In some cases, memblock is queried to determine whether a physical
address corresponds to memory present in a system even if unused by
the OS for the linear mapping, highmem, etc. For example, the ACPI
core needs this information to determine which attributes to use when
mapping ACPI regions. Use of incorrect memory types can result in
faults, data corruption, or other issues.
Removing memory with memblock_enforce_memory_limit throws away this
information, and so a kernel booted with 'mem=' may suffers from the
issues described above. To avoid this, we need to keep those NOMAP
regions instead of removing all above limit, which preserves the
information we need while preventing other use of the regions.
This patch adds new insfrastructure to retain all NOMAP memblock regions
while removing others, to cater for this.
At last, we add 'size' and 'flag' debug output in the memblock debugfs
for ease of the memblock debug.
The '/sys/kernel/debug/memblock/memory' output looks like before:
0: 0x0000008000000000..0x0000008001e7ffff
1: 0x0000008001e80000..0x00000083ff184fff
2: 0x00000083ff185000..0x00000083ff1c2fff
3: 0x00000083ff1c3000..0x00000083ff222fff
4: 0x00000083ff223000..0x00000083ffe42fff
5: 0x00000083ffe43000..0x00000083ffffffff
After applied:
0: 0x0000008000000000..0x0000008001e7ffff 0x0000000001e80000 0x4
1: 0x0000008001e80000..0x00000083ff184fff 0x00000003fd305000 0x0
2: 0x00000083ff185000..0x00000083ff1c2fff 0x000000000003e000 0x4
3: 0x00000083ff1c3000..0x00000083ff222fff 0x0000000000060000 0x0
4: 0x00000083ff223000..0x00000083ffe42fff 0x0000000000c20000 0x4
5: 0x00000083ffe43000..0x00000083ffffffff 0x00000000001bd000 0x0
Signed-off-by: Dennis Chen <dennis.chen@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Steve Capper <steve.capper@xxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-acpi@xxxxxxxxxxxxxxx
Cc: linux-efi@xxxxxxxxxxxxxxx
---
include/linux/memblock.h | 1 +
mm/memblock.c | 55 +++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 48 insertions(+), 8 deletions(-)
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 6c14b61..2925da2 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -332,6 +332,7 @@ 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_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);
int memblock_is_region_memory(phys_addr_t base, phys_addr_t size);
diff --git a/mm/memblock.c b/mm/memblock.c
index ca09915..8099f1a 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1465,14 +1465,11 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void)
return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
}
-void __init memblock_enforce_memory_limit(phys_addr_t limit)
+static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
{
phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
struct memblock_region *r;
- if (!limit)
- return;
-
/* find out max address */
for_each_memblock(memory, r) {
if (limit <= r->size) {
@@ -1482,6 +1479,20 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
limit -= r->size;
}
+ return max_addr;
+}
+
+void __init memblock_enforce_memory_limit(phys_addr_t limit)
+{
+ phys_addr_t max_addr;
+
+ if (!limit)
+ return;
+
+ max_addr = __find_max_addr(limit);
+ if (max_addr == (phys_addr_t)ULLONG_MAX)
+ return;
+
/* truncate both memory and reserved regions */
memblock_remove_range(&memblock.memory, max_addr,
(phys_addr_t)ULLONG_MAX);
@@ -1489,6 +1500,32 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
(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;
+
+ max_addr = __find_max_addr(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) {
+ WARN_ONCE(1, "Mem limit failed, will not be applied!\n");
+ return;
+ }
+
+ for (i = end_rgn - 1; i >= start_rgn; i--) {
+ if (!memblock_is_nomap(&type->regions[i]))
+ memblock_remove_region(type, i);
+ }
+}
+
static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
{
unsigned int left = 0, right = type->cnt;
@@ -1677,13 +1714,15 @@ static int memblock_debug_show(struct seq_file *m, void *private)
reg = &type->regions[i];
seq_printf(m, "%4d: ", i);
if (sizeof(phys_addr_t) == 4)
- seq_printf(m, "0x%08lx..0x%08lx\n",
+ seq_printf(m, "0x%08lx..0x%08lx 0x%08lx 0x%lx\n",
(unsigned long)reg->base,
- (unsigned long)(reg->base + reg->size - 1));
+ (unsigned long)(reg->base + reg->size - 1),
+ (unsigned long)reg->size, reg->flags);
else
- seq_printf(m, "0x%016llx..0x%016llx\n",
+ seq_printf(m, "0x%016llx..0x%016llx 0x%016llx 0x%lx\n",
(unsigned long long)reg->base,
- (unsigned long long)(reg->base + reg->size - 1));
+ (unsigned long long)(reg->base + reg->size - 1),
+ (unsigned long long)reg->size, reg->flags);
}
return 0;
--
1.8.3.1
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