[PATCH v27 2/9] arm64: limit memory regions based on DT property, usable-memory-range
From: AKASHI Takahiro <hidden>
Date: 2016-11-02 04:52:43
Also in:
kexec
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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 <redacted> Reviewed-by: Geoff Levand <geoff@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
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2.10.0