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Date:   Mon, 10 Dec 2018 15:11:07 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     "Dmitry V. Levin" <ldv@altlinux.org>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Elvira Khabirova <lineprinter@altlinux.org>,
        Eugene Syromyatnikov <esyr@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Jann Horn <jannh@google.com>, linux-api@vger.kernel.org,
        strace-devel@lists.strace.io, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 24/25] ptrace: add PTRACE_GET_SYSCALL_INFO request
Message-ID: <20181210141107.GB4177@redhat.com>
References: <20181210042352.GA6092@altlinux.org>
 <20181210043126.GX6131@altlinux.org>
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On 12/10, Dmitry V. Levin wrote:
>
> +struct ptrace_syscall_info {
> +	__u8 op;	/* PTRACE_SYSCALL_INFO_* */
> +	__u8 __pad0[3];
> +	__u32 arch;
> +	__u64 instruction_pointer;
> +	__u64 stack_pointer;
> +	__u64 frame_pointer;
> +	union {
> +		struct {
> +			__u64 nr;
> +			__u64 args[6];
> +		} entry;
> +		struct {
> +			__s64 rval;
> +			__u8 is_error;
> +			__u8 __pad1[7];
> +		} exit;
> +		struct {
> +			__u64 nr;
> +			__u64 args[6];
> +			__u32 ret_data;
> +			__u8 __pad2[4];
> +		} seccomp;
> +	};
> +};

Could you explain why ptrace_syscall_info needs __pad{0,1,2} ? I simply can't
understand why...

Otherwise the patch looks good to me. I am not going to discuss the API and
data layout, I am fine with anything which suits user-space needs.

I think the patch is technically correct, feel free to add

Reviewed-by: Oleg Nesterov <oleg@redhat.com>