Subject: [PATCH v19 06/13] arm64: kdump: reserve memory for crash dump kernel

From: [email-masked] (James Morse)
Date: Mon, 20 Jun 2016 17:07:11 +0100

Hi,

On 17/06/16 00:48, Geoff Levand wrote:
> From: AKASHI Takahiro <[email-masked]>
> 
> On the startup of primary kernel, the memory region used by crash dump
> kernel must be specified by "crashkernel=" kernel parameter.
> reserve_crashkernel() will allocate and reserve the region for later use.
> 
> User space tools, like kexec-tools, will be able to find that region marked
> as "Crash kernel" in /proc/iomem.

> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index d45f862..45f1319 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -34,6 +34,7 @@
>  #include <linux/dma-contiguous.h>
>  #include <linux/efi.h>
>  #include <linux/swiotlb.h>
> +#include <linux/kexec.h>
>  
>  #include <asm/boot.h>
>  #include <asm/fixmap.h>
> @@ -76,6 +77,65 @@ static int __init early_initrd(char *p)
>  early_param("initrd", early_initrd);
>  #endif
>  
> +#ifdef CONFIG_KEXEC_CORE
> +/*
> + * reserve_crashkernel() - reserves memory for crash kernel
> + *
> + * This function reserves memory area given in "crashkernel=" kernel command
> + * line parameter. The memory reserved is used by dump capture kernel when
> + * primary kernel is crashing.
> + */
> +static void __init reserve_crashkernel(void)
> +{
> +	unsigned long long crash_size = 0, crash_base = 0;
> +	int ret;
> +
> +	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> +				&crash_size, &crash_base);
> +	/* no crashkernel= or invalid value specified */
> +	if (!crash_size)
> +		return;

Should we check ret too?

> +
> +	if (crash_base == 0) {
> +		/* Current arm64 boot protocol requires 2MB alignment */
> +		crash_base = memblock_find_in_range(0,
> +				MEMBLOCK_ALLOC_ACCESSIBLE, crash_size, SZ_2M);
> +		if (crash_base == 0) {
> +			pr_warn("Unable to allocate crashkernel (size:%llx)\n",
> +				crash_size);
> +			return;
> +		}
> +		memblock_reserve(crash_base, crash_size);

What if memblock_reserve() fails?

> +
> +	} else {
> +		/* User specifies base address explicitly. */
> +		if (!memblock_is_region_memory(crash_base, crash_size) ||
> +			memblock_is_region_reserved(crash_base, crash_size)) {
> +			pr_warn("crashkernel has wrong address or size\n");
> +			return;
> +		}
> +
> +		if (IS_ALIGNED(crash_base, SZ_2M)) {

!IS_ALIGNED()...

> +			pr_warn("crashkernel base address is not 2MB aligned\n");
> +			return;
> +		}
> +
> +		memblock_reserve(crash_base, crash_size);

What if memblock_reserve() fails?

> +	}
> +
> +	pr_info("Reserving %lldMB of memory at %lldMB for crashkernel\n",
> +		crash_size >> 20, crash_base >> 20);
> +
> +	crashk_res.start = crash_base;
> +	crashk_res.end = crash_base + crash_size - 1;
> +}
> +#else
> +static void __init reserve_crashkernel(void)
> +{
> +	;
> +}
> +#endif /* CONFIG_KEXEC_CORE */
> +
>  /*
>   * 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
> @@ -291,6 +351,8 @@ void __init arm64_memblock_init(void)
>  	}
>  #endif
>  
> +	reserve_crashkernel();
> +
>  	early_init_fdt_scan_reserved_mem();
>  
>  	/* 4GB maximum for 32-bit only capable devices */
> 

With those,
Reviewed-by: James Morse <[email-masked]>

Thanks,

James