[Makedumpfile PATCH] book3s/ppc64: Lower the max real address to 53 bits for kernels >= v4.11

[Hari Bathini]

On Monday 11 September 2017 07:05 AM, Dave Young wrote:
> Cc more people.
>
> On 09/08/17 at 10:10am, Bhupesh Sharma wrote:
>> Kernel commit 2f18d533757da3899f4bedab0b2c051b080079dc lowered the
>> max real address on ppc64 to 53 bits.
>>
>> Make similar changes in makedumpfile (on basis of the underlying kernel
>> version), without which the makedumpfile will fail to create a dumpfile
>> and instead throw a SEGV fault as shown below on kernels >= v4.11:
>>
>>   # makedumpfile --split -d 31 -x vmlinux vmcore dumpfile_{1,2,3} 2>&1
>>
>>   The kernel version is not supported.
>>   The makedumpfile operation may be incomplete.
>>   [ 1196.252094] makedumpfile[2367]: unhandled signal 11 at
>>   00000100f7011ca8 nip 000000001001eecc lr 000000001001f3c0 code 30001
>>   Segmentation fault

I have not hit the above problem, but for the sake of correctness,
this patch is needed for >= 4.11.0 kernels. So..

Acked-by: Hari Bathini <hbathini at linux.vnet.ibm.com>

>> Signed-off-by: Bhupesh Sharma <bhsharma at redhat.com>
>> ---
>>   makedumpfile.h | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/makedumpfile.h b/makedumpfile.h
>> index 7d81bbcf2234..142753d84e8d 100644
>> --- a/makedumpfile.h
>> +++ b/makedumpfile.h
>> @@ -684,8 +684,9 @@ unsigned long get_kvbase_arm64(void);
>>   #define PMD_MASKED_BITS_64K_4_6  0xc0000000000000ffUL
>>   
>>   #define PTE_RPN_MASK_DEFAULT  0xffffffffffffffffUL
>> -#define PTE_RPN_SIZE_L4_4_6   (info->page_size == 65536 ? 41 : 45)
>> -#define PTE_RPN_MASK_L4_4_6   (((1UL << PTE_RPN_SIZE_L4_4_6) - 1) << info->page_shift)
>> +#define PAGE_PA_MAX_L4_4_6    (info->kernel_version >= KERNEL_VERSION(4,11,0) ? 53 : 57)
>> +#define PTE_RPN_MASK_L4_4_6   \
>> +	(((1UL << PAGE_PA_MAX_L4_4_6) - 1) & ~((1UL << info->page_shift) - 1))
>>   #define PTE_RPN_SHIFT_L4_4_6  info->page_shift
>>   
>>   #define PGD_MASKED_BITS_4_7  0xc0000000000000ffUL
>> -- 
>> 2.7.4
>>