[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <de08c24f-782d-69e5-6547-6efe0c4ca94a@intel.com>
Date: Wed, 11 Jan 2023 18:49:39 -0800
From: Sohil Mehta <sohil.mehta@...el.com>
To: "Chen, Yian" <yian.chen@...el.com>, <linux-kernel@...r.kernel.org>,
<x86@...nel.org>, Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ravi Shankar <ravi.v.shankar@...el.com>,
"Tony Luck" <tony.luck@...el.com>, Paul Lai <paul.c.lai@...el.com>
Subject: Re: [PATCH 4/7] x86/vsyscall: Setup vsyscall to compromise LASS
protection
>> The existing documentation here is incorrect. The default vsyscall
>> mode is actually xonly. This has been so since:
>> commit 625b7b7f79c6 (x86/vsyscall: Change the default vsyscall mode to
>> xonly)
>>
> Yes, you are right. but this patch can overwrite and correct existing
> one. I am assuming we don't need to correct the existing document first
> before update it for LASS.
>
We should fix this independent of the LASS enabling. I sent a patch
earlier today to address it. I apologize, I missed cc'ing you.
https://lore.kernel.org/lkml/20230111193211.1987047-1-sohil.mehta@intel.com/
>>> + In newer versions of Intel platforms that come with
>>
>> Words such as "newer" in the kernel start losing meaning very quickly.
>> Also, this comment looks out of place in between the vsyscall
>> sub-options.
>>
>>> + LASS(Linear Address Space separation) protection,
>>> + vsyscall is disabled by default. Enabling vsyscall
>>> + via the parameter overrides LASS protection.
>>> +
> Sure, I will take out this part change.
Actually, having some text here might be ok. I mistook it to be placed
between the sub-options. But avoid merging it with the previous
paragraph as is the case right now.
>> Instead of doing this dance, can we provide a simplified behavior to
>> the user/admin and move the decision making to compile time?
>>
> Current strategy is to disable vsyscall by default only for LASS capable
> platforms. So that the dynamic decision is likely a necessary.
>
Making this dynamic and platform dependent would make things hard to
debug and isolate. It would be a perfect recipe for "But, it works on my
system!" type of issues.
Let's see what others have to say.
-Sohil
Powered by blists - more mailing lists