We call arch_cpu_idle() with RCU disabled, but then use
local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.

Switch all arch_cpu_idle() implementations to use
raw_local_irq_{en,dis}able() and carefully manage the
lockdep,rcu,tracing state like we do in entry.

(XXX: we really should change arch_cpu_idle() to not return with
interrupts enabled)

Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org

All the callers currently do this, clean it up and move the clearing
into tracehook_notify_resume() instead.

Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull kernel_clone() updates from Christian Brauner:
 "During the v5.9 merge window we reworked the process creation
  codepaths across multiple architectures. After this work we were only
  left with the _do_fork() helper based on the struct kernel_clone_args
  calling convention. As was pointed out _do_fork() isn't valid
  kernelese especially for a helper that isn't just static.

  This series removes the _do_fork() helper and introduces the new
  kernel_clone() helper. The process creation cleanup didn't change the
  name to something more reasonable mainly because _do_fork() was used
  in quite a few places. So sending this as a separate series seemed the
  better strategy.

  I originally intended to send this early in the v5.9 development cycle
  after the merge window had closed but given that this was touching
  quite a few places I decided to defer this until the v5.10 merge
  window"

* tag 'kernel-clone-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  sched: remove _do_fork()
  tracing: switch to kernel_clone()
  kgdbts: switch to kernel_clone()
  kprobes: switch to kernel_clone()
  x86: switch to kernel_clone()
  sparc: switch to kernel_clone()
  nios2: switch to kernel_clone()
  m68k: switch to kernel_clone()
  ia64: switch to kernel_clone()
  h8300: switch to kernel_clone()
  fork: introduce kernel_clone()

The .comment section doesn't belong in STABS_DEBUG. Split it out into a
new macro named ELF_DETAILS. This will gain other non-debug sections
that need to be accounted for when linking with --orphan-handling=warn.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-arch@vger.kernel.org
Link: https://lore.kernel.org/r/20200821194310.3089815-5-keescook@chromium.org

The old _do_fork() helper is removed in favor of the new kernel_clone() helper.
The latter adheres to naming conventions for kernel internal syscall helpers.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Link: https://lore.kernel.org/r/20200819104655.436656-6-christian.brauner@ubuntu.com

Pull regset conversion fix from Al Viro:
 "Fix a regression from an unnoticed bisect hazard in the regset series.

  A bunch of old (aout, originally) primitives used by coredumps became
  dead code after fdpic conversion to regsets. Removal of that dead code
  had been the first commit in the followups to regset series;
  unfortunately, it happened to hide the bisect hazard on sh (extern for
  fpregs_get() had not been updated in the main series when it should
  have been; followup simply made fpregs_get() static). And without that
  followup commit this bisect hazard became breakage in the mainline"

Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kill unused dump_fpu() instances

Pull ptrace regset updates from Al Viro:
 "Internal regset API changes:

   - regularize copy_regset_{to,from}_user() callers

   - switch to saner calling conventions for ->get()

   - kill user_regset_copyout()

  The ->put() side of things will have to wait for the next cycle,
  unfortunately.

  The balance is about -1KLoC and replacements for ->get() instances are
  a lot saner"

* 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
  regset: kill user_regset_copyout{,_zero}()
  regset(): kill ->get_size()
  regset: kill ->get()
  csky: switch to ->regset_get()
  xtensa: switch to ->regset_get()
  parisc: switch to ->regset_get()
  nds32: switch to ->regset_get()
  nios2: switch to ->regset_get()
  hexagon: switch to ->regset_get()
  h8300: switch to ->regset_get()
  openrisc: switch to ->regset_get()
  riscv: switch to ->regset_get()
  c6x: switch to ->regset_get()
  ia64: switch to ->regset_get()
  arc: switch to ->regset_get()
  arm: switch to ->regset_get()
  sh: convert to ->regset_get()
  arm64: switch to ->regset_get()
  mips: switch to ->regset_get()
  sparc: switch to ->regset_get()
  ...

dump_fpu() is used only on the architectures that support elf
and have neither CORE_DUMP_USE_REGSET nor ELF_CORE_COPY_FPREGS
defined.

Currently that's csky, m68k, microblaze, nds32 and unicore32.  The rest
of the instances are dead code.

NB: THIS MUST GO AFTER ELF_FDPIC CONVERSION

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Now that HAVE_COPY_THREAD_TLS has been removed, rename copy_thread_tls()
back simply copy_thread(). It's a simpler name, and doesn't imply that only
tls is copied here. This finishes an outstanding chunk of internal process
creation work since we've added clone3().

Cc: linux-arch@vger.kernel.org
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>A
Acked-by: Stafford Horne <shorne@gmail.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>A
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>