Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function

From: Andy Lutomirski
Date: Fri Jun 07 2019 - 18:31:38 EST

> On Jun 7, 2019, at 2:09 PM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> On 6/7/19 1:06 PM, Yu-cheng Yu wrote:
>>> Huh, how does glibc know about all possible past and future legacy code
>>> in the application?
>> When dlopen() gets a legacy binary and the policy allows that, it will manage
>> the bitmap:
>> If a bitmap has not been created, create one.
>> Set bits for the legacy code being loaded.
> I was thinking about code that doesn't go through GLIBC like JITs.

CRIU is another consideration: it would be rather annoying if CET programs canât migrate between LA57 and normal machines.