[PATCH] arm64: mark reserved memblock regions explicitly in iomem

On Mon, Aug 22, 2016 at 03:55:24PM +0900, AKASHI Takahiro wrote:

Kdump(kexec-tools) parses /proc/iomem to identify all the memory regions
on the system. Since the current kernel names "nomap" regions, like UEFI
runtime services code/data, as "System RAM," kexec-tools sets up elf core
header to include them in a crash dump file (/proc/vmcore).

Then crash dump kernel parses UEFI memory map again, re-marks those regions
as "nomap" and does not create a memory mapping for them unlike the other
areas of System RAM. In this case, copying /proc/vmcore through
copy_oldmem_page() on crash dump kernel will end up with a kernel abort,
as reported in [1].

This patch names all the "nomap" regions explicitly as "reserved" so that
we can exclude them from a crash dump file. acpi_os_ioremap() must also
be modified because those regions have WB attributes [2].

Apart from kdump, this change also matches x86's use of acpi (and
/proc/iomem).

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-August/448186.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-August/450089.html

Signed-off-by: AKASHI Takahiro <redacted>
---
 arch/arm64/include/asm/acpi.h | 8 ++++++--
 arch/arm64/kernel/setup.c     | 9 +++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

The patch looks fine to me but it would be good if James gave it a try.
FWIW:

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>