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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2016-07-18 14:35:13 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-07-31 05:27:57 -0400
commitbc29b7ac1d9f09f5024b0e257e91bf5df611ccd4 (patch)
treef32fddeba065a46d018f6c427f220317b1dc5b89 /arch/s390
parentbad60e6f259a01cf9f29a1ef8d435ab6c60b2de9 (diff)
s390/mm: clean up pte/pmd encoding
The hugetlbfs pte<->pmd conversion functions currently assume that the pmd bit layout is consistent with the pte layout, which is not really true. The SW read and write bits are encoded as the sequence "wr" in a pte, but in a pmd it is "rw". The hugetlbfs conversion assumes that the sequence is identical in both cases, which results in swapped read and write bits in the pmd. In practice this is not a problem, because those pmd bits are only relevant for THP pmds and not for hugetlbfs pmds. The hugetlbfs code works on (fake) ptes, and the converted pte bits are correct. There is another variation in pte/pmd encoding which affects dirty prot-none ptes/pmds. In this case, a pmd has both its HW read-only and invalid bit set, while it is only the invalid bit for a pte. This also has no effect in practice, but it should better be consistent. This patch fixes both inconsistencies by changing the SW read/write bit layout for pmds as well as the PAGE_NONE encoding for ptes. It also makes the hugetlbfs conversion functions more robust by introducing a move_set_bit() macro that uses the pte/pmd bit #defines instead of constant shifts. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/include/asm/pgtable.h20
-rw-r--r--arch/s390/mm/hugetlbpage.c52
2 files changed, 48 insertions, 24 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index ea1533e07271..48d383af078f 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -242,8 +242,8 @@ static inline int is_module_addr(void *addr)
* swap .11..ttttt.0
* prot-none, clean, old .11.xx0000.1
* prot-none, clean, young .11.xx0001.1
- * prot-none, dirty, old .10.xx0010.1
- * prot-none, dirty, young .10.xx0011.1
+ * prot-none, dirty, old .11.xx0010.1
+ * prot-none, dirty, young .11.xx0011.1
* read-only, clean, old .11.xx0100.1
* read-only, clean, young .01.xx0101.1
* read-only, dirty, old .11.xx0110.1
@@ -323,8 +323,8 @@ static inline int is_module_addr(void *addr)
#define _SEGMENT_ENTRY_DIRTY 0x2000 /* SW segment dirty bit */
#define _SEGMENT_ENTRY_YOUNG 0x1000 /* SW segment young bit */
#define _SEGMENT_ENTRY_LARGE 0x0400 /* STE-format control, large page */
-#define _SEGMENT_ENTRY_READ 0x0002 /* SW segment read bit */
-#define _SEGMENT_ENTRY_WRITE 0x0001 /* SW segment write bit */
+#define _SEGMENT_ENTRY_WRITE 0x0002 /* SW segment write bit */
+#define _SEGMENT_ENTRY_READ 0x0001 /* SW segment read bit */
#ifdef CONFIG_MEM_SOFT_DIRTY
#define _SEGMENT_ENTRY_SOFT_DIRTY 0x4000 /* SW segment soft dirty bit */
@@ -335,15 +335,15 @@ static inline int is_module_addr(void *addr)
/*
* Segment table and region3 table entry encoding
* (R = read-only, I = invalid, y = young bit):
- * dy..R...I...rw
+ * dy..R...I...wr
* prot-none, clean, old 00..1...1...00
* prot-none, clean, young 01..1...1...00
* prot-none, dirty, old 10..1...1...00
* prot-none, dirty, young 11..1...1...00
- * read-only, clean, old 00..1...1...10
- * read-only, clean, young 01..1...0...10
- * read-only, dirty, old 10..1...1...10
- * read-only, dirty, young 11..1...0...10
+ * read-only, clean, old 00..1...1...01
+ * read-only, clean, young 01..1...0...01
+ * read-only, dirty, old 10..1...1...01
+ * read-only, dirty, young 11..1...0...01
* read-write, clean, old 00..1...1...11
* read-write, clean, young 01..1...0...11
* read-write, dirty, old 10..0...1...11
@@ -382,7 +382,7 @@ static inline int is_module_addr(void *addr)
/*
* Page protection definitions.
*/
-#define PAGE_NONE __pgprot(_PAGE_PRESENT | _PAGE_INVALID)
+#define PAGE_NONE __pgprot(_PAGE_PRESENT | _PAGE_INVALID | _PAGE_PROTECT)
#define PAGE_READ __pgprot(_PAGE_PRESENT | _PAGE_READ | \
_PAGE_INVALID | _PAGE_PROTECT)
#define PAGE_WRITE __pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
index e19d853883be..cd404aa3931c 100644
--- a/arch/s390/mm/hugetlbpage.c
+++ b/arch/s390/mm/hugetlbpage.c
@@ -11,6 +11,12 @@
#include <linux/mm.h>
#include <linux/hugetlb.h>
+/*
+ * If the bit selected by single-bit bitmask "a" is set within "x", move
+ * it to the position indicated by single-bit bitmask "b".
+ */
+#define move_set_bit(x, a, b) (((x) & (a)) >> ilog2(a) << ilog2(b))
+
static inline unsigned long __pte_to_rste(pte_t pte)
{
unsigned long rste;
@@ -37,13 +43,22 @@ static inline unsigned long __pte_to_rste(pte_t pte)
*/
if (pte_present(pte)) {
rste = pte_val(pte) & PAGE_MASK;
- rste |= (pte_val(pte) & _PAGE_READ) >> 4;
- rste |= (pte_val(pte) & _PAGE_WRITE) >> 4;
- rste |= (pte_val(pte) & _PAGE_INVALID) >> 5;
- rste |= (pte_val(pte) & _PAGE_PROTECT);
- rste |= (pte_val(pte) & _PAGE_DIRTY) << 10;
- rste |= (pte_val(pte) & _PAGE_YOUNG) << 10;
- rste |= (pte_val(pte) & _PAGE_SOFT_DIRTY) << 13;
+ rste |= move_set_bit(pte_val(pte), _PAGE_READ,
+ _SEGMENT_ENTRY_READ);
+ rste |= move_set_bit(pte_val(pte), _PAGE_WRITE,
+ _SEGMENT_ENTRY_WRITE);
+ rste |= move_set_bit(pte_val(pte), _PAGE_INVALID,
+ _SEGMENT_ENTRY_INVALID);
+ rste |= move_set_bit(pte_val(pte), _PAGE_PROTECT,
+ _SEGMENT_ENTRY_PROTECT);
+ rste |= move_set_bit(pte_val(pte), _PAGE_DIRTY,
+ _SEGMENT_ENTRY_DIRTY);
+ rste |= move_set_bit(pte_val(pte), _PAGE_YOUNG,
+ _SEGMENT_ENTRY_YOUNG);
+#ifdef CONFIG_MEM_SOFT_DIRTY
+ rste |= move_set_bit(pte_val(pte), _PAGE_SOFT_DIRTY,
+ _SEGMENT_ENTRY_SOFT_DIRTY);
+#endif
} else
rste = _SEGMENT_ENTRY_INVALID;
return rste;
@@ -82,13 +97,22 @@ static inline pte_t __rste_to_pte(unsigned long rste)
if (present) {
pte_val(pte) = rste & _SEGMENT_ENTRY_ORIGIN_LARGE;
pte_val(pte) |= _PAGE_LARGE | _PAGE_PRESENT;
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_READ) << 4;
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_WRITE) << 4;
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_INVALID) << 5;
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_PROTECT);
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_DIRTY) >> 10;
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_YOUNG) >> 10;
- pte_val(pte) |= (rste & _SEGMENT_ENTRY_SOFT_DIRTY) >> 13;
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_READ,
+ _PAGE_READ);
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_WRITE,
+ _PAGE_WRITE);
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_INVALID,
+ _PAGE_INVALID);
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_PROTECT,
+ _PAGE_PROTECT);
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_DIRTY,
+ _PAGE_DIRTY);
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_YOUNG,
+ _PAGE_YOUNG);
+#ifdef CONFIG_MEM_SOFT_DIRTY
+ pte_val(pte) |= move_set_bit(rste, _SEGMENT_ENTRY_SOFT_DIRTY,
+ _PAGE_DIRTY);
+#endif
} else
pte_val(pte) = _PAGE_INVALID;
return pte;