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Re: long double redirects and dynamic loader behavior
- From: Carlos O'Donell <carlos at redhat dot com>
- To: Paul E Murphy <murphyp at linux dot ibm dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Cc: Tulio Magno Quites Machado Filho <tuliom at linux dot ibm dot com>
- Date: Tue, 25 Feb 2020 21:15:21 -0500
- Subject: Re: long double redirects and dynamic loader behavior
- References: <4602467a-2114-34d5-4f99-bf5ac4ef3d6d@linux.ibm.com>
On 2/24/20 3:10 PM, Paul E Murphy wrote:
> Tulio mentioned that he and Carlos discussed this topic during
> Cauldron last year.
>
> As far as I understand it, dlopen becomes problematic when loading
> code compiled against an unknown long double ABI. My understanding
> is the gnu-attribute exists to help catch those cases at link time.
Correct GNU Object attributes can be used for link time.
> I am unsure how, or if it does anything to assist dynamically loaded
> libraries.
There is. We use it for Intel CET. It is the Note GNU Property section.
Static link time --- GNU Object attributes.
Dyanmic link time --- Note GNU Properties.
> dlsym is more tricky. The redirects obfuscate the naming of many
> common symbols. I.e dlsym(...,"printf") might give you something
> which almost works, but is broken.
If dlopen denies you the ability to load an ABI-incompatible library
then we should be OK?
> What is the current thinking regarding the behavior of these features
> when redirects are used?
--
Cheers,
Carlos.