Date: Tue, 9 Jul 2019 20:28:54 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r349866 - head/sys/arm64/arm64 Message-ID: <201907092028.x69KSsx1051840@repo.freebsd.org>
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Author: alc Date: Tue Jul 9 20:28:53 2019 New Revision: 349866 URL: https://svnweb.freebsd.org/changeset/base/349866 Log: Introduce pmap_clear(), which zeroes a page table entry, and use it, instead of pmap_load_clear(), in places where we don't care about the page table entry's prior contents. Eliminate an unnecessary pmap_load() from pmap_remove_all(). Instead, use the value returned by the pmap_load_clear() on the very next line. (In the future, when we support "hardware dirty bit management", using the value from the pmap_load() rather than the pmap_load_clear() would have actually been an error because the dirty bit could potentially change between the pmap_load() and the pmap_load_clear().) A KASSERT() in pmap_enter(), which originated in the amd64 pmap, was meant to check the value returned by the pmap_load_clear() on the previous line. However, we were ignoring the value returned by the pmap_load_clear(), and so the KASSERT() was not serving its intended purpose. Use the value returned by the pmap_load_clear() in the KASSERT(). MFC after: 2 weeks Modified: head/sys/arm64/arm64/pmap.c Modified: head/sys/arm64/arm64/pmap.c ============================================================================== --- head/sys/arm64/arm64/pmap.c Tue Jul 9 19:32:31 2019 (r349865) +++ head/sys/arm64/arm64/pmap.c Tue Jul 9 20:28:53 2019 (r349866) @@ -315,6 +315,7 @@ static __inline vm_page_t pmap_remove_pt_page(pmap_t p * They need to be atomic as the System MMU may write to the table at * the same time as the CPU. */ +#define pmap_clear(table) atomic_store_64(table, 0) #define pmap_load_store(table, entry) atomic_swap_64(table, entry) #define pmap_set(table, mask) atomic_set_64(table, mask) #define pmap_load_clear(table) atomic_swap_64(table, 0) @@ -1208,7 +1209,7 @@ pmap_kremove(vm_offset_t va) KASSERT(pte != NULL, ("pmap_kremove: Invalid address")); KASSERT(lvl == 3, ("pmap_kremove: Invalid pte level %d", lvl)); - pmap_load_clear(pte); + pmap_clear(pte); pmap_invalidate_page(kernel_pmap, va); } @@ -1230,7 +1231,7 @@ pmap_kremove_device(vm_offset_t sva, vm_size_t size) KASSERT(pte != NULL, ("Invalid page table, va: 0x%lx", va)); KASSERT(lvl == 3, ("Invalid device pagetable level: %d != 3", lvl)); - pmap_load_clear(pte); + pmap_clear(pte); va += PAGE_SIZE; size -= PAGE_SIZE; @@ -1315,7 +1316,7 @@ pmap_qremove(vm_offset_t sva, int count) KASSERT(lvl == 3, ("Invalid device pagetable level: %d != 3", lvl)); if (pte != NULL) { - pmap_load_clear(pte); + pmap_clear(pte); } va += PAGE_SIZE; @@ -1374,19 +1375,19 @@ _pmap_unwire_l3(pmap_t pmap, vm_offset_t va, vm_page_t pd_entry_t *l0; l0 = pmap_l0(pmap, va); - pmap_load_clear(l0); + pmap_clear(l0); } else if (m->pindex >= NUL2E) { /* l2 page */ pd_entry_t *l1; l1 = pmap_l1(pmap, va); - pmap_load_clear(l1); + pmap_clear(l1); } else { /* l3 page */ pd_entry_t *l2; l2 = pmap_l2(pmap, va); - pmap_load_clear(l2); + pmap_clear(l2); } pmap_resident_count_dec(pmap, 1); if (m->pindex < NUL2E) { @@ -2760,8 +2761,7 @@ retry: tpde = pmap_load(pde); pte = pmap_l2_to_l3(pde, pv->pv_va); - tpte = pmap_load(pte); - pmap_load_clear(pte); + tpte = pmap_load_clear(pte); pmap_invalidate_page(pmap, pv->pv_va); if (tpte & ATTR_SW_WIRED) pmap->pm_stats.wired_count--; @@ -2986,7 +2986,7 @@ pmap_update_entry(pmap_t pmap, pd_entry_t *pte, pd_ent critical_enter(); /* Clear the old mapping */ - pmap_load_clear(pte); + pmap_clear(pte); pmap_invalidate_range_nopin(pmap, va, va + size); /* Create the new mapping */ @@ -3265,9 +3265,10 @@ havel3: } /* - * The physical page has changed. + * The physical page has changed. Temporarily invalidate + * the mapping. */ - (void)pmap_load_clear(l3); + orig_l3 = pmap_load_clear(l3); KASSERT((orig_l3 & ~ATTR_MASK) == opa, ("pmap_enter: unexpected pa update for %#lx", va)); if ((orig_l3 & ATTR_SW_MANAGED) != 0) { @@ -4282,7 +4283,12 @@ pmap_remove_pages(pmap_t pmap) ("pmap_remove_pages: bad pte %#jx", (uintmax_t)tpte)); - pmap_load_clear(pte); + /* + * Because this pmap is not active on other + * processors, the dirty bit cannot have + * changed state since we last loaded pte. + */ + pmap_clear(pte); /* * Update the vm_page_t clean/reference bits. @@ -5002,7 +5008,7 @@ pmap_unmapbios(vm_offset_t va, vm_size_t size) ("pmap_unmapbios: Invalid page entry, va: 0x%lx", va_trunc)); l2 = pmap_l1_to_l2(pde, va_trunc); - pmap_load_clear(l2); + pmap_clear(l2); if (block == (l2_blocks - 1)) break;
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