summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/pgtable_64.h
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/include/asm/pgtable_64.h')
-rw-r--r--arch/x86/include/asm/pgtable_64.h38
1 files changed, 27 insertions, 11 deletions
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index acb6970e7bcf..f773d5e6c8cc 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -188,7 +188,7 @@ extern void sync_global_pgds(unsigned long start, unsigned long end);
*
* | ... | 11| 10| 9|8|7|6|5| 4| 3|2| 1|0| <- bit number
* | ... |SW3|SW2|SW1|G|L|D|A|CD|WT|U| W|P| <- bit names
- * | OFFSET (14->63) | TYPE (9-13) |0|0|X|X| X| X|X|SD|0| <- swp entry
+ * | TYPE (59-63) | ~OFFSET (9-58) |0|0|X|X| X| X|X|SD|0| <- swp entry
*
* G (8) is aliased and used as a PROT_NONE indicator for
* !present ptes. We need to start storing swap entries above
@@ -201,20 +201,34 @@ extern void sync_global_pgds(unsigned long start, unsigned long end);
*
* Bit 7 in swp entry should be 0 because pmd_present checks not only P,
* but also L and G.
+ *
+ * The offset is inverted by a binary not operation to make the high
+ * physical bits set.
*/
-#define SWP_TYPE_FIRST_BIT (_PAGE_BIT_PROTNONE + 1)
-#define SWP_TYPE_BITS 5
-/* Place the offset above the type: */
-#define SWP_OFFSET_FIRST_BIT (SWP_TYPE_FIRST_BIT + SWP_TYPE_BITS)
+#define SWP_TYPE_BITS 5
+
+#define SWP_OFFSET_FIRST_BIT (_PAGE_BIT_PROTNONE + 1)
+
+/* We always extract/encode the offset by shifting it all the way up, and then down again */
+#define SWP_OFFSET_SHIFT (SWP_OFFSET_FIRST_BIT+SWP_TYPE_BITS)
#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
-#define __swp_type(x) (((x).val >> (SWP_TYPE_FIRST_BIT)) \
- & ((1U << SWP_TYPE_BITS) - 1))
-#define __swp_offset(x) ((x).val >> SWP_OFFSET_FIRST_BIT)
-#define __swp_entry(type, offset) ((swp_entry_t) { \
- ((type) << (SWP_TYPE_FIRST_BIT)) \
- | ((offset) << SWP_OFFSET_FIRST_BIT) })
+/* Extract the high bits for type */
+#define __swp_type(x) ((x).val >> (64 - SWP_TYPE_BITS))
+
+/* Shift up (to get rid of type), then down to get value */
+#define __swp_offset(x) (~(x).val << SWP_TYPE_BITS >> SWP_OFFSET_SHIFT)
+
+/*
+ * Shift the offset up "too far" by TYPE bits, then down again
+ * The offset is inverted by a binary not operation to make the high
+ * physical bits set.
+ */
+#define __swp_entry(type, offset) ((swp_entry_t) { \
+ (~(unsigned long)(offset) << SWP_OFFSET_SHIFT >> SWP_TYPE_BITS) \
+ | ((unsigned long)(type) << (64-SWP_TYPE_BITS)) })
+
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) })
#define __pmd_to_swp_entry(pmd) ((swp_entry_t) { pmd_val((pmd)) })
#define __swp_entry_to_pte(x) ((pte_t) { .pte = (x).val })
@@ -258,5 +272,7 @@ static inline bool gup_fast_permitted(unsigned long start, int nr_pages,
return true;
}
+#include <asm/pgtable-invert.h>
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_PGTABLE_64_H */