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    SubjectRe: [PATCH 24/27] x86/fpu: Add a fastpath to __fpu__restore_sig()
    On Mon, 8 Apr 2019, Sebastian Andrzej Siewior wrote:

    > On 2019-04-08 19:05:56 [+0200], Thomas Gleixner wrote:
    > > > diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
    > > > index a5b086ec426a5..f20e1d1fffa29 100644
    > > > --- a/arch/x86/kernel/fpu/signal.c
    > > > +++ b/arch/x86/kernel/fpu/signal.c
    > > > @@ -242,10 +242,10 @@ sanitize_restored_xstate(union fpregs_state *state,
    > > > /*
    > > > * Restore the extended state if present. Otherwise, restore the FP/SSE state.
    > > > */
    > > > -static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
    > > > +static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
    > > > {
    > > > if (use_xsave()) {
    > > > - if ((unsigned long)buf % 64 || fx_only) {
    > > > + if (fx_only) {
    > >
    > > This change is weird and not mentioned in the changelog....
    >
    > if you scroll up there is this:
    > | * to loaded again on return to userland (overriding last_cpu avoids the
    > | * optimisation).
    > | */
    > | set_thread_flag(TIF_NEED_FPU_LOAD);
    > | __fpu_invalidate_fpregs_state(fpu);
    > |
    > | if ((unsigned long)buf_fx % 64)
    > | fx_only = 1;
    > …
    > | ret = copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only);
    > | pagefault_enable();
    >
    >
    > so I just removed that part because it was already done earlier.
    > Is it still weird and should be mentioned in the changelog?

    Bah. Staring at this for too long. All good ...
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