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From: "dje at google dot com" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug gdb/11786] PIE support may not work for some PIEs
Date: Fri, 25 Oct 2013 18:56:00 -0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=11786

--- Comment #10 from dje at google dot com ---
(In reply to Paul Pluzhnikov from comment #7)
> Would it be reasonable to check NT_GNU_BUILD_ID, and skip the Phdr check
> entirely on a match?
> 
> (In reply to Jan Kratochvil from comment #6)
> > Differently than... bfd ld?  gold vs. ld executables are a different build
> > which cannot match / is not guaranteed to match.
> 
> The flow here (Google b/10274851) is:
> 
>   (gold-linked, PIE) unstripped -> "strip -g" -> stripped -> core
> 
>   gdb stripped core    # works, but no debug info :-(
>   gdb unstripped core  # fails to relocate the binary :-(
> 
> Gold and strip do not agree on p_flags and p_align of GNU_RELRO,
> but the "unstripped" and "stripped" *are* exact match.

What if the core file doesn't have NT_GNU_BUILD_ID?
E.g., what if the program headers in the core file (obtained via auxv search,
ref: gdb/solib-svr4.c:read_program_header) refer to addresses only in the
executable?

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