svn commit: r356207 - in head/sys/arm64: arm64 include

[Alan Cox]

Author: alc
Date: Mon Dec 30 20:30:31 2019
New Revision: 356207
URL: https://svnweb.freebsd.org/changeset/base/356207

Log:
  Determine whether the MMU hardware is capable of updating a page table
  entry's access flag and dirty state, and enable this feature when it's
  available.
  
  Ensure that we don't overlook a dirty state update that is concurrent
  with a call to pmap_enter().  (Previously, all dirty state updates would
  have occurred with the containing pmap's lock held, so a page table entry's
  dirty state could not have changed while pmap_enter() held that same lock.)
  
  Reviewed by:	andrew, markj
  MFC after:	2 weeks
  Differential Revision:	https://reviews.freebsd.org/D22907

Modified:
  head/sys/arm64/arm64/locore.S
  head/sys/arm64/arm64/pmap.c
  head/sys/arm64/include/armreg.h

Modified: head/sys/arm64/arm64/locore.S
==============================================================================
--- head/sys/arm64/arm64/locore.S	Mon Dec 30 18:11:06 2019	(r356206)
+++ head/sys/arm64/arm64/locore.S	Mon Dec 30 20:30:31 2019	(r356207)
@@ -683,7 +683,8 @@ start_mmu:
 
 	/*
 	 * Setup TCR according to the PARange and ASIDBits fields
-	 * from ID_AA64MMFR0_EL1.  More precisely, set TCR_EL1.AS
+	 * from ID_AA64MMFR0_EL1 and the HAFDBS field from the
+	 * ID_AA64MMFR1_EL1.  More precisely, set TCR_EL1.AS
 	 * to 1 only if the ASIDBits field equals 0b0010.
 	 */
 	ldr	x2, tcr
@@ -700,6 +701,21 @@ start_mmu:
 	/* Set TCR.AS with x3 */
 	bfi	x2, x3, #(TCR_ASID_SHIFT), #(TCR_ASID_WIDTH)
 
+	/*
+	 * Check if the HW supports access flag and dirty state updates,
+	 * and set TCR_EL1.HA and TCR_EL1.HD accordingly.
+	 */
+	mrs	x3, id_aa64mmfr1_el1
+	and	x3, x3, #(ID_AA64MMFR1_HAFDBS_MASK)
+	cmp	x3, #1
+	b.ne	1f
+	orr 	x2, x2, #(TCR_HA)
+	b	2f
+1:
+	cmp	x3, #2
+	b.ne	2f
+	orr 	x2, x2, #(TCR_HA | TCR_HD)
+2:
 	msr	tcr_el1, x2
 
 	/*

Modified: head/sys/arm64/arm64/pmap.c
==============================================================================
--- head/sys/arm64/arm64/pmap.c	Mon Dec 30 18:11:06 2019	(r356206)
+++ head/sys/arm64/arm64/pmap.c	Mon Dec 30 20:30:31 2019	(r356207)
@@ -3510,8 +3510,7 @@ validate:
 		KASSERT(opa == pa, ("pmap_enter: invalid update"));
 		if ((orig_l3 & ~ATTR_AF) != (new_l3 & ~ATTR_AF)) {
 			/* same PA, different attributes */
-			/* XXXMJ need to reload orig_l3 for hardware DBM. */
-			pmap_load_store(l3, new_l3);
+			orig_l3 = pmap_load_store(l3, new_l3);
 			pmap_invalidate_page(pmap, va);
 			if ((orig_l3 & ATTR_SW_MANAGED) != 0 &&
 			    pmap_pte_dirty(orig_l3))

Modified: head/sys/arm64/include/armreg.h
==============================================================================
--- head/sys/arm64/include/armreg.h	Mon Dec 30 18:11:06 2019	(r356206)
+++ head/sys/arm64/include/armreg.h	Mon Dec 30 20:30:31 2019	(r356207)
@@ -619,6 +619,11 @@
 #define	PSR_FLAGS	0xf0000000
 
 /* TCR_EL1 - Translation Control Register */
+#define	TCR_HD_SHIFT	40
+#define	TCR_HD		(0x1UL << TCR_HD_SHIFT)
+#define	TCR_HA_SHIFT	39
+#define	TCR_HA		(0x1UL << TCR_HA_SHIFT)
+
 #define	TCR_ASID_SHIFT	36
 #define	TCR_ASID_WIDTH	1
 #define	TCR_ASID_16	(0x1UL << TCR_ASID_SHIFT)