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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2022-10-17 02:36:32 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2022-10-17 02:36:32 -0700
commitc29a017f9df34d190fbc7917d30dbefce7d9dc1f (patch)
tree98919b99c7aba0404c4fdbbf953dc72084509c06 /include/linux/overflow.h
parentd4a596eddb90114f5f5f32a440057a175517b090 (diff)
parent9abf2313adc1ca1b6180c508c25f22f9395cc780 (diff)
Merge tag 'v6.1-rc1' into next
Merge with mainline to bring in the latest changes to twl4030 driver.
Diffstat (limited to 'include/linux/overflow.h')
-rw-r--r--include/linux/overflow.h73
1 files changed, 41 insertions, 32 deletions
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index f1221d11f8e5..19dfdd74835e 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -30,7 +30,6 @@
* https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html -
* credit to Christian Biere.
*/
-#define is_signed_type(type) (((type)(-1)) < (type)1)
#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
#define type_min(T) ((T)((T)-type_max(T)-(T)1))
@@ -52,40 +51,50 @@ static inline bool __must_check __must_check_overflow(bool overflow)
return unlikely(overflow);
}
-/*
- * For simplicity and code hygiene, the fallback code below insists on
- * a, b and *d having the same type (similar to the min() and max()
- * macros), whereas gcc's type-generic overflow checkers accept
- * different types. Hence we don't just make check_add_overflow an
- * alias for __builtin_add_overflow, but add type checks similar to
- * below.
+/** check_add_overflow() - Calculate addition with overflow checking
+ *
+ * @a: first addend
+ * @b: second addend
+ * @d: pointer to store sum
+ *
+ * Returns 0 on success.
+ *
+ * *@d holds the results of the attempted addition, but is not considered
+ * "safe for use" on a non-zero return value, which indicates that the
+ * sum has overflowed or been truncated.
*/
-#define check_add_overflow(a, b, d) __must_check_overflow(({ \
- typeof(a) __a = (a); \
- typeof(b) __b = (b); \
- typeof(d) __d = (d); \
- (void) (&__a == &__b); \
- (void) (&__a == __d); \
- __builtin_add_overflow(__a, __b, __d); \
-}))
+#define check_add_overflow(a, b, d) \
+ __must_check_overflow(__builtin_add_overflow(a, b, d))
-#define check_sub_overflow(a, b, d) __must_check_overflow(({ \
- typeof(a) __a = (a); \
- typeof(b) __b = (b); \
- typeof(d) __d = (d); \
- (void) (&__a == &__b); \
- (void) (&__a == __d); \
- __builtin_sub_overflow(__a, __b, __d); \
-}))
+/** check_sub_overflow() - Calculate subtraction with overflow checking
+ *
+ * @a: minuend; value to subtract from
+ * @b: subtrahend; value to subtract from @a
+ * @d: pointer to store difference
+ *
+ * Returns 0 on success.
+ *
+ * *@d holds the results of the attempted subtraction, but is not considered
+ * "safe for use" on a non-zero return value, which indicates that the
+ * difference has underflowed or been truncated.
+ */
+#define check_sub_overflow(a, b, d) \
+ __must_check_overflow(__builtin_sub_overflow(a, b, d))
-#define check_mul_overflow(a, b, d) __must_check_overflow(({ \
- typeof(a) __a = (a); \
- typeof(b) __b = (b); \
- typeof(d) __d = (d); \
- (void) (&__a == &__b); \
- (void) (&__a == __d); \
- __builtin_mul_overflow(__a, __b, __d); \
-}))
+/** check_mul_overflow() - Calculate multiplication with overflow checking
+ *
+ * @a: first factor
+ * @b: second factor
+ * @d: pointer to store product
+ *
+ * Returns 0 on success.
+ *
+ * *@d holds the results of the attempted multiplication, but is not
+ * considered "safe for use" on a non-zero return value, which indicates
+ * that the product has overflowed or been truncated.
+ */
+#define check_mul_overflow(a, b, d) \
+ __must_check_overflow(__builtin_mul_overflow(a, b, d))
/** check_shl_overflow() - Calculate a left-shifted value and check overflow
*