On Wed, Oct 16, 2013 at 01:52:27PM -0700, Andi Kleen wrote: > > So avoid having to call copy_from_user_nmi() for every instruction. > > Since we already limit the max basic block size, we can easily > > pre-allocate a piece of memory to copy the entire thing into in one > > go. > > It would be better/more generic if you split copy_from_user_nmi() into > init() copy() end() > > (and some state that checks if the underlying page changes) > > Then first you don't need the buffer and it could be also > be applied to the other cases, like the stack unwinding, > where copying everything is likely too slow.
You'd need to make an iterator interface because of the kmap_atomic crap needed for 32bit. But yes, something like that might work, it shouldn't be that hard to cobble on top of that GUP patch I send out the other day. The only real nasty part is where an instruction straddles a page boundary, in that case the iterator stuff fails to be fully transparant and you need a temp copy of sorts. Anyway; if you want to have a go at this, feel free. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
