Re: [PATCH 1/2 v3] x86: introduce int3-based instruction patching

[H. Peter Anvin]

On 07/11/2013 02:04 PM, Borislav Petkov wrote:
> On Thu, Jul 11, 2013 at 01:53:16PM -0700, H. Peter Anvin wrote:
>> Has anyone talked to AMD or VIA about this at all?
> 
> I guess I can try to take care of the AMD part. Just to confirm, is this
> the exact sequence we're interested in:
> 
> 1. Setup int3 handler for fixup.
> 
> 2. Put a breakpoint (int3) on the first byte of modifying region, and
> synchronize code on all CPUs.
> 
> 3. Modify other bytes of modifying region.
> 
> 4. Modify the first byte of modifying region, and synchronize code on
> all CPUs.
> 
> 5. Clear int3 handler.
> 
> If a suitable int3 handler is left permanently in place then the
> synchronization in step 4 is unnecessary.
> 

Correct.

	-hpa

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/