m68k: Make sys_atomic_cmpxchg_32 work on classic m68k
Andreas Schwab [Fri, 27 Jul 2012 22:20:34 +0000 (00:20 +0200)]
User space access must always go through uaccess accessors, since on
classic m68k user space and kernel space are completely separate.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Tested-by: Thorsten Glaser <tg@debian.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org

arch/m68k/kernel/sys_m68k.c

index 8623f8d..9a5932e 100644 (file)
@@ -479,9 +479,13 @@ sys_atomic_cmpxchg_32(unsigned long newval, int oldval, int d3, int d4, int d5,
                        goto bad_access;
                }
 
-               mem_value = *mem;
+               /*
+                * No need to check for EFAULT; we know that the page is
+                * present and writable.
+                */
+               __get_user(mem_value, mem);
                if (mem_value == oldval)
-                       *mem = newval;
+                       __put_user(newval, mem);
 
                pte_unmap_unlock(pte, ptl);
                up_read(&mm->mmap_sem);