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Index: head/sys/amd64/amd64/pmap.c
===================================================================
--- head/sys/amd64/amd64/pmap.c
+++ head/sys/amd64/amd64/pmap.c
@@ -7574,7 +7574,7 @@
pmap_t pmap;
pv_entry_t next_pv, pv;
pd_entry_t oldpde, *pde;
- pt_entry_t oldpte, *pte, PG_M, PG_RW, PG_V;
+ pt_entry_t *pte, PG_M, PG_RW;
struct rwlock *lock;
vm_offset_t va;
int md_gen, pvh_gen;
@@ -7610,33 +7610,23 @@
}
}
PG_M = pmap_modified_bit(pmap);
- PG_V = pmap_valid_bit(pmap);
PG_RW = pmap_rw_bit(pmap);
va = pv->pv_va;
pde = pmap_pde(pmap, va);
oldpde = *pde;
- if ((oldpde & PG_RW) != 0) {
- if (pmap_demote_pde_locked(pmap, pde, va, &lock)) {
- if ((oldpde & PG_W) == 0) {
- /*
- * Write protect the mapping to a
- * single page so that a subsequent
- * write access may repromote.
- */
- va += VM_PAGE_TO_PHYS(m) - (oldpde &
- PG_PS_FRAME);
- pte = pmap_pde_to_pte(pde, va);
- oldpte = *pte;
- if ((oldpte & PG_V) != 0) {
- while (!atomic_cmpset_long(pte,
- oldpte,
- oldpte & ~(PG_M | PG_RW)))
- oldpte = *pte;
- vm_page_dirty(m);
- pmap_invalidate_page(pmap, va);
- }
- }
- }
+ /* If oldpde has PG_RW set, then it also has PG_M set. */
+ if ((oldpde & PG_RW) != 0 &&
+ pmap_demote_pde_locked(pmap, pde, va, &lock) &&
+ (oldpde & PG_W) == 0) {
+ /*
+ * Write protect the mapping to a single page so that
+ * a subsequent write access may repromote.
+ */
+ va += VM_PAGE_TO_PHYS(m) - (oldpde & PG_PS_FRAME);
+ pte = pmap_pde_to_pte(pde, va);
+ atomic_clear_long(pte, PG_M | PG_RW);
+ vm_page_dirty(m);
+ pmap_invalidate_page(pmap, va);
}
PMAP_UNLOCK(pmap);
}
Index: head/sys/arm64/arm64/pmap.c
===================================================================
--- head/sys/arm64/arm64/pmap.c
+++ head/sys/arm64/arm64/pmap.c
@@ -4889,28 +4889,22 @@
va = pv->pv_va;
l2 = pmap_l2(pmap, va);
oldl2 = pmap_load(l2);
- if ((oldl2 & ATTR_SW_DBM) != 0) {
- if (pmap_demote_l2_locked(pmap, l2, va, &lock)) {
- if ((oldl2 & ATTR_SW_WIRED) == 0) {
- /*
- * Write protect the mapping to a
- * single page so that a subsequent
- * write access may repromote.
- */
- va += VM_PAGE_TO_PHYS(m) -
- (oldl2 & ~ATTR_MASK);
- l3 = pmap_l2_to_l3(l2, va);
- oldl3 = pmap_load(l3);
- if (pmap_l3_valid(oldl3)) {
- while (!atomic_fcmpset_long(l3,
- &oldl3, (oldl3 & ~ATTR_SW_DBM) |
- ATTR_AP(ATTR_AP_RO)))
- cpu_spinwait();
- vm_page_dirty(m);
- pmap_invalidate_page(pmap, va);
- }
- }
- }
+ /* If oldl2 has ATTR_SW_DBM set, then it is also dirty. */
+ if ((oldl2 & ATTR_SW_DBM) != 0 &&
+ pmap_demote_l2_locked(pmap, l2, va, &lock) &&
+ (oldl2 & ATTR_SW_WIRED) == 0) {
+ /*
+ * Write protect the mapping to a single page so that
+ * a subsequent write access may repromote.
+ */
+ va += VM_PAGE_TO_PHYS(m) - (oldl2 & ~ATTR_MASK);
+ l3 = pmap_l2_to_l3(l2, va);
+ oldl3 = pmap_load(l3);
+ while (!atomic_fcmpset_long(l3, &oldl3,
+ (oldl3 & ~ATTR_SW_DBM) | ATTR_AP(ATTR_AP_RO)))
+ cpu_spinwait();
+ vm_page_dirty(m);
+ pmap_invalidate_page(pmap, va);
}
PMAP_UNLOCK(pmap);
}
Index: head/sys/i386/i386/pmap.c
===================================================================
--- head/sys/i386/i386/pmap.c
+++ head/sys/i386/i386/pmap.c
@@ -5280,7 +5280,7 @@
pv_entry_t next_pv, pv;
pmap_t pmap;
pd_entry_t oldpde, *pde;
- pt_entry_t oldpte, *pte;
+ pt_entry_t *pte;
vm_offset_t va;
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
@@ -5307,34 +5307,24 @@
PMAP_LOCK(pmap);
pde = pmap_pde(pmap, va);
oldpde = *pde;
- if ((oldpde & PG_RW) != 0) {
- if (pmap_demote_pde(pmap, pde, va)) {
- if ((oldpde & PG_W) == 0) {
- /*
- * Write protect the mapping to a
- * single page so that a subsequent
- * write access may repromote.
- */
- va += VM_PAGE_TO_PHYS(m) - (oldpde &
- PG_PS_FRAME);
- pte = pmap_pte_quick(pmap, va);
- oldpte = *pte;
- if ((oldpte & PG_V) != 0) {
- /*
- * Regardless of whether a pte is 32 or 64 bits
- * in size, PG_RW and PG_M are among the least
- * significant 32 bits.
- */
- while (!atomic_cmpset_int((u_int *)pte,
- oldpte,
- oldpte & ~(PG_M | PG_RW)))
- oldpte = *pte;
- vm_page_dirty(m);
- pmap_invalidate_page_int(pmap,
- va);
- }
- }
- }
+ /* If oldpde has PG_RW set, then it also has PG_M set. */
+ if ((oldpde & PG_RW) != 0 &&
+ pmap_demote_pde(pmap, pde, va) &&
+ (oldpde & PG_W) == 0) {
+ /*
+ * Write protect the mapping to a single page so that
+ * a subsequent write access may repromote.
+ */
+ va += VM_PAGE_TO_PHYS(m) - (oldpde & PG_PS_FRAME);
+ pte = pmap_pte_quick(pmap, va);
+ /*
+ * Regardless of whether a pte is 32 or 64 bits
+ * in size, PG_RW and PG_M are among the least
+ * significant 32 bits.
+ */
+ atomic_clear_int((u_int *)pte, PG_M | PG_RW);
+ vm_page_dirty(m);
+ pmap_invalidate_page_int(pmap, va);
}
PMAP_UNLOCK(pmap);
}
Index: head/sys/riscv/riscv/pmap.c
===================================================================
--- head/sys/riscv/riscv/pmap.c
+++ head/sys/riscv/riscv/pmap.c
@@ -4105,7 +4105,7 @@
pmap_t pmap;
pv_entry_t next_pv, pv;
pd_entry_t *l2, oldl2;
- pt_entry_t *l3, oldl3;
+ pt_entry_t *l3;
vm_offset_t va;
int md_gen, pvh_gen;
@@ -4143,28 +4143,19 @@
va = pv->pv_va;
l2 = pmap_l2(pmap, va);
oldl2 = pmap_load(l2);
- if ((oldl2 & PTE_W) != 0) {
- if (pmap_demote_l2_locked(pmap, l2, va, &lock)) {
- if ((oldl2 & PTE_SW_WIRED) == 0) {
- /*
- * Write protect the mapping to a
- * single page so that a subsequent
- * write access may repromote.
- */
- va += VM_PAGE_TO_PHYS(m) -
- PTE_TO_PHYS(oldl2);
- l3 = pmap_l2_to_l3(l2, va);
- oldl3 = pmap_load(l3);
- if ((oldl3 & PTE_V) != 0) {
- while (!atomic_fcmpset_long(l3,
- &oldl3, oldl3 & ~(PTE_D |
- PTE_W)))
- cpu_spinwait();
- vm_page_dirty(m);
- pmap_invalidate_page(pmap, va);
- }
- }
- }
+ /* If oldl2 has PTE_W set, then it also has PTE_D set. */
+ if ((oldl2 & PTE_W) != 0 &&
+ pmap_demote_l2_locked(pmap, l2, va, &lock) &&
+ (oldl2 & PTE_SW_WIRED) == 0) {
+ /*
+ * Write protect the mapping to a single page so that
+ * a subsequent write access may repromote.
+ */
+ va += VM_PAGE_TO_PHYS(m) - PTE_TO_PHYS(oldl2);
+ l3 = pmap_l2_to_l3(l2, va);
+ pmap_clear_bits(l3, PTE_D | PTE_W);
+ vm_page_dirty(m);
+ pmap_invalidate_page(pmap, va);
}
PMAP_UNLOCK(pmap);
}

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