Commit c9ca9b4e authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Catalin Marinas
Browse files

memblock: add memblock_cap_memory_range() 



Add memblock_cap_memory_range() which will remove all the memblock regions
except the memory range specified in the arguments. In addition, rework is
done on memblock_mem_limit_remove_map() to re-implement it using
memblock_cap_memory_range().

This function, like memblock_mem_limit_remove_map(), will not remove
memblocks with MEMMAP_NOMAP attribute as they may be mapped and accessed
later as "device memory."
See the commit a571d4eb ("mm/memblock.c: add new infrastructure to
address the mem limit issue").

This function is used, in a succeeding patch in the series of arm64 kdump
suuport, to limit the range of usable memory, or System RAM, on crash dump
kernel.
(Please note that "mem=" parameter is of little use for this purpose.)

Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarDennis Chen <dennis.chen@arm.com>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 4c546b8a

include/linux/memblock.h

+1 −0
Original line number Diff line number Diff line
@@ -336,6 +336,7 @@ phys_addr_t memblock_mem_size(unsigned long limit_pfn); 
phys_addr_t memblock_start_of_DRAM(void);

phys_addr_t memblock_end_of_DRAM(void);

void memblock_enforce_memory_limit(phys_addr_t memory_limit);

void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);

void memblock_mem_limit_remove_map(phys_addr_t limit);

bool memblock_is_memory(phys_addr_t addr);

int memblock_is_map_memory(phys_addr_t addr);

mm/memblock.c

+29 −15
Original line number Diff line number Diff line
@@ -1543,11 +1543,37 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) 
			      (phys_addr_t)ULLONG_MAX);

}



void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)

{

	int start_rgn, end_rgn;

	int i, ret;



	if (!size)

		return;



	ret = memblock_isolate_range(&memblock.memory, base, size,

						&start_rgn, &end_rgn);

	if (ret)

		return;



	/* remove all the MAP regions */

	for (i = memblock.memory.cnt - 1; i >= end_rgn; i--)

		if (!memblock_is_nomap(&memblock.memory.regions[i]))

			memblock_remove_region(&memblock.memory, i);



	for (i = start_rgn - 1; i >= 0; i--)

		if (!memblock_is_nomap(&memblock.memory.regions[i]))

			memblock_remove_region(&memblock.memory, i);



	/* truncate the reserved regions */

	memblock_remove_range(&memblock.reserved, 0, base);

	memblock_remove_range(&memblock.reserved,

			base + size, (phys_addr_t)ULLONG_MAX);

}



void __init memblock_mem_limit_remove_map(phys_addr_t limit)

{

	struct memblock_type *type = &memblock.memory;

	phys_addr_t max_addr;

	int i, ret, start_rgn, end_rgn;



	if (!limit)

		return;
@@ -1558,19 +1584,7 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit) 
	if (max_addr == (phys_addr_t)ULLONG_MAX)

		return;



	ret = memblock_isolate_range(type, max_addr, (phys_addr_t)ULLONG_MAX,

				&start_rgn, &end_rgn);

	if (ret)

		return;



	/* remove all the MAP regions above the limit */

	for (i = end_rgn - 1; i >= start_rgn; i--) {

		if (!memblock_is_nomap(&type->regions[i]))

			memblock_remove_region(type, i);

	}

	/* truncate the reserved regions */

	memblock_remove_range(&memblock.reserved, max_addr,

			      (phys_addr_t)ULLONG_MAX);

	memblock_cap_memory_range(0, max_addr);

}



static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)

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