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Subject[074/121] m68k: Truncate base in do_div()
3.2.51-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andreas Schwab <schwab@linux-m68k.org>

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
--- 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; \
})


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