ARM: enable IRQ stacks and vmap'ed stacks for UP

First, enable the use of the TLS register to hold the 'current' pointer
for all configurations that can support it, including non-SMP ones that
target v6k or later CPUs, and multi-platform SMP ones that also support
v6 based UP systems.

The remaining configurations are all strictly UP, which means we can
switch to a global variable to hold the current pointer. By doing this,
we can enable THREAD_INFO_IN_TASK, which moves thread info off the
stack, protecting it from overflows. It also permits us to enable IRQ
stacks and vmap'ed stacks for UP configurations as well.

Supporting v6 cores without SMP extensions in SMP configurations (e.g.,
omap2plus_defconfig or imx_v6_v7_defconfig) makes this a bit tricky, and
this is a feature we may consider dropping entirely in the future. But
for the time being, we can support this mode as well.

The accesses to the global variable holding 'current' are constructed in
a way that ensures that no literal pool accesses (and associated D-cache
misses) are needed unless the access is from a module and module PLTs
are enabled. This means that accessing 'current' is just as costly as
before, as it used to require some arithmetic involving the stack
pointer and a load from the thread_info::task field.

However, accessing thread_info itself now also involves a load, although
it should be noted that all thread_info and current accesses now go via
the same variable, which is therefore expected to be hot in the caches
at all times.

Changes since v2:
- support THREAD_INFO_IN_TASK and the IRQ stack on v7m as well,
- incorporate a v7m cleanup from Vladimir to enable the above,
- avoid declaring smp_on_up globally,
- fix an oversight in the IOP32x IRQ #0 fix
- add some more acks

Changes since RFC/v1:
- add five preparatory patches that move RiscPC, IOP32x and Footbridge
  to GENERIC_IRQ_MULTI_HANDLER so that even these ancient platforms can
  benefit from the IRQ stacks changes for UP that this series proposes
  (contributed by Arnd)
- fix various issues related to SMP+v6 corner cases that were caught by
  kernelci testing;
- add acks from Nico and Linus (thanks!)

Cc: Russell King <linux@armlinux.org.uk>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Keith Packard <keithpac@amazon.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Jesse Taube <mr.bossman075@gmail.com>

Ard Biesheuvel (8):
  ARM: entry: preserve thread_info pointer in switch_to
  ARM: module: implement support for PC-relative group relocations
  ARM: assembler: add optimized ldr/str macros to load variables from
    memory
  ARM: percpu: add SMP_ON_UP support
  ARM: use TLS register for 'current' on !SMP as well
  ARM: smp: defer TPIDRURO update for SMP v6 configurations too
  ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems
  ARM: v7m: enable support for IRQ stacks

Arnd Bergmann (5):
  ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER
  ARM: footbridge: use GENERIC_IRQ_MULTI_HANDLER
  ARM: iop32x: offset IRQ numbers by 1
  ARM: iop32x: use GENERIC_IRQ_MULTI_HANDLER
  ARM: remove old-style irq entry

Vladimir Murzin (1):
  irqchip: nvic: Use GENERIC_IRQ_MULTI_HANDLER

 arch/arm/Kconfig                                    |  22 +--
 arch/arm/include/asm/assembler.h                    | 185 ++++++++++++++++----
 arch/arm/include/asm/current.h                      |  37 ++--
 arch/arm/include/asm/elf.h                          |   3 +
 arch/arm/include/asm/entry-macro-multi.S            |  16 --
 arch/arm/include/asm/hardware/entry-macro-iomd.S    | 131 --------------
 arch/arm/include/asm/insn.h                         |  24 +++
 arch/arm/include/asm/irq.h                          |   1 -
 arch/arm/include/asm/mach/arch.h                    |   2 -
 arch/arm/include/asm/percpu.h                       |  25 ++-
 arch/arm/include/asm/switch_to.h                    |   3 +-
 arch/arm/include/asm/thread_info.h                  |  27 ---
 arch/arm/include/asm/tls.h                          |  13 +-
 arch/arm/include/asm/v7m.h                          |   3 +-
 arch/arm/kernel/asm-offsets.c                       |   3 -
 arch/arm/kernel/entry-armv.S                        |  48 ++---
 arch/arm/kernel/entry-common.S                      |  16 +-
 arch/arm/kernel/entry-header.S                      |  13 +-
 arch/arm/kernel/entry-v7m.S                         |  39 +++--
 arch/arm/kernel/head-common.S                       |   4 +-
 arch/arm/kernel/irq.c                               |  17 --
 arch/arm/kernel/module.c                            |  63 +++++++
 arch/arm/kernel/process.c                           |   7 +-
 arch/arm/kernel/sleep.S                             |   4 +-
 arch/arm/kernel/smp.c                               |  11 ++
 arch/arm/kernel/traps.c                             |   4 +
 arch/arm/mach-footbridge/common.c                   |  87 +++++++++
 arch/arm/mach-footbridge/include/mach/entry-macro.S | 107 -----------
 arch/arm/mach-iop32x/cp6.c                          |  10 +-
 arch/arm/mach-iop32x/include/mach/entry-macro.S     |  31 ----
 arch/arm/mach-iop32x/include/mach/irqs.h            |   2 +-
 arch/arm/mach-iop32x/iop3xx.h                       |   1 +
 arch/arm/mach-iop32x/irq.c                          |  29 ++-
 arch/arm/mach-iop32x/irqs.h                         |  60 ++++---
 arch/arm/mach-rpc/fiq.S                             |   5 +-
 arch/arm/mach-rpc/include/mach/entry-macro.S        |  13 --
 arch/arm/mach-rpc/irq.c                             | 145 +++++++++++++++
 arch/arm/mm/Kconfig                                 |   1 +
 drivers/irqchip/Kconfig                             |   1 +
 drivers/irqchip/irq-nvic.c                          |  22 +--
 40 files changed, 695 insertions(+), 540 deletions(-)
 delete mode 100644 arch/arm/include/asm/entry-macro-multi.S
 delete mode 100644 arch/arm/include/asm/hardware/entry-macro-iomd.S
 delete mode 100644 arch/arm/mach-footbridge/include/mach/entry-macro.S
 delete mode 100644 arch/arm/mach-iop32x/include/mach/entry-macro.S
 delete mode 100644 arch/arm/mach-rpc/include/mach/entry-macro.S

-- 
2.30.2


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