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

[Atsushi Kumagai]

Hello Bradley,

Sorry for my late reply, I'll merge this patch into v1.6.3.
Thanks for your work.

Regards,
Atsushi Kumagai

>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>
>---
> arch/arm64.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
>diff --git a/arch/arm64.c b/arch/arm64.c
>index 958f57f..cae4b70 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 */
>+		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");
>--
>1.9.3
>
>
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