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Fix some issues with the riscv pmap_protect() implementation.

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- Handle VM_PROT_EXECUTE.
- Clear PTE_D and mark the page dirty when removing write access
  from a mapping.
- Atomically clear PTE_W to avoid clobbering a hardware PTE update.

Reviewed by:	jhb, kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D18719
This commit is contained in:
Mark Johnston 2019-01-03 16:21:44 +00:00
parent 8ccaccd522
commit 60af34002e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=342734
1 changed files with 26 additions and 16 deletions
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42
sys/riscv/riscv/pmap.c
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@ -1853,22 +1853,28 @@ pmap_remove_all(vm_page_t m)
void
pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
vm_offset_t va_next;
pd_entry_t *l1, *l2;
pt_entry_t *l3p, l3;
pt_entry_t entry;
pt_entry_t *l3, l3e, mask;
vm_page_t m;
vm_offset_t va_next;
if ((prot & VM_PROT_READ) == 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;
mask = 0;
if ((prot & VM_PROT_WRITE) == 0)
mask |= PTE_W | PTE_D;
if ((prot & VM_PROT_EXECUTE) == 0)
mask |= PTE_X;
PMAP_LOCK(pmap);
for (; sva < eva; sva = va_next) {
l1 = pmap_l1(pmap, sva);
if (pmap_load(l1) == 0) {
va_next = (sva + L1_SIZE) & ~L1_OFFSET;
@ -1882,9 +1888,7 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
va_next = eva;
l2 = pmap_l1_to_l2(l1, sva);
if (l2 == NULL)
continue;
if (pmap_load(l2) == 0)
if (l2 == NULL || pmap_load(l2) == 0)
continue;
if ((pmap_load(l2) & PTE_RX) != 0)
continue;
@ -1892,16 +1896,22 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
if (va_next > eva)
va_next = eva;
for (l3p = pmap_l2_to_l3(l2, sva); sva != va_next; l3p++,
for (l3 = pmap_l2_to_l3(l2, sva); sva != va_next; l3++,
sva += L3_SIZE) {
l3 = pmap_load(l3p);
if ((l3 & PTE_V) != 0) {
entry = pmap_load(l3p);
entry &= ~PTE_W;
pmap_store(l3p, entry);
/* XXX: Use pmap_invalidate_range */
pmap_invalidate_page(pmap, sva);
l3e = pmap_load(l3);
retry:
if ((l3e & PTE_V) == 0)
continue;
if ((prot & VM_PROT_WRITE) == 0 &&
(l3e & (PTE_SW_MANAGED | PTE_D)) ==
(PTE_SW_MANAGED | PTE_D)) {
m = PHYS_TO_VM_PAGE(PTE_TO_PHYS(l3e));
vm_page_dirty(m);
}
if (!atomic_fcmpset_long(l3, &l3e, l3e & ~mask))
goto retry;
/* XXX: Use pmap_invalidate_range */
pmap_invalidate_page(pmap, sva);
}
}
PMAP_UNLOCK(pmap);