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Start to use the User and Privileged execute-never bits in the arm64

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pagetables. This sets both bits when entering an address we know shouldn't
be executed.

I expect we could mark all userspace pages as Privileged execute-never to
ensure the kernel doesn't branch to one of these addresses.

While here add the ARMv8.1 upper attributes.

Reviewed by:	alc, kib (previous version)
MFC after:	1 week
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D10360
This commit is contained in:
Andrew Turner 2017-04-12 16:28:40 +00:00
parent af032a9dec
commit 56ab86aa3e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=316734
2 changed files with 28 additions and 9 deletions
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32
sys/arm64/arm64/pmap.c
View File

@ -606,7 +606,7 @@ pmap_bootstrap_dmap(vm_offset_t kern_l1, vm_paddr_t min_pa, vm_paddr_t max_pa)
l1_slot = ((va - DMAP_MIN_ADDRESS) >> L1_SHIFT);
pmap_load_store(&pagetable_dmap[l1_slot],
(pa & ~L1_OFFSET) | ATTR_DEFAULT |
(pa & ~L1_OFFSET) | ATTR_DEFAULT | ATTR_XN |
ATTR_IDX(CACHED_MEMORY) | L1_BLOCK);
}
@ -2428,14 +2428,16 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
vm_offset_t va, va_next;
pd_entry_t *l0, *l1, *l2;
pt_entry_t *l3p, l3;
pt_entry_t *l3p, l3, nbits;
if ((prot & VM_PROT_READ) == VM_PROT_NONE) {
KASSERT((prot & ~VM_PROT_ALL) == 0, ("invalid prot %x", prot));
if (prot == VM_PROT_NONE) {
pmap_remove(pmap, sva, eva);
return;
}
if ((prot & VM_PROT_WRITE) == VM_PROT_WRITE)
if ((prot & (VM_PROT_WRITE | VM_PROT_EXECUTE)) ==
(VM_PROT_WRITE | VM_PROT_EXECUTE))
return;
PMAP_LOCK(pmap);
@ -2480,17 +2482,25 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
for (l3p = pmap_l2_to_l3(l2, sva); sva != va_next; l3p++,
sva += L3_SIZE) {
l3 = pmap_load(l3p);
if (pmap_l3_valid(l3)) {
if (!pmap_l3_valid(l3))
continue;
nbits = 0;
if ((prot & VM_PROT_WRITE) == 0) {
if ((l3 & ATTR_SW_MANAGED) &&
pmap_page_dirty(l3)) {
vm_page_dirty(PHYS_TO_VM_PAGE(l3 &
~ATTR_MASK));
}
pmap_set(l3p, ATTR_AP(ATTR_AP_RO));
PTE_SYNC(l3p);
/* XXX: Use pmap_invalidate_range */
pmap_invalidate_page(pmap, va);
nbits |= ATTR_AP(ATTR_AP_RO);
}
if ((prot & VM_PROT_EXECUTE) == 0)
nbits |= ATTR_XN;
pmap_set(l3p, nbits);
PTE_SYNC(l3p);
/* XXX: Use pmap_invalidate_range */
pmap_invalidate_page(pmap, va);
}
}
PMAP_UNLOCK(pmap);
@ -2709,6 +2719,8 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
L3_PAGE);
if ((prot & VM_PROT_WRITE) == 0)
new_l3 |= ATTR_AP(ATTR_AP_RO);
if ((prot & VM_PROT_EXECUTE) == 0)
new_l3 |= ATTR_XN;
if ((flags & PMAP_ENTER_WIRED) != 0)
new_l3 |= ATTR_SW_WIRED;
if ((va >> 63) == 0)
@ -3115,6 +3127,8 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
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)
pa |= ATTR_XN;
/*
* Now validate mapping with RO protection

5
sys/arm64/include/pte.h
View File

@ -46,6 +46,11 @@ typedef uint64_t pt_entry_t; /* page table entry */
/* Bits 58:55 are reserved for software */
#define ATTR_SW_MANAGED (1UL << 56)
#define ATTR_SW_WIRED (1UL << 55)
#define ATTR_UXN (1UL << 54)
#define ATTR_PXN (1UL << 53)
#define ATTR_XN (ATTR_PXN | ATTR_UXN)
#define ATTR_CONTIGUOUS (1UL << 52)
#define ATTR_DBM (1UL << 51)
#define ATTR_nG (1 << 11)
#define ATTR_AF (1 << 10)
#define ATTR_SH(x) ((x) << 8)