[PATCH 2/2] Revert "[PATCH V2 1/4] x86_64: Calculate page_offset from pt_load"

[Pratyush Anand]

On Tuesday 23 May 2017 08:53 AM, Pratyush Anand wrote:
> Hi Hatayama,
>
> On Tuesday 23 May 2017 08:24 AM, Hatayama, Daisuke wrote:
>> This reverts commit 0c9dd01d8ee2e4ec1821a11f5e174fdba56012b8 because
>> the logic works well only on the kdump ELF format. It doesn't work
>> well on sadump vmcores and qemu/KVM guest vmcores created by virsh
>> dump --memory-only command where info->page_offset results in 0. These
>> formats have to depend on kernel version dependency in the current
>> situation.
>
> I do not think that we should just revert it. Revert will break things on
> KASLR enabled kernel.
>
> I have already posted a patch to calculate page_offset when pt_load is not
> available.
>
> http://lists.infradead.org/pipermail/kexec/2017-May/018747.html
>
> Probably,I can improve that patch in next version so that it takes care of
> sadump case as well.
>

Can you please try following patches from  
https://github.com/pratyushanand/makedumpfile.git : devel

https://github.com/pratyushanand/makedumpfile/commit/ba93c349ac5d097a51c221e39816da5fef2e5f58
https://github.com/pratyushanand/makedumpfile/commit/241ecc6d96afbf7be6e02f51e882ce5e1e2eb9d0

~Pratyush


> Thanks for reporting this issue.
>
> ~Pratyush
>>
>> Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
>> Cc: Baoquan He <bhe at redhat.com>
>> Cc: Pratyush Anand <panand at redhat.com>
>> ---
>>  arch/x86_64.c | 25 ++++---------------------
>>  1 file changed, 4 insertions(+), 21 deletions(-)
>>
>> diff --git a/arch/x86_64.c b/arch/x86_64.c
>> index e978a36..13f0c3f 100644
>> --- a/arch/x86_64.c
>> +++ b/arch/x86_64.c
>> @@ -33,25 +33,6 @@ get_xen_p2m_mfn(void)
>>      return NOT_FOUND_LONG_VALUE;
>>  }
>>
>> -static int
>> -get_page_offset_x86_64(void)
>> -{
>> -    int i;
>> -    unsigned long long phys_start;
>> -    unsigned long long virt_start;
>> -
>> -    for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); i++) {
>> -        if (virt_start < __START_KERNEL_map
>> -                && phys_start != NOT_PADDR) {
>> -            info->page_offset = virt_start - phys_start;
>> -            return TRUE;
>> -        }
>> -    }
>> -
>> -    ERRMSG("Can't get any pt_load to calculate page offset.\n");
>> -    return FALSE;
>> -}
>> -
>>  int
>>  get_phys_base_x86_64(void)
>>  {
>> @@ -179,8 +160,10 @@ get_versiondep_info_x86_64(void)
>>      else
>>          info->max_physmem_bits  = _MAX_PHYSMEM_BITS_2_6_31;
>>
>> -    if (!get_page_offset_x86_64())
>> -        return FALSE;
>> +    if (info->kernel_version < KERNEL_VERSION(2, 6, 27))
>> +        info->page_offset = __PAGE_OFFSET_ORIG;
>> +    else
>> +        info->page_offset = __PAGE_OFFSET_2_6_27;
>>
>>      if (info->kernel_version < KERNEL_VERSION(2, 6, 31)) {
>>          info->vmemmap_start = VMEMMAP_START_ORIG;
>>