Re: [tip:sched/core 7/28] rseq.c:139:37: error: 'AT_RSEQ_ALIGN' undeclared; did you mean 'R_SH_ALIGN'?

[Mathieu Desnoyers]

On 2023-01-17 04:06, Ingo Molnar wrote:
> * Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > On 1/16/23 13:18, Mathieu Desnoyers wrote:
> > > On 2023-01-16 14:40, kernel test robot wrote:
> > > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core
> > > > head:   79ba1e607d68178db7d3fe4f6a4aa38f06805e7b
> > > > commit: 03f5c0272d1b59343144e199becc911dae52c37e [7/28] selftests/rseq: Use ELF auxiliary vector for extensible rseq
> > > > compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> > > > reproduce:
> > > >           # https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=03f5c0272d1b59343144e199becc911dae52c37e
> > > >           git remote add tip https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
> > > >           git fetch --no-tags tip sched/core
> > > >           git checkout 03f5c0272d1b59343144e199becc911dae52c37e
> > > >           make O=/tmp/kselftest headers
> > > >           make O=/tmp/kselftest -C tools/testing/selftests
> > > >
> > > > If you fix the issue, kindly add following tag where applicable
> > > > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > >
> > > In order to fix this, I need to change -I../../../../usr/include/ for $(KHDR_INCLUDES) in tools/testing/selftests/rseq/Makefile
> > >
> > > I can find 25 odd uses of the same pattern in the kernel selftests. Should I fix them all in one go ?
> >
> > kselftest build depends on headers installed in the root directory.

By "root directory", do you mean kernel sources root directory or build 
output root directory ?

> > The main makefile enforces this dependency.

How ? I figure that tools/testing/selftests/lib.mk overrides 
KHDR_INCLUDES if it is not defined yet:

ifeq ($(KHDR_INCLUDES),)
KHDR_INCLUDES := -isystem $(top_srcdir)/usr/include
endif

and selftests makefiles include ../lib.mk.

This KHDR_INCLUDES can be modified by O=... when built from the kernel 
top level, thus using tools/testing/selftests/Makefile:

ifneq ($(KBUILD_OUTPUT),)
[...]
  KHDR_INCLUDES := -isystem ${abs_objtree}/usr/include
else
[...]
  KHDR_INCLUDES := -isystem ${abs_srctree}/usr/include
endif

But it's up to the individual selftests to actually use 
$(KHDR_INCLUDES). In many cases, they hardcode 
-I../../../../usr/include/ which is bogus when the build root (O=...) 
differs from the source root.

 If this test is being
> > built without installing headers by itself, I think the scripts that
> > build individual tests have to makes sure headers are installed first.

The headers were previously built by "make O=/tmp/kselftest headers", as 
it should, it's just that the selftest makefile uses a hardcoded path 
that is relative to the source directory, and it appears that this 
pattern is repeated all across the selftests.

> Why isn't the Makefile saying anything about it & enforcing it? self-tests
> are usually self-sufficient to build in the individual directories.

In an ideal world, we'd have a way to _remove_ the build environment 
kernel headers from the include search paths, because this is a problem 
for reproducibility of the tests.

Thanks,

Mathieu

> Thanks,
>
> 	Ingo

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com