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    Subject[PATCH 003/208] x86/fpu: Add debugging check to fpu__save()
    Date
    Document the function a bit more and add debugging check that we are only
    running this with the current task.

    Reviewed-by: Borislav Petkov <bp@alien8.de>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/kernel/i387.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
    index ac47278cde71..66f1053ae2cd 100644
    --- a/arch/x86/kernel/i387.c
    +++ b/arch/x86/kernel/i387.c
    @@ -119,9 +119,13 @@ EXPORT_SYMBOL(__kernel_fpu_end);

    /*
    * Save the FPU state (initialize it if necessary):
    + *
    + * This only ever gets called for the current task.
    */
    void fpu__save(struct task_struct *tsk)
    {
    + WARN_ON(tsk != current);
    +
    preempt_disable();
    if (__thread_has_fpu(tsk)) {
    if (use_eager_fpu()) {
    --
    2.1.0


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