[PATCH v4] pagemap: switch to the new format and do some cleanup
From: Konstantin Khlebnikov
Date: Mon Jun 15 2015 - 01:57:13 EST
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
This patch removes page-shift bits (scheduled to remove since 3.11) and
completes migration to the new bit layout. Also it cleans messy macro.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
---
v4: fix misprint PM_PFEAME_BITS -> PM_PFRAME_BITS
---
fs/proc/task_mmu.c | 147 ++++++++++++++++---------------------------------
tools/vm/page-types.c | 29 +++-------
2 files changed, 58 insertions(+), 118 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f1b9ae8..99fa2ae 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -710,23 +710,6 @@ const struct file_operations proc_tid_smaps_operations = {
.release = proc_map_release,
};
-/*
- * We do not want to have constant page-shift bits sitting in
- * pagemap entries and are about to reuse them some time soon.
- *
- * Here's the "migration strategy":
- * 1. when the system boots these bits remain what they are,
- * but a warning about future change is printed in log;
- * 2. once anyone clears soft-dirty bits via clear_refs file,
- * these flag is set to denote, that user is aware of the
- * new API and those page-shift bits change their meaning.
- * The respective warning is printed in dmesg;
- * 3. In a couple of releases we will remove all the mentions
- * of page-shift in pagemap entries.
- */
-
-static bool soft_dirty_cleared __read_mostly;
-
enum clear_refs_types {
CLEAR_REFS_ALL = 1,
CLEAR_REFS_ANON,
@@ -887,13 +870,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
if (type < CLEAR_REFS_ALL || type >= CLEAR_REFS_LAST)
return -EINVAL;
- if (type == CLEAR_REFS_SOFT_DIRTY) {
- soft_dirty_cleared = true;
- pr_warn_once("The pagemap bits 55-60 has changed their meaning!"
- " See the linux/Documentation/vm/pagemap.txt for "
- "details.\n");
- }
-
task = get_proc_task(file_inode(file));
if (!task)
return -ESRCH;
@@ -961,38 +937,26 @@ typedef struct {
struct pagemapread {
int pos, len; /* units: PM_ENTRY_BYTES, not bytes */
pagemap_entry_t *buffer;
- bool v2;
bool show_pfn;
};
#define PAGEMAP_WALK_SIZE (PMD_SIZE)
#define PAGEMAP_WALK_MASK (PMD_MASK)
-#define PM_ENTRY_BYTES sizeof(pagemap_entry_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) (((u64) (x) << PM_PSHIFT_OFFSET) & PM_PSHIFT_MASK)
-#define PM_PFRAME_MASK ((1LL << PM_PSHIFT_OFFSET) - 1)
-#define PM_PFRAME(x) ((x) & PM_PFRAME_MASK)
-/* in "new" pagemap pshift bits are occupied with more status bits */
-#define PM_STATUS2(v2, x) (__PM_PSHIFT(v2 ? x : PAGE_SHIFT))
-
-#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_PFRAME_BITS 54
+#define PM_PFRAME_MASK GENMASK_ULL(PM_PFRAME_BITS - 1, 0)
+#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..e1d5ff8 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_PFRAME_BITS 54
+#define PM_PFRAME_MASK ((1LL << PM_PFRAME_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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