Re: Intel CPU design flaw - FreeBSD affected? // disabling LDTSC

From: Klaus P. Ohrhallinger <k_at_7he.at>
Date: Thu, 4 Jan 2018 19:23:56 +0100
Hello,

I disabled the ldtsc and ldtscp instructions for usermode on one of my
production servers:

% ./spectre
Reading 40 bytes:
Bus error (core dumped)

All PoC code I have seen today relies on those instructions.
Is there any other way to measure the memory/cache access times ?

On 10.4-RELEASE I had to rebuild world and some ports, but now
everything seems to be working fine.
Patches attached.

Regards, Klaus

Received on Thu Jan 04 2018 - 17:26:49 UTC

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