On Thu, Sep 14, 2017 at 07:25:56PM +0100, Mark Rutland wrote: > On Thu, Sep 07, 2017 at 11:36:05AM -0600, Tycho Andersen wrote: > > From: Juerg Haefliger <[email protected]> > > > > If the page is unmapped by XPFO, a data cache flush results in a fatal > > page fault, so let's temporarily map the region, flush the cache, and then > > unmap it. > > > > v6: actually flush in the face of xpfo, and temporarily map the underlying > > memory so it can be flushed correctly > > > > CC: [email protected] > > Signed-off-by: Juerg Haefliger <[email protected]> > > Signed-off-by: Tycho Andersen <[email protected]> > > --- > > arch/arm64/mm/flush.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c > > index 21a8d828cbf4..e335e3fd4fca 100644 > > --- a/arch/arm64/mm/flush.c > > +++ b/arch/arm64/mm/flush.c > > @@ -20,6 +20,7 @@ > > #include <linux/export.h> > > #include <linux/mm.h> > > #include <linux/pagemap.h> > > +#include <linux/xpfo.h> > > > > #include <asm/cacheflush.h> > > #include <asm/cache.h> > > @@ -28,9 +29,15 @@ > > void sync_icache_aliases(void *kaddr, unsigned long len) > > { > > unsigned long addr = (unsigned long)kaddr; > > + unsigned long num_pages = XPFO_NUM_PAGES(addr, len); > > + void *mapping[num_pages]; > > > > if (icache_is_aliasing()) { > > + xpfo_temp_map(kaddr, len, mapping, > > + sizeof(mapping[0]) * num_pages); > > __clean_dcache_area_pou(kaddr, len); > > + xpfo_temp_unmap(kaddr, len, mapping, > > + sizeof(mapping[0]) * num_pages); > > Does this create the mapping in-place? > > Can we not just kmap_atomic() an alias? Or is there a problem with that?
I think what we really want is something like vmap(), looking at xpfo_temp_map() it seems like the implementation is completely wrong. I wonder if what you mentioned at LSS is possible though: doing cache management with userspace primitives instead of mapping the region just to flush it. Cheers, Tycho
