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Date:   Tue, 15 Sep 2020 17:55:46 +0200
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org,
        Thadeu Lima de Souza Cascardo <cascardo@canonical.com>,
        Max Filippov <jcmvbkbc@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Christian Brauner <christian@brauner.io>,
        Andy Lutomirski <luto@amacapital.net>,
        Will Drewry <wad@chromium.org>,
        linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org,
        linux-xtensa@linux-xtensa.org,
        linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 03/15] selftests/seccomp: mips: Define SYSCALL_NUM_SET
 macro
Message-ID: <20200915155546.ht4vo7nqswxrgymb@wittgenstein>
References: <20200912110820.597135-1-keescook@chromium.org>
 <20200912110820.597135-4-keescook@chromium.org>
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On Sat, Sep 12, 2020 at 04:08:08AM -0700, Kees Cook wrote:
> Remove the mips special-case in change_syscall().
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  tools/testing/selftests/seccomp/seccomp_bpf.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index 1c83e743bfb1..02a9a6599746 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -1742,6 +1742,13 @@ TEST_F(TRACE_poke, getpid_runs_normally)
>  # define ARCH_REGS		struct pt_regs
>  # define SYSCALL_NUM(_regs)	(_regs).regs[2]
>  # define SYSCALL_SYSCALL_NUM	regs[4]
> +# define SYSCALL_NUM_SET(_regs, _nr)			\
> +	do {						\
> +		if ((_regs).regs[2] == __NR_O32_Linux)	\
> +			(_regs).regs[4] = _nr;		\
> +		else					\
> +			(_regs).regs[2] = _nr;		\
> +	} while (0)

I think that

# define SYSCALL_NUM_SET(_regs, _nr)				\
	do {							\
		if (SYSCALL_NUM(_regs) == __NR_O32_Linux)	\
			(_regs).regs[4] = _nr;			\
		else						\
			(_regs).regs[2] = _nr;			\
	} while (0)

would read better but that's just a matter of taste. :)

Looks good!
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>