Hi,
There is another buffer overflow somewhere I think.
The code in kbdputsc() in kbd.c does not look very safe:
kbscan-kc[kbscan-nk++] = c; - no bound checking, can
overflow.
c = latin1(kbscan-kc, kbscan-nk);
if(c -1) /* need more
the astounding thing is that t1-t0 is often ~ 60,000 cycles.
it only hits a small fraction of the time, and the average is
much lower. but that just blows the mind. 6 cycles!
(other versions with sched were much worse.)
as far as i can tell, there are no funny bits in the
On Fri Jun 20 01:04:20 EDT 2014, devon.od...@gmail.com wrote:
Weird. I assume cycles is using rdtsc or rdtscp. Perhaps some of it is due
to a combination of contention and rdtsc(p) being serializing instructions?
On Jun 19, 2014 12:04 PM, erik quanstrom quans...@quanstro.net wrote:
other than
On Fri Jun 20 06:24:25 EDT 2014, p...@fb.com wrote:
good catch, but...
The code in kbdputsc() in kbd.c does not look very safe:
kbscan-kc[kbscan-nk++] = c; - no bound checking, can
overflow.
this behavior depends entirely on what latin1() does. if
latin1() will
2014-06-20 7:50 GMT-04:00 erik quanstrom quans...@quanstro.net:
On Fri Jun 20 01:04:20 EDT 2014, devon.od...@gmail.com wrote:
Weird. I assume cycles is using rdtsc or rdtscp. Perhaps some of it is due
to a combination of contention and rdtsc(p) being serializing instructions?
I forget that
It disables out-of-order execution by the processor, so there's a
pipeline stall.
we know there's going to be a stall already, since we can't get
the cacheline we're looking for.
There's overhead to calling the tsc instructions, but not that much.
Does `srb-wmach != m-machno` imply that t0
