Revert the changes made in rev 1.82. It is important to use pmap_enter(9)

and pmap_remove(9) here since we're dealing with managed pages here.  Found
out the hard way by deraadt@ on landisk where we're running into issues
with virtual cache aliases because multiple mappings exist for the
pages we're dealing with here.  The pmap_enter(9) and pmap_remove(9)
functions handle conflicting cache aliases, whereas pmap_map_direct(9) and
pmap_kenter_pa(9) assume that the pages is exclusively mapped in the kernel
pmap.

ok deraadt@

diff --git a/sys/uvm/uvm_pager.c b/sys/uvm/uvm_pager.c
index f01df5a..6e0ad75 100644 (file)
--- a/sys/uvm/uvm_pager.c
+++ b/sys/uvm/uvm_pager.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uvm_pager.c,v 1.83 2022/07/11 11:33:17 mpi Exp $      */
+/*     $OpenBSD: uvm_pager.c,v 1.84 2022/07/17 17:59:35 kettenis Exp $ */
 /*     $NetBSD: uvm_pager.c,v 1.36 2000/11/27 18:26:41 chs Exp $       */
 
 /*
@@ -258,16 +258,6 @@ uvm_pagermapin(struct vm_page **pps, int npages, int flags)
        vsize_t size;
        struct vm_page *pp;
 
-#ifdef __HAVE_PMAP_DIRECT
-       /* use direct mappings for single page */
-       if (npages == 1) {
-               KASSERT(pps[0]);
-               KASSERT(pps[0]->pg_flags & PG_BUSY);
-               kva = pmap_map_direct(pps[0]);
-               return kva;
-       }
-#endif
-
        prot = PROT_READ;
        if (flags & UVMPAGER_MAPIN_READ)
                prot |= PROT_WRITE;
@@ -283,7 +273,14 @@ uvm_pagermapin(struct vm_page **pps, int npages, int flags)
                pp = *pps++;
                KASSERT(pp);
                KASSERT(pp->pg_flags & PG_BUSY);
-               pmap_kenter_pa(cva, VM_PAGE_TO_PHYS(pp), prot);
+               /* Allow pmap_enter to fail. */
+               if (pmap_enter(pmap_kernel(), cva, VM_PAGE_TO_PHYS(pp),
+                   prot, PMAP_WIRED | PMAP_CANFAIL | prot) != 0) {
+                       pmap_remove(pmap_kernel(), kva, cva);
+                       pmap_update(pmap_kernel());
+                       uvm_pseg_release(kva);
+                       return 0;
+               }
        }
        pmap_update(pmap_kernel());
        return kva;
@@ -297,15 +294,8 @@ uvm_pagermapin(struct vm_page **pps, int npages, int flags)
 void
 uvm_pagermapout(vaddr_t kva, int npages)
 {
-#ifdef __HAVE_PMAP_DIRECT
-       /* use direct mappings for single page */
-       if (npages == 1) {
-               pmap_unmap_direct(kva);
-               return;
-       }
-#endif
 
-       pmap_kremove(kva, (vsize_t)npages << PAGE_SHIFT);
+       pmap_remove(pmap_kernel(), kva, kva + ((vsize_t)npages << PAGE_SHIFT));
        pmap_update(pmap_kernel());
        uvm_pseg_release(kva);