From owner-dev-commits-src-all@freebsd.org Sun Jun 6 20:45:11 2021 Return-Path: Delivered-To: dev-commits-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 20BD563D679; Sun, 6 Jun 2021 20:45:11 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FypRC0FFWz3v8N; Sun, 6 Jun 2021 20:45:11 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id CA3A52201; Sun, 6 Jun 2021 20:45:10 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 156KjASb051958; Sun, 6 Jun 2021 20:45:10 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 156KjAb0051957; Sun, 6 Jun 2021 20:45:10 GMT (envelope-from git) Date: Sun, 6 Jun 2021 20:45:10 GMT Message-Id: <202106062045.156KjAb0051957@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: a48f51b3d396 - main - arm64: Use the right PTE when downgrading perms in pmap_promote_l2() MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: a48f51b3d396664f9b0a91f016159f4e4324da85 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for all branches of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 06 Jun 2021 20:45:11 -0000 The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=a48f51b3d396664f9b0a91f016159f4e4324da85 commit a48f51b3d396664f9b0a91f016159f4e4324da85 Author: Mark Johnston AuthorDate: 2021-06-06 20:40:29 +0000 Commit: Mark Johnston CommitDate: 2021-06-06 20:44:46 +0000 arm64: Use the right PTE when downgrading perms in pmap_promote_l2() When promoting a run of small mappings to a superpage, we have to downgrade clean, writable mappings to read-only, to handle the possibility that the MMU will concurrently mark one of the mappings as dirty. The code which performed this operation for the first PTE in the run used the wrong PTE pointer. As a result, the comparison would always fail, aborting the promotion. This only occurs when promoting writable, clean mappings. Fixes: ca2cae0b4dd Reviewed by: alc, kib MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D30642 --- sys/arm64/arm64/pmap.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c index bc5d228af5ad..c26c3d8fce17 100644 --- a/sys/arm64/arm64/pmap.c +++ b/sys/arm64/arm64/pmap.c @@ -3518,7 +3518,11 @@ setl2: if ((newl2 & (ATTR_S1_AP_RW_BIT | ATTR_SW_DBM)) == (ATTR_S1_AP(ATTR_S1_AP_RO) | ATTR_SW_DBM)) { - if (!atomic_fcmpset_64(l2, &newl2, newl2 & ~ATTR_SW_DBM)) + /* + * When the mapping is clean, i.e., ATTR_S1_AP_RO is set, + * ATTR_SW_DBM can be cleared without a TLB invalidation. + */ + if (!atomic_fcmpset_64(firstl3, &newl2, newl2 & ~ATTR_SW_DBM)) goto setl2; newl2 &= ~ATTR_SW_DBM; } @@ -3529,6 +3533,11 @@ setl2: setl3: if ((oldl3 & (ATTR_S1_AP_RW_BIT | ATTR_SW_DBM)) == (ATTR_S1_AP(ATTR_S1_AP_RO) | ATTR_SW_DBM)) { + /* + * When the mapping is clean, i.e., ATTR_S1_AP_RO is + * set, ATTR_SW_DBM can be cleared without a TLB + * invalidation. + */ if (!atomic_fcmpset_64(l3, &oldl3, oldl3 & ~ATTR_SW_DBM)) goto setl3;