On Mon, 18 May 2015, Dave Hansen wrote: > From: Dave Hansen <dave.han...@linux.intel.com> > > The MPX registers (bndcsr/bndcfgu/bndstatus) are not directly > accessible via normal instructions. They essentially act as > if they were floating point registers and are saved/restored > along with those registers. > > There are two main paths in the MPX code where we care about > the contents of these registers: > 1. #BR (bounds) faults > 2. the prctl() code where we are setting MPX up > > Both of those paths _might_ be called without the FPU having > been used. That means that 'tsk->thread.fpu.state' might > never be allocated. > > Also, fpu_save_init() is not preempt-safe. It was a bug to > call it without disabling preemption. The new > get_xsave_addr() calls unlazy_fpu() instead and properly > disables preemption. > > Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
Reviewed-by: Thomas Gleixner <t...@linutronix.de> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
