From 1796316a8b028a148be48ba5d4e7be493a39d173 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 16 Dec 2008 11:35:24 +0000 Subject: 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 Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pgtable-3level.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/include/asm/pgtable-3level.h') diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h index 52597aeadff..447da43cddb 100644 --- a/arch/x86/include/asm/pgtable-3level.h +++ b/arch/x86/include/asm/pgtable-3level.h @@ -166,6 +166,7 @@ static inline int pte_none(pte_t pte) #define PTE_FILE_MAX_BITS 32 /* Encode and de-code a swap entry */ +#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > 5) #define __swp_type(x) (((x).val) & 0x1f) #define __swp_offset(x) ((x).val >> 5) #define __swp_entry(type, offset) ((swp_entry_t){(type) | (offset) << 5}) -- cgit v1.2.3-70-g09d2