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 X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3985FC2BA19 for ; Mon, 13 Apr 2020 15:56:04 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0B2AA20735 for ; Mon, 13 Apr 2020 15:56:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="kap0DYQK"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="XmVGSp6K" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B2AA20735 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=cI6Jaq1YqnMS5M6cX31tCpDkLVT4HFdNXRpwQRNwdWo=; b=kap0DYQK0pWGqUMb8hfQE9HKaP /Qn65xwDa3YMzKF/KV2wfWTRa00IhVZJvdNCWPY2d/NtojdJ4hZRNEfLBwXhsAJtdLWFxu098IJ+e 123xM+v3NpQQOTAoxTrUD0k+Ohjmvf8OrNe6jaQpxj+NWqmBGBr3Yo0SioXPIdIo60HO98LjxCiz+ 6+MTXD1xNWCz17fVUyO5fV+umJFvYAn2nXatwQ+YOXLQSq6MXAIj+xOlJ+iA9l9bXHJBC9Nw7bfsR rlRftivEUWy3084W3PLdHDqlDWsx08OSC7TPc3cqwB7GWBXXugqsaAZU2HqomwMdQiAy8LVi/BvZx Xnuus6ig==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jO1RL-0007UK-6b; Mon, 13 Apr 2020 15:56:03 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jO1Qs-00076J-SO for linux-arm-kernel@lists.infradead.org; Mon, 13 Apr 2020 15:55:36 +0000 Received: from e123331-lin.home (amontpellier-657-1-18-247.w109-210.abo.wanadoo.fr [109.210.65.247]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 10DE12073E; Mon, 13 Apr 2020 15:55:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586793334; bh=u/xP6CoK1MUmVKKpWlYTdz2lShxhmNKAh4XSY+FwLjI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XmVGSp6K0VdVrP8HgOexa5iwmmQ7IZXGt680OIuFlIlps3CN2EErfqgDuArDyLSQ0 /rk+ZqvnWOJPZnSX68Dw5Qci19oft/3skEE3O+fPakg4/23QR2K1I7nz51gIXzpXE6 tVSs+YfGNgOtENgwLEZkMypZX33UI4gYotTbOS70= From: Ard Biesheuvel To: linux-efi@vger.kernel.org Subject: [PATCH v2 2/8] efi/libstub/random: increase random alloc granularity Date: Mon, 13 Apr 2020 17:55:15 +0200 Message-Id: <20200413155521.24698-3-ardb@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200413155521.24698-1-ardb@kernel.org> References: <20200413155521.24698-1-ardb@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200413_085534_964941_541BA270 X-CRM114-Status: GOOD ( 12.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, catalin.marinas@arm.com, nivedita@alum.mit.edu, Jonathan.Cameron@huawei.com, will@kernel.org, Ard Biesheuvel , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org The implementation of efi_random_alloc() arbitrarily truncates the provided random seed to 16 bits, which limits the granularity of the randomly chosen allocation offset in memory. This is currently only an issue if the size of physical memory exceeds 128 GB, but going forward, we will reduce the allocation alignment to 64 KB, and this means we need to increase the granularity to ensure that the random memory allocations are distributed evenly. We will need to switch to 64-bit arithmetic for the multiplication, but this does not result in 64-bit integer intrinsic calls on ARM or on i386. Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/randomalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c index 6200dfa650f5..a408df474d83 100644 --- a/drivers/firmware/efi/libstub/randomalloc.c +++ b/drivers/firmware/efi/libstub/randomalloc.c @@ -87,7 +87,7 @@ efi_status_t efi_random_alloc(unsigned long size, } /* find a random number between 0 and total_slots */ - target_slot = (total_slots * (u16)random_seed) >> 16; + target_slot = (total_slots * (u64)(random_seed & U32_MAX)) >> 32; /* * target_slot is now a value in the range [0, total_slots), and so -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel