Re: [RFC 3/3] s390/mm: Define arch_get_addressable_range()

[Anshuman Khandual <anshuman.khandual@xxxxxxx>]

On 11/25/20 10:57 PM, David Hildenbrand wrote:
> On 23.11.20 03:28, Anshuman Khandual wrote:
>> This overrides arch_get_addressable_range() on s390 platform and drops
>> now redudant similar check in vmem_add_mapping().
>>
>> Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
>> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
>> Cc: David Hildenbrand <david@xxxxxxxxxx>
>> Cc: linux-s390@xxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
>> ---
>>  arch/s390/include/asm/mmu.h |  2 ++
>>  arch/s390/mm/vmem.c         | 16 ++++++++++++----
>>  2 files changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
>> index e12ff0f29d1a..f92d3926b188 100644
>> --- a/arch/s390/include/asm/mmu.h
>> +++ b/arch/s390/include/asm/mmu.h
>> @@ -55,4 +55,6 @@ static inline int tprot(unsigned long addr)
>>  	return rc;
>>  }
>>  
>> +#define arch_get_addressable_range arch_get_addressable_range
>> +struct range arch_get_addressable_range(bool need_mapping);
>>  #endif
>> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
>> index b239f2ba93b0..e03ad0ed13a7 100644
>> --- a/arch/s390/mm/vmem.c
>> +++ b/arch/s390/mm/vmem.c
>> @@ -532,14 +532,22 @@ void vmem_remove_mapping(unsigned long start, unsigned long size)
>>  	mutex_unlock(&vmem_mutex);
>>  }
>>  
>> +struct range arch_get_addressable_range(bool need_mapping)
>> +{
>> +	struct range memhp_range;
>> +
>> +	memhp_range.start = 0;
>> +	if (need_mapping)
>> +		memhp_range.end =  VMEM_MAX_PHYS;
>> +	else
>> +		memhp_range.end = (1ULL << (MAX_PHYSMEM_BITS + 1)) - 1;
>> +	return memhp_range;
>> +}
>> +
>>  int vmem_add_mapping(unsigned long start, unsigned long size)
>>  {
>>  	int ret;
>>  
>> -	if (start + size > VMEM_MAX_PHYS ||
>> -	    start + size < start)
>> -		return -ERANGE;
>> -
>>  	mutex_lock(&vmem_mutex);
>>  	ret = vmem_add_range(start, size);
>>  	if (ret)
>>
> 
> Note that vmem_add_mapping() is also called from extmem
> (arch/s390/mm/extmem.c).

Right, probably something like this should be able to take care of
the range check, it lost out earlier.

diff --git a/arch/s390/mm/extmem.c b/arch/s390/mm/extmem.c
index 5060956b8e7d..c61620ae5ee6 100644
--- a/arch/s390/mm/extmem.c
+++ b/arch/s390/mm/extmem.c
@@ -337,6 +337,11 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
                goto out_free_resource;
        }
 
+       if (seg->end + 1 > VMEM_MAX_PHYS || seg->end + 1 < seg->start) {
+               rc = -ERANGE;
+               goto out_resource;
+       }
+
        rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
        if (rc)
                goto out_resource;