• J
    x86: consolidate __swp_XXX() macros · 1796316a
    Jan Beulich 提交于
    Impact: cleanup, code robustization
    
    The __swp_...() macros silently relied upon which bits are used for
    _PAGE_FILE and _PAGE_PROTNONE. After having changed _PAGE_PROTNONE in
    our Xen kernel to no longer overlap _PAGE_PAT, live locks and crashes
    were reported that could have been avoided if these macros properly
    used the symbolic constants. Since, as pointed out earlier, for Xen
    Dom0 support mainline likewise will need to eliminate the conflict
    between _PAGE_PAT and _PAGE_PROTNONE, this patch does all the necessary
    adjustments, plus it introduces a mechanism to check consistency
    between MAX_SWAPFILES_SHIFT and the actual encoding macros.
    
    This also fixes a latent bug in that x86-64 used a 6-bit mask in
    __swp_type(), and if MAX_SWAPFILES_SHIFT was increased beyond 5 in (the
    seemingly unrelated) linux/swap.h, this would have resulted in a
    collision with _PAGE_FILE.
    
    Non-PAE 32-bit code gets similarly adjusted for its pte_to_pgoff() and
    pgoff_to_pte() calculations.
    Signed-off-by: NJan Beulich <jbeulich@novell.com>
    Signed-off-by: NIngo Molnar <mingo@elte.hu>
    1796316a
pgtable_64.h 8.2 KB