m68k: Truncate base in do_div()

commit ea077b1b96e073eac5c3c5590529e964767fc5f7 upstream.

Explicitly truncate the second operand of do_div() to 32 bits to guard
against bogus code calling it with a 64-bit divisor.

[Thorsten]

After upgrading from 3.2 to 3.10, mounting a btrfs volume fails with:

btrfs: setting nodatacow, compression disabled
btrfs: enabling auto recovery
btrfs: disk space caching is enabled

diff --git a/arch/m68k/include/asm/div64.h b/arch/m68k/include/asm/div64.h
index edb6614..7558032 100644 (file)
--- a/arch/m68k/include/asm/div64.h
+++ b/arch/m68k/include/asm/div64.h
@@ -13,16 +13,17 @@
                unsigned long long n64;                         \
        } __n;                                                  \
        unsigned long __rem, __upper;                           \
+       unsigned long __base = (base);                          \
                                                                \
        __n.n64 = (n);                                          \
        if ((__upper = __n.n32[0])) {                           \
                asm ("divul.l %2,%1:%0"                         \
-                       : "=d" (__n.n32[0]), "=d" (__upper)     \
-                       : "d" (base), "0" (__n.n32[0]));        \
+                    : "=d" (__n.n32[0]), "=d" (__upper)        \
+                    : "d" (__base), "0" (__n.n32[0]));         \
        }                                                       \
        asm ("divu.l %2,%1:%0"                                  \
-               : "=d" (__n.n32[1]), "=d" (__rem)               \
-               : "d" (base), "1" (__upper), "0" (__n.n32[1])); \
+            : "=d" (__n.n32[1]), "=d" (__rem)                  \
+            : "d" (__base), "1" (__upper), "0" (__n.n32[1]));  \
        (n) = __n.n64;                                          \
        __rem;                                                  \
 })