Commit d05cfbd9 authored by Peng Liu's avatar Peng Liu Committed by Zheng Zengkai
Browse files

arm64: Add support for memmap kernel parameters 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4NYPZ


CVE: NA

-------------------------------------------------

Add support for memmap kernel parameters for ARM64. The three below
modes are supported:

memmap=exactmap
Enable setting of an exact memory map, as specified by the user.

memmap=nn[KMG]@ss[KMG]
Force usage of a specific region of memory.

memmap=nn[KMG]$ss[KMG]
Region of memory to be reserved is from ss to ss+nn, the region must
be in the range of existed memory, otherwise will be ignored.

If users set memmap=exactmap before memmap=nn[KMG]@ss[KMG], they will
get the exact memory specified by memmap=nn[KMG]@ss[KMG]. For example,
on one machine with 4GB memory, "memmap=exactmap memmap=1G@1G" will
make kernel use the memory from 1GB to 2GB only.

Signed-off-by: default avatarPeng Liu <liupeng256@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 8c34e5f6

Documentation/admin-guide/kernel-parameters.txt

+6 −3
Original line number Diff line number Diff line
@@ -2794,8 +2794,8 @@ 
			option.

			See Documentation/admin-guide/mm/memory-hotplug.rst.



	memmap=exactmap	[KNL,X86] Enable setting of an exact

			E820 memory map, as specified by the user.

	memmap=exactmap	[KNL,X86,ARM64] Enable setting of an exact

			E820 and ARM64 memory map, as specified by the user.

			Such memmap=exactmap lines can be constructed based on

			BIOS output or other requirements. See the memmap=nn@ss

			option description.
@@ -2806,7 +2806,8 @@ 
			If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],

			which limits max address to nn[KMG].

			Multiple different regions can be specified,

			comma delimited.

			comma delimited, example as follows is not supported to

			ARM64.

			Example:

				memmap=100M@2G,100M#3G,1G!1024G
@@ -2817,6 +2818,8 @@ 
	memmap=nn[KMG]$ss[KMG]

			[KNL,ACPI] Mark specific memory as reserved.

			Region of memory to be reserved is from ss to ss+nn.

			For ARM64, reserved memory must be in the range of

			existed memory.

			Example: Exclude memory from 0x18690000-0x1869ffff

			         memmap=64K$0x18690000

			         or

arch/arm64/mm/init.c

+59 −0
Original line number Diff line number Diff line
@@ -404,6 +404,65 @@ static int __init reserve_park_mem(void) 
}

#endif



static int need_remove_real_memblock __initdata;



static int __init parse_memmap_one(char *p)

{

	char *oldp;

	u64 start_at, mem_size;



	if (!p)

		return -EINVAL;



	if (!strncmp(p, "exactmap", 8)) {

		need_remove_real_memblock = 1;

		return -EINVAL;

	}



	oldp = p;

	mem_size = memparse(p, &p);

	if (p == oldp)

		return -EINVAL;



	if (!mem_size)

		return -EINVAL;



	if (*p == '@') {

		start_at = memparse(p + 1, &p);

		/*

		 * use the exactmap defined by nn[KMG]@ss[KMG], remove

		 * memblock populated by DT etc.

		 */

		if (need_remove_real_memblock) {

			need_remove_real_memblock = 0;

			memblock_remove(0, ULLONG_MAX);

		}

		memblock_add(start_at, mem_size);

	} else if (*p == '$') {

		start_at = memparse(p + 1, &p);

		memblock_reserve(start_at, mem_size);

	} else

		pr_info("Unrecognized memmap option, please check the parameter.\n");



	return *p == '\0' ? 0 : -EINVAL;

}



static int __init parse_memmap_opt(char *str)

{

	while (str) {

		char *k = strchr(str, ',');



		if (k)

			*k++ = 0;



		parse_memmap_one(str);

		str = k;

	}



	return 0;

}

early_param("memmap", parse_memmap_opt);



void __init arm64_memblock_init(void)

{

	const s64 linear_region_size = BIT(vabits_actual - 1);