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 7C3CAC433EF for ; Fri, 18 Feb 2022 21:15:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239682AbiBRVQO (ORCPT ); Fri, 18 Feb 2022 16:16:14 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:42124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236379AbiBRVQJ (ORCPT ); Fri, 18 Feb 2022 16:16:09 -0500 X-Greylist: delayed 543 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Fri, 18 Feb 2022 13:15:49 PST Received: from mail.efficios.com (mail.efficios.com [167.114.26.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D660B23D5F9; Fri, 18 Feb 2022 13:15:49 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 2A75D3BA57A; Fri, 18 Feb 2022 16:06:43 -0500 (EST) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id ybaUpoQkLKpV; Fri, 18 Feb 2022 16:06:42 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id AB9663BAB0D; Fri, 18 Feb 2022 16:06:42 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com AB9663BAB0D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1645218402; bh=BioWaSozmqqbtmvJnfrlpWvhCFvnAXGhaRyjzgR7bfg=; h=From:To:Date:Message-Id; b=qJ1Rej0T6Ag4BSkPDBefCUB3AueJVIOFrWgZZ/cH/NKQqteqma3aje6GTj4ZIA+Gs lfXtKHgbCUgEtXcnhgGSPijvKHd664txolFGAS6giC9RqM+szFYugvBTy0DUk2r5oP xzAe4OnxSwLcfD9/9zLEoAI9xqXO/OR2AbsmcKS7gLSWklT/eXa2rGg9d2jbbmCbm7 EmhSotusL5fWkF+f8kECCi8WbwqD/zi4vJn7Vav3mvvrwZTQ0/ngh7ABveNaTswCd2 Gbc5xPnDpfio9hLAzrpSFqnBm+pCpaobAQZ7GPpeg+1BxLz6YZhcYa7xLTljAe3VTk tu7SKiiSVws5A== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id n_LFVrDxj7ru; Fri, 18 Feb 2022 16:06:42 -0500 (EST) Received: from localhost.localdomain (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by mail.efficios.com (Postfix) with ESMTPSA id 679133BA94B; Fri, 18 Feb 2022 16:06:42 -0500 (EST) From: Mathieu Desnoyers To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , "Paul E . McKenney" , Boqun Feng , "H . Peter Anvin" , Paul Turner , linux-api@vger.kernel.org, Christian Brauner , Florian Weimer , David.Laight@ACULAB.COM, carlos@redhat.com, Peter Oskolkov , Mathieu Desnoyers Subject: [RFC PATCH v2 01/11] rseq: Introduce feature size and alignment ELF auxiliary vector entries Date: Fri, 18 Feb 2022 16:06:23 -0500 Message-Id: <20220218210633.23345-2-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220218210633.23345-1-mathieu.desnoyers@efficios.com> References: <20220218210633.23345-1-mathieu.desnoyers@efficios.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Export the rseq feature size supported by the kernel as well as the required allocation alignment for the rseq per-thread area to user-space through ELF auxiliary vector entries. This is part of the extensible rseq ABI. Signed-off-by: Mathieu Desnoyers --- fs/binfmt_elf.c | 5 +++++ include/uapi/linux/auxvec.h | 2 ++ include/uapi/linux/rseq.h | 5 +++++ 3 files changed, 12 insertions(+) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 605017eb9349..77776582e76d 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include @@ -286,6 +287,10 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, if (bprm->have_execfd) { NEW_AUX_ENT(AT_EXECFD, bprm->execfd); } +#ifdef CONFIG_RSEQ + NEW_AUX_ENT(AT_RSEQ_FEATURE_SIZE, offsetof(struct rseq, end)); + NEW_AUX_ENT(AT_RSEQ_ALIGN, __alignof__(struct rseq)); +#endif #undef NEW_AUX_ENT /* AT_NULL is zero; clear the rest too */ memset(elf_info, 0, (char *)mm->saved_auxv + diff --git a/include/uapi/linux/auxvec.h b/include/uapi/linux/auxvec.h index c7e502bf5a6f..6991c4b8ab18 100644 --- a/include/uapi/linux/auxvec.h +++ b/include/uapi/linux/auxvec.h @@ -30,6 +30,8 @@ * differ from AT_PLATFORM. */ #define AT_RANDOM 25 /* address of 16 random bytes */ #define AT_HWCAP2 26 /* extension of AT_HWCAP */ +#define AT_RSEQ_FEATURE_SIZE 27 /* rseq supported feature size */ +#define AT_RSEQ_ALIGN 28 /* rseq allocation alignment */ #define AT_EXECFN 31 /* filename of program */ diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index 77ee207623a9..05d3c4cdeb40 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -130,6 +130,11 @@ struct rseq { * this thread. */ __u32 flags; + + /* + * Flexible array member at end of structure, after last feature field. + */ + char end[]; } __attribute__((aligned(4 * sizeof(__u64)))); #endif /* _UAPI_LINUX_RSEQ_H */ -- 2.17.1