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Date:   Wed, 3 Apr 2019 14:29:30 +0300
From:   Mike Rapoport <rppt@linux.ibm.com>
To:     Chen Zhou <chenzhou10@huawei.com>
Cc:     catalin.marinas@arm.com, will.deacon@arm.com,
        akpm@linux-foundation.org, ard.biesheuvel@linaro.org,
        takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
        linux-mm@kvack.org, wangkefeng.wang@huawei.com
Subject: Re: [PATCH 2/3] arm64: kdump: support more than one crash kernel
 regions
References: <20190403030546.23718-1-chenzhou10@huawei.com>
 <20190403030546.23718-3-chenzhou10@huawei.com>
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On Wed, Apr 03, 2019 at 11:05:45AM +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]>
> 
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> ---
>  arch/arm64/mm/init.c     | 37 +++++++++++++++++++++++++------------
>  include/linux/memblock.h |  1 +
>  mm/memblock.c            | 40 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 66 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index ceb2a25..769c77a 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -64,6 +64,8 @@ EXPORT_SYMBOL(memstart_addr);
>  phys_addr_t arm64_dma_phys_limit __ro_after_init;
>  
>  #ifdef CONFIG_KEXEC_CORE
> +# define CRASH_MAX_USABLE_RANGES        2
> +
>  static int __init reserve_crashkernel_low(void)
>  {
>  	unsigned long long base, low_base = 0, low_size = 0;
> @@ -346,8 +348,8 @@ 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;
> @@ -356,22 +358,33 @@ 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,
> -	};
> -
> -	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
> -
> -	if (reg.size)
> -		memblock_cap_memory_range(reg.base, reg.size);
> +	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)
> +		memblock_cap_memory_ranges(regs, cnt);

Why not simply call memblock_cap_memory_range() for each region?

>  }
>  
>  void __init arm64_memblock_init(void)
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 47e3c06..aeade34 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -446,6 +446,7 @@ phys_addr_t memblock_start_of_DRAM(void);
>  phys_addr_t memblock_end_of_DRAM(void);
>  void memblock_enforce_memory_limit(phys_addr_t memory_limit);
>  void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);
> +void memblock_cap_memory_ranges(struct memblock_region *regs, int cnt);
>  void memblock_mem_limit_remove_map(phys_addr_t limit);
>  bool memblock_is_memory(phys_addr_t addr);
>  bool memblock_is_map_memory(phys_addr_t addr);
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 28fa8926..1a7f4ee7c 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1697,6 +1697,46 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
>  			base + size, PHYS_ADDR_MAX);
>  }
>  
> +void __init memblock_cap_memory_ranges(struct memblock_region *regs, int cnt)
> +{
> +	int start_rgn[INIT_MEMBLOCK_REGIONS], end_rgn[INIT_MEMBLOCK_REGIONS];
> +	int i, j, ret, nr = 0;
> +
> +	for (i = 0; i < cnt; i++) {
> +		ret = memblock_isolate_range(&memblock.memory, regs[i].base,
> +				regs[i].size, &start_rgn[i], &end_rgn[i]);
> +		if (ret)
> +			break;
> +		nr++;
> +	}
> +	if (!nr)
> +		return;
> +
> +	/* remove all the MAP regions */
> +	for (i = memblock.memory.cnt - 1; i >= end_rgn[nr - 1]; i--)
> +		if (!memblock_is_nomap(&memblock.memory.regions[i]))
> +			memblock_remove_region(&memblock.memory, i);
> +
> +	for (i = nr - 1; i > 0; i--)
> +		for (j = start_rgn[i] - 1; j >= end_rgn[i - 1]; j--)
> +			if (!memblock_is_nomap(&memblock.memory.regions[j]))
> +				memblock_remove_region(&memblock.memory, j);
> +
> +	for (i = start_rgn[0] - 1; i >= 0; i--)
> +		if (!memblock_is_nomap(&memblock.memory.regions[i]))
> +			memblock_remove_region(&memblock.memory, i);
> +
> +	/* truncate the reserved regions */
> +	memblock_remove_range(&memblock.reserved, 0, regs[0].base);
> +
> +	for (i = nr - 1; i > 0; i--)
> +		memblock_remove_range(&memblock.reserved,
> +				regs[i].base, regs[i - 1].base + regs[i - 1].size);
> +
> +	memblock_remove_range(&memblock.reserved,
> +			regs[nr - 1].base + regs[nr - 1].size, PHYS_ADDR_MAX);
> +}
> +
>  void __init memblock_mem_limit_remove_map(phys_addr_t limit)
>  {
>  	phys_addr_t max_addr;
> -- 
> 2.7.4
> 

-- 
Sincerely yours,
Mike.