[PATCH v13 6/8] arm64: kdump: reimplement crashkernel=X
Baoquan He
bhe at redhat.com
Tue Nov 10 20:59:26 EST 2020
On 10/31/20 at 03:44pm, Chen Zhou wrote:
> There are following issues in arm64 kdump:
> 1. We use crashkernel=X to reserve crashkernel below 4G, which
> will fail when there is no enough low memory.
> 2. If reserving crashkernel above 4G, in this case, crash dump
> kernel will boot failure because there is no low memory available
> for allocation.
> 3. Since commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32"),
> if the memory reserved for crash dump kernel falled in ZONE_DMA32,
> the devices in crash dump kernel need to use ZONE_DMA will alloc
> fail.
>
> To solve these issues, change the behavior of crashkernel=X and
> introduce crashkernel=X,[high,low]. crashkernel=X tries low allocation
> in DMA zone or DMA32 zone if CONFIG_ZONE_DMA is disabled, and fall back
> to high allocation if it fails.
> We can also use "crashkernel=X,high" to select a region above DMA zone,
> which also tries to allocate at least 256M in DMA zone automatically
> (or the DMA32 zone if CONFIG_ZONE_DMA is disabled).
> "crashkernel=Y,low" can be used to allocate specified size low memory.
>
> Another minor change, there may be two regions reserved for crash
> dump kernel, in order to distinct from the high region and make no
> effect to the use of existing kexec-tools, rename the low region as
> "Crash kernel (low)".
>
> Signed-off-by: Chen Zhou <chenzhou10 at huawei.com>
> Tested-by: John Donnelly <John.p.donnelly at oracle.com>
> ---
> arch/arm64/include/asm/kexec.h | 9 +++++
> arch/arm64/kernel/setup.c | 13 +++++++-
> arch/arm64/mm/init.c | 60 ++--------------------------------
> arch/arm64/mm/mmu.c | 4 +++
> kernel/crash_core.c | 8 +++--
> 5 files changed, 34 insertions(+), 60 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
> index 402d208265a3..79909ae5e22e 100644
> --- a/arch/arm64/include/asm/kexec.h
> +++ b/arch/arm64/include/asm/kexec.h
> @@ -28,7 +28,12 @@
> /* 2M alignment for crash kernel regions */
> #define CRASH_ALIGN SZ_2M
>
> +#ifdef CONFIG_ZONE_DMA
> +#define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit
> +#else
> #define CRASH_ADDR_LOW_MAX arm64_dma32_phys_limit
> +#endif
> +
> #define CRASH_ADDR_HIGH_MAX MEMBLOCK_ALLOC_ACCESSIBLE
>
> #ifndef __ASSEMBLY__
> @@ -96,6 +101,10 @@ static inline void crash_prepare_suspend(void) {}
> static inline void crash_post_resume(void) {}
> #endif
>
> +#ifdef CONFIG_KEXEC_CORE
> +extern void __init reserve_crashkernel(void);
> +#endif
> +
> #ifdef CONFIG_KEXEC_FILE
> #define ARCH_HAS_KIMAGE_ARCH
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 133257ffd859..6aff30de8f47 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -238,7 +238,18 @@ static void __init request_standard_resources(void)
> kernel_data.end <= res->end)
> request_resource(res, &kernel_data);
> #ifdef CONFIG_KEXEC_CORE
> - /* Userspace will find "Crash kernel" region in /proc/iomem. */
> + /*
> + * Userspace will find "Crash kernel" or "Crash kernel (low)"
> + * region in /proc/iomem.
> + * In order to distinct from the high region and make no effect
> + * to the use of existing kexec-tools, rename the low region as
> + * "Crash kernel (low)".
> + */
> + if (crashk_low_res.end && crashk_low_res.start >= res->start &&
> + crashk_low_res.end <= res->end) {
> + crashk_low_res.name = "Crash kernel (low)";
> + request_resource(res, &crashk_low_res);
> + }
> if (crashk_res.end && crashk_res.start >= res->start &&
> crashk_res.end <= res->end)
> request_resource(res, &crashk_res);
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index a07fd8e1f926..888c4f7eadc3 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -34,6 +34,7 @@
> #include <asm/fixmap.h>
> #include <asm/kasan.h>
> #include <asm/kernel-pgtable.h>
> +#include <asm/kexec.h>
> #include <asm/memory.h>
> #include <asm/numa.h>
> #include <asm/sections.h>
> @@ -62,66 +63,11 @@ EXPORT_SYMBOL(memstart_addr);
> phys_addr_t arm64_dma_phys_limit __ro_after_init;
> phys_addr_t arm64_dma32_phys_limit __ro_after_init;
>
> -#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(CRASH_ALIGN, CRASH_ADDR_LOW_MAX,
> - crash_size, CRASH_ALIGN);
> - 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, CRASH_ALIGN)) {
> - 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
> +#ifndef CONFIG_KEXEC_CORE
> static void __init reserve_crashkernel(void)
> {
> }
> -#endif /* CONFIG_KEXEC_CORE */
> +#endif
>
> #ifdef CONFIG_CRASH_DUMP
> static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 1c0f3e02f731..c55cee290bbb 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -488,6 +488,10 @@ static void __init map_mem(pgd_t *pgdp)
> */
> memblock_mark_nomap(kernel_start, kernel_end - kernel_start);
> #ifdef CONFIG_KEXEC_CORE
> + if (crashk_low_res.end)
> + memblock_mark_nomap(crashk_low_res.start,
> + resource_size(&crashk_low_res));
> +
> if (crashk_res.end)
> memblock_mark_nomap(crashk_res.start,
> resource_size(&crashk_res));
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index d39892bdb9ae..cdef7d8c91a6 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -321,7 +321,7 @@ int __init parse_crashkernel_low(char *cmdline,
>
> int __init reserve_crashkernel_low(void)
> {
> -#ifdef CONFIG_X86_64
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
Not very sure if a CONFIG_64BIT checking is better.
> unsigned long long base, low_base = 0, low_size = 0;
> unsigned long low_mem_limit;
> int ret;
> @@ -362,12 +362,14 @@ int __init reserve_crashkernel_low(void)
>
> crashk_low_res.start = low_base;
> crashk_low_res.end = low_base + low_size - 1;
> +#ifdef CONFIG_X86_64
> insert_resource(&iomem_resource, &crashk_low_res);
> +#endif
> #endif
> return 0;
> }
>
> -#ifdef CONFIG_X86
> +#if defined(CONFIG_X86) || defined(CONFIG_ARM64)
Should we make this weak default so that we can remove the ARCH config?
> #ifdef CONFIG_KEXEC_CORE
> /*
> * reserve_crashkernel() - reserves memory for crash kernel
> @@ -453,7 +455,9 @@ void __init reserve_crashkernel(void)
>
> crashk_res.start = crash_base;
> crashk_res.end = crash_base + crash_size - 1;
> +#ifdef CONFIG_X86
> insert_resource(&iomem_resource, &crashk_res);
> +#endif
> }
> #endif /* CONFIG_KEXEC_CORE */
> #endif
> --
> 2.20.1
>
>
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