Re: [PATCH 07/11] of: reserved_mem: add no-dump crash_mem exclusion helpers

[Wandun <chenwandun1@gmail.com>]

On 5/6/26 22:50, Rob Herring wrote:
> On Wed, Apr 29, 2026 at 02:58:27PM +0800, Chen Wandun wrote:
>> Provide two kdump-oriented helpers so that arch kexec_file code does
>> not have to open-code the no-dump filtering loop:
>>
>>   - of_reserved_mem_no_dump_nr_ranges() returns the number of reserved
>>     regions flagged with linux,no-dump. Each exclusion may split one
>>     existing crash_mem range into two, so callers use this count to
>>     pre-size their crash_mem allocation.
>>
>>   - of_reserved_mem_exclude_no_dump() walks the reserved_mem[] array
>>     and calls crash_exclude_mem_range() for each no-dump region.
>>
>> Both helpers are guarded by CONFIG_KEXEC_FILE; empty inline stubs are
>> provided for the !KEXEC_FILE case so architecture code can call them
>> unconditionally.
>>
>> The consumers are added in the following arm64, riscv and loongarch
>> patches in this series.
>>
>> Signed-off-by: Chen Wandun <chenwandun@lixiang.com>
>> Tested-by: Zhao Meijing <zhaomeijing@lixiang.com>
>> ---
>>   drivers/of/of_reserved_mem.c    | 54 +++++++++++++++++++++++++++++++++
>>   include/linux/of_reserved_mem.h | 15 +++++++++
>>   2 files changed, 69 insertions(+)
>>
>> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
>> index 4b80420da2d2..038056a6408a 100644
>> --- a/drivers/of/of_reserved_mem.c
>> +++ b/drivers/of/of_reserved_mem.c
>> @@ -27,6 +27,10 @@
>>   
>>   #include "of_private.h"
>>   
>> +#ifdef CONFIG_KEXEC_FILE
>> +#include <linux/crash_core.h>
>> +#endif
> You shouldn't need ifdef around includes.
>
>> +
>>   static struct reserved_mem reserved_mem_array[MAX_RESERVED_REGIONS] __initdata;
>>   static struct reserved_mem *reserved_mem __refdata = reserved_mem_array;
>>   static int total_reserved_mem_cnt = MAX_RESERVED_REGIONS;
>> @@ -916,6 +920,56 @@ struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
>>   }
>>   EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);
>>   
>> +#ifdef CONFIG_KEXEC_FILE
> Use 'if (IS_ENABLED())' within the function.
Get it, thanks.
>
>> +/**
>> + * of_reserved_mem_no_dump_nr_ranges() - count reserved regions flagged
>> + * with the linux,no-dump property.
>> + *
>> + * Each such region may split an existing crash_mem range into two when
>> + * it is excluded, so callers can use this count to pre-size their
>> + * crash_mem allocation.
>> + */
>> +unsigned int of_reserved_mem_no_dump_nr_ranges(void)
>> +{
>> +	unsigned int i, n = 0;
>> +
>> +	for (i = 0; i < reserved_mem_count; i++)
>> +		if (reserved_mem[i].no_dump)
>> +			n++;
>> +	return n;
>> +}
>> +
>> +/**
>> + * of_reserved_mem_exclude_no_dump() - exclude no-dump reserved regions
>> + * from a crash_mem list.
>> + * @cmem: crash memory list to modify
>> + *
>> + * Walks the reserved_mem[] array and calls crash_exclude_mem_range() for
>> + * every region with no_dump set. Intended to be called from arch kdump
>> + * code when constructing the elfcorehdr.
>> + *
>> + * Returns 0 on success, or a negative error returned by
>> + * crash_exclude_mem_range() on the first failure.
>> + */
>> +int of_reserved_mem_exclude_no_dump(struct crash_mem *cmem)
>> +{
>> +	unsigned int i;
>> +	int ret;
>> +
>> +	for (i = 0; i < reserved_mem_count; i++) {
>> +		struct reserved_mem *r = &reserved_mem[i];
>> +
>> +		if (!r->no_dump || !r->size)
>> +			continue;
>> +		ret = crash_exclude_mem_range(cmem, r->base,
>> +					      r->base + r->size - 1);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +	return 0;
>> +}
>> +#endif /* CONFIG_KEXEC_FILE */