpf.h header used to > compile BPF skeleton header) sizes of those strucs, which can differ ^^ nit: "struct" > from the actual sizes at runtime when libbpf is used as a shared > library. >=20 > We have a few places were we just index array of maps/progs/vars, which > implicitly uses these potentially invalid sizes of structs. >=20 > This patch aims to fix this problem going forward. Once this lands, > we'll backport these changes in Github repo to create patched releases > for older libbpfs. >=20 > Fixes: d66562fba1ce ("libbpf: Add BPF object skeleton support") > Fixes: 430025e5dca5 ("libbpf: Add subskeleton scaffolding") > Co-developed-by: Mykyta Yatsenko > Signed-off-by: Andrii Nakryiko > --- I double-checked all uses of bpf_object_skeleton->{maps,progs}, all seems in order. Acked-by: Eduard Zingerman [...]