linux-kernel - Re: [PATCH v20 2/5] arm64: kdump: introduce some macros for crash kernel reservation

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Date:   Mon, 14 Feb 2022 14:22:19 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Baoquan He <bhe@...hat.com>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        <x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>,
        <linux-kernel@...r.kernel.org>, Dave Young <dyoung@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        <kexec@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>, "Jonathan Corbet" <corbet@....net>,
        <linux-doc@...r.kernel.org>, Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>,
        "John Donnelly" <John.p.donnelly@...cle.com>,
        Dave Kleikamp <dave.kleikamp@...cle.com>
Subject: Re: [PATCH v20 2/5] arm64: kdump: introduce some macros for crash
 kernel reservation



On 2022/2/11 18:39, Baoquan He wrote:
> On 01/24/22 at 04:47pm, Zhen Lei wrote:
>> From: Chen Zhou <chenzhou10@...wei.com>
>>
>> Introduce macro CRASH_ALIGN for alignment, macro CRASH_ADDR_LOW_MAX
>> for upper bound of low crash memory, macro CRASH_ADDR_HIGH_MAX for
>> upper bound of high crash memory, use macros instead.
>>
>> Signed-off-by: Chen Zhou <chenzhou10@...wei.com>
>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>> Tested-by: John Donnelly <John.p.donnelly@...cle.com>
>> Tested-by: Dave Kleikamp <dave.kleikamp@...cle.com>
>> ---
>>  arch/arm64/mm/init.c | 11 ++++++++---
>>  1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 90f276d46b93bc6..6c653a2c7cff052 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -65,6 +65,12 @@ EXPORT_SYMBOL(memstart_addr);
>>  phys_addr_t arm64_dma_phys_limit __ro_after_init;
>>  
>>  #ifdef CONFIG_KEXEC_CORE
>> +/* Current arm64 boot protocol requires 2MB alignment */
>> +#define CRASH_ALIGN		SZ_2M
>> +
>> +#define CRASH_ADDR_LOW_MAX	arm64_dma_phys_limit
>> +#define CRASH_ADDR_HIGH_MAX	MEMBLOCK_ALLOC_ACCESSIBLE
> 
> MEMBLOCK_ALLOC_ACCESSIBLE is obvoiously a alloc flag for memblock
> allocator, I don't think it's appropriate to make HIGH_MAX get its value.

Right, thanks.

> You can make it as memblock.current_limit, or do not define it, but using
> MEMBLOCK_ALLOC_ACCESSIBLE direclty in memblock_phys_alloc_range() with
> a code comment. 

This patch is not required at present. These macros are added to eliminate
differences to share code with x86.

> 
> 
>> +
>>  /*
>>   * reserve_crashkernel() - reserves memory for crash kernel
>>   *
>> @@ -75,7 +81,7 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
>>  static void __init reserve_crashkernel(void)
>>  {
>>  	unsigned long long crash_base, crash_size;
>> -	unsigned long long crash_max = arm64_dma_phys_limit;
>> +	unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
>>  	int ret;
>>  
>>  	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
>> @@ -90,8 +96,7 @@ static void __init reserve_crashkernel(void)
>>  	if (crash_base)
>>  		crash_max = crash_base + crash_size;
>>  
>> -	/* Current arm64 boot protocol requires 2MB alignment */
>> -	crash_base = memblock_phys_alloc_range(crash_size, SZ_2M,
>> +	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
>>  					       crash_base, crash_max);
>>  	if (!crash_base) {
>>  		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
>> -- 
>> 2.25.1
>>
> 
> .
> 

-- 
Regards,
  Zhen Lei