From 3a6413d81e66f32d3ca4a800aa4cc5ec145a1ca4 Mon Sep 17 00:00:00 2001
From: Andrew Turner <andrew@FreeBSD.org>
Date: Wed, 17 Jun 2020 19:45:05 +0000
Subject: [PATCH] Support pmap_extract_and_hold on arm64 stage 2 mappings

Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D24469
---
 sys/arm64/arm64/pmap.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index 7204a6bd9704..43a16d185ed9 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -1228,8 +1228,7 @@ pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
 	vm_offset_t off;
 	vm_page_t m;
 	int lvl;
-
-	PMAP_ASSERT_STAGE1(pmap);
+	bool use;
 
 	m = NULL;
 	PMAP_LOCK(pmap);
@@ -1244,8 +1243,19 @@ pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
 		    (lvl < 3 && (tpte & ATTR_DESCR_MASK) == L1_BLOCK),
 		    ("pmap_extract_and_hold: Invalid pte at L%d: %lx", lvl,
 		     tpte & ATTR_DESCR_MASK));
-		if (((tpte & ATTR_S1_AP_RW_BIT) == ATTR_S1_AP(ATTR_S1_AP_RW)) ||
-		    ((prot & VM_PROT_WRITE) == 0)) {
+
+		use = false;
+		if ((prot & VM_PROT_WRITE) == 0)
+			use = true;
+		else if (pmap->pm_stage == PM_STAGE1 &&
+		    (tpte & ATTR_S1_AP_RW_BIT) == ATTR_S1_AP(ATTR_S1_AP_RW))
+			use = true;
+		else if (pmap->pm_stage == PM_STAGE2 &&
+		    ((tpte & ATTR_S2_S2AP(ATTR_S2_S2AP_WRITE)) ==
+		     ATTR_S2_S2AP(ATTR_S2_S2AP_WRITE)))
+			use = true;
+
+		if (use) {
 			switch(lvl) {
 			case 1:
 				off = va & L1_OFFSET;