1 files changed, 44 insertions, 0 deletions

diff --git a/mm/util.c b/mm/util.c
index 7c35ad95f927..b377ce430803 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -4,6 +4,10 @@
 #include <linux/module.h>
 #include <linux/err.h>
 #include <linux/sched.h>
+#include <linux/hugetlb.h>
+#include <linux/syscalls.h>
+#include <linux/mman.h>
+#include <linux/file.h>
 #include <asm/uaccess.h>
 
 #define CREATE_TRACE_POINTS
@@ -268,6 +272,46 @@ int __attribute__((weak)) get_user_pages_fast(unsigned long start,
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
 
+SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
+                unsigned long, prot, unsigned long, flags,
+                unsigned long, fd, unsigned long, pgoff)
+{
+        struct file * file = NULL;
+        unsigned long retval = -EBADF;
+
+        if (!(flags & MAP_ANONYMOUS)) {
+                if (unlikely(flags & MAP_HUGETLB))
+                        return -EINVAL;
+                file = fget(fd);
+                if (!file)
+                        goto out;
+        } else if (flags & MAP_HUGETLB) {
+                struct user_struct *user = NULL;
+                /*
+                 * VM_NORESERVE is used because the reservations will be
+                 * taken when vm_ops->mmap() is called
+                 * A dummy user value is used because we are not locking
+                 * memory so no accounting is necessary
+                 */
+                len = ALIGN(len, huge_page_size(&default_hstate));
+                file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
+                                                &user, HUGETLB_ANONHUGE_INODE);
+                if (IS_ERR(file))
+                        return PTR_ERR(file);
+        }
+
+        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
+
+        down_write(&current->mm->mmap_sem);
+        retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
+        up_write(&current->mm->mmap_sem);
+
+        if (file)
+                fput(file);
+out:
+        return retval;
+}
+
 /* Tracepoints definitions. */
 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);