}
retry:
if (!pmd_present(pmdval)) {
+ /*
+ * Should never reach here, if thp migration is not supported;
+ * Otherwise, it must be a thp migration entry.
+ */
+ VM_BUG_ON(!thp_migration_supported() ||
+ !is_pmd_migration_entry(pmdval));
+
if (likely(!(flags & FOLL_MIGRATION)))
return no_page_table(vma, flags);
- VM_BUG_ON(thp_migration_supported() &&
- !is_pmd_migration_entry(pmdval));
- if (is_pmd_migration_entry(pmdval))
- pmd_migration_entry_wait(mm, pmd);
+
+ pmd_migration_entry_wait(mm, pmd);
pmdval = READ_ONCE(*pmd);
/*
* MADV_DONTNEED may convert the pmd to null because
/* mlock all present pages, but do not fault in new pages */
if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
return -ENOENT;
+ if (*flags & FOLL_NOFAULT)
+ return -EFAULT;
if (*flags & FOLL_WRITE)
fault_flags |= FAULT_FLAG_WRITE;
if (*flags & FOLL_REMOTE)
}
#endif /* !CONFIG_MMU */
+/**
+ * fault_in_writeable - fault in userspace address range for writing
+ * @uaddr: start of address range
+ * @size: size of address range
+ *
+ * Returns the number of bytes not faulted in (like copy_to_user() and
+ * copy_from_user()).
+ */
+size_t fault_in_writeable(char __user *uaddr, size_t size)
+{
+ char __user *start = uaddr, *end;
+
+ if (unlikely(size == 0))
+ return 0;
+ if (!user_write_access_begin(uaddr, size))
+ return size;
+ if (!PAGE_ALIGNED(uaddr)) {
+ unsafe_put_user(0, uaddr, out);
+ uaddr = (char __user *)PAGE_ALIGN((unsigned long)uaddr);
+ }
+ end = (char __user *)PAGE_ALIGN((unsigned long)start + size);
+ if (unlikely(end < start))
+ end = NULL;
+ while (uaddr != end) {
+ unsafe_put_user(0, uaddr, out);
+ uaddr += PAGE_SIZE;
+ }
+
+out:
+ user_write_access_end();
+ if (size > uaddr - start)
+ return size - (uaddr - start);
+ return 0;
+}
+EXPORT_SYMBOL(fault_in_writeable);
+
+/*
+ * fault_in_safe_writeable - fault in an address range for writing
+ * @uaddr: start of address range
+ * @size: length of address range
+ *
+ * Faults in an address range using get_user_pages, i.e., without triggering
+ * hardware page faults. This is primarily useful when we already know that
+ * some or all of the pages in the address range aren't in memory.
+ *
+ * Other than fault_in_writeable(), this function is non-destructive.
+ *
+ * Note that we don't pin or otherwise hold the pages referenced that we fault
+ * in. There's no guarantee that they'll stay in memory for any duration of
+ * time.
+ *
+ * Returns the number of bytes not faulted in, like copy_to_user() and
+ * copy_from_user().
+ */
+size_t fault_in_safe_writeable(const char __user *uaddr, size_t size)
+{
+ unsigned long start = (unsigned long)untagged_addr(uaddr);
+ unsigned long end, nstart, nend;
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma = NULL;
+ int locked = 0;
+
+ nstart = start & PAGE_MASK;
+ end = PAGE_ALIGN(start + size);
+ if (end < nstart)
+ end = 0;
+ for (; nstart != end; nstart = nend) {
+ unsigned long nr_pages;
+ long ret;
+
+ if (!locked) {
+ locked = 1;
+ mmap_read_lock(mm);
+ vma = find_vma(mm, nstart);
+ } else if (nstart >= vma->vm_end)
+ vma = vma->vm_next;
+ if (!vma || vma->vm_start >= end)
+ break;
+ nend = end ? min(end, vma->vm_end) : vma->vm_end;
+ if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+ continue;
+ if (nstart < vma->vm_start)
+ nstart = vma->vm_start;
+ nr_pages = (nend - nstart) / PAGE_SIZE;
+ ret = __get_user_pages_locked(mm, nstart, nr_pages,
+ NULL, NULL, &locked,
+ FOLL_TOUCH | FOLL_WRITE);
+ if (ret <= 0)
+ break;
+ nend = nstart + ret * PAGE_SIZE;
+ }
+ if (locked)
+ mmap_read_unlock(mm);
+ if (nstart == end)
+ return 0;
+ return size - min_t(size_t, nstart - start, size);
+}
+EXPORT_SYMBOL(fault_in_safe_writeable);
+
+/**
+ * fault_in_readable - fault in userspace address range for reading
+ * @uaddr: start of user address range
+ * @size: size of user address range
+ *
+ * Returns the number of bytes not faulted in (like copy_to_user() and
+ * copy_from_user()).
+ */
+size_t fault_in_readable(const char __user *uaddr, size_t size)
+{
+ const char __user *start = uaddr, *end;
+ volatile char c;
+
+ if (unlikely(size == 0))
+ return 0;
+ if (!user_read_access_begin(uaddr, size))
+ return size;
+ if (!PAGE_ALIGNED(uaddr)) {
+ unsafe_get_user(c, uaddr, out);
+ uaddr = (const char __user *)PAGE_ALIGN((unsigned long)uaddr);
+ }
+ end = (const char __user *)PAGE_ALIGN((unsigned long)start + size);
+ if (unlikely(end < start))
+ end = NULL;
+ while (uaddr != end) {
+ unsafe_get_user(c, uaddr, out);
+ uaddr += PAGE_SIZE;
+ }
+
+out:
+ user_read_access_end();
+ (void)c;
+ if (size > uaddr - start)
+ return size - (uaddr - start);
+ return 0;
+}
+EXPORT_SYMBOL(fault_in_readable);
+
/**
* get_dump_page() - pin user page in memory while writing it to core dump
* @addr: user address
{
int nr_start = *nr;
struct dev_pagemap *pgmap = NULL;
- int ret = 1;
do {
struct page *page = pfn_to_page(pfn);
pgmap = get_dev_pagemap(pfn, pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
- ret = 0;
break;
}
SetPageReferenced(page);
pages[*nr] = page;
if (unlikely(!try_grab_page(page, flags))) {
undo_dev_pagemap(nr, nr_start, flags, pages);
- ret = 0;
break;
}
(*nr)++;
} while (addr += PAGE_SIZE, addr != end);
put_dev_pagemap(pgmap);
- return ret;
+ return addr == end;
}
static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
FOLL_FORCE | FOLL_PIN | FOLL_GET |
- FOLL_FAST_ONLY)))
+ FOLL_FAST_ONLY | FOLL_NOFAULT)))
return -EINVAL;
if (gup_flags & FOLL_PIN)
projects / linux-2.6-microblaze.git / blobdiff