On 28 March 2017 at 07:51, AKASHI Takahiro <takahiro.akashi at linaro.org> wrote:
> "crashkernel=" kernel parameter specifies the size (and optionally
> the start address) of the system ram to be used by crash dump kernel.
> reserve_crashkernel() will allocate and reserve that memory at boot time
> of primary kernel.
>
> The memory range will be exposed to userspace as a resource named
> "Crash kernel" in /proc/iomem.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> Signed-off-by: Mark Salter <msalter at redhat.com>
> Signed-off-by: Pratyush Anand <panand at redhat.com>
> Reviewed-by: James Morse <james.morse at arm.com>
> Acked-by: Catalin Marinas <catalin.marinas at arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
> arch/arm64/kernel/setup.c | 7 ++++-
> arch/arm64/mm/init.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 72 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 42274bda0ccb..28855ec1be95 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>
> @@ -226,6 +225,12 @@ static void __init request_standard_resources(void)
> if (kernel_data.start >= res->start &&
> kernel_data.end <= res->end)
> request_resource(res, &kernel_data);
> +#ifdef CONFIG_KEXEC_CORE
> + /* Userspace will find "Crash kernel" region in /proc/iomem. */
> + if (crashk_res.end && crashk_res.start >= res->start &&
> + crashk_res.end <= res->end)
> + request_resource(res, &crashk_res);
> +#endif
> }
> }
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 290794b1a0f1..09d19207362d 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -30,6 +30,7 @@
> #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>
> @@ -37,6 +38,7 @@
> #include <linux/swiotlb.h>
> #include <linux/vmalloc.h>
> #include <linux/mm.h>
> +#include <linux/kexec.h>
>
> #include <asm/boot.h>
> #include <asm/fixmap.h>
> @@ -77,6 +79,67 @@ 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_base, crash_size;
> + 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;
> +
> + crash_size = PAGE_ALIGN(crash_size);
> +
> + if (crash_base == 0) {
> + /* Current arm64 boot protocol requires 2MB alignment */
> + crash_base = memblock_find_in_range(0, ARCH_LOW_ADDRESS_LIMIT,
> + crash_size, SZ_2M);
> + if (crash_base == 0) {
> + pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> + crash_size);
> + return;
> + }
> + } else {
> + /* User specifies base address explicitly. */
> + if (!memblock_is_region_memory(crash_base, crash_size)) {
> + pr_warn("cannot reserve crashkernel: region is not memory\n");
> + return;
> + }
> +
> + if (memblock_is_region_reserved(crash_base, crash_size)) {
> + pr_warn("cannot reserve crashkernel: region overlaps reserved memory\n");
> + return;
> + }
> +
> + if (!IS_ALIGNED(crash_base, SZ_2M)) {
> + pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
> + return;
> + }
> + }
> + memblock_reserve(crash_base, crash_size);
> +
> + pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
> + crash_base, crash_base + crash_size, crash_size >> 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
> @@ -332,6 +395,9 @@ void __init arm64_memblock_init(void)
> arm64_dma_phys_limit = max_zone_dma_phys();
> else
> arm64_dma_phys_limit = PHYS_MASK + 1;
> +
> + reserve_crashkernel();
> +
> dma_contiguous_reserve(arm64_dma_phys_limit);
>
> memblock_allow_resize();
> --
> 2.11.1
>
