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Index: head/sys/arm64/arm64/pmap.c
===================================================================
--- head/sys/arm64/arm64/pmap.c
+++ head/sys/arm64/arm64/pmap.c
@@ -1128,40 +1128,35 @@
pmap_kextract(vm_offset_t va)
{
pt_entry_t *pte, tpte;
- vm_paddr_t pa;
- int lvl;
- if (va >= DMAP_MIN_ADDRESS && va < DMAP_MAX_ADDRESS) {
- pa = DMAP_TO_PHYS(va);
- } else {
- pa = 0;
- pte = pmap_pte(kernel_pmap, va, &lvl);
- if (pte != NULL) {
- tpte = pmap_load(pte);
- pa = tpte & ~ATTR_MASK;
- switch(lvl) {
- case 1:
- KASSERT((tpte & ATTR_DESCR_MASK) == L1_BLOCK,
- ("pmap_kextract: Invalid L1 pte found: %lx",
- tpte & ATTR_DESCR_MASK));
- pa |= (va & L1_OFFSET);
- break;
- case 2:
- KASSERT((tpte & ATTR_DESCR_MASK) == L2_BLOCK,
- ("pmap_kextract: Invalid L2 pte found: %lx",
- tpte & ATTR_DESCR_MASK));
- pa |= (va & L2_OFFSET);
- break;
- case 3:
- KASSERT((tpte & ATTR_DESCR_MASK) == L3_PAGE,
- ("pmap_kextract: Invalid L3 pte found: %lx",
- tpte & ATTR_DESCR_MASK));
- pa |= (va & L3_OFFSET);
- break;
- }
- }
- }
- return (pa);
+ if (va >= DMAP_MIN_ADDRESS && va < DMAP_MAX_ADDRESS)
+ return (DMAP_TO_PHYS(va));
+ pte = pmap_l1(kernel_pmap, va);
+ if (pte == NULL)
+ return (0);
+
+ /*
+ * A concurrent pmap_update_entry() will clear the entry's valid bit
+ * but leave the rest of the entry unchanged. Therefore, we treat a
+ * non-zero entry as being valid, and we ignore the valid bit when
+ * determining whether the entry maps a block, page, or table.
+ */
+ tpte = pmap_load(pte);
+ if (tpte == 0)
+ return (0);
+ if ((tpte & ATTR_DESCR_TYPE_MASK) == ATTR_DESCR_TYPE_BLOCK)
+ return ((tpte & ~ATTR_MASK) | (va & L1_OFFSET));
+ pte = pmap_l1_to_l2(&tpte, va);
+ tpte = pmap_load(pte);
+ if (tpte == 0)
+ return (0);
+ if ((tpte & ATTR_DESCR_TYPE_MASK) == ATTR_DESCR_TYPE_BLOCK)
+ return ((tpte & ~ATTR_MASK) | (va & L2_OFFSET));
+ pte = pmap_l2_to_l3(&tpte, va);
+ tpte = pmap_load(pte);
+ if (tpte == 0)
+ return (0);
+ return ((tpte & ~ATTR_MASK) | (va & L3_OFFSET));
}
/***************************************************
@@ -3021,8 +3016,12 @@
intr = intr_disable();
critical_enter();
- /* Clear the old mapping */
- pmap_clear(pte);
+ /*
+ * Clear the old mapping's valid bit, but leave the rest of the entry
+ * unchanged, so that a lockless, concurrent pmap_kextract() can still
+ * lookup the physical address.
+ */
+ pmap_clear_bits(pte, ATTR_DESCR_VALID);
pmap_invalidate_range_nopin(pmap, va, va + size);
/* Create the new mapping */
Index: head/sys/arm64/include/pte.h
===================================================================
--- head/sys/arm64/include/pte.h
+++ head/sys/arm64/include/pte.h
@@ -71,7 +71,12 @@
#define ATTR_DEFAULT (ATTR_AF | ATTR_SH(ATTR_SH_IS))
-#define ATTR_DESCR_MASK 3
+#define ATTR_DESCR_MASK 3
+#define ATTR_DESCR_VALID 1
+#define ATTR_DESCR_TYPE_MASK 2
+#define ATTR_DESCR_TYPE_TABLE 2
+#define ATTR_DESCR_TYPE_PAGE 2
+#define ATTR_DESCR_TYPE_BLOCK 0
/* Level 0 table, 512GiB per entry */
#define L0_SHIFT 39

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