mm-replace-remap_file_pages-syscall-with-emulation-fix

[karo-tx-linux.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index d3decd9cec8c04534242db830310a9b70e233135..2b957975a0a0f464e56a65bdcba00bb608030176 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2587,6 +2587,72 @@ SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
        return vm_munmap(addr, len);
 }
 
+
+/*
+ * Emulation of deprecated remap_file_pages() syscall.
+ */
+SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
+               unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
+{
+
+       struct mm_struct *mm = current->mm;
+       struct vm_area_struct *vma;
+       unsigned long populate;
+       unsigned long ret = -EINVAL;
+
+       pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
+                       "See Documentation/vm/remap_file_pages.txt.\n",
+                       current->comm, current->pid);
+
+       if (prot)
+               return ret;
+       start = start & PAGE_MASK;
+       size = size & PAGE_MASK;
+
+       if (start + size <= start)
+               return ret;
+
+       /* Does pgoff wrap? */
+       if (pgoff + (size >> PAGE_SHIFT) < pgoff)
+               return ret;
+
+       down_write(&mm->mmap_sem);
+       vma = find_vma(mm, start);
+
+       if (!vma || !(vma->vm_flags & VM_SHARED))
+               goto out;
+
+       if (start < vma->vm_start || start + size > vma->vm_end)
+               goto out;
+
+       if (pgoff == linear_page_index(vma, start)) {
+               ret = 0;
+               goto out;
+       }
+
+       prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
+       prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
+       prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
+
+       flags &= MAP_NONBLOCK;
+       flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
+       if (vma->vm_flags & VM_LOCKED) {
+               flags |= MAP_LOCKED;
+               /* drop PG_Mlocked flag for over-mapped range */
+               munlock_vma_pages_range(vma, start, start + size);
+       }
+
+       ret = do_mmap_pgoff(vma->vm_file, start, size,
+                       prot, flags, pgoff, &populate);
+out:
+       up_write(&mm->mmap_sem);
+       if (populate)
+               mm_populate(ret, populate);
+       if (!IS_ERR_VALUE(ret))
+               ret = 0;
+       return ret;
+}
+
 static inline void verify_mm_writelocked(struct mm_struct *mm)
 {
 #ifdef CONFIG_DEBUG_VM