On Mon, Dec 14, 2015 at 1:24 PM, Arjan van de Ven <ar...@linux.intel.com> wrote: > >> That's weird. The only API to do that seems to be manually setting >> kmap_prot to _PAGE_KERNEL_EXEC, and nothing does that. (Why is >> kmap_prot a variable on x86 at all? It has exactly one writer, and >> that's the code that initializes it in the first place. Shouldn't we >> #define kmap_prot _PAGE_KERNEL? > > > iirc it changes based on runtime detection of NX capability >
Maybe it did, but if it still does, I can't find the code. What *does* change is __supported_pte_mask. If we're willing to make disable_nx work a little less well, we could try to initialize __supported_pte_mask from the very beginning. (We currently seem to detect and enable NX even before we enable paging.) I suspect that Pavel is seeing a kmap mapping left over from so early that it didn't have NX set (killed by massage_pgprot). Borislav, could we do that? (Why do we have disable_nx at all? I suspect it was for debugging a long, long time ago.) Alternatively, we could go through and set NX everywhere after we decide we have NX, but that seems rather error-prone. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- 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/
