On Sat, Sep 28, 2019 at 12:41:29PM +0000, Ingo Molnar wrote:
>
> * Randy Dunlap <rdun...@infradead.org> wrote:
>
> > On 9/3/19 8:50 AM, Andreas Smas wrote:
> > > Hi,
> > >
> > > For me, kernels built including this commit
> > > b059f801a937 (x86/purgatory: Use CFLAGS_REMOVE rather than reset
> > > KBUILD_CFLAGS)
> > >
> > > results in kexec() failing to load the kernel:
> > >
> > > kexec: Undefined symbol: __stack_chk_fail
> > > kexec-bzImage64: Loading purgatory failed
> > >
> > > Can be seen:
> > >
> > > $ readelf -a arch/x86/purgatory/purgatory.ro | grep UND
> > > 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
> > > 51: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND
> > > __stack_chk_fail
> > >
> > > Using: gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)
> > >
> > > Adding -ffreestanding or -fno-stack-protector to ccflags-y in
> > > arch/x86/purgatory/Makefile
> > > fixes the problem. Not sure which would be preferred.
> > >
> >
> > Hi,
> > Do you have a kernel .config file that causes this?
> > I can't seem to reproduce it.
>
> Does it go away with this fix in x86/urgent:
>
> ca14c996afe7: ("x86/purgatory: Disable the stackleak GCC plugin for the
> purgatory")
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/urgent
>
> ?
>
> Thanks,
>
> Ing
This one was fixed by [1] e16c2983fba0f ("x86/purgatory: Change compiler
flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation
errors") from Steve Wahl, which in addition to changing mcmodel also
added back -ffreestanding (and -fno-zero-initialized-in-bss). It was
merged on the 12th. The stackleak one is a different undefined symbol
error.
[1] https://marc.info/?l=git-commits-head&m=156829711224800
