----- Original Message -----
> Hi Dave,
>
> On Wed, 02 May 2012 09:21:57 -0400 (EDT)
> Dave Anderson <anderson@xxxxxxxxxx> wrote:
> >
> > ----- Original Message -----
> >
> > > >
> > > > And that's because when a "machdep->uvtop()" operation is done on
> > > > a user page that is not resident, the machine-dependent function
> > > > should return FALSE -- but it should return the PTE value in the
> > > > paddr pointer field so that it can be translated by
> > > > vm_area_page_dump(). The s390x_uvtop() does not return the PTE,
> > > > so the failed output can vary, because it's using an
> > > > uninitialized "paddr" stack variable. But this is another easy
> > > > fix, in this case to s390x_vtop():
> > > >
> > > > /* lookup virtual address in page tables */
> > > > int s390x_vtop(ulong table, ulong vaddr, physaddr_t *phys_addr,
> > > > int verbose) {
> > > > ulong entry, paddr;
> > > > int level, len;
> > > >
> > > > + *phys_addr = 0;
> > >
> > >
> > > Looks also good. But probably I should implement a better fix that
> > > returns the pte for s390x swap entries.
> >
> > That's true -- so since you've got the __swp_type() and __swp_offset()
> > macros #define'd for s390x, presumably it should work if you just pass
> > it back as is? Even though you've got the common s390x_vtop()
> > function used by both s390x_kvtop() and s390x_uvtop(), I think it
> > would be safe to pass the PTE entry back in either case, because
> > kvtop() operations don't care about the paddr contents if you return
> > FALSE.
>
> The following patch implements swap entry support for s390x and
> fixes your issues (2) and (3).
>
> Michael
> ---
> s390x.c | 32 +++++++++++++++++++++++++-------
> 1 file changed, 25 insertions(+), 7 deletions(-)
>
> --- a/s390x.c
> +++ b/s390x.c
> @@ -574,6 +574,19 @@ static ulong _kl_rsg_table_deref_s390x(u
> return entry;
> }
>
> +/* Check for swap entry */
> +static int swap_entry(ulong entry)
> +{
> + if (THIS_KERNEL_VERSION < LINUX(2,6,19)) {
> + if ((entry & 0x601ULL) == 0x600ULL)
> + return 1;
> + } else {
> + if ((entry & 0x403ULL) == 0x403ULL)
> + return 1;
> + }
> + return 0;
> +}
> +
> /* Page table traversal function */
> static ulong _kl_pg_table_deref_s390x(ulong vaddr, ulong table)
> {
> @@ -583,13 +596,11 @@ static ulong _kl_pg_table_deref_s390x(ul
> readmem(table + offset, KVADDR, &entry, sizeof(entry), "entry",
> FAULT_ON_ERROR);
> /*
> - * Check if the page table entry could be read and doesn't have
> - * any of the reserved bits set.
> + * Return zero if the page table entry has any of the reserved bits
> + * set (0x900) or the invalid bit (0x400) is set and it is not a
> + * swap entry.
> */
> - if (entry & 0x900ULL)
> - return 0;
> - /* Check if the page table entry has the invalid bit set. */
> - if (entry & 0x400ULL)
> + if ((entry & 0xd00ULL) && !swap_entry(entry))
> return 0;
> /* Page table entry is valid and well formed. */
> return entry;
> @@ -601,6 +612,7 @@ int s390x_vtop(ulong table, ulong vaddr,
> ulong entry, paddr;
> int level, len;
>
> + *phys_addr = 0;
> /*
> * Walk the region and segment tables.
> * We assume that the table length field in the asce is set to the
> @@ -619,7 +631,7 @@ int s390x_vtop(ulong table, ulong vaddr,
> while (level >= 0) {
> entry = _kl_rsg_table_deref_s390x(vaddr, table, len, level);
> if (!entry)
> - return 0;
> + return FALSE;
> table = entry & ~0xfffULL;
> len = entry & 0x3ULL;
> level--;
> @@ -637,6 +649,12 @@ int s390x_vtop(ulong table, ulong vaddr,
> if (!entry)
> return FALSE;
>
> + /* For swap entries we have to return FALSE and phys_addr = PTE */
> + if (swap_entry(entry)) {
> + *phys_addr = entry;
> + return FALSE;
> + }
> +
> /* Isolate the page origin from the page table entry. */
> paddr = entry & ~0xfffULL;
Nice -- queued for crash-6.0.7.
Thanks,
Dave
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