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In cases where a file was resident in memory mmap(..., PROT_NONE, ...)

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would actually map the file with read access enabled.  According to
http://www.opengroup.org/onlinepubs/007904975/functions/mmap.html this is
an error.  Similarly, an madvise(..., MADV_WILLNEED) would enable read
access on a virtual address range that was PROT_NONE.

The solution implemented herein is (1) to pass a vm_prot_t to
vm_map_pmap_enter() describing the allowed access and (2) to make
vm_map_pmap_enter() responsible for understanding the limitations of
pmap_enter_quick().

Submitted by:	"Mark W. Krentel" <krentel@dreamscape.com>
PR:		kern/64573
This commit is contained in:
Alan Cox 2004-04-24 03:46:44 +00:00
parent 50069af197
commit 4da4d293df
2 changed files with 6 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
sys/vm/vm_map.c
View File

@ -877,7 +877,7 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
#endif
if (cow & (MAP_PREFAULT|MAP_PREFAULT_PARTIAL)) {
vm_map_pmap_enter(map, start,
vm_map_pmap_enter(map, start, prot,
object, OFF_TO_IDX(offset), end - start,
cow & MAP_PREFAULT_PARTIAL);
}
@ -1243,19 +1243,19 @@ vm_map_submap(
/*
* vm_map_pmap_enter:
*
* Preload the mappings for the given object into the specified
* Preload read-only mappings for the given object into the specified
* map. This eliminates the soft faults on process startup and
* immediately after an mmap(2).
*/
void
vm_map_pmap_enter(vm_map_t map, vm_offset_t addr,
vm_map_pmap_enter(vm_map_t map, vm_offset_t addr, vm_prot_t prot,
vm_object_t object, vm_pindex_t pindex, vm_size_t size, int flags)
{
vm_offset_t tmpidx;
int psize;
vm_page_t p, mpte;
if (object == NULL)
if ((prot & VM_PROT_READ) == 0 || object == NULL)
return;
mtx_lock(&Giant);
VM_OBJECT_LOCK(object);
@ -1547,6 +1547,7 @@ vm_map_madvise(
if (behav == MADV_WILLNEED) {
vm_map_pmap_enter(map,
useStart,
current->protection,
current->object.vm_object,
pindex,
(count << PAGE_SHIFT),

2
sys/vm/vm_map.h
View File

@ -333,7 +333,7 @@ int vm_map_lookup (vm_map_t *, vm_offset_t, vm_prot_t, vm_map_entry_t *, vm_obje
vm_pindex_t *, vm_prot_t *, boolean_t *);
void vm_map_lookup_done (vm_map_t, vm_map_entry_t);
boolean_t vm_map_lookup_entry (vm_map_t, vm_offset_t, vm_map_entry_t *);
void vm_map_pmap_enter(vm_map_t map, vm_offset_t addr,
void vm_map_pmap_enter(vm_map_t map, vm_offset_t addr, vm_prot_t prot,
vm_object_t object, vm_pindex_t pindex, vm_size_t size, int flags);
int vm_map_protect (vm_map_t, vm_offset_t, vm_offset_t, vm_prot_t, boolean_t);
int vm_map_remove (vm_map_t, vm_offset_t, vm_offset_t);