• Johannes Berg's avatar
    Revert "um: Enable CONFIG_CONSTRUCTORS" · 87c9366e
    Johannes Berg authored
    This reverts commit 786b2384 ("um: Enable CONFIG_CONSTRUCTORS").
    
    There are two issues with this commit, uncovered by Anton in tests
    on some (Debian) systems:
    
    1) I completely forgot to call any constructors if CONFIG_CONSTRUCTORS
       isn't set. Don't recall now if it just wasn't needed on my system, or
       if I never tested this case.
    
    2) With that fixed, it works - with CONFIG_CONSTRUCTORS *unset*. If I
       set CONFIG_CONSTRUCTORS, it fails again, which isn't totally
       unexpected since whatever wanted to run is likely to have to run
       before the kernel init etc. that calls the constructors in this case.
    
    Basically, some constructors that gcc emits (libc has?) need to run
    very early during init; the failure mode otherwise was that the ptrace
    fork test already failed:
    
    ----------------------
    $ ./linux mem=512M
    Core dump limits :
    	soft - 0
    	hard - NONE
    Checking that ptrace can change system call numbers...check_ptrace : child exited with exitcode 6, while expecting 0; status 0x67f
    Aborted
    ----------------------
    
    Thinking more about this, it's clear that we simply cannot support
    CONFIG_CONSTRUCTORS in UML. All the cases we need now (gcov, kasan)
    involve not use of the __attribute__((constructor)), but instead
    some constructor code/entry generated by gcc. Therefore, we cannot
    distinguish between kernel constructors and system constructors.
    
    Thus, revert this commit.
    
    Cc: stable@vger.kernel.org [5.4+]
    Fixes: 786b2384 ("um: Enable CONFIG_CONSTRUCTORS")
    Reported-by: default avatarAnton Ivanov <anton.ivanov@cambridgegreys.com>
    Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
    Acked-by: default avatarAnton Ivanov <anton.ivanov@cambridgegreys.co.uk>
    Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
    87c9366e
Kconfig 2.03 KB