ARM: support for IRQ and vmap'ed stacks
This PR covers all the work related to implementing IRQ stacks and
vmap'ed stacks for all 32-bit ARM systems that are currently supported
by the Linux kernel, including RiscPC and Footbridge. It has been
submitted for review in three different waves:
- IRQ stacks support for v7 SMP systems [0],
- vmap'ed stacks support for v7 SMP systems[1],
- extending support for both IRQ stacks and vmap'ed stacks for all
remaining configurations, including v6/v7 SMP multiplatform kernels
and uniprocessor configurations including v7-M [2]
[0] https://lore.kernel.org/linux-arm-kernel/
20211115084732.3704393-1-ardb@kernel.org/
[1] https://lore.kernel.org/linux-arm-kernel/
20211122092816.2865873-1-ardb@kernel.org/
[2] https://lore.kernel.org/linux-arm-kernel/
20211206164659.1495084-1-ardb@kernel.org/