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 16ADEC433EF for ; Tue, 19 Apr 2022 21:52:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356492AbiDSVy7 (ORCPT ); Tue, 19 Apr 2022 17:54:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350809AbiDSVy6 (ORCPT ); Tue, 19 Apr 2022 17:54:58 -0400 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [IPv6:2607:fcd0:100:8a00::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EFC13B01B for ; Tue, 19 Apr 2022 14:52:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1650405133; bh=DGQOkSXoSA2ZhBn+vc7S9ZuuYN9Ma1uDIzjAodtilDY=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=ap56u+R+qo6odqrDuwbSho31u/Ztl/n0HevhZzrNHmkZ5Gw/LQ9UxvoYz3RBNf3YH 5Owtlq7yWIYIs5XYW/nFxrS+mH2R/TMtmOuKDAhJhamcI8NBtfBRu8ceK1SHnHjCqc ksl28VQZ1pAEeC8RAzZko5gUmvdiGkYv+7NDXejo= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 972C11288CA0; Tue, 19 Apr 2022 17:52:13 -0400 (EDT) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id C0j5kN3uIuVx; Tue, 19 Apr 2022 17:52:13 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1650405133; bh=DGQOkSXoSA2ZhBn+vc7S9ZuuYN9Ma1uDIzjAodtilDY=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=ap56u+R+qo6odqrDuwbSho31u/Ztl/n0HevhZzrNHmkZ5Gw/LQ9UxvoYz3RBNf3YH 5Owtlq7yWIYIs5XYW/nFxrS+mH2R/TMtmOuKDAhJhamcI8NBtfBRu8ceK1SHnHjCqc ksl28VQZ1pAEeC8RAzZko5gUmvdiGkYv+7NDXejo= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4300:c551::c14]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 0E38A1288C9F; Tue, 19 Apr 2022 17:52:12 -0400 (EDT) Message-ID: <137e0b6f4dcaceafeac4b1ecfa30e4249939028d.camel@HansenPartnership.com> Subject: Re: Recurring INEQUIVALENT ALIASES issues and userland corruption/crashes From: James Bottomley To: John David Anglin , Sam James Cc: linux-parisc@vger.kernel.org, hppa@gentoo.org Date: Tue, 19 Apr 2022 17:52:11 -0400 In-Reply-To: <7a25a890-461b-0ba4-0b77-57d639de0007@bell.net> References: <63DA313A-FCE1-4535-9BF3-11E36B2DE422@gentoo.org> <94439119-D2B6-4961-B61D-95784E09798D@gentoo.org> <383d6dfa-bef1-e56f-8f82-dfc0682cdacc@bell.net> <93BE3A28-6EBE-4DC4-92BE-867E7ACB255B@gentoo.org> <7a25a890-461b-0ba4-0b77-57d639de0007@bell.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Tue, 2022-04-19 at 17:29 -0400, John David Anglin wrote: > We know that the PDC call to determine cache > characteristics indicates that the alias boundary on PA8800/PA8900 is > larger than 16 MB. Sorry, late to the party. What the PDC tells you is unreliable. However, the Architecture guide Appendix F says "These rules provide offset aliasing on 16 Mbyte boundaries, with optional support for offset aliasing on smaller power of two sized boundaries, and either restricted or unlimited space aliasing." So unless someone has an update to the architecture guide, 16MB as a cache stride is architecturally required to work. The tmpalias code in pacache.S is predicated on an assurance by the old HP chip designers that no chip was released with a cache stride greater than 4MB, meaning we could safely relax the 16MB architectural rules down to 4MB. James