arm64: mark reserved memblock regions explicitly in iomem

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

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: James Morse <james.morse@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 536dce22fe76..514b4e3ba029 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -206,10 +206,15 @@ static void __init request_standard_resources(void)
 
         for_each_memblock(memory, region) {
                 res = alloc_bootmem_low(sizeof(*res));
-                res->name  = "System RAM";
+                if (memblock_is_nomap(region)) {
+                        res->name  = "reserved";
+                        res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+                } else {
+                        res->name  = "System RAM";
+                        res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+                }
                 res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
                 res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
-                res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 
                 request_resource(&iomem_resource, res);