Messages in this thread | | | From | Andy Lutomirski <> | Date | Tue, 1 Sep 2015 17:51:44 -0700 | Subject | RFC: adding Linux vsyscall-disable and similar backwards-incompatibility flags to ELF headers? |
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Hi all-
Linux has a handful of weird features that are only supported for backwards compatibility. The big one is the x86_64 vsyscall page, but uselib probably belongs on the list, too, and we might end up with more at some point.
I'd like to add a way that new programs can turn these features off. In particular, I want the vsyscall page to be completely gone from the perspective of any new enough program. This is straightforward if we add a system call to ask for the vsyscall page to be disabled, but I'm wondering if we can come up with a non-syscall way to do it.
I think that the ideal behavior would be that anything linked against a sufficiently new libc would be detected, but I don't see a good way to do that using existing toolchain features.
Ideas? We could add a new phdr for this, but then we'd need to play linker script games, and I'm not sure that could be done in a clean, extensible way.
--Andy
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