commit 1796316a8b028a148be48ba5d4e7be493a39d173
author Jan Beulich <jbeulich@novell.com> Tue Dec 16 11:35:24 2008 +0000
committer Ingo Molnar <mingo@elte.hu> Tue Dec 16 18:34:51 2008 +0100
tree 628848bb98909632bbb503b1db27c2a6db9291e6
parent 9470565579f29486f4ed0ffa50774268b64994b0

x86: consolidate __swp_XXX() macros

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: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>