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xen-gntdev: Avoid double-mapping memory 

If an already-mapped area of the device was mapped into userspace a
second time, a hypercall was incorrectly made to remap the memory
again. Avoid the hypercall on later mmap calls, and fail the mmap call
if a writable mapping is attempted on a read-only range.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Daniel De Graaf 2011-02-09 16:11:32 -05:00 committed by Konrad Rzeszutek Wilk
parent b57c18694e
commit 12996fc38a
1 changed files with 12 additions and 3 deletions
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15
drivers/xen/gntdev.c
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@ -258,6 +258,9 @@ static int map_grant_pages(struct grant_map *map)
phys_addr_t addr;
if (!use_ptemod) {
/* Note: it could already be mapped */
if (map->map_ops[0].handle)
return 0;
for (i = 0; i < map->count; i++) {
addr = (phys_addr_t)
pfn_to_kaddr(page_to_pfn(map->pages[i]));
@ -668,9 +671,15 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
if (use_ptemod)
map->vma = vma;
map->flags = GNTMAP_host_map;
if (!(vma->vm_flags & VM_WRITE))
map->flags |= GNTMAP_readonly;
if (map->flags) {
if ((vma->vm_flags & VM_WRITE) &&
(map->flags & GNTMAP_readonly))
return -EINVAL;
} else {
map->flags = GNTMAP_host_map;
if (!(vma->vm_flags & VM_WRITE))
map->flags |= GNTMAP_readonly;
}
spin_unlock(&priv->lock);