Module Name: src
Committed By: chs
Date: Fri May 19 15:30:19 UTC 2017
Modified Files:
src/sys/uvm: uvm_map.c uvm_mmap.c
Log Message:
make MAP_FIXED mapping operations atomic. fixes PR 52239.
previously, unmapping any entries being replaced was done separately
from entering the new mapping, which allowed another thread doing
a non-MAP_FIXED mapping to allocate the range out from under the
MAP_FIXED thread.
To generate a diff of this commit:
cvs rdiff -u -r1.346 -r1.347 src/sys/uvm/uvm_map.c
cvs rdiff -u -r1.164 -r1.165 src/sys/uvm/uvm_mmap.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/uvm/uvm_map.c
diff -u src/sys/uvm/uvm_map.c:1.346 src/sys/uvm/uvm_map.c:1.347
--- src/sys/uvm/uvm_map.c:1.346 Fri May 19 14:42:00 2017
+++ src/sys/uvm/uvm_map.c Fri May 19 15:30:19 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: uvm_map.c,v 1.346 2017/05/19 14:42:00 christos Exp $ */
+/* $NetBSD: uvm_map.c,v 1.347 2017/05/19 15:30:19 chs Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -66,7 +66,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_map.c,v 1.346 2017/05/19 14:42:00 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_map.c,v 1.347 2017/05/19 15:30:19 chs Exp $");
#include "opt_ddb.h"
#include "opt_pax.h"
@@ -1163,8 +1163,25 @@ retry:
}
vm_map_lock(map); /* could sleep here */
}
- prev_entry = uvm_map_findspace(map, start, size, &start,
- uobj, uoffset, align, flags);
+ if (flags & UVM_FLAG_FIXED) {
+ KASSERT((flags & UVM_FLAG_NOWAIT) == 0);
+
+ /*
+ * Set prev_entry to what it will need to be after any existing
+ * entries are removed later in uvm_map_enter().
+ */
+
+ if (uvm_map_lookup_entry(map, start, &prev_entry)) {
+ if (start == prev_entry->start)
+ prev_entry = prev_entry->prev;
+ else
+ UVM_MAP_CLIP_END(map, prev_entry, start);
+ SAVE_HINT(map, map->hint, prev_entry);
+ }
+ } else {
+ prev_entry = uvm_map_findspace(map, start, size, &start,
+ uobj, uoffset, align, flags);
+ }
if (prev_entry == NULL) {
unsigned int timestamp;
@@ -1255,7 +1272,7 @@ uvm_map_enter(struct vm_map *map, const
struct vm_map_entry *new_entry)
{
struct vm_map_entry *prev_entry = args->uma_prev;
- struct vm_map_entry *dead = NULL;
+ struct vm_map_entry *dead = NULL, *dead_entries = NULL;
const uvm_flag_t flags = args->uma_flags;
const vm_prot_t prot = UVM_PROTECTION(flags);
@@ -1284,6 +1301,8 @@ uvm_map_enter(struct vm_map *map, const
KASSERT(map->hint == prev_entry); /* bimerge case assumes this */
KASSERT(vm_map_locked_p(map));
+ KASSERT((flags & (UVM_FLAG_NOWAIT | UVM_FLAG_FIXED)) !=
+ (UVM_FLAG_NOWAIT | UVM_FLAG_FIXED));
if (uobj)
newetype = UVM_ET_OBJ;
@@ -1297,6 +1316,27 @@ uvm_map_enter(struct vm_map *map, const
}
/*
+ * For fixed mappings, remove any old entries now. Adding the new
+ * entry cannot fail because that can only happen if UVM_FLAG_NOWAIT
+ * is set, and we do not support nowait and fixed together.
+ */
+
+ if (flags & UVM_FLAG_FIXED) {
+ uvm_unmap_remove(map, start, start + size, &dead_entries, 0);
+#ifdef DEBUG
+ struct vm_map_entry *tmp_entry;
+ bool rv;
+
+ rv = uvm_map_lookup_entry(map, start, &tmp_entry);
+ KASSERT(!rv);
+ KASSERTMSG(prev_entry == tmp_entry,
+ "args %p prev_entry %p tmp_entry %p",
+ args, prev_entry, tmp_entry);
+#endif
+ SAVE_HINT(map, map->hint, prev_entry);
+ }
+
+ /*
* try and insert in map by extending previous entry, if possible.
* XXX: we don't try and pull back the next entry. might be useful
* for a stack, but we are currently allocating our stack in advance.
@@ -1569,17 +1609,19 @@ nomerge:
UVMHIST_LOG(maphist,"<- done!", 0, 0, 0, 0);
error = 0;
+
done:
vm_map_unlock(map);
if (new_entry) {
uvm_mapent_free(new_entry);
}
-
if (dead) {
KDASSERT(merged);
uvm_mapent_free(dead);
}
+ if (dead_entries)
+ uvm_unmap_detach(dead_entries, 0);
return error;
}
Index: src/sys/uvm/uvm_mmap.c
diff -u src/sys/uvm/uvm_mmap.c:1.164 src/sys/uvm/uvm_mmap.c:1.165
--- src/sys/uvm/uvm_mmap.c:1.164 Sat May 6 21:34:52 2017
+++ src/sys/uvm/uvm_mmap.c Fri May 19 15:30:19 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: uvm_mmap.c,v 1.164 2017/05/06 21:34:52 joerg Exp $ */
+/* $NetBSD: uvm_mmap.c,v 1.165 2017/05/19 15:30:19 chs Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -46,7 +46,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_mmap.c,v 1.164 2017/05/06 21:34:52 joerg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_mmap.c,v 1.165 2017/05/19 15:30:19 chs Exp $");
#include "opt_compat_netbsd.h"
#include "opt_pax.h"
@@ -924,7 +924,7 @@ uvm_mmap(struct vm_map *map, vaddr_t *ad
/*
* for non-fixed mappings, round off the suggested address.
- * for fixed mappings, check alignment and zap old mappings.
+ * for fixed mappings, check alignment.
*/
if ((flags & MAP_FIXED) == 0) {
@@ -933,7 +933,6 @@ uvm_mmap(struct vm_map *map, vaddr_t *ad
if (*addr & PAGE_MASK)
return EINVAL;
uvmflag |= UVM_FLAG_FIXED;
- (void) uvm_unmap(map, *addr, *addr + size);
}
/*
