commit c6a385539175ebc603da53aafb7753d39089f32e upstream.

So Sebastian turned off the PIE for kernel builds but that was too late
- Kbuild.include already uses KBUILD_CFLAGS and trying to disable gcc
options with, say cc-disable-warning, fails:

  gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs
  ...
  -Wno-sign-compare -fno-asynchronous-unwind-tables -Wframe-address -c -x c /dev/null -o .31392.tmp
  /dev/null:1:0: error: code model kernel does not support PIC mode

because that returns an error and we can't disable the warning. For
example in this case:

KBUILD_CFLAGS   += $(call cc-disable-warning,frame-address,)

which leads to gcc issuing all those warnings again.

So let's turn off PIE/PIC at the earliest possible moment, when we
declare KBUILD_CFLAGS so that cc-disable-warning picks it up too.

Also, we need the $(call cc-option ...) because -fno-PIE is supported
since gcc v3.4 and our lowest supported gcc version is 3.2 right now.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Michal Marek <mmarek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 8ae94224c9d72fc4d9aaac93b2d7833cf46d7141 upstream.

Debian started to build the gcc with -fPIE by default so the kernel
build ends before it starts properly with:
|kernel/bounds.c:1:0: error: code model kernel does not support PIC mode

Also add to KBUILD_AFLAGS due to:

|gcc -Wp,-MD,arch/x86/entry/vdso/vdso32/.note.o.d … -mfentry -DCC_USING_FENTRY … vdso/vdso32/note.S
|arch/x86/entry/vdso/vdso32/note.S:1:0: sorry, unimplemented: -mfentry isn’t supported for 32-bit in combination with -fpic

Tagging it stable so it is possible to compile recent stable kernels as
well.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Michal Marek <mmarek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 124a3d88fa20e1869fc229d7d8c740cc81944264 upstream.

Newer versions of gcc warn about the use of __builtin_return_address()
with a non-zero argument when "-Wall" is specified:

  kernel/trace/trace_irqsoff.c: In function ‘stop_critical_timings’:
  kernel/trace/trace_irqsoff.c:433:86: warning: calling ‘__builtin_return_address’ with a nonzero argument is unsafe [-Wframe-address]
     stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
  [ .. repeats a few times for other similar cases .. ]

It is true that a non-zero argument is somewhat dangerous, and we do not
actually have very many uses of that in the kernel - but the ftrace code
does use it, and as Stephen Rostedt says:

 "We are well aware of the danger of using __builtin_return_address() of
  > 0.  In fact that's part of the reason for having the "thunk" code in
  x86 (See arch/x86/entry/thunk_{64,32}.S).  [..] it adds extra frames
  when tracking irqs off sections, to prevent __builtin_return_address()
  from accessing bad areas.  In fact the thunk_32.S states: 'Trampoline to
  trace irqs off.  (otherwise CALLER_ADDR1 might crash)'."

For now, __builtin_return_address() with a non-zero argument is the best
we can do, and the warning is not helpful and can end up making people
miss other warnings for real problems.

So disable the frame-address warning on compilers that need it.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>