From nobody Thu Apr 2 18:11:42 2026 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 237BAC4332F for ; Thu, 3 Nov 2022 20:05:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231238AbiKCUFD (ORCPT ); Thu, 3 Nov 2022 16:05:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230370AbiKCUE6 (ORCPT ); Thu, 3 Nov 2022 16:04:58 -0400 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C8D720341; Thu, 3 Nov 2022 13:04:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1667505895; bh=3FQzak7NFQCeQ17sM6xyWBPLJooy+CEjUwRxboNNo2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dAmf0mXn5RkJ3x6/KHkopdNJXvvg2iobvcOjLiAfAsqWc/33JXzDgWwpOQqfJWfbf oGyzaCqlz2ksF+qFWZnjm6wKXPg8OtJtbLDp4o+Em1BaqgM7MbIhddYe0O/NwPiVJe N0I2On7stcX1xBs9vX45gnhiZBSeeOdpwxOYQT7j9kGxU0WbusCImSkt7P6KS9dmCh ZDvT7OH7QoTUfVQY329rInsldiBI7wXmRcf+M2P2ziYG98jQlFUHBcLz7DjlpeYFDQ YIQPjSg6SXXzqcbpur378S0JQ1CpRZjlRSXFSl98bKi6/IrGplV5pgk1IR+5d/5uNk oxDOghXPopc0Q== Received: from localhost.localdomain (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4N3F93273NzfW5; Thu, 3 Nov 2022 16:04:55 -0400 (EDT) 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 , Alexander Mikhalitsyn , Chris Kennelly , Mathieu Desnoyers Subject: [PATCH v5 01/24] rseq: Introduce feature size and alignment ELF auxiliary vector entries Date: Thu, 3 Nov 2022 16:03:36 -0400 Message-Id: <20221103200359.328736-2-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221103200359.328736-1-mathieu.desnoyers@efficios.com> References: <20221103200359.328736-1-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 63c7ebb0da89..04fca1e4cbd2 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include =20 @@ -288,6 +289,10 @@ create_elf_tables(struct linux_binprm *bprm, const str= uct 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 */ =20 #define AT_EXECFN 31 /* filename of program */ =20 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)))); =20 #endif /* _UAPI_LINUX_RSEQ_H */ --=20 2.25.1