Pull regset updates from Al Viro:
 "Dead code removal, mostly.

  The only exception is a bit of cleanups on itanic (getting rid of
  redundant stack unwinds - each access_uarea() call does it and we call
  that 7 times in a row in ptrace_[sg]etregs(), *after* having done it
  ourselves in the caller; location where the user registers have been
  spilled won't change under us, and we can bloody well just call
  access_elf_reg() directly, giving it the unw_frame_info we'd
  calculated for our own purposes)"

* 'regset.followup' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  c6x: kill ELF_CORE_COPY_FPREGS
  whack-a-mole: USE_ELF_CORE_DUMP
  [ia64] ptrace_[sg]etregs(): use access_elf_reg() instead of access_uarea()
  [ia64] missed cleanups from switch to regset coredumps
  arm: kill dump_task_regs()

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

the last user had been fdpic

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

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

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>

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>

This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.

The change is generated using coccinelle with the following rule:

// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .

@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This is required for clone3 which passes the TLS value through a
struct rather than a register.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: <stable@vger.kernel.org> # 5.3.x
Link: https://lore.kernel.org/r/20200102172413.654385-4-amanieu@gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

The get_signal_page() function is defined in signal.c and used in
process.c but there is no shared definition. Add one in signal.h to
silence the following warning:

arch/arm/kernel/signal.c:683:13: warning: symbol 'get_signal_page' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arm uses a top-down mmap layout by default that exactly fits the generic
functions, so get rid of arch specific code and use the generic version by
selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.

As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE,
use the generic version of arch_randomize_brk since it also fits.  Note
that this commit also removes the possibility for arm to have elf
randomization and no MMU: without MMU, the security added by randomization
is worth nothing.

Note that it is safe to remove STACK_RND_MASK since it matches the default
value.

Link: http://lkml.kernel.org/r/20190730055113.23635-9-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>