Messages in this thread | | | Date | Mon, 02 Feb 2015 10:11:23 -0800 | From | Dave Hansen <> | Subject | Re: [PATCH 0/3]: x86, fpu: unlazy_fpu fixes/cleanups |
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On 01/29/2015 05:33 PM, Rik van Riel wrote: >> > Hmm, if the the thread was not using the FPU, and this fails to >> > save anything in to the xsave_buf, what will bndcsr point to? > If the thread was not using the FPU, can we reach the > bound range exception? > > I believe the MPX feature uses information in the xstate.
There are really two kinds of bounds exceptions. There is an "old" 'BOUND' instruction that will generate #BR's as well as the new MPX instructions. The new ones require xstate and poking the FPU, etc... The old one did not.
So, we _can_ as far as I know get in to do_bounds() without using the FPU.
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