Re: [PATCH 2/2] selftests/seccomp: add sparc64 support

[Kees Cook <kees@kernel.org>]

On Wed, Sep 02, 2026 at 12:08:11AM +0200, Stian Halseth wrote:
> sparc64 now selects HAVE_ARCH_SECCOMP_FILTER, so teach seccomp_bpf
> how to read and write its registers: the syscall number lives in %g1
> and the return value in %o0, addressed through the NT_PRSTATUS regset
> (16 u_regs, 16 window registers, then tstate/tpc/tnpc/y).
> 
> Errors are signaled by the carry bit in tstate with a positive errno
> value in %o0, so provide a SYSCALL_RET_SET that maintains both, and
> mark the arch SYSCALL_RET_SET_ON_PTRACE_EXIT since a return value
> poked at entry would be overwritten by the syscall skip path, as on
> powerpc.
> 
> Passes 95 of 95 on an UltraSPARC T4-1 (16 skipped for missing
> optional features such as uprobes).

Thanks for getting the working on sparc! :)

> 
> Link: https://github.com/sparclinux/issues/issues/11
> Signed-off-by: Stian Halseth <stian@itx.no>
> ---
>  tools/testing/selftests/seccomp/seccomp_bpf.c | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index 0622bc2acad4..30b777f357d8 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -1872,6 +1872,41 @@ TEST_F(TRACE_poke, getpid_runs_normally)
>  # define ARCH_REGS		struct user_regs_struct
>  # define SYSCALL_NUM(_regs)	(_regs).orig_d0
>  # define SYSCALL_RET(_regs)	(_regs).d0
> +#elif defined(__sparc__) && defined(__arch64__)
> +/*
> + * The NT_PRSTATUS regset: %g0-%g7 and %o0-%o7, the 16 window
> + * registers as read back from the stack, then tstate, tpc, tnpc
> + * and y.
> + */
> +struct sparc64_user_regs {
> +	__u64 u_regs[16];
> +	__u64 window[16];
> +	__u64 tstate;
> +	__u64 tpc;
> +	__u64 tnpc;
> +	__u64 y;
> +};
> +# define ARCH_REGS		struct sparc64_user_regs

Is struct sparc64_user_regs not exported to userspace anywhere? We
haven't normally needed to put the raw user_regs struct definition into
the test before.

But beyond that question, looks good!

-Kees

-- 
Kees Cook