diff mbox series

[v2,6/8] s390/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE

Message ID 20220329164329.208407-7-david@redhat.com (mailing list archive)
State New, archived
Headers show
Series mm: COW fixes part 3: reliable GUP R/W FOLL_GET of anonymous pages | expand

Commit Message

David Hildenbrand March 29, 2022, 4:43 p.m. UTC
Let's use bit 52, which is unused.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/s390/include/asm/pgtable.h | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

Comments

Gerald Schaefer March 30, 2022, 4:48 p.m. UTC | #1
On Tue, 29 Mar 2022 18:43:27 +0200
David Hildenbrand <david@redhat.com> wrote:

> Let's use bit 52, which is unused.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  arch/s390/include/asm/pgtable.h | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
> index 3982575bb586..a397b072a580 100644
> --- a/arch/s390/include/asm/pgtable.h
> +++ b/arch/s390/include/asm/pgtable.h
> @@ -181,6 +181,8 @@ static inline int is_module_addr(void *addr)
>  #define _PAGE_SOFT_DIRTY 0x000
>  #endif
>  
> +#define _PAGE_SWP_EXCLUSIVE _PAGE_LARGE	/* SW pte exclusive swap bit */
> +
>  /* Set of bits not changed in pte_modify */
>  #define _PAGE_CHG_MASK		(PAGE_MASK | _PAGE_SPECIAL | _PAGE_DIRTY | \
>  				 _PAGE_YOUNG | _PAGE_SOFT_DIRTY)
> @@ -826,6 +828,22 @@ static inline int pmd_protnone(pmd_t pmd)
>  }
>  #endif
>  
> +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE
> +static inline int pte_swp_exclusive(pte_t pte)
> +{
> +	return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
> +}
> +
> +static inline pte_t pte_swp_mkexclusive(pte_t pte)
> +{
> +	return set_pte_bit(pte, __pgprot(_PAGE_SWP_EXCLUSIVE));
> +}
> +
> +static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> +{
> +	return clear_pte_bit(pte, __pgprot(_PAGE_SWP_EXCLUSIVE));
> +}
> +
>  static inline int pte_soft_dirty(pte_t pte)
>  {
>  	return pte_val(pte) & _PAGE_SOFT_DIRTY;
> @@ -1715,14 +1733,15 @@ static inline int has_transparent_hugepage(void)
>   * Bits 54 and 63 are used to indicate the page type. Bit 53 marks the pte
>   * as invalid.
>   * A swap pte is indicated by bit pattern (pte & 0x201) == 0x200
> - * |			  offset			|X11XX|type |S0|
> + * |			  offset			|E11XX|type |S0|
>   * |0000000000111111111122222222223333333333444444444455|55555|55566|66|
>   * |0123456789012345678901234567890123456789012345678901|23456|78901|23|
>   *
>   * Bits 0-51 store the offset.
> + * Bit 52 (E) is used to remember PG_anon_exclusive.
>   * Bits 57-61 store the type.
>   * Bit 62 (S) is used for softdirty tracking.
> - * Bits 52, 55 and 56 (X) are unused.
> + * Bits 55 and 56 (X) are unused.
>   */
>  
>  #define __SWP_OFFSET_MASK	((1UL << 52) - 1)

Thanks David!

Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
diff mbox series

Patch

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 3982575bb586..a397b072a580 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -181,6 +181,8 @@  static inline int is_module_addr(void *addr)
 #define _PAGE_SOFT_DIRTY 0x000
 #endif
 
+#define _PAGE_SWP_EXCLUSIVE _PAGE_LARGE	/* SW pte exclusive swap bit */
+
 /* Set of bits not changed in pte_modify */
 #define _PAGE_CHG_MASK		(PAGE_MASK | _PAGE_SPECIAL | _PAGE_DIRTY | \
 				 _PAGE_YOUNG | _PAGE_SOFT_DIRTY)
@@ -826,6 +828,22 @@  static inline int pmd_protnone(pmd_t pmd)
 }
 #endif
 
+#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE
+static inline int pte_swp_exclusive(pte_t pte)
+{
+	return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
+}
+
+static inline pte_t pte_swp_mkexclusive(pte_t pte)
+{
+	return set_pte_bit(pte, __pgprot(_PAGE_SWP_EXCLUSIVE));
+}
+
+static inline pte_t pte_swp_clear_exclusive(pte_t pte)
+{
+	return clear_pte_bit(pte, __pgprot(_PAGE_SWP_EXCLUSIVE));
+}
+
 static inline int pte_soft_dirty(pte_t pte)
 {
 	return pte_val(pte) & _PAGE_SOFT_DIRTY;
@@ -1715,14 +1733,15 @@  static inline int has_transparent_hugepage(void)
  * Bits 54 and 63 are used to indicate the page type. Bit 53 marks the pte
  * as invalid.
  * A swap pte is indicated by bit pattern (pte & 0x201) == 0x200
- * |			  offset			|X11XX|type |S0|
+ * |			  offset			|E11XX|type |S0|
  * |0000000000111111111122222222223333333333444444444455|55555|55566|66|
  * |0123456789012345678901234567890123456789012345678901|23456|78901|23|
  *
  * Bits 0-51 store the offset.
+ * Bit 52 (E) is used to remember PG_anon_exclusive.
  * Bits 57-61 store the type.
  * Bit 62 (S) is used for softdirty tracking.
- * Bits 52, 55 and 56 (X) are unused.
+ * Bits 55 and 56 (X) are unused.
  */
 
 #define __SWP_OFFSET_MASK	((1UL << 52) - 1)