[PATCH v28 2/9] arm64: limit memory regions based on DT property, usable-memory-range
AKASHI Takahiro
takahiro.akashi at linaro.org
Thu Nov 24 01:58:03 PST 2016
Crash dump kernel utilizes only a subset of available memory as System RAM.
On arm64 kdump, This memory range is advertized to crash dump kernel via
a device-tree property under /chosen,
linux,usable-memory-range = <BASE SIZE>
Crash dump kernel reads this property at boot time and calls
memblock_cap_memory_range() to limit usable memory ranges which are
described as entries in UEFI memory map table or "memory" nodes in
a device tree blob.
Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
Reviewed-by: Geoff Levand <geoff at infradead.org>
---
arch/arm64/mm/init.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 212c4d1..65f1241 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -187,10 +187,45 @@ static int __init early_mem(char *p)
}
early_param("mem", early_mem);
+static int __init early_init_dt_scan_usablemem(unsigned long node,
+ const char *uname, int depth, void *data)
+{
+ struct memblock_region *usablemem = (struct memblock_region *)data;
+ const __be32 *reg;
+ int len;
+
+ usablemem->size = 0;
+
+ if (depth != 1 || strcmp(uname, "chosen") != 0)
+ return 0;
+
+ reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
+ if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
+ return 1;
+
+ usablemem->base = dt_mem_next_cell(dt_root_addr_cells, ®);
+ usablemem->size = dt_mem_next_cell(dt_root_size_cells, ®);
+
+ return 1;
+}
+
+static void __init fdt_enforce_memory_region(void)
+{
+ struct memblock_region reg;
+
+ of_scan_flat_dt(early_init_dt_scan_usablemem, ®);
+
+ if (reg.size)
+ memblock_cap_memory_range(reg.base, reg.size);
+}
+
void __init arm64_memblock_init(void)
{
const s64 linear_region_size = -(s64)PAGE_OFFSET;
+ /* Handle linux,usable-memory-range property */
+ fdt_enforce_memory_region();
+
/*
* Ensure that the linear region takes up exactly half of the kernel
* virtual address space. This way, we can distinguish a linear address
--
2.10.0
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