Subject: [PATCH v22 1/8] arm64: kdump: reserve memory for crash dump kernel

From: [email-masked] (Dennis Chen)
Date: Tue, 19 Jul 2016 17:39:07 +0800

Hello AKASHI,

On Tue, Jul 12, 2016 at 02:05:07PM +0900, AKASHI Takahiro wrote:
> 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 as
>       - "Crash kernel" in /proc/iomem, or
>       - "linux,crashkernel-base" and "linux,crashkernel-size" under
>         /sys/firmware/devicetree/base/chosen
>
> Signed-off-by: AKASHI Takahiro <[email-masked]>
> Signed-off-by: Mark Salter <[email-masked]>
> Signed-off-by: Pratyush Anand <[email-masked]>
> Reviewed-by: James Morse <[email-masked]>
> ---
>  arch/arm64/kernel/setup.c |   7 ++-
>  arch/arm64/mm/init.c      | 115 ++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 121 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index c1509e6..cb5eee0 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -31,7 +31,6 @@
>  #include <linux/screen_info.h>
>  #include <linux/init.h>
>  #include <linux/kexec.h>
> -#include <linux/crash_dump.h>
>  #include <linux/root_dev.h>
>  #include <linux/cpu.h>
>  #include <linux/interrupt.h>
> @@ -222,6 +221,12 @@ static void __init request_standard_resources(void)
>                   kernel_data.end <= res->end)
>                       request_resource(res, &kernel_data);
>       }
> +
> +#ifdef CONFIG_KEXEC_CORE
> +     /* User space tools will find "Crash kernel" region in /proc/iomem. */
> +     if (crashk_res.end)
> +             insert_resource(&iomem_resource, &crashk_res);
> +#endif
>  }
>
>  u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 2ade7a6..51b1302 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -29,11 +29,13 @@
>  #include <linux/gfp.h>
>  #include <linux/memblock.h>
>  #include <linux/sort.h>
> +#include <linux/of.h>
>  #include <linux/of_fdt.h>
>  #include <linux/dma-mapping.h>
>  #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 +78,117 @@ static int __init early_initrd(char *p)
>  early_param("initrd", early_initrd);
>  #endif
>
> +#ifdef CONFIG_KEXEC_CORE
> +static unsigned long long crash_size, crash_base;
> +static struct property crash_base_prop = {
> +     .name = "linux,crashkernel-base",
> +     .length = sizeof(u64),
> +     .value = &crash_base
> +};
> +static struct property crash_size_prop = {
> +     .name = "linux,crashkernel-size",
> +     .length = sizeof(u64),
> +     .value = &crash_size,
> +};
> +
> +static int __init export_crashkernel(void)
> +{
> +     struct device_node *node;
> +     int ret;
> +
> +     if (!crashk_res.end)
> +             return 0;
> +
> +     crash_base = cpu_to_be64(crashk_res.start);
> +     crash_size = cpu_to_be64(crashk_res.end - crashk_res.start + 1);
> +
> +     /* Add /chosen/linux,crashkernel-* properties */
> +     node = of_find_node_by_path("/chosen");
> +     if (!node)
> +             return -ENOENT;
> +
> +     /*
> +      * There might be existing crash kernel properties, but we can't
> +      * be sure what's in them, so remove them.
> +      */
> +     of_remove_property(node, of_find_property(node,
> +                             "linux,crashkernel-base", NULL));
> +     of_remove_property(node, of_find_property(node,
> +                             "linux,crashkernel-size", NULL));
> +
> +     ret = of_add_property(node, &crash_base_prop);
> +     if (ret)
> +             goto ret_err;
> +
> +     ret = of_add_property(node, &crash_size_prop);
> +     if (ret)
> +             goto ret_err;
> +
> +     return 0;
> +
> +ret_err:
> +     pr_warn("Exporting crashkernel region to device tree failed\n");
> +     return ret;
> +}
> +late_initcall(export_crashkernel);
> +
> +/*
> + * 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)
> +{
> +     int ret;
> +
> +     ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> +                             &crash_size, &crash_base);
> +     /* no crashkernel= or invalid value specified */
> +     if (ret || !crash_size)
> +             return;
> +
> +     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);
>
I am not pretty sure the context here, but
can we use below code piece instead of the above lines?
        if (crash_base == 0)
                memblock_alloc(crash_size, SZ_2M);

Thanks,
Dennis

> +
> +     } 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)) {
> +                     pr_warn("crashkernel base address is not 2MB aligned\n");
> +                     return;
> +             }
> +
> +             memblock_reserve(crash_base, crash_size);
> +     }
> +
> +     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
> @@ -289,6 +402,8 @@ void __init arm64_memblock_init(void)
>       }
>  #endif
>
> +     reserve_crashkernel();
> +
>       early_init_fdt_scan_reserved_mem();
>
>       /* 4GB maximum for 32-bit only capable devices */
> --
> 2.9.0
>
>
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