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 E5FC6C19F2D for ; Fri, 29 Jul 2022 19:02:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238498AbiG2TCq (ORCPT ); Fri, 29 Jul 2022 15:02:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238394AbiG2TCo (ORCPT ); Fri, 29 Jul 2022 15:02:44 -0400 Received: from mail.efficios.com (mail.efficios.com [167.114.26.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3EFB86C29; Fri, 29 Jul 2022 12:02:42 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 85E853187FD; Fri, 29 Jul 2022 15:02:41 -0400 (EDT) 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 lZRNnGx2Vadg; Fri, 29 Jul 2022 15:02:41 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 42463318C62; Fri, 29 Jul 2022 15:02:41 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 42463318C62 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1659121361; bh=pVzuqM3AzOqHAueSPhwC/tpBjnInPIjAGgyb3P8mKbE=; h=From:To:Date:Message-Id; b=IWLUHNDa0ARHMb0upK8yadGFtdj49z9UG0xmbIbC3OZctpFsK9jQeUQJLi25zfV5n YrqP5FavcxqA+m5qRbSPtxH7dOZQz4x36xaw/KKR0+BVfSlxN3Cbg67R+PiKU56+PR aJZFePL0f8L7eXD4Y3AWZ1wytZWUnJjoMTYEM8yqDeYL2HPqzUeNOrvZihE73bwUfb djZS3FEOtEde+5jgVvylgieA14T3LMEuqNv2zadE3+4b3V8mbjM9vgipKATLD9K01i H/wQq9sUX/JXg6o0V7VrMtPvW98KyTLndWizxf816+nh9M900CIMdW/GWVIKQgeErB UpqWb2RUT6fSg== 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 jmNhjaRfoRE9; Fri, 29 Jul 2022 15:02:41 -0400 (EDT) Received: from localhost.localdomain (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by mail.efficios.com (Postfix) with ESMTPSA id E6044318F87; Fri, 29 Jul 2022 15:02:40 -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 , Mathieu Desnoyers Subject: [PATCH v3 01/23] rseq: Introduce feature size and alignment ELF auxiliary vector entries Date: Fri, 29 Jul 2022 15:02:03 -0400 Message-Id: <20220729190225.12726-2-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220729190225.12726-1-mathieu.desnoyers@efficios.com> References: <20220729190225.12726-1-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 63c7ebb0da89..04fca1e4cbd2 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include @@ -288,6 +289,10 @@ 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