Re: [PATCH] arm: fix PIC vs SHARED typos

[Mike Frysinger <vapier at gentoo dot org>]

On Monday, September 19, 2011 15:35:40 Joseph S. Myers wrote:
> On Mon, 19 Sep 2011, Mike Frysinger wrote:
> > the logic in setjmp/__longjmp incorrectly tie to "PIC" to figure out
> > whether the code is going into a shared library when it should be using
> > "SHARED".  otherwise, building static PIC code goes wrong.
> 
> You'll need to give a better explanation (testcase) of what you mean by
> "goes wrong".

failure to link due to wrong symbol name used

> Static PIEs aren't supported on x86_64 so I don't suppose they are
> supported on ARM; PIEs have to use shared libraries.

upstream glibc tends to list static PIEs as unsupported.  in practice, they do 
work because glibc has proper "PIC" and "SHARED" differentiation, and Gentoo 
has long enabled support for these when people ask (our hardened setup builds 
everything as PIC/PIE).

> But if they were
> supported, the PIC code here looks better than the non-PIC - you can't
> just put an absolute address in a constant pool in the text section in
> position-independent code the way the non-PIC code does; the conditional
> really does seem to be about "must the text be position-independent?".

so it sounds there are two issues.  there is PIC code behind "#ifdef PIC" 
which is good, but the code also decides which symbol name (which is a SHARED 
define) via PIC ?  that's the part that i'm trying to fix.
-mike

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