}
__setup("norandmaps", disable_randmaps);
+unsigned long zero_pfn __read_mostly;
+unsigned long highest_memmap_pfn __read_mostly;
+
+/*
+ * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
+ */
+static int __init init_zero_pfn(void)
+{
+ zero_pfn = page_to_pfn(ZERO_PAGE(0));
+ return 0;
+}
+core_initcall(init_zero_pfn);
/*
* If a p?d_bad entry is found while walking page tables, report
return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}
+#ifndef is_zero_pfn
+static inline int is_zero_pfn(unsigned long pfn)
+{
+ return pfn == zero_pfn;
+}
+#endif
+
+#ifndef my_zero_pfn
+static inline unsigned long my_zero_pfn(unsigned long addr)
+{
+ return zero_pfn;
+}
+#endif
+
/*
* vm_normal_page -- This function gets the "struct page" associated with a pte.
*
if (HAVE_PTE_SPECIAL) {
if (likely(!pte_special(pte)))
goto check_pfn;
- if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
+ if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
+ return NULL;
+ if (!is_zero_pfn(pfn))
print_bad_pte(vma, addr, pte, NULL);
return NULL;
}
}
}
+ if (is_zero_pfn(pfn))
+ return NULL;
check_pfn:
if (unlikely(pfn > highest_memmap_pfn)) {
print_bad_pte(vma, addr, pte, NULL);
goto no_page;
if ((flags & FOLL_WRITE) && !pte_write(pte))
goto unlock;
+
page = vm_normal_page(vma, address, pte);
- if (unlikely(!page))
- goto bad_page;
+ if (unlikely(!page)) {
+ if ((flags & FOLL_DUMP) ||
+ !is_zero_pfn(pte_pfn(pte)))
+ goto bad_page;
+ page = pte_page(pte);
+ }
if (flags & FOLL_GET)
get_page(page);
}
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long start, int nr_pages, int flags,
+ unsigned long start, int nr_pages, unsigned int gup_flags,
struct page **pages, struct vm_area_struct **vmas)
{
int i;
- unsigned int vm_flags = 0;
- int write = !!(flags & GUP_FLAGS_WRITE);
- int force = !!(flags & GUP_FLAGS_FORCE);
+ unsigned long vm_flags;
if (nr_pages <= 0)
return 0;
+
+ VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
+
/*
* Require read or write permissions.
- * If 'force' is set, we only require the "MAY" flags.
+ * If FOLL_FORCE is set, we only require the "MAY" flags.
*/
- vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
- vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
+ vm_flags = (gup_flags & FOLL_WRITE) ?
+ (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+ vm_flags &= (gup_flags & FOLL_FORCE) ?
+ (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
i = 0;
do {
struct vm_area_struct *vma;
- unsigned int foll_flags;
vma = find_extend_vma(mm, start);
if (!vma && in_gate_area(tsk, start)) {
pte_t *pte;
/* user gate pages are read-only */
- if (write)
+ if (gup_flags & FOLL_WRITE)
return i ? : -EFAULT;
if (pg > TASK_SIZE)
pgd = pgd_offset_k(pg);
!(vm_flags & vma->vm_flags))
return i ? : -EFAULT;
- foll_flags = FOLL_TOUCH;
- if (pages)
- foll_flags |= FOLL_GET;
- if (flags & GUP_FLAGS_DUMP)
- foll_flags |= FOLL_DUMP;
- if (write)
- foll_flags |= FOLL_WRITE;
-
if (is_vm_hugetlb_page(vma)) {
i = follow_hugetlb_page(mm, vma, pages, vmas,
- &start, &nr_pages, i, foll_flags);
+ &start, &nr_pages, i, gup_flags);
continue;
}
do {
struct page *page;
+ unsigned int foll_flags = gup_flags;
/*
* If we have a pending SIGKILL, don't keep faulting
if (unlikely(fatal_signal_pending(current)))
return i ? i : -ERESTARTSYS;
- if (write)
- foll_flags |= FOLL_WRITE;
-
cond_resched();
while (!(page = follow_page(vma, start, foll_flags))) {
int ret;
unsigned long start, int nr_pages, int write, int force,
struct page **pages, struct vm_area_struct **vmas)
{
- int flags = 0;
+ int flags = FOLL_TOUCH;
+ if (pages)
+ flags |= FOLL_GET;
if (write)
- flags |= GUP_FLAGS_WRITE;
+ flags |= FOLL_WRITE;
if (force)
- flags |= GUP_FLAGS_FORCE;
+ flags |= FOLL_FORCE;
return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
}
struct page *page;
if (__get_user_pages(current, current->mm, addr, 1,
- GUP_FLAGS_FORCE | GUP_FLAGS_DUMP, &page, &vma) < 1)
- return NULL;
- if (page == ZERO_PAGE(0)) {
- page_cache_release(page);
+ FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
return NULL;
- }
flush_cache_page(vma, addr, page_to_pfn(page));
return page;
}
* If we don't have pte special, then we have to use the pfn_valid()
* based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
* refcount the page if pfn_valid is true (hence insert_page rather
- * than insert_pfn).
+ * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
+ * without pte special, it would there be refcounted as a normal page.
*/
if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
struct page *page;
if (unlikely(anon_vma_prepare(vma)))
goto oom;
- VM_BUG_ON(old_page == ZERO_PAGE(0));
- new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
- if (!new_page)
- goto oom;
+
+ if (is_zero_pfn(pte_pfn(orig_pte))) {
+ new_page = alloc_zeroed_user_highpage_movable(vma, address);
+ if (!new_page)
+ goto oom;
+ } else {
+ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+ if (!new_page)
+ goto oom;
+ cow_user_page(new_page, old_page, address, vma);
+ }
+ __SetPageUptodate(new_page);
+
/*
* Don't let another task, with possibly unlocked vma,
* keep the mlocked page.
clear_page_mlock(old_page);
unlock_page(old_page);
}
- cow_user_page(new_page, old_page, address, vma);
- __SetPageUptodate(new_page);
if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
goto oom_free_new;
spinlock_t *ptl;
pte_t entry;
+ if (!(flags & FAULT_FLAG_WRITE)) {
+ entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
+ vma->vm_page_prot));
+ ptl = pte_lockptr(mm, pmd);
+ spin_lock(ptl);
+ if (!pte_none(*page_table))
+ goto unlock;
+ goto setpte;
+ }
+
/* Allocate our own private page. */
pte_unmap(page_table);
goto oom_free_page;
entry = mk_pte(page, vma->vm_page_prot);
- entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ if (vma->vm_flags & VM_WRITE)
+ entry = pte_mkwrite(pte_mkdirty(entry));
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
if (!pte_none(*page_table))
inc_mm_counter(mm, anon_rss);
page_add_new_anon_rmap(page, vma, address);
+setpte:
set_pte_at(mm, address, page_table, entry);
/* No need to invalidate - it was non-present before */
projects / deliverable / linux.git / blobdiff