Re: [PATCH] selftests/user_events: cast pointers through uintptr_t

[David Laight]

On Tue,  3 Nov 2026 11:39:13 -0500
Sasha Levin <sashal@xxxxxxxxxx> wrote:

> From: Sasha Levin <sashal@xxxxxxxxxx>
> To: Steven Rostedt <rostedt@xxxxxxxxxxx>,  Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx>,  linux-trace-kernel@xxxxxxxxxxxxxxx,  Shuah Khan <shuah@xxxxxxxxxx>,  linux-kselftest@xxxxxxxxxxxxxxx,  linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH] selftests/user_events: cast pointers through uintptr_t
> Date: Tue,  3 Nov 2026 11:39:13 -0500
> 
> The tests put pointers into the 64-bit fields of struct user_reg and
> struct user_unreg with a plain (__u64) cast, which warns on 32-bit
> architectures:
> 
>   abi_test.c:182:25: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> 
> Cast through uintptr_t.
> 
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> Found with 32-bit builds of the selftests (gcc 16 and clang 21 with
> -m32, with and without -D_TIME_BITS=64 -D_FILE_OFFSET_BITS=64);
> KernelCI's 32-bit arm builds show the same warnings. The changed files
> build without them now, and the x86_64 builds don't change.
> 
>  .../testing/selftests/user_events/abi_test.c  | 10 +++---
>  .../testing/selftests/user_events/dyn_test.c  |  6 ++--
>  .../selftests/user_events/ftrace_test.c       | 32 +++++++++----------
>  .../testing/selftests/user_events/perf_test.c | 10 +++---
>  4 files changed, 29 insertions(+), 29 deletions(-)
> 
> diff --git a/tools/testing/selftests/user_events/abi_test.c b/tools/testing/selftests/user_events/abi_test.c
> index b71813eaf5c04..21e1e3cca1979 100644
> --- a/tools/testing/selftests/user_events/abi_test.c
> +++ b/tools/testing/selftests/user_events/abi_test.c
> @@ -179,10 +179,10 @@ static int reg_enable_multi(void *enable, int size, int bit, int flags,
>  	}
>  
>  	reg.size = sizeof(reg);
> -	reg.name_args = (__u64)full_args;
> +	reg.name_args = (__u64)(uintptr_t)full_args;

I'm sure you can't need both casts.

David