From 9e2760d18b3cf179534bbc27692c84879c61b97c Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@linux-m68k.org>
Date: Sat, 28 Jul 2012 00:20:34 +0200
Subject: m68k: Make sys_atomic_cmpxchg_32 work on classic m68k

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

diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 8623f8d..9a5932e 100644
--- a/arch/m68k/kernel/sys_m68k.c
+++ b/arch/m68k/kernel/sys_m68k.c
@@ -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);
-- 
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