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Message-ID: <5dc357f5858f8036cad5847cfe214401bb9138bf.camel@intel.com>
Subject: Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup
 function
From:   Yu-cheng Yu <yu-cheng.yu@intel.com>
To:     Dave Hansen <dave.hansen@intel.com>,
        Andy Lutomirski <luto@amacapital.net>
Cc:     Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
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        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
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Date:   Mon, 10 Jun 2019 09:05:13 -0700
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On Fri, 2019-06-07 at 14:09 -0700, Dave Hansen 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.

If JIT manages the bitmap, it knows where it is.
It can always read the bitmap again, right?

Yu-cheng