[PATCH] asm-generic: Check divisor size in do_div()

[Geert Uytterhoeven]

The second parameter of do_div() should be a 32-bit number.
Enforce this using BUILD_BUG_ON().

The first parameter of do_div() should be a 64-bit number,
enforce this on 64-bit architectures, just like is done on 32-bit
architectures.

Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
 include/asm-generic/div64.h |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/asm-generic/div64.h b/include/asm-generic/div64.h
index 8f4e319..69c0307 100644
--- a/include/asm-generic/div64.h
+++ b/include/asm-generic/div64.h
@@ -19,12 +19,15 @@
 
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <linux/bug.h>
 
 #if BITS_PER_LONG == 64
 
 # define do_div(n,base) ({					\
 	uint32_t __base = (base);				\
 	uint32_t __rem;						\
+	(void)(((typeof((n)) *)0) == ((uint64_t *)0));		\
+	BUILD_BUG_ON(sizeof(base) != 4);			\
 	__rem = ((uint64_t)(n)) % __base;			\
 	(n) = ((uint64_t)(n)) / __base;				\
 	__rem;							\
@@ -41,6 +44,7 @@ extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
 	uint32_t __base = (base);			\
 	uint32_t __rem;					\
 	(void)(((typeof((n)) *)0) == ((uint64_t *)0));	\
+	BUILD_BUG_ON(sizeof(base) != 4);		\
 	if (likely(((n) >> 32) == 0)) {			\
 		__rem = (uint32_t)(n) % __base;		\
 		(n) = (uint32_t)(n) / __base;		\
-- 
1.7.9.5

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/