From: Kees Cook keescook@chromium.org
[ Upstream commit bd1ebf2467f9c5d157bec7b025e83f8ffdae1318 ]
A common use of type_max() is to find the max for the type of a variable. Using the pattern type_max(typeof(var)) is needlessly verbose. Instead, since typeof(type) == type we can just explicitly call typeof() on the argument to type_max() and type_min(). Add wrappers for readability.
We can do some replacements right away:
$ git grep '\btype_(min|max)(typeof' | wc -l 11
Link: https://lore.kernel.org/r/20240301062221.work.840-kees@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/overflow.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 7b5cf4a5cd191..51af56522915e 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -31,8 +31,10 @@ * credit to Christian Biere. */ #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)) +#define __type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T))) +#define type_max(t) __type_max(typeof(t)) +#define __type_min(T) ((T)((T)-type_max(T)-(T)1)) +#define type_min(t) __type_min(typeof(t))
/* * Avoids triggering -Wtype-limits compilation warning, @@ -130,10 +132,10 @@ static inline bool __must_check __must_check_overflow(bool overflow)
#define __overflows_type_constexpr(x, T) ( \ is_unsigned_type(typeof(x)) ? \ - (x) > type_max(typeof(T)) : \ + (x) > type_max(T) : \ is_unsigned_type(typeof(T)) ? \ - (x) < 0 || (x) > type_max(typeof(T)) : \ - (x) < type_min(typeof(T)) || (x) > type_max(typeof(T))) + (x) < 0 || (x) > type_max(T) : \ + (x) < type_min(T) || (x) > type_max(T))
#define __overflows_type(x, T) ({ \ typeof(T) v = 0; \