On 2017/10/21 14:52, Tim Stewart wrote:
> Stuart Henderson <s...@spacehopper.org> writes:
>
> > On 2017/10/21 12:04, Tim Stewart wrote:
> >> *49727 296965 0 0 7 0x14200 crynlk
> >
> > aha, it was that one. Try this diff on top.
> >
> > Index: fpu.c
> > ===================================================================
> > RCS file: /cvs/src/sys/arch/amd64/amd64/fpu.c,v
> > retrieving revision 1.38
> > diff -u -p -r1.38 fpu.c
> > --- fpu.c 14 Oct 2017 04:44:43 -0000 1.38
> > +++ fpu.c 21 Oct 2017 16:16:14 -0000
> > @@ -347,7 +347,7 @@ void
> > fpu_kernel_enter(void)
> > {
> > struct cpu_info *ci = curcpu();
> > - uint32_t cw;
> > + struct savefpu *sfp;
> > int s;
> >
> > /*
> > @@ -376,10 +376,11 @@ fpu_kernel_enter(void)
> >
> > /* Initialize the FPU */
> > fninit();
> > - cw = __INITIAL_NPXCW__;
> > - fldcw(&cw);
> > - cw = __INITIAL_MXCSR__;
> > - ldmxcsr(&cw);
> > + sfp = &proc0.p_addr->u_pcb.pcb_savefpu;
> > + memset(&sfp->fp_fxsave, 0, sizeof(sfp->fp_fxsave));
> > + sfp->fp_fxsave.fx_fcw = __INITIAL_NPXCW__;
> > + sfp->fp_fxsave.fx_mxcsr = __INITIAL_MXCSR__;
> > + fxrstor(&sfp->fp_fxsave);
> > }
> >
> > void
>
> I've been running with this additional patch for a couple of hours and
> the hang has not reappeared. I'll keep the system active and confirm
> thta everything looks good tomorrow.
>
> I swear I've seen this patch before on a list but can't find the
> original. Can someone give me or point me at some context, so I know
> what I've just done? :)
Diff is from mikeb. It initializes the fpu more completely, we suspect
something in the userland state wasn't getting cleared when entering the
kernel. I saw some problems with aes-ni up after the "Correctly handle
exceptions when restoring an invalid FPU context" commit. (aes-ni uses
floating point registers).
