On Mon, Feb 05, 2024 at 04:48:43PM +0100, Heiko Carstens wrote: > With INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO enabled the kernel will > be compiled with -ftrivial-auto-var-init=<...> which causes initialization > of stack variables at function entry time. > > In order to avoid the performance impact that comes with this users can use > the "uninitialized" attribute to prevent such initialization. > > Therefore provide the __uninitialized macro which can be used for cases > where INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO is enabled, but only > selected variables should not be initialized. > > Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx> Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> > --- > include/linux/compiler_attributes.h | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h > index 28566624f008..f5859b8c68b4 100644 > --- a/include/linux/compiler_attributes.h > +++ b/include/linux/compiler_attributes.h > @@ -333,6 +333,18 @@ > */ > #define __section(section) __attribute__((__section__(section))) > > +/* > + * Optional: only supported since gcc >= 12 > + * > + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-uninitialized-variable-attribute > + * clang: https://clang.llvm.org/docs/AttributeReference.html#uninitialized > + */ > +#if __has_attribute(__uninitialized__) > +# define __uninitialized __attribute__((__uninitialized__)) > +#else > +# define __uninitialized > +#endif > + > /* > * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute > * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute > -- > 2.40.1 >
