Re: [PATCH v3 4/4] pagemap: switch to the new format and do some cleanup

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One tiny nitpick / typo, inline below - functionally, this looks good
from our side...

Reviewed-by: mwilliamson@xxxxxxxxxxxxxxxxx
Tested-by: mwilliamson@xxxxxxxxxxxxxxxxx

On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov <koct9i@xxxxxxxxx> wrote:
> From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>

<...snip...>

> -#define __PM_SOFT_DIRTY      (1LL)
> -#define __PM_MMAP_EXCLUSIVE  (2LL)
> -#define PM_PRESENT          PM_STATUS(4LL)
> -#define PM_SWAP             PM_STATUS(2LL)
> -#define PM_FILE             PM_STATUS(1LL)
> -#define PM_NOT_PRESENT(v2)  PM_STATUS2(v2, 0)
> +#define PM_ENTRY_BYTES         sizeof(pagemap_entry_t)
> +#define PM_PFEAME_BITS         54
> +#define PM_PFRAME_MASK         GENMASK_ULL(PM_PFEAME_BITS - 1, 0)

s/PM_FEAME_BITS/PM_FRAME_BITS/ I presume?

> +#define PM_SOFT_DIRTY          BIT_ULL(55)
> +#define PM_MMAP_EXCLUSIVE      BIT_ULL(56)
> +#define PM_FILE                        BIT_ULL(61)
> +#define PM_SWAP                        BIT_ULL(62)
> +#define PM_PRESENT             BIT_ULL(63)
> +
>  #define PM_END_OF_BUFFER    1
>
> -static inline pagemap_entry_t make_pme(u64 val)
> +static inline pagemap_entry_t make_pme(u64 frame, u64 flags)
>  {
> -       return (pagemap_entry_t) { .pme = val };
> +       return (pagemap_entry_t) { .pme = (frame & PM_PFRAME_MASK) | flags };
>  }
>
>  static int add_to_pagemap(unsigned long addr, pagemap_entry_t *pme,
> @@ -1013,7 +977,7 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
>
>         while (addr < end) {
>                 struct vm_area_struct *vma = find_vma(walk->mm, addr);
> -               pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
> +               pagemap_entry_t pme = make_pme(0, 0);
>                 /* End of address space hole, which we mark as non-present. */
>                 unsigned long hole_end;
>
> @@ -1033,7 +997,7 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
>
>                 /* Addresses in the VMA. */
>                 if (vma->vm_flags & VM_SOFTDIRTY)
> -                       pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
> +                       pme = make_pme(0, PM_SOFT_DIRTY);
>                 for (; addr < min(end, vma->vm_end); addr += PAGE_SIZE) {
>                         err = add_to_pagemap(addr, &pme, pm);
>                         if (err)
> @@ -1044,50 +1008,44 @@ out:
>         return err;
>  }
>
> -static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
> +static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
>                 struct vm_area_struct *vma, unsigned long addr, pte_t pte)
>  {
> -       u64 frame = 0, flags;
> +       u64 frame = 0, flags = 0;
>         struct page *page = NULL;
> -       int flags2 = 0;
>
>         if (pte_present(pte)) {
>                 if (pm->show_pfn)
>                         frame = pte_pfn(pte);
> -               flags = PM_PRESENT;
> +               flags |= PM_PRESENT;
>                 page = vm_normal_page(vma, addr, pte);
>                 if (pte_soft_dirty(pte))
> -                       flags2 |= __PM_SOFT_DIRTY;
> +                       flags |= PM_SOFT_DIRTY;
>         } else if (is_swap_pte(pte)) {
>                 swp_entry_t entry;
>                 if (pte_swp_soft_dirty(pte))
> -                       flags2 |= __PM_SOFT_DIRTY;
> +                       flags |= PM_SOFT_DIRTY;
>                 entry = pte_to_swp_entry(pte);
>                 frame = swp_type(entry) |
>                         (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
> -               flags = PM_SWAP;
> +               flags |= PM_SWAP;
>                 if (is_migration_entry(entry))
>                         page = migration_entry_to_page(entry);
> -       } else {
> -               if (vma->vm_flags & VM_SOFTDIRTY)
> -                       flags2 |= __PM_SOFT_DIRTY;
> -               *pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2));
> -               return;
>         }
>
>         if (page && !PageAnon(page))
>                 flags |= PM_FILE;
>         if (page && page_mapcount(page) == 1)
> -               flags2 |= __PM_MMAP_EXCLUSIVE;
> -       if ((vma->vm_flags & VM_SOFTDIRTY))
> -               flags2 |= __PM_SOFT_DIRTY;
> +               flags |= PM_MMAP_EXCLUSIVE;
> +       if (vma->vm_flags & VM_SOFTDIRTY)
> +               flags |= PM_SOFT_DIRTY;
>
> -       *pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, flags2) | flags);
> +       return make_pme(frame, flags);
>  }
>
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
> -               pmd_t pmd, int offset, int pmd_flags2)
> +static pagemap_entry_t thp_pmd_to_pagemap_entry(struct pagemapread *pm,
> +               pmd_t pmd, int offset, u64 flags)
>  {
>         u64 frame = 0;
>
> @@ -1099,15 +1057,16 @@ static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *p
>         if (pmd_present(pmd)) {
>                 if (pm->show_pfn)
>                         frame = pmd_pfn(pmd) + offset;
> -               *pme = make_pme(PM_PFRAME(frame) | PM_PRESENT |
> -                               PM_STATUS2(pm->v2, pmd_flags2));
> -       } else
> -               *pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, pmd_flags2));
> +               flags |= PM_PRESENT;
> +       }
> +
> +       return make_pme(frame, flags);
>  }
>  #else
> -static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
> -               pmd_t pmd, int offset, int pmd_flags2)
> +static pagemap_entry_t thp_pmd_to_pagemap_entry(struct pagemapread *pm,
> +               pmd_t pmd, int offset, u64 flags)
>  {
> +       return make_pme(0, 0);
>  }
>  #endif
>
> @@ -1121,18 +1080,16 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>         int err = 0;
>
>         if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
> -               int pmd_flags2;
> +               u64 flags = 0;
>
>                 if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
> -                       pmd_flags2 = __PM_SOFT_DIRTY;
> -               else
> -                       pmd_flags2 = 0;
> +                       flags |= PM_SOFT_DIRTY;
>
>                 if (pmd_present(*pmd)) {
>                         struct page *page = pmd_page(*pmd);
>
>                         if (page_mapcount(page) == 1)
> -                               pmd_flags2 |= __PM_MMAP_EXCLUSIVE;
> +                               flags |= PM_MMAP_EXCLUSIVE;
>                 }
>
>                 for (; addr != end; addr += PAGE_SIZE) {
> @@ -1141,7 +1098,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>
>                         offset = (addr & ~PAGEMAP_WALK_MASK) >>
>                                         PAGE_SHIFT;
> -                       thp_pmd_to_pagemap_entry(&pme, pm, *pmd, offset, pmd_flags2);
> +                       pme = thp_pmd_to_pagemap_entry(pm, *pmd, offset, flags);
>                         err = add_to_pagemap(addr, &pme, pm);
>                         if (err)
>                                 break;
> @@ -1161,7 +1118,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>         for (; addr < end; pte++, addr += PAGE_SIZE) {
>                 pagemap_entry_t pme;
>
> -               pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
> +               pme = pte_to_pagemap_entry(pm, vma, addr, *pte);
>                 err = add_to_pagemap(addr, &pme, pm);
>                 if (err)
>                         break;
> @@ -1174,19 +1131,18 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>  }
>
>  #ifdef CONFIG_HUGETLB_PAGE
> -static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
> -                                       pte_t pte, int offset, int flags2)
> +static pagemap_entry_t huge_pte_to_pagemap_entry(struct pagemapread *pm,
> +                                       pte_t pte, int offset, u64 flags)
>  {
>         u64 frame = 0;
>
>         if (pte_present(pte)) {
>                 if (pm->show_pfn)
>                         frame = pte_pfn(pte) + offset;
> -               *pme = make_pme(PM_PFRAME(frame) | PM_PRESENT |
> -                               PM_STATUS2(pm->v2, flags2));
> -       } else
> -               *pme = make_pme(PM_NOT_PRESENT(pm->v2)                  |
> -                               PM_STATUS2(pm->v2, flags2));
> +               flags |= PM_PRESENT;
> +       }
> +
> +       return make_pme(frame, flags);
>  }
>
>  /* This function walks within one hugetlb entry in the single call */
> @@ -1197,17 +1153,15 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
>         struct pagemapread *pm = walk->private;
>         struct vm_area_struct *vma = walk->vma;
>         int err = 0;
> -       int flags2;
> +       u64 flags = 0;
>         pagemap_entry_t pme;
>
>         if (vma->vm_flags & VM_SOFTDIRTY)
> -               flags2 = __PM_SOFT_DIRTY;
> -       else
> -               flags2 = 0;
> +               flags |= PM_SOFT_DIRTY;
>
>         for (; addr != end; addr += PAGE_SIZE) {
>                 int offset = (addr & ~hmask) >> PAGE_SHIFT;
> -               huge_pte_to_pagemap_entry(&pme, pm, *pte, offset, flags2);
> +               pme = huge_pte_to_pagemap_entry(pm, *pte, offset, flags);
>                 err = add_to_pagemap(addr, &pme, pm);
>                 if (err)
>                         return err;
> @@ -1228,7 +1182,9 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
>   * Bits 0-54  page frame number (PFN) if present
>   * Bits 0-4   swap type if swapped
>   * Bits 5-54  swap offset if swapped
> - * Bits 55-60 page shift (page size = 1<<page shift)
> + * Bit  55    pte is soft-dirty (see Documentation/vm/soft-dirty.txt)
> + * Bit  56    page exclusively mapped
> + * Bits 57-60 zero
>   * Bit  61    page is file-page or shared-anon
>   * Bit  62    page swapped
>   * Bit  63    page present
> @@ -1269,7 +1225,6 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
>
>         /* do not disclose physical addresses: attack vector */
>         pm.show_pfn = file_ns_capable(file, &init_user_ns, CAP_SYS_ADMIN);
> -       pm.v2 = soft_dirty_cleared;
>         pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
>         pm.buffer = kmalloc(pm.len * PM_ENTRY_BYTES, GFP_TEMPORARY);
>         ret = -ENOMEM;
> @@ -1339,10 +1294,6 @@ static int pagemap_open(struct inode *inode, struct file *file)
>  {
>         struct mm_struct *mm;
>
> -       pr_warn_once("Bits 55-60 of /proc/PID/pagemap entries are about "
> -                       "to stop being page-shift some time soon. See the "
> -                       "linux/Documentation/vm/pagemap.txt for details.\n");
> -
>         mm = proc_mem_open(inode, PTRACE_MODE_READ);
>         if (IS_ERR(mm))
>                 return PTR_ERR(mm);
> diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
> index 3a9f193..1fa872e 100644
> --- a/tools/vm/page-types.c
> +++ b/tools/vm/page-types.c
> @@ -57,26 +57,15 @@
>   * pagemap kernel ABI bits
>   */
>
> -#define PM_ENTRY_BYTES      sizeof(uint64_t)
> -#define PM_STATUS_BITS      3
> -#define PM_STATUS_OFFSET    (64 - PM_STATUS_BITS)
> -#define PM_STATUS_MASK      (((1LL << PM_STATUS_BITS) - 1) << PM_STATUS_OFFSET)
> -#define PM_STATUS(nr)       (((nr) << PM_STATUS_OFFSET) & PM_STATUS_MASK)
> -#define PM_PSHIFT_BITS      6
> -#define PM_PSHIFT_OFFSET    (PM_STATUS_OFFSET - PM_PSHIFT_BITS)
> -#define PM_PSHIFT_MASK      (((1LL << PM_PSHIFT_BITS) - 1) << PM_PSHIFT_OFFSET)
> -#define __PM_PSHIFT(x)      (((uint64_t) (x) << PM_PSHIFT_OFFSET) & PM_PSHIFT_MASK)
> -#define PM_PFRAME_MASK      ((1LL << PM_PSHIFT_OFFSET) - 1)
> -#define PM_PFRAME(x)        ((x) & PM_PFRAME_MASK)
> -
> -#define __PM_SOFT_DIRTY      (1LL)
> -#define __PM_MMAP_EXCLUSIVE  (2LL)
> -#define PM_PRESENT          PM_STATUS(4LL)
> -#define PM_SWAP             PM_STATUS(2LL)
> -#define PM_FILE             PM_STATUS(1LL)
> -#define PM_SOFT_DIRTY       __PM_PSHIFT(__PM_SOFT_DIRTY)
> -#define PM_MMAP_EXCLUSIVE   __PM_PSHIFT(__PM_MMAP_EXCLUSIVE)
> -
> +#define PM_ENTRY_BYTES         8
> +#define PM_PFEAME_BITS         54
> +#define PM_PFRAME_MASK         ((1LL << PM_PFEAME_BITS) - 1)
> +#define PM_PFRAME(x)           ((x) & PM_PFRAME_MASK)
> +#define PM_SOFT_DIRTY          (1ULL << 55)
> +#define PM_MMAP_EXCLUSIVE      (1ULL << 56)
> +#define PM_FILE                        (1ULL << 61)
> +#define PM_SWAP                        (1ULL << 62)
> +#define PM_PRESENT             (1ULL << 63)
>
>  /*
>   * kernel page flags
>

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