svn commit: r352584 - head/sys/arm64/arm64
Alan Cox
alc at FreeBSD.org
Sat Sep 21 19:51:58 UTC 2019
Author: alc
Date: Sat Sep 21 19:51:57 2019
New Revision: 352584
URL: https://svnweb.freebsd.org/changeset/base/352584
Log:
In case a translation fault on the kernel address space occurs from
within a critical section, we must perform a lock-free check on the
faulting address.
Reported by: andrew
Reviewed by: andrew, markj
X-MFC with: r350579
Differential Revision: https://reviews.freebsd.org/D21685
Modified:
head/sys/arm64/arm64/pmap.c
Modified: head/sys/arm64/arm64/pmap.c
==============================================================================
--- head/sys/arm64/arm64/pmap.c Sat Sep 21 19:05:38 2019 (r352583)
+++ head/sys/arm64/arm64/pmap.c Sat Sep 21 19:51:57 2019 (r352584)
@@ -5810,23 +5810,33 @@ pmap_fault(pmap_t pmap, uint64_t esr, uint64_t far)
case ISS_DATA_DFSC_TF_L1:
case ISS_DATA_DFSC_TF_L2:
case ISS_DATA_DFSC_TF_L3:
- PMAP_LOCK(pmap);
- /* Ask the MMU to check the address */
- intr = intr_disable();
- if (pmap == kernel_pmap)
- par = arm64_address_translate_s1e1r(far);
- else
- par = arm64_address_translate_s1e0r(far);
- intr_restore(intr);
- PMAP_UNLOCK(pmap);
-
/*
- * If the translation was successful the address was invalid
- * due to a break-before-make sequence. We can unlock and
- * return success to the trap handler.
+ * Retry the translation. A break-before-make sequence can
+ * produce a transient fault.
*/
- if (PAR_SUCCESS(par))
- rv = KERN_SUCCESS;
+ if (pmap == kernel_pmap) {
+ /*
+ * The translation fault may have occurred within a
+ * critical section. Therefore, we must check the
+ * address without acquiring the kernel pmap's lock.
+ */
+ if (pmap_kextract(far) != 0)
+ rv = KERN_SUCCESS;
+ } else {
+ PMAP_LOCK(pmap);
+ /* Ask the MMU to check the address. */
+ intr = intr_disable();
+ par = arm64_address_translate_s1e0r(far);
+ intr_restore(intr);
+ PMAP_UNLOCK(pmap);
+
+ /*
+ * If the translation was successful, then we can
+ * return success to the trap handler.
+ */
+ if (PAR_SUCCESS(par))
+ rv = KERN_SUCCESS;
+ }
break;
}
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