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Date: Wed, 29 Mar 2006 01:46:00 -0000
Message-Id: <20060328.174701.11633966.davem@davemloft.net>
To: libc-hacker@sources.redhat.com
Subject: Re: weird versioning crash...
From: "David S. Miller" <davem@davemloft.net>
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From: "David S. Miller" <davem@davemloft.net>
Date: Tue, 28 Mar 2006 16:23:24 -0800 (PST)

> The "ndx" VERSYM entry for _etext is "0xa822", which is 0x2822 with
> the "hidden" 0x8000 bit masked out.  That is way out of range.
> 
> Sometimes things work because something happens to be mapped at that
> offset from the map->l_versions[] table.
> 
> What I can't figure out is if that bogus hidden _etext entry is there
> due to a binutils bug, or perhaps bad arguments given to the link of
> the mono binary at build time.  What could cause such a hidden
> version entry to _etext to end up in a binary like that?

It seems that this is caused by the verioning linker scripts that mono
uses.

First it links libmono.so with this:

VER_1 {
      global: 
              mono_*;
              GC_push_all_stack;
              GC_start_blocking;
              GC_end_blocking;
              gc_thread_vtable;
      local:
              *;
};

Then it links everything together, including libmono.so, into the
"mono" binary using this versioning linker script:

{
      global: 
              mono_*;
              GC_push_all_stack;
              GC_start_blocking;
              GC_end_blocking;
              gc_thread_vtable;
      local:
              *;
};

and that seems to be how we end up with that weird _etext versioning
entry above.