[PATCH v2] makedumpfile: arm64: Fix page table walk of 1GB section

[Atsushi Kumagai]

>On Thursday 17 August 2017 05:31 AM, Bradley Bolen wrote:
>> From: Bradley Bolen <bbolen at lexmark.com>
>>
>> makedumpfile was generating large (> 500MB) vmcore files for an arm64
>> board with 2GB of DRAM.  It was not excluding any pages because the
>> mem_map address was not being converted correctly.
>>
>> readmem: Can't convert a virtual address(ffffffc07fff6000) to physical
>> address.
>> readmem: type_addr: 0, addr:ffffffc07fff6000, size:16
>> section_mem_map_addr: Can't get a struct mem_section(ffffffc07fff6000).
>> mem_map (0)
>> mem_map : 0
>>
>> makedumpfile was not handling 1GB sections in the PGD and was trying to
>> drill down to a PTE in which it was trying to dereference invalid
>> memory.  This patch adds code to check the PGD for a section type and
>> handle it instead of treating it as a table entry.
>>
>> Signed-off-by: Bradley Bolen <bradleybolen at gmail.com>

I'll merge this patch into v1.6.3, thanks,

>Reviewed-by: Pratyush Anand <panand at redhat.com>

Thanks for your comment for the comments, actually I was just wondering
about those comments.

Regards,
Atsushi Kumagai

>> ---
>> Changes in v2:
>> - updated comments
>>
>>   arch/arm64.c | 15 ++++++++++++++-
>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64.c b/arch/arm64.c
>> index 958f57f..25d7a1f 100644
>> --- a/arch/arm64.c
>> +++ b/arch/arm64.c
>> @@ -57,6 +57,8 @@ static unsigned long kimage_voffset;
>>   #define PGDIR_SHIFT		((PAGESHIFT() - 3) * pgtable_level + 3)
>>   #define PTRS_PER_PGD		(1 << (va_bits - PGDIR_SHIFT))
>>   #define PUD_SHIFT		get_pud_shift_arm64()
>> +#define PUD_SIZE		(1UL << PUD_SHIFT)
>> +#define PUD_MASK		(~(PUD_SIZE - 1))
>>   #define PTRS_PER_PTE		(1 << (PAGESHIFT() - 3))
>>   #define PTRS_PER_PUD		PTRS_PER_PTE
>>   #define PMD_SHIFT		((PAGESHIFT() - 3) * 2 + 3)
>> @@ -79,6 +81,10 @@ static unsigned long kimage_voffset;
>>   #define PMD_TYPE_SECT		1
>>   #define PMD_TYPE_TABLE		3
>>
>> +#define PUD_TYPE_MASK		3
>> +#define PUD_TYPE_SECT		1
>> +#define PUD_TYPE_TABLE		3
>> +
>>   #define pgd_index(vaddr) 		(((vaddr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
>>   #define pgd_offset(pgdir, vaddr)	((pgd_t *)(pgdir) + pgd_index(vaddr))
>>
>> @@ -253,6 +259,13 @@ vaddr_to_paddr_arm64(unsigned long vaddr)
>>   		return NOT_PADDR;
>>   	}
>>
>> +	if ((pud_val(pudv) & PUD_TYPE_MASK) == PUD_TYPE_SECT) {
>> +		/* 1GB section for Page Table level = 4 and Page Size = 4KB */
>> +		paddr = (pud_val(pudv) & (PUD_MASK & PMD_SECTION_MASK))
>> +					+ (vaddr & (PUD_SIZE - 1));
>> +		return paddr;
>> +	}
>> +
>>   	pmda = pmd_offset(puda, &pudv, vaddr);
>>   	if (!readmem(PADDR, (unsigned long long)pmda, &pmdv, sizeof(pmdv))) {
>>   		ERRMSG("Can't read pmd\n");
>> @@ -278,7 +291,7 @@ vaddr_to_paddr_arm64(unsigned long vaddr)
>>   		}
>>   		break;
>>   	case PMD_TYPE_SECT:
>> -		/* 1GB section */
>> +		/* 512MB section for Page Table level = 3 and Page Size = 64KB*/
>>   		paddr = (pmd_val(pmdv) & (PMD_MASK & PMD_SECTION_MASK))
>>   					+ (vaddr & (PMD_SIZE - 1));
>>   		break;
>>
>
>--
>Regards
>Pratyush
>
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