Re: [PATCH v15 1/7] kcfi: Introduce KCFI typeinfo mangling API

[Kees Cook <kees@kernel.org>]

On Wed, Sep 23, 2026 at 11:25:07AM +0200, Juergen Christ wrote:
> thanks for your work on this.  I will implement the s390x specific
> part once this series is accepted.

Great; thank you!

> I looked at this on s390x.  We actually change the mangling of long
> double if we are on a target where long double is 128bit IEEE to a
> "g".  This causes this self-test to fail.  I suggest to add this patch
> on top of our patch to fix this:
> 
> diff --git a/gcc/kcfi-typeinfo.cc b/gcc/kcfi-typeinfo.cc
> index b6723fac48da..fab06249ae16 100644
> --- a/gcc/kcfi-typeinfo.cc
> +++ b/gcc/kcfi-typeinfo.cc
> @@ -659,7 +659,14 @@ test_typeinfo_basic_types ()
>    ASSERT_STREQ ("y", kcfi_test_mangle (long_long_unsigned_type_node).c_str ());
>    ASSERT_STREQ ("f", kcfi_test_mangle (float_type_node).c_str ());
>    ASSERT_STREQ ("d", kcfi_test_mangle (double_type_node).c_str ());
> +#if defined (__s390x__)
> +  if (TARGET_LONG_DOUBLE_128)
> +    ASSERT_STREQ ("g", kcfi_test_mangle (long_double_type_node).c_str ());
> +  else
> +    ASSERT_STREQ ("e", kcfi_test_mangle (long_double_type_node).c_str ());
> +#else
>    ASSERT_STREQ ("e", kcfi_test_mangle (long_double_type_node).c_str ());
> +#endif
>  }
>  
>  /* Test mangling of pointer types.  */

So this portion is only needed once there is s390 support? I'm unclear
on patch ordering.

-Kees

-- 
Kees Cook