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This is the mail archive of thelibc-alpha@sourceware.orgmailing list for theglibc project.
Re: [PATCH] Enable hidden visibility in libc.a compiled with PIE
- From: Szabolcs Nagy <szabolcs dot nagy at arm dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: nd at arm dot com, GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 21 Aug 2017 17:50:05 +0100
- Subject: Re: [PATCH] Enable hidden visibility in libc.a compiled with PIE
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On 21/08/17 17:44, H.J. Lu wrote:> On Mon, Aug 21, 2017 at 9:31 AM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:>> On 08/08/17 17:40, H.J. Lu wrote:>>> When building libc.a with PIE, enable hidden visibility to allow direct>>> access to definitions within libc.a without using GOT.>> ...>>> -#if defined SHARED || defined LIBC_NONSHARED>>> +#if defined SHARED || defined LIBC_NONSHARED \>>> + || (BUILD_PIE_DEFAULT && IS_IN (libc))>>> # define attribute_hidden __attribute__ ((visibility ("hidden")))>>>> btw what happens if this is enabled for non-pie libc.a ?> > It makes those symbols in libc.a hidden.> >> i'd expect that to work too (it prevents some symbol>> interpositions?)>>> > You can't interpose any symbols in libc.a, PIE or non-PIE.> What my patch does is to avoid GOT/PLT in PIE libc.a when> accessing them within libc.a.> yes, but my point is that the ifdef can be simplifiedif it's valid for the non-pie case too.
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