Hi Ning, I was packaging tboot for Gentoo Linux and it would never actually manage to load linux. It managed to SENTER fine but once it tried to jump to the linux entry point it would fail and reboot. Gentoo Hardened adds fstack-check by default (among other things) to the gcc specs.
After a lot of trial and error disabling SSP with -fstack-check=no made it work. tboot already disables fstack-protector and fstack-protector-all which are similar so it makes sense that fstack-check must also be disabled. There is no comment explaining why fstack-protector is disabled in the makefile unfortunately. I do not have a very good way of debugging since it wouldnt work in an emulator so I do not know *exactly* where it broke but the assembly generated by my gcc and the objdump'd one from fedora were quite different at the last stages of tboot. I saw the "jumping to Linux @0xxx" message on the console and then it would reboot so it was very late in the initialization. I was using Gcc 4.8.4 from Gentoo Hardened[1]. If you are on a different distro, add -fstack-check to the CFLAGs and you will probably be able to replicate. Thanks, Jason [1]: https://wiki.gentoo.org/wiki/Hardened/Toolchain#Default_addition_of_the_Stack_Smashing_Protector_.28SSP.29 On Thu, May 07, 2015 at 05:51:53PM +0000, Sun, Ning wrote: > Hi Zaman, > > Thanks for your patch, for us to better understand the purpose of your > patch, can you explain in which scenario fstack-check will break tboot? > > Thanks very much! > -ning > > > > -----Original Message----- > From: Jason Zaman [mailto:ja...@perfinion.com] > Sent: Thursday, May 07, 2015 8:55 AM > To: tboot-devel@lists.sourceforge.net > Subject: [tboot-devel] [PATCH] Disable fstack-check during build > > fstack-check breaks tboot this disables it in CFLAGS. > > Signed-off-by: Jason Zaman <ja...@perfinion.com> ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ tboot-devel mailing list tboot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tboot-devel
