[Crash-utility] [PATCH] s390x: Add page table walk information to vtop command

[Dave Anderson]

Hi Michael,

I'm leaving for a 2-week vacation as we speak -- I'll get back
to this on or about August 7th.

Thanks,
  Dave


> Hello Dave,
>
> This patch adds some output to the vtop command on s390x. Like on x86 we
> now
> print information for the page table walk:
>
>  * "Region-First-Table Entry" (RFTE)
>  * "Region-Second-Table Entry" (RSTE)
>  * "Region-Third-Table Entry" (RTTE)
>  * "Segment Table Entry" (STE)
>  * "Page Table Entry" (PTE)
>  * "Read address of page" (PAGE)
>
> Depending on the size of the address space the page tables can start at
> different levels.
>
> Example for three level page tables:
>
>   crash> vtop 3ff8000c000
>   VIRTUAL           PHYSICAL
>   3ff8000c000       2e3832000
>
>   PAGE DIRECTORY: 0000000000aaa000
>    RTTE: 0000000000aadff8 => 00000002e3c00007
>     STE: 00000002e3c00000 => 00000002e3df7000
>     PTE: 00000002e3df7060 => 00000002e383203d
>    PAGE: 00000002e3832000
>
>         PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
>   3d10b8e0c80      2e3832000                0        0  1 7fffc0000000000
>
> The first entry e.g. "PTE: 00000002e3df7060" is the physical address
> of the entry in the table. The second, e.g. "=> 00000002e383203d" is the
> content of the entry itself (address and flags).
>
> Reviewed-by: Heiko Carstens <heiko.carstens at de.ibm.com>
> Tested-by: Mikhail Zaslonko <zaslonko at linux.vnet.ibm.com>
> Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> ---
>  s390x.c | 31 +++++++++++++++++++++----------
>  1 file changed, 21 insertions(+), 10 deletions(-)
>
> diff --git a/s390x.c b/s390x.c
> index 96ce3dc..9246f75 100644
> --- a/s390x.c
> +++ b/s390x.c
> @@ -613,16 +613,19 @@ static inline int s390x_pte_present(unsigned long
> x){
>
>  /* Region or segment table traversal function */
>  static ulong _kl_rsg_table_deref_s390x(ulong vaddr, ulong table,
> -					 int len, int level)
> +				       int len, int level, int verbose)
>  {
> -	ulong offset, entry;
> +	const char *name_vec[] = {"STE", "RTTE", "RSTE", "RFTE"};
> +	ulong offset, entry, addr;
>
>  	offset = ((vaddr >> (11*level + 20)) & 0x7ffULL) * 8;
>  	if (offset >= (len + 1)*4096)
>  		/* Offset is over the table limit. */
>  		return 0;
> -	readmem(table + offset, KVADDR, &entry, sizeof(entry), "entry",
> -		FAULT_ON_ERROR);
> +	addr = table + offset;
> +	readmem(addr, KVADDR, &entry, sizeof(entry), "entry", FAULT_ON_ERROR);
> +	if (verbose)
> +		fprintf(fp, "%5s: %016lx => %016lx\n", name_vec[level], addr, entry);
>  	/*
>  	 * Check if the segment table entry could be read and doesn't have
>  	 * any of the reserved bits set.
> @@ -653,13 +656,17 @@ static int swap_entry(ulong entry)
>  }
>
>  /* Page table traversal function */
> -static ulong _kl_pg_table_deref_s390x(ulong vaddr, ulong table)
> +static ulong _kl_pg_table_deref_s390x(ulong vaddr, ulong table, int
> verbose)
>  {
> -	ulong offset, entry;
> +	ulong offset, entry, addr;
>
>  	offset = ((vaddr >> 12) & 0xffULL) * 8;
> -	readmem(table + offset, KVADDR, &entry, sizeof(entry), "entry",
> -		FAULT_ON_ERROR);
> +	addr = table + offset;
> +	readmem(addr, KVADDR, &entry, sizeof(entry), "entry", FAULT_ON_ERROR);
> +	if (verbose) {
> +		fprintf(fp, "%5s: %016lx => %016lx\n", "PTE", addr, entry);
> +		fprintf(fp, "%5s: %016llx\n", "PAGE", entry & ~0xfffULL);
> +	}
>  	/*
>  	 * Return zero if the page table entry has the reserved (0x800) or
>  	 * the invalid (0x400) bit set and it is not a swap entry.
> @@ -676,6 +683,9 @@ int s390x_vtop(ulong table, ulong vaddr, physaddr_t
> *phys_addr, int verbose)
>  	ulong entry, paddr;
>  	int level, len;
>
> +	if (verbose)
> +		fprintf(fp, "PAGE DIRECTORY: %016lx\n", table);
> +
>  	*phys_addr = 0;
>  	/*
>  	 * Walk the region and segment tables.
> @@ -693,7 +703,8 @@ int s390x_vtop(ulong table, ulong vaddr, physaddr_t
> *phys_addr, int verbose)
>  		return FALSE;
>  	}
>  	while (level >= 0) {
> -		entry = _kl_rsg_table_deref_s390x(vaddr, table, len, level);
> +		entry = _kl_rsg_table_deref_s390x(vaddr, table, len, level,
> +						  verbose);
>  		if (!entry)
>  			return FALSE;
>  		table = entry & ~0xfffULL;
> @@ -717,7 +728,7 @@ int s390x_vtop(ulong table, ulong vaddr, physaddr_t
> *phys_addr, int verbose)
>  	}
>
>  	/* Get the page table entry */
> -	entry = _kl_pg_table_deref_s390x(vaddr, entry & ~0x7ffULL);
> +	entry = _kl_pg_table_deref_s390x(vaddr, entry & ~0x7ffULL, verbose);
>  	if (!entry)
>  		return FALSE;
>
> --
> 2.11.2
>
> --
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