openbsd/src
1
0
Fork 0
mirror of https://github.com/openbsd/src.git synced 2026-06-18 07:13:36 +02:00
Code Activity

Address the case 2b version of inconsistent view across threads of

Browse Source 
a page undergoing copy-on-write faulting.  We fixed the case 1b
version in rev 1.125 (2022-02-01), but missed this other path.

jsg@ noted that in NetBSD Chuck Silvers had a relevant commit, their
rev 1.234 (2023-08-13), which looks like it fixed both cases due
to their refactoring of common code into a uvmfault_promote()
function.

ok mpi@ jca@
This commit is contained in:
guenther
2023-09-05 05:08:26 +00:00
parent 36a3d429cd
commit b3774972aa
1 changed files with 15 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
sys/uvm/uvm_fault.c
+15 -2
View File
@@ -1,4 +1,4 @@
/* $OpenBSD: uvm_fault.c,v 1.134 2023/09/02 08:24:40 mpi Exp $ */
/* $OpenBSD: uvm_fault.c,v 1.135 2023/09/05 05:08:26 guenther Exp $ */
/* $NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 thorpej Exp $ */
/*
@@ -1455,7 +1455,20 @@ uvm_fault_lower(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
*/
if ((amap_flags(amap) & AMAP_SHARED) != 0) {
pmap_page_protect(uobjpage, PROT_NONE);
}
}
#if defined(MULTIPROCESSOR) && !defined(__HAVE_PMAP_MPSAFE_ENTER_COW)
/*
* Otherwise:
* If there are multiple threads, either uvm or the
* pmap has to make sure no threads see the old RO
* mapping once any have seen the new RW mapping.
* uvm does it here by forcing it to PROT_NONE before
* inserting the new mapping.
*/
else if (P_HASSIBLING(curproc)) {
pmap_page_protect(uobjpage, PROT_NONE);
}
#endif
/* dispose of uobjpage. drop handle to uobj as well. */
if (uobjpage->pg_flags & PG_WANTED)