mm: consolidate the get_user_pages* implementations
Always build mm/gup.c so that we don't have to provide separate nommu
stubs. Also merge the get_user_pages_fast and __get_user_pages_fast stubs
when HAVE_FAST_GUP into the main implementations, which will never call
the fast path if HAVE_FAST_GUP is not set.
This also ensures the new put_user_pages* helpers are available for nommu,
as those are currently missing, which would create a problem as soon as we
actually grew users for it.
Link: http://lkml.kernel.org/r/20190625143715.1689-13-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/gup.c b/mm/gup.c
index d36b82c..cc5ddd8 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
}
EXPORT_SYMBOL(put_user_pages);
+#ifdef CONFIG_MMU
static struct page *no_page_table(struct vm_area_struct *vma,
unsigned int flags)
{
@@ -1322,6 +1323,51 @@ struct page *get_dump_page(unsigned long addr)
return page;
}
#endif /* CONFIG_ELF_CORE */
+#else /* CONFIG_MMU */
+static long __get_user_pages_locked(struct task_struct *tsk,
+ struct mm_struct *mm, unsigned long start,
+ unsigned long nr_pages, struct page **pages,
+ struct vm_area_struct **vmas, int *locked,
+ unsigned int foll_flags)
+{
+ struct vm_area_struct *vma;
+ unsigned long vm_flags;
+ int i;
+
+ /* calculate required read or write permissions.
+ * If FOLL_FORCE is set, we only require the "MAY" flags.
+ */
+ vm_flags = (foll_flags & FOLL_WRITE) ?
+ (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+ vm_flags &= (foll_flags & FOLL_FORCE) ?
+ (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
+
+ for (i = 0; i < nr_pages; i++) {
+ vma = find_vma(mm, start);
+ if (!vma)
+ goto finish_or_fault;
+
+ /* protect what we can, including chardevs */
+ if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
+ !(vm_flags & vma->vm_flags))
+ goto finish_or_fault;
+
+ if (pages) {
+ pages[i] = virt_to_page(start);
+ if (pages[i])
+ get_page(pages[i]);
+ }
+ if (vmas)
+ vmas[i] = vma;
+ start = (start + PAGE_SIZE) & PAGE_MASK;
+ }
+
+ return i;
+
+finish_or_fault:
+ return i ? : -EFAULT;
+}
+#endif /* !CONFIG_MMU */
#if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
@@ -1484,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
{
return nr_pages;
}
-#endif
+#endif /* CONFIG_CMA */
/*
* __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
@@ -2160,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
return;
} while (pgdp++, addr = next, addr != end);
}
+#else
+static inline void gup_pgd_range(unsigned long addr, unsigned long end,
+ unsigned int flags, struct page **pages, int *nr)
+{
+}
+#endif /* CONFIG_HAVE_FAST_GUP */
#ifndef gup_fast_permitted
/*
@@ -2177,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
* the regular GUP.
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
+ *
+ * If the architecture does not support this function, simply return with no
+ * pages pinned.
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
@@ -2206,7 +2261,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
* block IPIs that come from THPs splitting.
*/
- if (gup_fast_permitted(start, end)) {
+ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
+ gup_fast_permitted(start, end)) {
local_irq_save(flags);
gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
local_irq_restore(flags);
@@ -2214,6 +2270,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
return nr;
}
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
@@ -2270,7 +2327,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
if (unlikely(!access_ok((void __user *)start, len)))
return -EFAULT;
- if (gup_fast_permitted(start, end)) {
+ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
+ gup_fast_permitted(start, end)) {
local_irq_disable();
gup_pgd_range(addr, end, gup_flags, pages, &nr);
local_irq_enable();
@@ -2296,5 +2354,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
return ret;
}
-
-#endif /* CONFIG_HAVE_GENERIC_GUP */
+EXPORT_SYMBOL_GPL(get_user_pages_fast);