Date: Thu, 2 Nov 2023 18:47:47 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 71b77a7172c2 - main - riscv: Remove unnecessary invalidations in pmap_enter_quick_locked() Message-ID: <202311021847.3A2IllTH044804@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=71b77a7172c26783a9d2181d3bed27cf62974200 commit 71b77a7172c26783a9d2181d3bed27cf62974200 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2023-11-02 18:34:26 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2023-11-02 18:34:26 +0000 riscv: Remove unnecessary invalidations in pmap_enter_quick_locked() This function always overwrites an invalid PTE, so if pmap_try_insert_pv_entry() fails it is certainly not necessary to invalidate anything, because the PTE has not yet been written by that point. It should also not be necessary to invalidate TLBs after overwriting an invalid entry. In principle the TLB could cache negative entries, but then the worst case scenario is a spurious fault. Since pmap_enter() does not bother issuing an sfence.vma, pmap_enter_quick_locked() should behave similarly. Reviewed by: kib MFC after: 1 month Differential Revision: https://reviews.freebsd.org/D42291 --- sys/riscv/riscv/pmap.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/sys/riscv/riscv/pmap.c b/sys/riscv/riscv/pmap.c index ebb0f069b4ab..f0108b611937 100644 --- a/sys/riscv/riscv/pmap.c +++ b/sys/riscv/riscv/pmap.c @@ -3458,11 +3458,9 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m, if (l3 == NULL) panic("pmap_enter_quick_locked: No l3"); if (pmap_load(l3) != 0) { - if (mpte != NULL) { + if (mpte != NULL) mpte->ref_count--; - mpte = NULL; - } - return (mpte); + return (NULL); } /* @@ -3472,13 +3470,10 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m, !pmap_try_insert_pv_entry(pmap, va, m, lockp)) { if (mpte != NULL) { SLIST_INIT(&free); - if (pmap_unwire_ptp(pmap, va, mpte, &free)) { - pmap_invalidate_page(pmap, va); + if (pmap_unwire_ptp(pmap, va, mpte, &free)) vm_page_free_pages_toq(&free, false); - } - mpte = NULL; } - return (mpte); + return (NULL); } /* @@ -3524,7 +3519,6 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m, } #endif - pmap_invalidate_page(pmap, va); return (mpte); }
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