[Buildroot] [PATCH 1/1] Config.in: disable PIC/PIE if the toolchain does not support PIE

Fabrice Fontaine fontaine.fabrice at gmail.com
Mon Oct 28 08:32:49 UTC 2019


Dear Matthew,

Le lun. 28 oct. 2019 à 00:22, Matthew Weber
<matthew.weber at collins.com> a écrit :
>
> Fabrice,
>
> On Sun, Oct 27, 2019 at 5:03 PM Fabrice Fontaine
> <fontaine.fabrice at gmail.com> wrote:
> >
> > m68k does not seem to really support PIE as it raises the following
> > build failure with aer-inject:
> > /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/host/opt/ext-toolchain/bin/../lib/gcc/m68k-buildroot-linux-uclibc/7.4.0/../../../../m68k-buildroot-linux-uclibc/bin/ld: /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/host/m68k-buildroot-linux-uclibc/sysroot/usr/lib/Scrt1.o: in function `lib_main':
> > (.text+0x4): undefined reference to `__shared_flat_add_library'
> > /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/host/opt/ext-toolchain/bin/../lib/gcc/m68k-buildroot-linux-uclibc/7.4.0/../../../../m68k-buildroot-linux-uclibc/bin/ld: final link failed: bad value
> >
>
> I wonder where this ever got to add support as in 2006 as they were
> trying for m68k.
> https://lists.uclibc.org/pipermail/uclibc/2006-July/036766.html
>
> > We also have another build failure with uclibc on microblazeel:
> > /home/buildroot/autobuild/instance-1/output-1/host/lib/gcc/microblazeel-buildroot-linux-uclibc/8.3.0/../../../../microblazeel-buildroot-linux-uclibc/bin/ld: final link failed: bad value
> > collect2: error: ld returned 1 exit status
> > Makefile.in:114: recipe for target '../utils/getconf' failed
> >
>
> This one looks like it might be fixable and an issue with compile
> flags missing but link time options being set.  I'm wondering what its
> doing as the error is in the target install step of the package.
I tried to fix it for a couple of hours without any luck. What I found
until now is that the build failure is linked to the
BR2_UCLIBC_INSTALL_UTILS option which builds and installs uclibc
utilities such as getconf for the target. Build and install is done in
UCLIBC_INSTALL_UTILS_TARGET (which is strange but I assume this is to
avoid an UCLIBC_BUILD_UTILS_TARGET). Build failure is raised by
Scrt1.o which is built during the previous step but I don't know why
binutils complains about a missing -fPIC especially that is does
complain only for microblaze :-/.
>
>
> > So add a BR2_TOOLCHAIN_SUPPORTS_PIE dependency on BR2_PIC_PIE
> >
> > Fixes:
> >  - http://autobuild.buildroot.net/results/4cdd6f0368cc9d3c6e88f01b1a8929eb0839b638
> >  - http://autobuild.buildroot.net/results/a82a484409149d7f9aff6140ddcb89f627f508c7
> >
> > Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
> > ---
> >  Config.in | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/Config.in b/Config.in
> > index ebbb6b41f4..010b0774e3 100644
> > --- a/Config.in
> > +++ b/Config.in
> > @@ -697,10 +697,15 @@ comment "Security Hardening Options"
> >  config BR2_PIC_PIE
> >         bool "Build code with PIC/PIE"
> >         depends on BR2_SHARED_LIBS
> > +       depends on BR2_TOOLCHAIN_SUPPORTS_PIE
> >         help
> >           Generate Position-Independent Code (PIC) and link
> >           Position-Independent Executables (PIE).
> >
> > +comment "PIC/PIE needs a toolchain w/ PIE"
> > +       depends on BR2_SHARED_LIBS
> > +       depends on !BR2_TOOLCHAIN_SUPPORTS_PIE
> > +
> >  choice
> >         bool "Stack Smashing Protection"
> >         default BR2_SSP_ALL if BR2_ENABLE_SSP # legacy
> > @@ -783,12 +788,16 @@ config BR2_RELRO_PARTIAL
> >
> >  config BR2_RELRO_FULL
> >         bool "Full"
> > +       depends on BR2_TOOLCHAIN_SUPPORTS_PIE
> >         select BR2_PIC_PIE
> >         help
> >           This option includes the partial configuration, but also marks
> >           the GOT as read-only at the cost of initialization time during
> >           program loading, i.e every time an executable is started.
> >
> > +comment "RELRO Full needs a toolchain w/ PIE"
> > +       depends on !BR2_TOOLCHAIN_SUPPORTS_PIE
> > +
> >  endchoice
> >
> >  comment "RELocation Read Only (RELRO) needs shared libraries"
> > --
> > 2.23.0
> >
> > _______________________________________________
> > buildroot mailing list
> > buildroot at busybox.net
> > http://lists.busybox.net/mailman/listinfo/buildroot
>
>
>
> --
>
> Matthew Weber | Associate Director Software Engineer | Commercial Avionics
>
> COLLINS AEROSPACE
>
> 400 Collins Road NE, Cedar Rapids, Iowa 52498, USA
>
> Tel: +1 319 295 7349 | FAX: +1 319 263 6099
>
> matthew.weber at collins.com | collinsaerospace.com
>
>
>
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Best Regards,

Fabrice


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