On 1/24/19 9:55 PM, dyoung@xxxxxxxxxx wrote:
> + Tom
> On 01/25/19 at 11:06am, lijiang wrote:
>> 在 2019年01月24日 06:16, Kazuhito Hagio 写道:
>>> On 1/22/2019 3:03 AM, Lianbo Jiang wrote:
>>>> For AMD machine with SME feature, if SME is enabled in the first
>>>> kernel, the crashed kernel's page table(pgd/pud/pmd/pte) contains
>>>> the memory encryption mask, so makedumpfile needs to remove the
>>>> memory encryption mask to obtain the true physical address.
>>>>
>>>> Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
>>>> ---
>>>> arch/x86_64.c | 3 +++
>>>> makedumpfile.c | 1 +
>>>> 2 files changed, 4 insertions(+)
>>>>
>>>> diff --git a/arch/x86_64.c b/arch/x86_64.c
>>>> index 537fb78..7651d36 100644
>>>> --- a/arch/x86_64.c
>>>> +++ b/arch/x86_64.c
>>>> @@ -346,6 +346,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>> return NOT_PADDR;
>>>> }
>>>> pud_paddr = pgd & ENTRY_MASK;
>>>> + pud_paddr = pud_paddr & ~(NUMBER(sme_mask));
>>>> }
>>>>
>>>> /*
>>>> @@ -371,6 +372,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>> * Get PMD.
>>>> */
>>>> pmd_paddr = pud_pte & ENTRY_MASK;
>>>> + pmd_paddr = pmd_paddr & ~(NUMBER(sme_mask));
>>>> pmd_paddr += pmd_index(vaddr) * sizeof(unsigned long);
>>>> if (!readmem(PADDR, pmd_paddr, &pmd_pte, sizeof pmd_pte)) {
>>>> ERRMSG("Can't get pmd_pte (pmd_paddr:%lx).\n", pmd_paddr);
>>>> @@ -391,6 +393,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>> * Get PTE.
>>>> */
>>>> pte_paddr = pmd_pte & ENTRY_MASK;
>>>> + pte_paddr = pte_paddr & ~(NUMBER(sme_mask));
>>>> pte_paddr += pte_index(vaddr) * sizeof(unsigned long);
>>>> if (!readmem(PADDR, pte_paddr, &pte, sizeof pte)) {
>>>> ERRMSG("Can't get pte (pte_paddr:%lx).\n", pte_paddr);
>>>> diff --git a/makedumpfile.c b/makedumpfile.c
>>>> index a03aaa1..81c7bb4 100644
>>>> --- a/makedumpfile.c
>>>> +++ b/makedumpfile.c
>>>> @@ -977,6 +977,7 @@ next_page:
>>>> read_size = MIN(info->page_size - PAGEOFFSET(paddr), size);
>>>>
>>>> pgaddr = PAGEBASE(paddr);
>>>> + pgaddr = pgaddr & ~(NUMBER(sme_mask));
>>>
>>> Since NUMBER(sme_mask) is initialized with -1 (NOT_FOUND_NUMBER),
>>> if the sme_mask is not in vmcoreinfo, ~(NUMBER(sme_mask)) will be 0.
>>> So the four lines added above need
>>>
>>> if (NUMBER(sme_mask) != NOT_FOUND_NUMBER)
>>> ...
>>>
>>
>> Thank you very much for pointing out my mistake.
>>
>> I will improve it and post again.
Might be worth creating a local variable that includes ENTRY_MASK and
NUMBER(sme_mask) so that you make the check just once. Then use that
variable in place of ENTRY_MASK in the remainder of the function so
that the correct value is used throughout.
This would also cover the 5-level path which would make this future
proof should AMD someday support 5-level paging.
>>
>>> and, what I'm wondering is whether it doesn't need to take hugepages
>>> into account such as this
>>>
>>> 392 if (pmd_pte & _PAGE_PSE) /* 2MB pages */
>>> 393 return (pmd_pte & ENTRY_MASK & PMD_MASK) +
>>> 394 (vaddr & ~PMD_MASK);
>>> "arch/x86_64.c"
>>>
>>
>> This is a good question. Theoretically, it should be modified accordingly for
>> huge pages case.
Yes, this should also have the ~(NUMBER(sme_mask)) applied to it. You
can probably add some debugging to see if you're hitting this case and
whether the encryption bit (sme_mask) is set just to help understand what
is occurring. This also goes for the 1GB page check above. However, if
you use my suggestion of a local variable then you should be covered.
Thanks,
Tom
>>
>> But makedumpfile still works well without this change. And i'm sure that the
>> huge pages are enabled in crashed kernel. This is very strange.
>>
>> Thanks.
>> Lianbo
>>
>>> Thanks,
>>> Kazu
>>>
>>>
>>>> pgbuf = cache_search(pgaddr, read_size);
>>>> if (!pgbuf) {
>>>> ++cache_miss;
>>>> --
>>>> 2.17.1
>>>>
>>>
>>>
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