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Date:      Thu, 13 Apr 2017 15:03:03 +0000 (UTC)
From:      Andrew Turner <andrew@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r316761 - head/sys/arm64/arm64
Message-ID:  <201704131503.v3DF33cS086790@repo.freebsd.org>
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Author: andrew
Date: Thu Apr 13 15:03:03 2017
New Revision: 316761
URL: https://svnweb.freebsd.org/changeset/base/316761

Log:
  Set the arm64 Execute-never bits in more places.
  
  We need to set the Execute-never bits when mapping device memory as the
  hardware may perform speculative instruction fetches.
  
  Set the Privileged Execute-ever bit on userspace memory to stop the kernel
  if it is tricked into executing it.
  
  Reviewed by:	kib
  Sponsored by:	DARPA, AFRL
  Differential Revision:	https://reviews.freebsd.org/D10382

Modified:
  head/sys/arm64/arm64/pmap.c

Modified: head/sys/arm64/arm64/pmap.c
==============================================================================
--- head/sys/arm64/arm64/pmap.c	Thu Apr 13 14:51:34 2017	(r316760)
+++ head/sys/arm64/arm64/pmap.c	Thu Apr 13 15:03:03 2017	(r316761)
@@ -1127,7 +1127,7 @@ static void
 pmap_kenter(vm_offset_t sva, vm_size_t size, vm_paddr_t pa, int mode)
 {
 	pd_entry_t *pde;
-	pt_entry_t *pte;
+	pt_entry_t *pte, attr;
 	vm_offset_t va;
 	int lvl;
 
@@ -1138,6 +1138,10 @@ pmap_kenter(vm_offset_t sva, vm_size_t s
 	KASSERT((size & PAGE_MASK) == 0,
 	    ("pmap_kenter: Mapping is not page-sized"));
 
+	attr = ATTR_DEFAULT | ATTR_IDX(mode) | L3_PAGE;
+	if (mode == DEVICE_MEMORY)
+		attr |= ATTR_XN;
+
 	va = sva;
 	while (size != 0) {
 		pde = pmap_pde(kernel_pmap, va, &lvl);
@@ -1146,8 +1150,7 @@ pmap_kenter(vm_offset_t sva, vm_size_t s
 		KASSERT(lvl == 2, ("pmap_kenter: Invalid level %d", lvl));
 
 		pte = pmap_l2_to_l3(pde, va);
-		pmap_load_store(pte, (pa & ~L3_OFFSET) | ATTR_DEFAULT |
-		    ATTR_IDX(mode) | L3_PAGE);
+		pmap_load_store(pte, (pa & ~L3_OFFSET) | attr);
 		PTE_SYNC(pte);
 
 		va += PAGE_SIZE;
@@ -1259,6 +1262,8 @@ pmap_qenter(vm_offset_t sva, vm_page_t *
 		m = ma[i];
 		pa = VM_PAGE_TO_PHYS(m) | ATTR_DEFAULT | ATTR_AP(ATTR_AP_RW) |
 		    ATTR_IDX(m->md.pv_memattr) | L3_PAGE;
+		if (m->md.pv_memattr == DEVICE_MEMORY)
+			pa |= ATTR_XN;
 		pte = pmap_l2_to_l3(pde, va);
 		pmap_load_store(pte, pa);
 		PTE_SYNC(pte);
@@ -2719,12 +2724,12 @@ pmap_enter(pmap_t pmap, vm_offset_t va, 
 	    L3_PAGE);
 	if ((prot & VM_PROT_WRITE) == 0)
 		new_l3 |= ATTR_AP(ATTR_AP_RO);
-	if ((prot & VM_PROT_EXECUTE) == 0)
+	if ((prot & VM_PROT_EXECUTE) == 0 || m->md.pv_memattr == DEVICE_MEMORY)
 		new_l3 |= ATTR_XN;
 	if ((flags & PMAP_ENTER_WIRED) != 0)
 		new_l3 |= ATTR_SW_WIRED;
 	if ((va >> 63) == 0)
-		new_l3 |= ATTR_AP(ATTR_AP_USER);
+		new_l3 |= ATTR_AP(ATTR_AP_USER) | ATTR_PXN;
 
 	CTR2(KTR_PMAP, "pmap_enter: %.16lx -> %.16lx", va, pa);
 
@@ -3127,8 +3132,10 @@ pmap_enter_quick_locked(pmap_t pmap, vm_
 
 	pa = VM_PAGE_TO_PHYS(m) | ATTR_DEFAULT | ATTR_IDX(m->md.pv_memattr) |
 	    ATTR_AP(ATTR_AP_RO) | L3_PAGE;
-	if ((prot & VM_PROT_EXECUTE) == 0)
+	if ((prot & VM_PROT_EXECUTE) == 0 || m->md.pv_memattr == DEVICE_MEMORY)
 		pa |= ATTR_XN;
+	else if (va < VM_MAXUSER_ADDRESS)
+		pa |= ATTR_PXN;
 
 	/*
 	 * Now validate mapping with RO protection
@@ -4263,6 +4270,8 @@ pmap_change_attr_locked(vm_offset_t va, 
 				l3 = pmap_load(pte);
 				l3 &= ~ATTR_IDX_MASK;
 				l3 |= ATTR_IDX(mode);
+				if (mode == DEVICE_MEMORY)
+					l3 |= ATTR_XN;
 
 				pmap_update_entry(kernel_pmap, pte, l3, tmpva,
 				    PAGE_SIZE);

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