>>>>> On 03 Feb 2005 15:58:16 -0500, Jes Sorensen <[EMAIL PROTECTED]> said:
Jes> I hear your concerns! However, at the same time, if something Jes> within the kernel starts mocking with memory it doesn't own, Jes> thats a bug. I'm not convinced of that. Jack already mentioned lcrash... Jes> I was more concerned that there would be a case where Jes> prefetching or speculation would spill into a page in another Jes> granule and thereby cause a cacheable operation on the Jes> memory. This is not an issue. The AltTLB miss-handlers ignore misses triggered by speculative accesses (including lfetch) or accesses triggered by user-level. Jack> What prevents lcrash (or /dev/kmem or /proc/kcore) from Jack> referencing special memory being used for fetchops? Granted, Jack> this takes root privilege but the consequences of a bad Jack> reference can cause silent data corruption that is impossible Jack> to debug. Should we add code to prohibit these area from Jack> referencing granules being used for mspec memory? Jes> I believe you will have the same problem with anyone messing Jes> with /dev/mem at random on the spill pages. /dev/mem does check the memory attributes and accesses the memory uncached if EFI_MEMORY_WB is _not_ set. This probably needs to be extended to check what the current usage of the page is (as opposed to what the potential usages are). Now that the kernel has it's own copy of the memory-map, that's probably something we can do more easily. OTOH, for pages which have a page-descriptor, a flag-bit would be the most logical choice and that would make it possible to efficiently check whether it is OK to access a page via a cacheable reference. Jes> Aha, I wasn't aware of this, I thought the region registers Jes> worked like some giant TLB. I'll add a flush for the granule Jes> when it's pulled into the allocator. Don't you have to purge the all TLBs completely anyhow? --david - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html