K 10
svn:author
V 8
jhibbits
K 8
svn:date
V 27
2020-02-06T01:25:30.286677Z
K 7
svn:log
V 533
powerpc: Fix altivec disabling in set_mcontext()

We somewhat blindly copy the srr1 from the new context to the trap frame,
but disable FPU and VSX unconditionally, relying on the trap to re-enable
them.  This works because the FPU manages the VSX extended FP registers,
which is governed by the PCB_FPFREGS flag.  However, with altivec, we
would blindly disable PSL_VEC, without touching PCB_VEC.  Handle this case
by disabling altivec in both srr1 and pcb_flags, if the mcontext doesn't
have _MC_AV_VALID set.

Reported by:	pkubaj

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