• Kirill A. Shutemov's avatar
    x86/mpx: Do not allow MPX if we have mappings above 47-bit · 44b04912
    Kirill A. Shutemov authored
    MPX (without MAWA extension) cannot handle addresses above 47 bits, so we
    need to make sure that MPX cannot be enabled if we already have a VMA above
    the boundary and forbid creating such VMAs once MPX is enabled.
    
    The patch implements mpx_unmapped_area_check() which is called from all
    variants of get_unmapped_area() to check if the requested address fits
    mpx.
    
    On enabling MPX, we check if we already have any vma above 47-bit
    boundary and forbit the enabling if we do.
    
    As long as DEFAULT_MAP_WINDOW is equal to TASK_SIZE_MAX, the change is
    nop. It will change when we allow userspace to have mappings above
    47-bits.
    Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-arch@vger.kernel.org
    Cc: linux-mm@kvack.org
    Link: http://lkml.kernel.org/r/20170716225954.74185-6-kirill.shutemov@linux.intel.com
    [ Readability edits. ]
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    44b04912
processor.h 23.8 KB