openrisc: Support storing and restoring fpu state

OpenRISC floating point state is not so expensive to save as OpenRISC uses
general purpose registers for floating point instructions. We need to save
only the floating point status and control register, FPCSR.

Add support to maintain the FPCSR unconditionally upon exceptions and
switches. On machines that do not support FPU this will always just
store 0x0 and restore is a no-op. On FPU systems this adds an
additional special purpose register read/write and read/write to memory
(already cached).

Signed-off-by: Stafford Horne <shorne@gmail.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

UAPI: (Scripted) Disintegrate arch/openrisc/include/asm

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>

openrisc: header file cleanups

elf.h: We can export some of these symbols to userspace. libc needs them
and we just as well provide them as asm/elf.h as copying them into separate
libc headers.

ptrace.h: Having padding in the user_regs_struct isn't of any particular
value and just confuses GDB. spr_defs isn't needed in userspace; libc
has its own copy anyway.

Signed-off-by: Jonas Bonn <jonas@southpole.se>

openrisc: sanitize use of orig_gpr11

The pt_regs struct had both a 'syscallno' field and an 'orig_gpr11' field
and it wasn't really clear how these were supposed to be used. This patch
removes the syscallno field altogether and makes orig_gpr11 work more
like other architectures: keep track of syscall number in progress or
hold -1 for non-syscall exceptions.

Signed-off-by: Jonas Bonn <jonas@southpole.se>

openrisc: Fix up audit_syscall_[entry|exit]() usage

Commits d7e7528bcd456f5c36ad4a202ccfb43c5aa98bc4 and
b05d8447e7821695bc2fa3359431f7a664232743 simplified the usage of the
audit_syscall_[entry|exit] functions. Unfortunately, the OpenRISC
architecture didn't get fixed up along with the other architectures when
those patches were pushed. This makes the relevant changes to this
architecture.

Signed-off-by: Jonas Bonn <jonas@southpole.se>

OpenRISC: PTrace

This patch implements minimal PTrace support. The pt_regs structure is
not exported to userspace for OpenRISC; rather, the GETREGSET mechanism
is intended to be used and the registers, as such, exported in the core
dump format which is ABI stable. This is in line with what is intended
for new architectures as of 2.6.34 and has the advantage of permitting
the layout of the registers on the kernel stack (as per pt_regs) to be
freely modified.

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>