Add memblock_cap_memory_range() which will remove all the memblock regions
except the range specified in the arguments.
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 a571d4eb55d8 ("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, System RAM, on crash dump
kernel.
(Please note that "mem=" parameter is of little use for this purpose.)
Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memblock.h | 1 +
mm/memblock.c | 28 ++++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 5b759c9..0e770af 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -334,6 +334,7 @@ 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_mem_limit_remove_map(phys_addr_t limit);
+void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);
bool memblock_is_memory(phys_addr_t addr);
int memblock_is_map_memory(phys_addr_t addr);
int memblock_is_region_memory(phys_addr_t base, phys_addr_t size);
diff --git a/mm/memblock.c b/mm/memblock.c
index 7608bc3..eb53876 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1544,6 +1544,34 @@ void __init memblock_mem_limit_remove_map(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);
+}
+
static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
{
unsigned int left = 0, right = type->cnt;
--
2.10.0
--
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