[PATCH v31 02/12] arm64: limit memory regions based on DT property, usable-memory-range

Mark Rutland
2017-02-01T15:07:00Z

Hi,

On Wed, Feb 01, 2017 at 09:46:21PM +0900, AKASHI Takahiro wrote:
> +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;

Nit: unnecessary cast.

> + const __be32 *reg;
> + int len;
> +
> + usablemem->size = 0;

Could we please lift this assignment/initialisation into the caller...

> +
> + 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;

... e.g. have:

struct memblock_region reg = {
.size = 0,
};

That saves us from making unnecessary assignments to the size field, and
makes it clear that reg.size has definitely been initialised, regardless
of what of_scan_flat_dt() happens to do.

With that:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks,
Mark.

> +
> + 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
> --
> 2.11.0
>