Re: [PATCH] Fix remaining return type of ifunc resolver declaration

[Martin Sebor <msebor@gmail.com>]

On 08/22/2017 12:02 PM, Gabriel F. T. Gomes wrote:
> Since Martin Sebor's commit
>
> commit ee4e992ebe5f9712faedeefe8958b67d61eaa0f2
> Author: Martin Sebor <msebor@redhat.com>
> Date:   Tue Aug 22 09:35:23 2017 -0600
>
>     Declare ifunc resolver to return a pointer to the same type as the target
>     function to help GCC detect incompatibilities between the two when it's
>     enhanced to do so.
>
> builds for powerpc64le fail in the declaration of some ifunc resolvers,
> because the ifunc is declared with unmatching return types.  One of the
> declarations comes from the __ifunc_resolver macro, which was patched by
> the aforementioned commit:
>
>     /* Helper / base  macros for indirect function symbols.  */
>     #define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
>       classifier inhibit_stack_protector                                   \
>       __typeof (type_name) *name##_ifunc (arg)                             \
>
> whereas the other comes from the unpatched __ifunc macro when
> HAVE_GCC_IFUNC is not defined:
>
>     # define __ifunc(type_name, name, expr, arg, init)                     \
>       extern __typeof (type_name) name;                                    \
>       void *name##_ifunc (arg) __asm__ (#name);                            \
>
> This patch changes the return type of the ifunc resolver in the __ifunc
> macro, so that it matches the return type of the target function,
> similarly to what the aforementioned commit does.

Sorry about that and thanks for patching it up.  I didn't think
to check all the other __ifunc macros in the file for their uses
of __ifunc_resolver.

Martin

>
> Tested for powerpc64le and s390x with unpatched GCC.
> ---
>  include/libc-symbols.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/libc-symbols.h b/include/libc-symbols.h
> index 42fc41a1a5..65738caaa7 100644
> --- a/include/libc-symbols.h
> +++ b/include/libc-symbols.h
> @@ -831,7 +831,7 @@ for linking")
>
>  # define __ifunc(type_name, name, expr, arg, init)			\
>    extern __typeof (type_name) name;					\
> -  void *name##_ifunc (arg) __asm__ (#name);				\
> +  extern __typeof (type_name) *name##_ifunc (arg) __asm__ (#name);	\
>    __ifunc_resolver (type_name, name, expr, arg, init,)			\
>   __asm__ (".type " #name ", %gnu_indirect_function");
>
>