Re: x86/purgatory: undefined symbol __stack_chk_fail
* Arvind Sankar wrote:
> On Sat, Sep 28, 2019 at 12:41:29PM +, Ingo Molnar wrote:
> >
> > * Randy Dunlap 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: 0 NOTYPE LOCAL DEFAULT UND
> > > > 51: 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=156829711224800
Great, so all known kexec bugs should be fixed for now in Linus's latest
kernel, right?
Thanks,
Ingo
Re: x86/purgatory: undefined symbol __stack_chk_fail
On Sat, Sep 28, 2019 at 12:41:29PM +, Ingo Molnar wrote:
>
> * Randy Dunlap 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: 0 NOTYPE LOCAL DEFAULT UND
> > > 51: 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=156829711224800
Re: x86/purgatory: undefined symbol __stack_chk_fail
On 03/09/2019 17.50, 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: 0 NOTYPE LOCAL DEFAULT UND > 51: 0 NOTYPE GLOBAL DEFAULT UND __stack_chk_fail > > Using: gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1) Ubuntu's gcc has -fstack-protector enabled by default, so this happens if one doesn't pass -fno-stack-protector (which I guess is implied by -ffreestanding) explicitly. > Adding -ffreestanding or -fno-stack-protector to ccflags-y in > arch/x86/purgatory/Makefile > fixes the problem. Not sure which would be preferred. Probably -fno-stack-protector, guarded by CONFIG_CC_HAS_STACKPROTECTOR_NONE (because not all gccs understand -fno-stack-protector), so ifdef CONFIG_CC_HAS_STACKPROTECTOR_NONE ccflags-y += -fno-stack-protector endif Rasmus
Re: x86/purgatory: undefined symbol __stack_chk_fail
* Randy Dunlap 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: 0 NOTYPE LOCAL DEFAULT UND
> > 51: 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,
Ingo
Re: x86/purgatory: undefined symbol __stack_chk_fail
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: 0 NOTYPE LOCAL DEFAULT UND > 51: 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. Thanks. -- ~Randy
x86/purgatory: undefined symbol __stack_chk_fail
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: 0 NOTYPE LOCAL DEFAULT UND 51: 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.
