[PATCH v4] powerpc/mm: Add page soft dirty tracking
Aneesh Kumar K.V
aneesh.kumar at linux.vnet.ibm.com
Thu Dec 3 02:51:41 AEDT 2015
Laurent Dufour <ldufour at linux.vnet.ibm.com> writes:
> User space checkpoint and restart tool (CRIU) needs the page's change
> to be soft tracked. This allows to do a pre checkpoint and then dump
> only touched pages.
>
> This is done by using a newly assigned PTE bit (_PAGE_SOFT_DIRTY) when
> the page is backed in memory, and a new _PAGE_SWP_SOFT_DIRTY bit when
> the page is swapped out.
>
> To introduce a new PTE _PAGE_SOFT_DIRTY bit value common to hash 4k
> and hash 64k pte, the bits already defined in hash-*4k.h should be
> shifted left by one.
>
> The _PAGE_SWP_SOFT_DIRTY bit is dynamically put after the swap type in
> the swap pte. A check is added to ensure that the bit is not
> overwritten by _PAGE_HPTEFLAGS.
>
> Signed-off-by: Laurent Dufour <ldufour at linux.vnet.ibm.com>
> CC: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
> ---
>
> This patch should to be applied on top of the Aneesh's series titled
> "[PATCH V6 00/35] powerpc/mm: Update page table format for book3s 64"
>
> v4:
> - updated to match Aneesh's v6 series.
> V3:
> - updated to match Aneesh's changes in the pte handling
> - updated to match commit a7b761749317 ("mm: add architecture
> primitives for software dirty bit clearing")
> V2:
> - Fix allnoconfig build
>
> arch/powerpc/Kconfig | 2 ++
> arch/powerpc/include/asm/book3s/64/hash-4k.h | 2 +-
> arch/powerpc/include/asm/book3s/64/hash-64k.h | 4 ++--
> arch/powerpc/include/asm/book3s/64/hash.h | 30 ++++++++++++++++++++++-----
> arch/powerpc/include/asm/book3s/64/pgtable.h | 26 +++++++++++++++++++++++
> 5 files changed, 56 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index db49e0d796b1..6e03f85b11cd 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -559,6 +559,7 @@ choice
>
> config PPC_4K_PAGES
> bool "4k page size"
> + select HAVE_ARCH_SOFT_DIRTY if CHECKPOINT_RESTORE && PPC_BOOK3S
>
> config PPC_16K_PAGES
> bool "16k page size"
> @@ -567,6 +568,7 @@ config PPC_16K_PAGES
> config PPC_64K_PAGES
> bool "64k page size"
> depends on !PPC_FSL_BOOK3E && (44x || PPC_STD_MMU_64 || PPC_BOOK3E_64)
> + select HAVE_ARCH_SOFT_DIRTY if CHECKPOINT_RESTORE && PPC_BOOK3S
>
> config PPC_256K_PAGES
> bool "256k page size"
> diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h b/arch/powerpc/include/asm/book3s/64/hash-4k.h
> index e59832c94609..ea0414d6659e 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
> @@ -52,7 +52,7 @@
> _PAGE_F_SECOND | _PAGE_F_GIX)
>
> /* shift to put page number into pte */
> -#define PTE_RPN_SHIFT (17)
> +#define PTE_RPN_SHIFT (18)
>
> #define _PAGE_4K_PFN 0
> #ifndef __ASSEMBLY__
> diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> index 9f9942998587..9e55e3b1fef0 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> @@ -25,8 +25,8 @@
> #define PGDIR_SIZE (1UL << PGDIR_SHIFT)
> #define PGDIR_MASK (~(PGDIR_SIZE-1))
>
> -#define _PAGE_COMBO 0x00020000 /* this is a combo 4k page */
> -#define _PAGE_4K_PFN 0x00040000 /* PFN is for a single 4k page */
> +#define _PAGE_COMBO 0x00040000 /* this is a combo 4k page */
> +#define _PAGE_4K_PFN 0x00080000 /* PFN is for a single 4k page */
> /*
> * Used to track subpage group valid if _PAGE_COMBO is set
> * This overloads _PAGE_F_GIX and _PAGE_F_SECOND
> diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
> index 8b929e531758..92a615b15fbf 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash.h
> @@ -33,6 +33,7 @@
> #define _PAGE_F_GIX_SHIFT 12
> #define _PAGE_F_SECOND 0x08000 /* Whether to use secondary hash or not */
> #define _PAGE_SPECIAL 0x10000 /* software: special page */
> +#define _PAGE_SOFT_DIRTY 0x20000 /* software: software dirty tracking */
>
> /*
> * THP pages can't be special. So use the _PAGE_SPECIAL
> @@ -50,7 +51,7 @@
> */
> #define _HPAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | \
> _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_SPLITTING | \
> - _PAGE_THP_HUGE | _PAGE_PTE)
> + _PAGE_THP_HUGE | _PAGE_PTE | _PAGE_SOFT_DIRTY)
>
> #ifdef CONFIG_PPC_64K_PAGES
> #include <asm/book3s/64/hash-64k.h>
> @@ -136,14 +137,16 @@
> * pgprot changes
> */
> #define _PAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
> - _PAGE_ACCESSED | _PAGE_SPECIAL | _PAGE_PTE)
> + _PAGE_ACCESSED | _PAGE_SPECIAL | _PAGE_PTE | \
> + _PAGE_SOFT_DIRTY)
> /*
> * Mask of bits returned by pte_pgprot()
> */
> #define PAGE_PROT_BITS (_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
> _PAGE_WRITETHRU | _PAGE_4K_PFN | \
> _PAGE_USER | _PAGE_ACCESSED | \
> - _PAGE_RW | _PAGE_DIRTY | _PAGE_EXEC)
> + _PAGE_RW | _PAGE_DIRTY | _PAGE_EXEC | \
> + _PAGE_SOFT_DIRTY)
> /*
> * We define 2 sets of base prot bits, one for basic pages (ie,
> * cacheable kernel and user pages) and one for non cacheable
> @@ -339,7 +342,8 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr,
> static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
> {
> unsigned long bits = pte_val(entry) &
> - (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
> + (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC |
> + _PAGE_SOFT_DIRTY);
>
> unsigned long old, tmp;
>
> @@ -366,6 +370,22 @@ static inline int pte_special(pte_t pte) { return !!(pte_val(pte) & _PAGE_SPECIA
> static inline int pte_none(pte_t pte) { return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
> static inline pgprot_t pte_pgprot(pte_t pte) { return __pgprot(pte_val(pte) & PAGE_PROT_BITS); }
>
> +#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
> +static inline int pte_soft_dirty(pte_t pte)
> +{
> + return !!(pte_val(pte) & _PAGE_SOFT_DIRTY);
> +}
> +static inline pte_t pte_mksoft_dirty(pte_t pte)
> +{
> + return __pte(pte_val(pte) | _PAGE_SOFT_DIRTY);
> +}
> +
> +static inline pte_t pte_clear_soft_dirty(pte_t pte)
> +{
> + return __pte(pte_val(pte) & ~_PAGE_SOFT_DIRTY);
> +}
> +#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
> +
> #ifdef CONFIG_NUMA_BALANCING
> /*
> * These work without NUMA balancing but the kernel does not care. See the
> @@ -424,7 +444,7 @@ static inline pte_t pte_mkwrite(pte_t pte)
>
> static inline pte_t pte_mkdirty(pte_t pte)
> {
> - return __pte(pte_val(pte) | _PAGE_DIRTY);
> + return __pte(pte_val(pte) | _PAGE_DIRTY | _PAGE_SOFT_DIRTY);
> }
>
> static inline pte_t pte_mkyoung(pte_t pte)
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index a2d4e0e37067..37fcc2072afb 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -146,6 +146,7 @@ static inline void pgd_set(pgd_t *pgdp, unsigned long val)
> * We filter HPTEFLAGS on set_pte. \
> */ \
> BUILD_BUG_ON(_PAGE_HPTEFLAGS & (0x1f << _PAGE_BIT_SWAP_TYPE)); \
> + BUILD_BUG_ON(_PAGE_HPTEFLAGS & _PAGE_SWP_SOFT_DIRTY); \
> } while (0)
> /*
> * on pte we don't need handle RADIX_TREE_EXCEPTIONAL_SHIFT;
> @@ -161,6 +162,24 @@ static inline void pgd_set(pgd_t *pgdp, unsigned long val)
> #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) })
> #define __swp_entry_to_pte(x) __pte((x).val)
>
> +#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
> +#define _PAGE_SWP_SOFT_DIRTY (1UL << (SWP_TYPE_BITS + _PAGE_BIT_SWAP_TYPE))
> +static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
> +{
> + return __pte(pte_val(pte) | _PAGE_SWP_SOFT_DIRTY);
> +}
> +static inline int pte_swp_soft_dirty(pte_t pte)
> +{
> + return pte_val(pte) & _PAGE_SWP_SOFT_DIRTY;
> +}
> +static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
> +{
> + return __pte(pte_val(pte) & ~_PAGE_SWP_SOFT_DIRTY);
> +}
> +#else
> +#define _PAGE_SWP_SOFT_DIRTY 0
> +#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
> +
> void pgtable_cache_add(unsigned shift, void (*ctor)(void *));
> void pgtable_cache_init(void);
>
> @@ -201,6 +220,13 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
> #define pmd_mkdirty(pmd) pte_pmd(pte_mkdirty(pmd_pte(pmd)))
> #define pmd_mkyoung(pmd) pte_pmd(pte_mkyoung(pmd_pte(pmd)))
> #define pmd_mkwrite(pmd) pte_pmd(pte_mkwrite(pmd_pte(pmd)))
> +
> +#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
> +#define pmd_soft_dirty(pmd) pte_soft_dirty(pmd_pte(pmd))
> +#define pmd_mksoft_dirty(pmd) pte_pmd(pte_mksoft_dirty(pmd_pte(pmd)))
> +#define pmd_clear_soft_dirty(pmd) pte_pmd(pte_clear_soft_dirty(pmd_pte(pmd)))
> +#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
> +
> #ifdef CONFIG_NUMA_BALANCING
> static inline int pmd_protnone(pmd_t pmd)
> {
> --
> 1.9.1
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