[Crash-utility] [PATCH RFC] arm64: fix vtop command when handling PUD mapping

[HAGIO KAZUHITO(萩尾 一仁)]

Hi,

thanks for the patch.

> -----Original Message-----
> Subject: [Crash-utility] [PATCH RFC] arm64: fix vtop command when handling PUD mapping 

I think probably this issue will appear not only with vtop command, so
I would suggest "arm64: handle 1GB block for VM_L4_4K" like the patch
fixing a similar issue for VM_L3_4K:

commit c25234e3573a7a0744430e922146ee362
Author: Johan Erlandsson <johan.erlandsson at sony.com>
Date:   Thu Mar 11 08:54:30 2021 +0000

    arm64: handle 1GB block for VM_L3_4K


Otherwise, the patch looks good to me.  With the change above:

Acked-by: Kazuhito Hagio <k-hagio-ab at nec.com>

Thanks,
Kazu

> When arm64 is configed with PAGE_SIZE=4k and 4 level
> translation, the pagetable of all pages may be created
> with block mapping or contiguous mapping as much as
> possible, likes disable CONFIG_RODATA_FULL_DEFAULT_ENABLED.
> But now, vtop command can not handle pud mapping well, and
> just shows a seek error:
> 
> crash> vtop ffff00184a800000
> VIRTUAL           PHYSICAL
> ffff00184a800000  188a800000
> 
> PAGE DIRECTORY: ffff8000110aa000
>    PGD: ffff8000110aa000 => 203fff9003
>    PUD: ffff001fffff9308 => 68001880000705
>    PMD: ffff0018400002a0 => ffff8000103b4fd0
> vtop: seek error: kernel virtual address: ffff7fffd03b4000  type: "page table"
> 
> This patch fixes it, and shows as following:
> 
> crash> vtop ffff00184a800000
> VIRTUAL           PHYSICAL
> ffff00184a800000  188a800000
> 
> PAGE DIRECTORY: ffff8000110aa000
>    PGD: ffff8000110aa000 => 203fff9003
>    PUD: ffff001fffff9308 => 68001880000705
>   PAGE: 1880000000  (1GB)
> 
>      PTE         PHYSICAL   FLAGS
> 68001880000705  1880000000  (VALID|SHARED|AF|PXN|UXN)
> 
>       PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS
> fffffe00610a0000 188a800000                0        0  0 77fffe0000000000
> 
> Signed-off-by: Rongwei Wang <rongwei.wang at linux.alibaba.com>
> ---
>  arm64.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/arm64.c b/arm64.c
> index 2177c52..65f6cdf 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -1999,6 +1999,16 @@ arm64_vtop_4level_4k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose)
>  	if (!pud_val)
>  		goto no_page;
> 
> +	if ((pud_val & PUD_TYPE_MASK) == PUD_TYPE_SECT) {
> +		ulong sectionbase = (pud_val & SECTION_PAGE_MASK_1GB) & PHYS_MASK;
> +		if (verbose) {
> +			fprintf(fp, "  PAGE: %lx  (1GB)\n\n", sectionbase);
> +			arm64_translate_pte(pud_val, 0, 0);
> +		}
> +		*paddr = sectionbase + (vaddr & ~SECTION_PAGE_MASK_1GB);
> +		return TRUE;
> +	}
> +
>  	pmd_base = (ulong *)PTOV(pud_val & PHYS_MASK & (s32)machdep->pagemask);
>  	FILL_PMD(pmd_base, KVADDR, PTRS_PER_PMD_L4_4K * sizeof(ulong));
>  	pmd_ptr = pmd_base + (((vaddr) >> PMD_SHIFT_L4_4K) & (PTRS_PER_PMD_L4_4K - 1));
> --
> 2.27.0
> 
> --
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