On Mon, Jan 23, 2017 at 07:36:20AM -0800, Dave Hansen wrote:
> The kernel xsave buffer should *ALWAYS* have the
> XCOMP_BV_COMPACTED_FORMAT bit set. It should have been set before the
> copyin and it should be set when it's finished.
>
> The best fix here would be not to paper over the issue in the copy
> function but find where it got clobbered, or where some initialization
> code failed to set it.
Someone else reported different issues from the same bug and a different
patch was just tested OK this morning. I think that adding xfeatures bits
to xcomp_bv should have been done in fpstate_init().
Also, in copy_init_fpstate_to_fpregs(), we do:
copy_kernel_to_xregs(&init_fpstate.xsave, -1).
That (-1) could mean (0) because the parameters are declared as:
copy_kernel_to_xregs(struct xregs_state *, u64)
Yu-cheng
