Received-SPF: pass (google.com: domain of linux-kernel+bounces-163171-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Precedence: bulk
MIME-Version: 1.0
References: <0000000000009dfa6d0617197994@google.com> <20240427231321.3978-1-hdanton@sina.com>
 <CAHk-=wjBvNvVggy14p9rkHA8W1ZVfoKXvW0oeX5NZWxWUv8gfQ@mail.gmail.com>
 <20240428232302.4035-1-hdanton@sina.com> <CAHk-=wjma_sSghVTgDCQxHHd=e2Lqi45PLh78oJ4WeBj8erV9Q@mail.gmail.com>
 <CAHk-=wh9D6f7HUkDgZHKmDCHUQmp+Co89GP+b8+z+G56BKeyNg@mail.gmail.com>
 <Zi9Ts1HcqiKzy9GX@gmail.com> <CAHk-=wj9=+4k+sY6hNsQy2oQA4HABNA369cBPSgBNaeRHbbTZg@mail.gmail.com>
 <CAHk-=wg63NPb-cEL7NTFTKN2=uM6Lygg_CcXwwDBTVCg=PeSRg@mail.gmail.com>
 <CAHk-=whuH+-swynMTVd9=uCB0uuhaoanQ5kfHEX=QaRZx7UgBw@mail.gmail.com> <CALCETrXHJ7837+cmahg-wjR3iRHbDJ6JtVGaoDFC4dx-L8r8OA@mail.gmail.com>
In-Reply-To: <CALCETrXHJ7837+cmahg-wjR3iRHbDJ6JtVGaoDFC4dx-L8r8OA@mail.gmail.com>
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 29 Apr 2024 17:05:38 -0700
Message-ID: <CAHk-=wiW=HyBNE2sx+rVyB2q+Xuuah+Ycp4o89+prgHUFHm_hQ@mail.gmail.com>
Subject: Re: [PATCH] x86/mm: Remove broken vsyscall emulation code from the
 page fault code
To: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>, Hillf Danton <hdanton@sina.com>, Peter Anvin <hpa@zytor.com>, 
	Adrian Bunk <bunk@kernel.org>, 
	syzbot <syzbot+83e7f982ca045ab4405c@syzkaller.appspotmail.com>, 
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, andrii@kernel.org, bpf@vger.kernel.org, 
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Content-Type: text/plain; charset="UTF-8"

On Mon, 29 Apr 2024 at 16:30, Andy Lutomirski <luto@amacapital.net> wrote:
>
> What strange page table handling do we do for XONLY?

Ahh, I misread set_vsyscall_pgtable_user_bits(). It's used for EMULATE
not for XONLY.

And the code in pti_setup_vsyscall() is just wrong, and does it for all cases.

> So I think we should remove EMULATE before removing XONLY.

Ok, looking at that again, I don't disagree. I misread that XONLY as
mapping it executable, but it is actually just mapping it readable

Yes, let's remove EMULATE, and keep XONLY.

           Linus