Commits
Dave Hansen committed a84eeaa96b3
x86/mpx: Use the new get_xsave_field_ptr()API 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.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dave Hansen <dave@sr71.net> 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: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Suresh Siddha <sbsiddha@gmail.com> Cc: bp@alien8.de Link: http://lkml.kernel.org/r/20150607183701.BC0D37CF@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>