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SubjectRe: [PATCH v3 3/4] arm64: kdump: support more than one crash kernel regions
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Hi Mike,

On 2019/4/14 20:13, Mike Rapoport wrote:
> Hi,
>
> On Tue, Apr 09, 2019 at 06:28:18PM +0800, Chen Zhou wrote:
>> After commit (arm64: kdump: support reserving crashkernel above 4G),
>> there may be two crash kernel regions, one is below 4G, the other is
>> above 4G.
>>
>> Crash dump kernel reads more than one crash kernel regions via a dtb
>> property under node /chosen,
>> linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>
>
> Somehow I've missed that previously, but how is this supposed to work on
> EFI systems?

Whatever the way in which the systems work, there is FDT pointer(__fdt_pointer)
in arm64 kernel and file /sys/firmware/fdt will be created in late_initcall.

Kexec-tools read and update file /sys/firmware/fdt in EFI systems to support kdump to
boot capture kernel.

For supporting more than one crash kernel regions, kexec-tools make changes accordingly.
Details are in below:
http://lists.infradead.org/pipermail/kexec/2019-April/022792.html

Thanks,
Chen Zhou

>
>> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
>> ---
>> arch/arm64/mm/init.c | 66 ++++++++++++++++++++++++++++++++++++++++--------
>> include/linux/memblock.h | 6 +++++
>> mm/memblock.c | 7 ++---
>> 3 files changed, 66 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 3bebddf..0f18665 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -65,6 +65,11 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
>>
>> #ifdef CONFIG_KEXEC_CORE
>>
>> +/* at most two crash kernel regions, low_region and high_region */
>> +#define CRASH_MAX_USABLE_RANGES 2
>> +#define LOW_REGION_IDX 0
>> +#define HIGH_REGION_IDX 1
>> +
>> /*
>> * reserve_crashkernel() - reserves memory for crash kernel
>> *
>> @@ -297,8 +302,8 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
>> const char *uname, int depth, void *data)
>> {
>> struct memblock_region *usablemem = data;
>> - const __be32 *reg;
>> - int len;
>> + const __be32 *reg, *endp;
>> + int len, nr = 0;
>>
>> if (depth != 1 || strcmp(uname, "chosen") != 0)
>> return 0;
>> @@ -307,22 +312,63 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
>> if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
>> return 1;
>>
>> - usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
>> - usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
>> + endp = reg + (len / sizeof(__be32));
>> + while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
>> + usablemem[nr].base = dt_mem_next_cell(dt_root_addr_cells, &reg);
>> + usablemem[nr].size = dt_mem_next_cell(dt_root_size_cells, &reg);
>> +
>> + if (++nr >= CRASH_MAX_USABLE_RANGES)
>> + break;
>> + }
>>
>> return 1;
>> }
>>
>> static void __init fdt_enforce_memory_region(void)
>> {
>> - struct memblock_region reg = {
>> - .size = 0,
>> - };
>> + int i, cnt = 0;
>> + struct memblock_region regs[CRASH_MAX_USABLE_RANGES];
>> +
>> + memset(regs, 0, sizeof(regs));
>> + of_scan_flat_dt(early_init_dt_scan_usablemem, regs);
>> +
>> + for (i = 0; i < CRASH_MAX_USABLE_RANGES; i++)
>> + if (regs[i].size)
>> + cnt++;
>> + else
>> + break;
>> +
>> + if (cnt - 1 == LOW_REGION_IDX)
>> + memblock_cap_memory_range(regs[LOW_REGION_IDX].base,
>> + regs[LOW_REGION_IDX].size);
>> + else if (cnt - 1 == HIGH_REGION_IDX) {
>> + /*
>> + * Two crash kernel regions, cap the memory range
>> + * [regs[LOW_REGION_IDX].base, regs[HIGH_REGION_IDX].end]
>> + * and then remove the memory range in the middle.
>> + */
>> + int start_rgn, end_rgn, i, ret;
>> + phys_addr_t mid_base, mid_size;
>> +
>> + mid_base = regs[LOW_REGION_IDX].base + regs[LOW_REGION_IDX].size;
>> + mid_size = regs[HIGH_REGION_IDX].base - mid_base;
>> + ret = memblock_isolate_range(&memblock.memory, mid_base,
>> + mid_size, &start_rgn, &end_rgn);
>>
>> - of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
>> + if (ret)
>> + return;
>>
>> - if (reg.size)
>> - memblock_cap_memory_range(reg.base, reg.size);
>> + memblock_cap_memory_range(regs[LOW_REGION_IDX].base,
>> + regs[HIGH_REGION_IDX].base -
>> + regs[LOW_REGION_IDX].base +
>> + regs[HIGH_REGION_IDX].size);
>> + for (i = end_rgn - 1; i >= start_rgn; i--) {
>> + if (!memblock_is_nomap(&memblock.memory.regions[i]))
>> + memblock_remove_region(&memblock.memory, i);
>> + }
>> + memblock_remove_range(&memblock.reserved, mid_base,
>> + mid_base + mid_size);
>> + }
>> }
>>
>> void __init arm64_memblock_init(void)
>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
>> index 294d5d8..787d252 100644
>> --- a/include/linux/memblock.h
>> +++ b/include/linux/memblock.h
>> @@ -110,9 +110,15 @@ void memblock_discard(void);
>>
>> phys_addr_t memblock_find_in_range(phys_addr_t start, phys_addr_t end,
>> phys_addr_t size, phys_addr_t align);
>> +void memblock_remove_region(struct memblock_type *type, unsigned long r);
>> void memblock_allow_resize(void);
>> int memblock_add_node(phys_addr_t base, phys_addr_t size, int nid);
>> int memblock_add(phys_addr_t base, phys_addr_t size);
>> +int memblock_isolate_range(struct memblock_type *type,
>> + phys_addr_t base, phys_addr_t size,
>> + int *start_rgn, int *end_rgn);
>> +int memblock_remove_range(struct memblock_type *type,
>> + phys_addr_t base, phys_addr_t size);
>> int memblock_remove(phys_addr_t base, phys_addr_t size);
>> int memblock_free(phys_addr_t base, phys_addr_t size);
>> int memblock_reserve(phys_addr_t base, phys_addr_t size);
>> diff --git a/mm/memblock.c b/mm/memblock.c
>> index e7665cf..1846e2d 100644
>> --- a/mm/memblock.c
>> +++ b/mm/memblock.c
>> @@ -357,7 +357,8 @@ phys_addr_t __init_memblock memblock_find_in_range(phys_addr_t start,
>> return ret;
>> }
>>
>> -static void __init_memblock memblock_remove_region(struct memblock_type *type, unsigned long r)
>> +void __init_memblock memblock_remove_region(struct memblock_type *type,
>> + unsigned long r)
>> {
>> type->total_size -= type->regions[r].size;
>> memmove(&type->regions[r], &type->regions[r + 1],
>> @@ -724,7 +725,7 @@ int __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
>> * Return:
>> * 0 on success, -errno on failure.
>> */
>> -static int __init_memblock memblock_isolate_range(struct memblock_type *type,
>> +int __init_memblock memblock_isolate_range(struct memblock_type *type,
>> phys_addr_t base, phys_addr_t size,
>> int *start_rgn, int *end_rgn)
>> {
>> @@ -784,7 +785,7 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,
>> return 0;
>> }
>>
>> -static int __init_memblock memblock_remove_range(struct memblock_type *type,
>> +int __init_memblock memblock_remove_range(struct memblock_type *type,
>> phys_addr_t base, phys_addr_t size)
>> {
>> int start_rgn, end_rgn;
>> --
>> 2.7.4
>>
>

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