Date: Mon, 14 Jun 2021 20:25:31 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: fa3cfd1a845a - stable/13 - arm64: Fix pmap_copy()'s handling of 2MB mappings Message-ID: <202106142025.15EKPVgP073364@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=fa3cfd1a845a33dbee88fcd80599c3ecc3268e26 commit fa3cfd1a845a33dbee88fcd80599c3ecc3268e26 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2021-06-06 20:40:45 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2021-06-14 20:25:15 +0000 arm64: Fix pmap_copy()'s handling of 2MB mappings When copying mappings from parent to child, we clear the accessed and dirty bits. This is done for both 4KB and 2MB PTEs. However, pmap_demote_l2() asserts that writable superpages must be dirty. This is to avoid races with the MMU setting the dirty bit during promotion and demotion. pmap_copy() can create clean, writable superpage mappings, so it violates this assertion. Modify pmap_copy() to preserve the accessed and dirty bits when copying 2MB mappings, like we do on amd64. Fixes: ca2cae0b4dd Reported by: Jenkins via mhorne Reviewed by: alc, kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D30643 (cherry picked from commit 4e4035ef1fb5e2f9da6b658ffae8a54862b4d018) --- sys/arm64/arm64/pmap.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c index b49ec4194e19..e9dd27981d61 100644 --- a/sys/arm64/arm64/pmap.c +++ b/sys/arm64/arm64/pmap.c @@ -4751,11 +4751,8 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len, ((srcptepaddr & ATTR_SW_MANAGED) == 0 || pmap_pv_insert_l2(dst_pmap, addr, srcptepaddr, PMAP_ENTER_NORECLAIM, &lock))) { - mask = ATTR_AF | ATTR_SW_WIRED; - nbits = 0; - if ((srcptepaddr & ATTR_SW_DBM) != 0) - nbits |= ATTR_S1_AP_RW_BIT; - pmap_store(l2, (srcptepaddr & ~mask) | nbits); + mask = ATTR_SW_WIRED; + pmap_store(l2, srcptepaddr & ~mask); pmap_resident_count_inc(dst_pmap, L2_SIZE / PAGE_SIZE); atomic_add_long(&pmap_l2_mappings, 1);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202106142025.15EKPVgP073364>