[PATCH v21 4/8] arm64: kdump: add kdump support

[Geoff Levand]

On Wed, 2016-07-06 at 16:52 +0900, AKASHI Takahiro wrote:
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -136,6 +137,57 @@ static void __init reserve_crashkernel(void)
>  }
>  #endif /* CONFIG_KEXEC_CORE */
>  
> +#ifdef CONFIG_CRASH_DUMP
> +static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
> +> 	> 	> const char *uname, int depth, void *data)
> +{
> +> 	> const __be32 *reg;
> +> 	> int len;
> +
> +> 	> if (depth != 1 || strcmp(uname, "chosen") != 0)
> +> 	> 	> return 0;
> +
> +> 	> reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
> +> 	> if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
> +> 	> 	> return 1;
> +
> +> 	> elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, ®);
> +> 	> elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, ®);
> +
> +> 	> return 1;
> +}
> +
> +/*
> + * reserve_elfcorehdr() - reserves memory for elf core header
> + *
> + * This function reserves elf core header given in "elfcorehdr=" kernel
> + * command line parameter. This region contains all the information about
> + * primary kernel's core image and is used by a dump capture kernel to
> + * access the system memory on primary kernel.
> + */
> +static void __init reserve_elfcorehdr(void)
> +{

It seems like you could get rid of all these conditionals by
just putting this here:

	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
		return;


> +> 	> of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);
> +
> +> 	> if (!elfcorehdr_size)
> +> 	> 	> return;
> +
> +> 	> if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
> +> 	> 	> pr_warn("elfcorehdr is overlapped\n");
> +> 	> 	> return;
> +> 	> }
> +
> +> 	> memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
> +
> +> 	> pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
> +> 	> 	> elfcorehdr_size >> 10, elfcorehdr_addr);
> +}
> +#else
> +static void __init reserve_elfcorehdr(void)
> +{
> +> 	> ;
> +}
> +#endif /* CONFIG_CRASH_DUMP */
>  /*
>   * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
>   * currently assumes that for memory starting above 4G, 32-bit devices will
> @@ -389,6 +441,8 @@ void __init arm64_memblock_init(void)
>  
>  > 	> reserve_crashkernel();
>  
> +> 	> reserve_elfcorehdr();
> +
>  > 	> early_init_fdt_scan_reserved_mem();
>  
>  > 	> /* 4GB maximum for 32-bit only capable devices */