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

> 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
>

--
Sincerely yours,
Mike.

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