> On Dec 11, 2018, at 4:03 PM, Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> wrote: > > This adds a more efficient x86 architecture specific implementation of > arch_vunmap, that can free any type of special permission memory with only 1 TLB > flush. > > In order to enable this, _set_pages_p and _set_pages_np are made non-static and > renamed set_pages_p_noflush and set_pages_np_noflush to better communicate > their different (non-flushing) behavior from the rest of the set_pages_* > functions. > > The method for doing this with only 1 TLB flush was suggested by Andy > Lutomirski. > [snip] > + /* > + * If the vm being freed has security sensitive capabilities such as > + * executable we need to make sure there is no W window on the directmap > + * before removing the X in the TLB. So we set not present first so we > + * can flush without any other CPU picking up the mapping. Then we reset > + * RW+P without a flush, since NP prevented it from being cached by > + * other cpus. > + */ > + set_area_direct_np(area); > + vm_unmap_aliases(); Does vm_unmap_aliases() flush in the TLB the direct mapping range as well? I can only find the flush of the vmalloc range.
