On Mon, Apr 07, 2014 at 02:57:51PM +0100, Jon Medhurst (Tixy) wrote: > How does fixmap cope with cache colouring? Looking at the implementation > it looks like it doesn't and so fixmap use on ARM is possibly buggy. > > For the text patching case where we know there are no writeable mappings > [1] this should be OK if we used set_fixmap_nocache here, so long as we > also invalidated the dcache later for the proper virtual address.
OK. The dcache invalidation for the proper virtual address is btw already there via the call to flush_icache_range(). > [1] Can we know there are no writeable mappings though, the ftrace code > modifying patches from Kees Cook have there own way of modifying text > code permissions. The ftrace patches does the modifications and the cache cleaning in stop_machine(), so there should not be any dirty cache lines from those writable mappings when we set up and write to these fixmaps. Do you still see a problem? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
