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arm64: limit memory regions based on DT property, usable-memory-range 

Crash dump kernel uses only a limited range of available memory as System
RAM. On arm64 kdump, This memory range is advertised 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 which are listed either
in UEFI memory map table or "memory" nodes of a device tree blob.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Geoff Levand <geoff@infradead.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
AKASHI Takahiro 2017-04-03 11:24:31 +09:00 committed by Catalin Marinas
parent c9ca9b4e21
commit 8f579b1c4e
1 changed files with 35 additions and 0 deletions
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35
arch/arm64/mm/init.c
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@ -188,10 +188,45 @@ 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 = data;
const __be32 *reg;
int len;
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, &reg);
usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
return 1;
}
static void __init fdt_enforce_memory_region(void)
{
struct memblock_region reg = {
.size = 0,
};
of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
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