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

Pull arch task_work cleanups from Jens Axboe:
 "Two cleanups that don't fit other categories:

   - Finally get the task_work_add() cleanup done properly, so we don't
     have random 0/1/false/true/TWA_SIGNAL confusing use cases. Updates
     all callers, and also fixes up the documentation for
     task_work_add().

   - While working on some TIF related changes for 5.11, this
     TIF_NOTIFY_RESUME cleanup fell out of that. Remove some arch
     duplication for how that is handled"

* tag 'arch-cleanup-2020-10-22' of git://git.kernel.dk/linux-block:
  task_work: cleanup notification modes
  tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume()

Pull initial set_fs() removal from Al Viro:
 "Christoph's set_fs base series + fixups"

* 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: Allow a NULL pos pointer to __kernel_read
  fs: Allow a NULL pos pointer to __kernel_write
  powerpc: remove address space overrides using set_fs()
  powerpc: use non-set_fs based maccess routines
  x86: remove address space overrides using set_fs()
  x86: make TASK_SIZE_MAX usable from assembly code
  x86: move PAGE_OFFSET, TASK_SIZE & friends to page_{32,64}_types.h
  lkdtm: remove set_fs-based tests
  test_bitmap: remove user bitmap tests
  uaccess: add infrastructure for kernel builds with set_fs()
  fs: don't allow splice read/write without explicit ops
  fs: don't allow kernel reads and writes without iter ops
  sysctl: Convert to iter interfaces
  proc: add a read_iter method to proc proc_ops
  proc: cleanup the compat vs no compat file ops
  proc: remove a level of indentation in proc_get_inode

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()

Pull copy_and_csum cleanups from Al Viro:
 "Saner calling conventions for csum_and_copy_..._user() and friends"

[ Removing 800+ lines of code and cleaning stuff up is good  - Linus ]

* 'work.csum_and_copy' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ppc: propagate the calling conventions change down to csum_partial_copy_generic()
  amd64: switch csum_partial_copy_generic() to new calling conventions
  sparc64: propagate the calling convention changes down to __csum_partial_copy_...()
  xtensa: propagate the calling conventions change down into csum_partial_copy_generic()
  mips: propagate the calling convention change down into __csum_partial_copy_..._user()
  mips: __csum_partial_copy_kernel() has no users left
  mips: csum_and_copy_{to,from}_user() are never called under KERNEL_DS
  sparc32: propagate the calling conventions change down to __csum_partial_copy_sparc_generic()
  i386: propagate the calling conventions change down to csum_partial_copy_generic()
  sh: propage the calling conventions change down to csum_partial_copy_generic()
  m68k: get rid of zeroing destination on error in csum_and_copy_from_user()
  arm: propagate the calling convention changes down to csum_partial_copy_from_user()
  alpha: propagate the calling convention changes down to csum_partial_copy.c helpers
  saner calling conventions for csum_and_copy_..._user()
  csum_and_copy_..._user(): pass 0xffffffff instead of 0 as initial sum
  csum_partial_copy_nocheck(): drop the last argument
  unify generic instances of csum_partial_copy_nocheck()
  icmp_push_reply(): reorder adding the checksum up
  skb_copy_and_csum_bits(): don't bother with the last argument

Add a CONFIG_SET_FS option that is selected by architecturess that
implement set_fs, which is all of them initially.  If the option is not
set stubs for routines related to overriding the address space are
provided so that architectures can start to opt out of providing set_fs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

quite a few architectures have the same csum_partial_copy_nocheck() -
simply memcpy() the data and then return the csum of the copy.

hexagon, parisc, ia64, s390, um: explicitly spelled out that way.

arc, arm64, csky, h8300, m68k/nommu, microblaze, mips/GENERIC_CSUM, nds32,
nios2, openrisc, riscv, unicore32: end up picking the same thing spelled
out in lib/checksum.h (with varying amounts of perversions along the way).

everybody else (alpha, arm, c6x, m68k/mmu, mips/!GENERIC_CSUM, powerpc,
sh, sparc, x86, xtensa) have non-generic variants.  For all except c6x
the declaration is in their asm/checksum.h.  c6x uses the wrapper
from asm-generic/checksum.h that would normally lead to the lib/checksum.h
instance, but in case of c6x we end up using an asm function from arch/c6x
instead.

Screw that mess - have architectures with private instances define
_HAVE_ARCH_CSUM_AND_COPY in their asm/checksum.h and have the default
one right in net/checksum.h conditional on _HAVE_ARCH_CSUM_AND_COPY
*not* defined.

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

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