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Commit e7cd1903 authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Will Deacon
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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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Tested-by: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 5ebe3a44

arch/arm64/include/asm/acpi.h

+6 −2
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ 
#ifndef _ASM_ACPI_H

#define _ASM_ACPI_H



#include <linux/mm.h>

#include <linux/memblock.h>

#include <linux/psci.h>



#include <asm/cputype.h>
@@ -32,7 +32,11 @@ 
static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,

					    acpi_size size)

{

	if (!page_is_ram(phys >> PAGE_SHIFT))

	/*

	 * EFI's reserve_regions() call adds memory with the WB attribute

	 * to memblock via early_init_dt_add_memory_arch().

	 */

	if (!memblock_is_memory(phys))

		return ioremap(phys, size);



	return ioremap_cache(phys, size);

arch/arm64/kernel/setup.c

+7 −2
Original line number Diff line number Diff line
@@ -206,10 +206,15 @@ static void __init request_standard_resources(void) 


	for_each_memblock(memory, region) {

		res = alloc_bootmem_low(sizeof(*res));

		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);