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Date:   Mon, 25 Feb 2019 19:57:41 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     David Miller <davem@davemloft.net>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        stable <stable@vger.kernel.org>,
        Changbin Du <changbin.du@gmail.com>,
        Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Andrew Lutomirski <luto@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Netdev <netdev@vger.kernel.org>, bpf@vger.kernel.org
Subject: Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access
 kernel memory that can fault
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On Fri, Feb 22, 2019 at 01:59:10PM -0800, Linus Torvalds wrote:
> On Fri, Feb 22, 2019 at 1:38 PM David Miller <davem@davemloft.net> wrote:
> >
> > Don't be surprised if we see more separation like this in the future too.
> 
> Yes, with the whole meltdown fiasco, there's actually more pressure to
> add more support for separation of kernel/user address spaces. As Andy
> pointed out, it's been discussed as a future wish-list for x86-64 too.

S/390 is another example.

I've also proposed a RISC-V extension for it, including prototypes
for Rocketchip and Qemu, and a Linux kernel support, but it didn't go
any way.