svn commit: r329263 - stable/11/sys/arm/arm
Svatopluk Kraus
skra at FreeBSD.org
Wed Feb 14 15:14:21 UTC 2018
Author: skra
Date: Wed Feb 14 15:14:20 2018
New Revision: 329263
URL: https://svnweb.freebsd.org/changeset/base/329263
Log:
MFC r325321:
Take into account race conditions in case of accessed or modified bit
emulation in fast path of data/prefetch abort common routine. Process these
bits only if related page table entries are consistent with provided abort
info. In case of inconsistency, do nothing and let processor to signal new
abort if still needed.
Modified:
stable/11/sys/arm/arm/pmap-v6.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/arm/arm/pmap-v6.c
==============================================================================
--- stable/11/sys/arm/arm/pmap-v6.c Wed Feb 14 15:12:09 2018 (r329262)
+++ stable/11/sys/arm/arm/pmap-v6.c Wed Feb 14 15:14:20 2018 (r329263)
@@ -6433,6 +6433,22 @@ pmap_fault(pmap_t pmap, vm_offset_t far, uint32_t fsr,
*/
PMAP_LOCK(pmap);
+#ifdef INVARIANTS
+ pte1 = pte1_load(pmap_pte1(pmap, far));
+ if (pte1_is_link(pte1)) {
+ /*
+ * Check in advance that associated L2 page table is mapped into
+ * PT2MAP space. Note that faulty access to not mapped L2 page
+ * table is caught in more general check above where "far" is
+ * checked that it does not lay in PT2MAP space. Note also that
+ * L1 page table and PT2TAB always exist and are mapped.
+ */
+ pte2 = pt2tab_load(pmap_pt2tab_entry(pmap, far));
+ if (!pte2_is_valid(pte2))
+ panic("%s: missing L2 page table (%p, %#x)",
+ __func__, pmap, far);
+ }
+#endif
#ifdef SMP
/*
* Special treatment is due to break-before-make approach done when
@@ -6453,10 +6469,23 @@ pmap_fault(pmap_t pmap, vm_offset_t far, uint32_t fsr,
* for aborts from user mode.
*/
if (idx == FAULT_ACCESS_L2) {
- pte2p = pt2map_entry(far);
- pte2 = pte2_load(pte2p);
- if (pte2_is_valid(pte2)) {
- pte2_store(pte2p, pte2 | PTE2_A);
+ pte1 = pte1_load(pmap_pte1(pmap, far));
+ if (pte1_is_link(pte1)) {
+ /* L2 page table should exist and be mapped. */
+ pte2p = pt2map_entry(far);
+ pte2 = pte2_load(pte2p);
+ if (pte2_is_valid(pte2)) {
+ pte2_store(pte2p, pte2 | PTE2_A);
+ PMAP_UNLOCK(pmap);
+ return (KERN_SUCCESS);
+ }
+ } else {
+ /*
+ * We got L2 access fault but PTE1 is not a link.
+ * Probably some race happened, do nothing.
+ */
+ CTR3(KTR_PMAP, "%s: FAULT_ACCESS_L2 - pmap %#x far %#x",
+ __func__, pmap, far);
PMAP_UNLOCK(pmap);
return (KERN_SUCCESS);
}
@@ -6468,6 +6497,15 @@ pmap_fault(pmap_t pmap, vm_offset_t far, uint32_t fsr,
pte1_store(pte1p, pte1 | PTE1_A);
PMAP_UNLOCK(pmap);
return (KERN_SUCCESS);
+ } else {
+ /*
+ * We got L1 access fault but PTE1 is not section
+ * mapping. Probably some race happened, do nothing.
+ */
+ CTR3(KTR_PMAP, "%s: FAULT_ACCESS_L1 - pmap %#x far %#x",
+ __func__, pmap, far);
+ PMAP_UNLOCK(pmap);
+ return (KERN_SUCCESS);
}
}
@@ -6480,12 +6518,25 @@ pmap_fault(pmap_t pmap, vm_offset_t far, uint32_t fsr,
* for aborts from user mode.
*/
if ((fsr & FSR_WNR) && (idx == FAULT_PERM_L2)) {
- pte2p = pt2map_entry(far);
- pte2 = pte2_load(pte2p);
- if (pte2_is_valid(pte2) && !(pte2 & PTE2_RO) &&
- (pte2 & PTE2_NM)) {
- pte2_store(pte2p, pte2 & ~PTE2_NM);
- tlb_flush(trunc_page(far));
+ pte1 = pte1_load(pmap_pte1(pmap, far));
+ if (pte1_is_link(pte1)) {
+ /* L2 page table should exist and be mapped. */
+ pte2p = pt2map_entry(far);
+ pte2 = pte2_load(pte2p);
+ if (pte2_is_valid(pte2) && !(pte2 & PTE2_RO) &&
+ (pte2 & PTE2_NM)) {
+ pte2_store(pte2p, pte2 & ~PTE2_NM);
+ tlb_flush(trunc_page(far));
+ PMAP_UNLOCK(pmap);
+ return (KERN_SUCCESS);
+ }
+ } else {
+ /*
+ * We got L2 permission fault but PTE1 is not a link.
+ * Probably some race happened, do nothing.
+ */
+ CTR3(KTR_PMAP, "%s: FAULT_PERM_L2 - pmap %#x far %#x",
+ __func__, pmap, far);
PMAP_UNLOCK(pmap);
return (KERN_SUCCESS);
}
@@ -6493,10 +6544,20 @@ pmap_fault(pmap_t pmap, vm_offset_t far, uint32_t fsr,
if ((fsr & FSR_WNR) && (idx == FAULT_PERM_L1)) {
pte1p = pmap_pte1(pmap, far);
pte1 = pte1_load(pte1p);
- if (pte1_is_section(pte1) && !(pte1 & PTE1_RO) &&
- (pte1 & PTE1_NM)) {
- pte1_store(pte1p, pte1 & ~PTE1_NM);
- tlb_flush(pte1_trunc(far));
+ if (pte1_is_section(pte1)) {
+ if (!(pte1 & PTE1_RO) && (pte1 & PTE1_NM)) {
+ pte1_store(pte1p, pte1 & ~PTE1_NM);
+ tlb_flush(pte1_trunc(far));
+ PMAP_UNLOCK(pmap);
+ return (KERN_SUCCESS);
+ }
+ } else {
+ /*
+ * We got L1 permission fault but PTE1 is not section
+ * mapping. Probably some race happened, do nothing.
+ */
+ CTR3(KTR_PMAP, "%s: FAULT_PERM_L1 - pmap %#x far %#x",
+ __func__, pmap, far);
PMAP_UNLOCK(pmap);
return (KERN_SUCCESS);
}
@@ -6507,33 +6568,6 @@ pmap_fault(pmap_t pmap, vm_offset_t far, uint32_t fsr,
* modify bits aborts, could be moved to ASM. Now we are
* starting to deal with not fast aborts.
*/
-
-#ifdef INVARIANTS
- /*
- * Read an entry in PT2TAB associated with both pmap and far.
- * It's safe because PT2TAB is always mapped.
- */
- pte2 = pt2tab_load(pmap_pt2tab_entry(pmap, far));
- if (pte2_is_valid(pte2)) {
- /*
- * Now, when we know that L2 page table is allocated,
- * we can use PT2MAP to get L2 page table entry.
- */
- pte2 = pte2_load(pt2map_entry(far));
- if (pte2_is_valid(pte2)) {
- /*
- * If L2 page table entry is valid, make sure that
- * L1 page table entry is valid too. Note that we
- * leave L2 page entries untouched when promoted.
- */
- pte1 = pte1_load(pmap_pte1(pmap, far));
- if (!pte1_is_valid(pte1)) {
- panic("%s: missing L1 page entry (%p, %#x)",
- __func__, pmap, far);
- }
- }
- }
-#endif
PMAP_UNLOCK(pmap);
return (KERN_FAILURE);
}
More information about the svn-src-all
mailing list