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    Subject[tip:x86/fpu] x86/fpu: Inline copy_user_to_fpregs_zeroing()
    Commit-ID:  e0d3602f933367881bddfff310a744e6e61c284c
    Gitweb: https://git.kernel.org/tip/e0d3602f933367881bddfff310a744e6e61c284c
    Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    AuthorDate: Wed, 3 Apr 2019 18:41:49 +0200
    Committer: Borislav Petkov <bp@suse.de>
    CommitDate: Thu, 11 Apr 2019 20:45:20 +0200

    x86/fpu: Inline copy_user_to_fpregs_zeroing()

    Start refactoring __fpu__restore_sig() by inlining
    copy_user_to_fpregs_zeroing(). The original function remains and will be
    used to restore from userland memory if possible.

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Reviewed-by: Dave Hansen <dave.hansen@intel.com>
    Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Jann Horn <jannh@google.com>
    Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
    Cc: kvm ML <kvm@vger.kernel.org>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Radim Krčmář <rkrcmar@redhat.com>
    Cc: Rik van Riel <riel@surriel.com>
    Cc: x86-ml <x86@kernel.org>
    Link: https://lkml.kernel.org/r/20190403164156.19645-21-bigeasy@linutronix.de
    ---
    arch/x86/kernel/fpu/signal.c | 20 +++++++++++++++++++-
    1 file changed, 19 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
    index 9b9dfdc96285..c2ff43fbbd07 100644
    --- a/arch/x86/kernel/fpu/signal.c
    +++ b/arch/x86/kernel/fpu/signal.c
    @@ -337,11 +337,29 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
    kfree(tmp);
    return err;
    } else {
    + int ret;
    +
    /*
    * For 64-bit frames and 32-bit fsave frames, restore the user
    * state to the registers directly (with exceptions handled).
    */
    - if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
    + if (use_xsave()) {
    + if ((unsigned long)buf_fx % 64 || fx_only) {
    + u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
    + copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
    + ret = copy_user_to_fxregs(buf_fx);
    + } else {
    + u64 init_bv = xfeatures_mask & ~xfeatures;
    + if (unlikely(init_bv))
    + copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
    + ret = copy_user_to_xregs(buf_fx, xfeatures);
    + }
    + } else if (use_fxsr()) {
    + ret = copy_user_to_fxregs(buf_fx);
    + } else
    + ret = copy_user_to_fregs(buf_fx);
    +
    + if (ret) {
    fpu__clear(fpu);
    return -1;
    }
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