Bug#841420: --enable-default-pie breaks kernel builds

[Arthur Gautier]

On Fri, Oct 21, 2016 at 08:07:03AM -0500, S. R. Wright wrote:
> As the kernel is the most important code gcc is ever likely to compile on
> debian or any other distro for that matter,  this change should be backed
> out,  and not reintroduced UNTIL the *official* kernel source is ready for
> it.

I agree with this, I would also recommend to wait for patchs to hit
the LTS releases of the kernel (4.4, 4.1). As those are used on
production systems.

I also tried the patched mentioned earlier without luck:
diff --git a/Makefile b/Makefile
index 0f9cb36d45c2c..b95a6774e4600 100644
--- a/Makefile
+++ b/Makefile
@@ -341,8 +341,8 @@ include scripts/Kbuild.include
 
 # Make variables (CC, etc...)
 AS = $(CROSS_COMPILE)as
-LD = $(CROSS_COMPILE)ld
-CC = $(CROSS_COMPILE)gcc
+LD = $(CROSS_COMPILE)ld -no-pie
+CC = $(CROSS_COMPILE)gcc -no-pie
 CPP= $(CC) -E
 AR = $(CROSS_COMPILE)ar
 NM = $(CROSS_COMPILE)nm

This does not work with gcc 6.2.0-7 on my environment.

For now I've rollbacked to 6.2.0-6 which works as expected:
$ cat /etc/apt/preferences.d/02_broken_kernel_builds
Package: gcc-6-base
Pin: version 6.2.0-7
Pin-Priority: -10


-- 
\o/ Arthur
 G  Gandi.net

Bug#841420: --enable-default-pie breaks kernel builds

[S. R. Wright]

I agree with Eric;  while the workaround is to back rev the gcc and its 
associated packages,  I also build kernels straight from kernel.org, 
usually within hours of their availability and this has been working for 
me for many years,  and it is not sufficient to justify this change by 
saying doing so "isn't a good idea."  A change of functionality of this 
scope warrants a minor version number increase,  this change was not 
merely a bug fix.


As the kernel is the most important code gcc is ever likely to compile 
on debian or any other distro for that matter,  this change should be 
backed out,  and not reintroduced UNTIL the *official* kernel source is 
ready for it.


-- sRw

On 10/21/2016 06:43 AM, Wolfgang Walter wrote:

On Friday, 21 October 2016 14:45:25 CEST Ritesh Raj Sarraf wrote:

The Debian kernel packages still have a dependency on gcc-5, which may mean
that the kernels are currently only built/supported with gcc-5.

vanilla kernels (Linus' tree and the stable ones) could be compiled just fine
with gcc 6.2.0-6 and that now fails.

I still think this is a major regression and regard gcc 6.2.0-7 simply as
broken.


On Thu, 2016-10-20 at 11:22 -0500, S R Wright wrote:

Concurring with Wolfgang;  pulling the source straight from kernel.org
and using identical .config files will work with 6.2.0-6 but fail with
6.2.0-7.   I was able to build and install 4.8.3 with no issues after
back-revving gcc et. al. to 6.2.0-6

-- sRw

On 10/20/16 11:09, Wolfgang Walter wrote:

Hello,

with this version of gcc-6 I can't build vanilla kernels any more. It
fails
with even with CC_STACKPROTECTOR_STRONG disabled:

scripts/kconfig/mconf  Kconfig
configuration written to .config

*** End of the configuration.
*** Execute 'make' to start the build or try 'make help'.

ksrc@ei:~/build/kernels/linux-4.8.3$ make
scripts/kconfig/conf  --silentoldconfig Kconfig
CHK include/config/kernel.release
CHK include/generated/uapi/linux/version.h
CHK include/generated/utsrelease.h
UPD include/generated/utsrelease.h
CC  kernel/bounds.s
kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
   /*
   
Kbuild:45: recipe for target 'kernel/bounds.s' failed

make[1]: *** [kernel/bounds.s] Error 1
Makefile:1015: recipe for target 'prepare0' failed
make: *** [prepare0] Error 2


I think this is a major regression if you can't build vanilla and stable
kernels any more.

Regards,

Regards,

Bug#841420: --enable-default-pie breaks kernel builds

[Wolfgang Walter]

On Friday, 21 October 2016 14:45:25 CEST Ritesh Raj Sarraf wrote:
> The Debian kernel packages still have a dependency on gcc-5, which may mean
> that the kernels are currently only built/supported with gcc-5.

vanilla kernels (Linus' tree and the stable ones) could be compiled just fine 
with gcc 6.2.0-6 and that now fails.

I still think this is a major regression and regard gcc 6.2.0-7 simply as 
broken.

> 
> On Thu, 2016-10-20 at 11:22 -0500, S R Wright wrote:
> > Concurring with Wolfgang;  pulling the source straight from kernel.org 
> > and using identical .config files will work with 6.2.0-6 but fail with 
> > 6.2.0-7.   I was able to build and install 4.8.3 with no issues after 
> > back-revving gcc et. al. to 6.2.0-6
> > 
> > -- sRw
> > 
> > On 10/20/16 11:09, Wolfgang Walter wrote:
> > > Hello,
> > > 
> > > with this version of gcc-6 I can't build vanilla kernels any more. It
> > > fails
> > > with even with CC_STACKPROTECTOR_STRONG disabled:
> > > 
> > > scripts/kconfig/mconf  Kconfig
> > > configuration written to .config
> > > 
> > > *** End of the configuration.
> > > *** Execute 'make' to start the build or try 'make help'.
> > > 
> > > ksrc@ei:~/build/kernels/linux-4.8.3$ make
> > > scripts/kconfig/conf  --silentoldconfig Kconfig
> > >CHK include/config/kernel.release
> > >CHK include/generated/uapi/linux/version.h
> > >CHK include/generated/utsrelease.h
> > >UPD include/generated/utsrelease.h
> > >CC  kernel/bounds.s
> > > kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
> > >   /*
> > >   
> > > Kbuild:45: recipe for target 'kernel/bounds.s' failed
> > > make[1]: *** [kernel/bounds.s] Error 1
> > > Makefile:1015: recipe for target 'prepare0' failed
> > > make: *** [prepare0] Error 2
> > > 
> > > 
> > > I think this is a major regression if you can't build vanilla and stable
> > > kernels any more.
> > > 
> > > Regards,

Regards,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts

Bug#841420: --enable-default-pie breaks kernel builds

[Ritesh Raj Sarraf]

The Debian kernel packages still have a dependency on gcc-5, which may mean that
the kernels are currently only built/supported with gcc-5.


On Thu, 2016-10-20 at 11:22 -0500, S R Wright wrote:
> Concurring with Wolfgang;  pulling the source straight from kernel.org 
> and using identical .config files will work with 6.2.0-6 but fail with 
> 6.2.0-7.   I was able to build and install 4.8.3 with no issues after 
> back-revving gcc et. al. to 6.2.0-6
> 
> -- sRw
> 
> 
> On 10/20/16 11:09, Wolfgang Walter wrote:
> > Hello,
> > 
> > with this version of gcc-6 I can't build vanilla kernels any more. It fails
> > with even with CC_STACKPROTECTOR_STRONG disabled:
> > 
> > scripts/kconfig/mconf  Kconfig
> > configuration written to .config
> > 
> > *** End of the configuration.
> > *** Execute 'make' to start the build or try 'make help'.
> > 
> > ksrc@ei:~/build/kernels/linux-4.8.3$ make
> > scripts/kconfig/conf  --silentoldconfig Kconfig
> >    CHK include/config/kernel.release
> >    CHK include/generated/uapi/linux/version.h
> >    CHK include/generated/utsrelease.h
> >    UPD include/generated/utsrelease.h
> >    CC  kernel/bounds.s
> > kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
> >   /*
> >   
> > Kbuild:45: recipe for target 'kernel/bounds.s' failed
> > make[1]: *** [kernel/bounds.s] Error 1
> > Makefile:1015: recipe for target 'prepare0' failed
> > make: *** [prepare0] Error 2
> > 
> > 
> > I think this is a major regression if you can't build vanilla and stable
> > kernels any more.
> > 
> > Regards,
> 
> 
-- 
Given the large number of mailing lists I follow, I request you to CC
me in replies for quicker response

signature.asc
Description: This is a digitally signed message part

Bug#841420: --enable-default-pie breaks kernel builds

[Bálint Réczey]

Control: tags -1 - patch

2016-10-20 18:48 GMT+02:00 Sven Joachim :
> On 2016-10-20 17:54 +0200, Bálint Réczey wrote:
>
>> Control: reassign -1 linux 4.7.8-1
>> Control: severity -1 serious
>> Control: tags -1 patch
>>
>> Hi David,
>>
>> 2016-10-20 14:02 GMT+02:00 David Weinehall :
>>> Package: gcc-6
>>> Severity: important
>>> Version: 6.2.0-7
>>>
>>> --enable-default-pie (first enabled in gcc-6 6.2.0-7) causes kernel
>>> builds to fail.  If the kernel is configured with the stack protector
>>> enabled it'll fail with a rather unhelpful error message claiming
>>> that the compiler doesn't support -fstack-protector,
>>> but the problem is in fact caused by:
>>>
>>> kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
>>>
>>> (The kernel is built with -mcmodel=kernel)
>>>
>>> I think it's fair to say that the kernel is kind of an important piece
>>> of software and that it's imperative that we don't break kernel builds...
>>
>> The kernel is very important indeed and it did break in our build test.
>> I'm sorry, somehow I missed filing bug for the linux package, just for
>> user-mode-linux.
>> The following patch fixes the FTBFS:
>>
>> --- linux-4.7.8/debian/rules.d/Makefile.inc
>> +++ linux-4.7.8/debian/rules.d/Makefile.inc
>> @@ -5,7 +5,8 @@
>>
>>  SHELL = /bin/sh -e
>>
>> -CC = $(CROSS_COMPILE)gcc
>> +CC = $(CROSS_COMPILE)gcc -no-pie
>> +LD = $(CROSS_COMPILE)ld -no-pie
>>  CXX = $(CROSS_COMPILE)g++
>>  CFLAGS := $(shell dpkg-buildflags --get CFLAGS) -Wall
>>  CPPFLAGS := $(shell dpkg-buildflags --get CPPFLAGS) \
>>
>> Maybe the ld part is obsolete, I have not checked that.
>
> That patch might work for the Debian package, but has anybody contacted
> the upstream kernel developers about that?  At least the 4.8.3 vanilla
> kernel fails in the same way, I haven't tested 4.9-rc1 yet.

Fixing it upstream would certainly be better. I also haven't booted
the built image,
thus please use this patch only as inspiration. :-)

Cheers,
Balint

>
> FWIW, this issue has been discussed in Ubuntu for six months(!), see
> https://bugs.launchpad.net/ubuntu/+source/gcc-defaults/+bug/1574982.
>
> Cheers,
>Sven

Processed: Re: Bug#841420: --enable-default-pie breaks kernel builds

[Debian Bug Tracking System]

Processing control commands:

> tags -1 - patch
Bug #841420 [linux] --enable-default-pie breaks kernel builds
Bug #841368 [linux] gcc-6 6.2.0-7 breaks kernel build if stack protection is 
enabled
Removed tag(s) patch.
Removed tag(s) patch.

-- 
841368: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=841368
841420: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=841420
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems

Bug#841420: --enable-default-pie breaks kernel builds

[Sven Joachim]

On 2016-10-20 17:54 +0200, Bálint Réczey wrote:

> Control: reassign -1 linux 4.7.8-1
> Control: severity -1 serious
> Control: tags -1 patch
>
> Hi David,
>
> 2016-10-20 14:02 GMT+02:00 David Weinehall :
>> Package: gcc-6
>> Severity: important
>> Version: 6.2.0-7
>>
>> --enable-default-pie (first enabled in gcc-6 6.2.0-7) causes kernel
>> builds to fail.  If the kernel is configured with the stack protector
>> enabled it'll fail with a rather unhelpful error message claiming
>> that the compiler doesn't support -fstack-protector,
>> but the problem is in fact caused by:
>>
>> kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
>>
>> (The kernel is built with -mcmodel=kernel)
>>
>> I think it's fair to say that the kernel is kind of an important piece
>> of software and that it's imperative that we don't break kernel builds...
>
> The kernel is very important indeed and it did break in our build test.
> I'm sorry, somehow I missed filing bug for the linux package, just for
> user-mode-linux.
> The following patch fixes the FTBFS:
>
> --- linux-4.7.8/debian/rules.d/Makefile.inc
> +++ linux-4.7.8/debian/rules.d/Makefile.inc
> @@ -5,7 +5,8 @@
>
>  SHELL = /bin/sh -e
>
> -CC = $(CROSS_COMPILE)gcc
> +CC = $(CROSS_COMPILE)gcc -no-pie
> +LD = $(CROSS_COMPILE)ld -no-pie
>  CXX = $(CROSS_COMPILE)g++
>  CFLAGS := $(shell dpkg-buildflags --get CFLAGS) -Wall
>  CPPFLAGS := $(shell dpkg-buildflags --get CPPFLAGS) \
>
> Maybe the ld part is obsolete, I have not checked that.

That patch might work for the Debian package, but has anybody contacted
the upstream kernel developers about that?  At least the 4.8.3 vanilla
kernel fails in the same way, I haven't tested 4.9-rc1 yet.

FWIW, this issue has been discussed in Ubuntu for six months(!), see
https://bugs.launchpad.net/ubuntu/+source/gcc-defaults/+bug/1574982.

Cheers,
   Sven

Bug#841420: --enable-default-pie breaks kernel builds

[S R Wright]

Concurring with Wolfgang;  pulling the source straight from kernel.org 
and using identical .config files will work with 6.2.0-6 but fail with 
6.2.0-7.   I was able to build and install 4.8.3 with no issues after 
back-revving gcc et. al. to 6.2.0-6


-- sRw


On 10/20/16 11:09, Wolfgang Walter wrote:

Hello,

with this version of gcc-6 I can't build vanilla kernels any more. It fails
with even with CC_STACKPROTECTOR_STRONG disabled:

scripts/kconfig/mconf  Kconfig
configuration written to .config

*** End of the configuration.
*** Execute 'make' to start the build or try 'make help'.

ksrc@ei:~/build/kernels/linux-4.8.3$ make
scripts/kconfig/conf  --silentoldconfig Kconfig
   CHK include/config/kernel.release
   CHK include/generated/uapi/linux/version.h
   CHK include/generated/utsrelease.h
   UPD include/generated/utsrelease.h
   CC  kernel/bounds.s
kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
  /*
  
Kbuild:45: recipe for target 'kernel/bounds.s' failed

make[1]: *** [kernel/bounds.s] Error 1
Makefile:1015: recipe for target 'prepare0' failed
make: *** [prepare0] Error 2


I think this is a major regression if you can't build vanilla and stable
kernels any more.

Regards,

Bug#841420: --enable-default-pie breaks kernel builds

[Wolfgang Walter]

Hello,

with this version of gcc-6 I can't build vanilla kernels any more. It fails 
with even with CC_STACKPROTECTOR_STRONG disabled:

scripts/kconfig/mconf  Kconfig
configuration written to .config

*** End of the configuration.
*** Execute 'make' to start the build or try 'make help'.

ksrc@ei:~/build/kernels/linux-4.8.3$ make
scripts/kconfig/conf  --silentoldconfig Kconfig
  CHK include/config/kernel.release
  CHK include/generated/uapi/linux/version.h
  CHK include/generated/utsrelease.h
  UPD include/generated/utsrelease.h
  CC  kernel/bounds.s
kernel/bounds.c:1:0: error: code model kernel does not support PIC mode
 /*
 
Kbuild:45: recipe for target 'kernel/bounds.s' failed
make[1]: *** [kernel/bounds.s] Error 1
Makefile:1015: recipe for target 'prepare0' failed
make: *** [prepare0] Error 2


I think this is a major regression if you can't build vanilla and stable 
kernels any more.

Regards,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts

Processed: Re: Bug#841420: --enable-default-pie breaks kernel builds

[Debian Bug Tracking System]

Processing control commands:

> reassign -1 linux 4.7.8-1
Bug #841420 [gcc-6] --enable-default-pie breaks kernel builds
Bug reassigned from package 'gcc-6' to 'linux'.
No longer marked as found in versions gcc-6/6.2.0-7.
Ignoring request to alter fixed versions of bug #841420 to the same values 
previously set
Bug #841420 [linux] --enable-default-pie breaks kernel builds
There is no source info for the package 'linux' at version '4.7.8-1' with 
architecture ''
Unable to make a source version for version '4.7.8-1'
Marked as found in versions 4.7.8-1.
> severity -1 serious
Bug #841420 [linux] --enable-default-pie breaks kernel builds
Severity set to 'serious' from 'important'
> tags -1 patch
Bug #841420 [linux] --enable-default-pie breaks kernel builds
Added tag(s) patch.

-- 
841420: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=841420
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems