powerpc/mm: Don't track subpage valid bit in pte_t
This free up 11 bits in pte_t. In the later patch we also change
the pte_t format so that we can start supporting migration pte
at pmd level. We now track 4k subpage valid bit as below
If we have _PAGE_COMBO set, we override the _PAGE_F_GIX_SHIFT
and _PAGE_F_SECOND. Together we have 4 bits, each of them
used to indicate whether any of the 4 4k subpage in that group
is valid. ie,
[ group 1 bit ] [ group 2 bit ] ..... [ group 4 ]
[ subpage 1 - 4] [ subpage 5- 8] ..... [ subpage 13 - 16]
We still track each 4k subpage slot number and secondary hash
information in the second half of pgtable_t. Removing the subpage
tracking have some significant overhead on aim9 and ebizzy benchmark and
to support THP with 4K subpage, we do need a pgtable_t of 4096 bytes.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/mm/hash64_64k.c b/arch/powerpc/mm/hash64_64k.c
index 9ffeae2..f1b86ba 100644
--- a/arch/powerpc/mm/hash64_64k.c
+++ b/arch/powerpc/mm/hash64_64k.c
@@ -15,6 +15,35 @@
#include <linux/mm.h>
#include <asm/machdep.h>
#include <asm/mmu.h>
+/*
+ * index from 0 - 15
+ */
+bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
+{
+ unsigned long g_idx;
+ unsigned long ptev = pte_val(rpte.pte);
+
+ g_idx = (ptev & _PAGE_COMBO_VALID) >> _PAGE_F_GIX_SHIFT;
+ index = index >> 2;
+ if (g_idx & (0x1 << index))
+ return true;
+ else
+ return false;
+}
+/*
+ * index from 0 - 15
+ */
+static unsigned long mark_subptegroup_valid(unsigned long ptev, unsigned long index)
+{
+ unsigned long g_idx;
+
+ if (!(ptev & _PAGE_COMBO))
+ return ptev;
+ index = index >> 2;
+ g_idx = 0x1 << index;
+
+ return ptev | (g_idx << _PAGE_F_GIX_SHIFT);
+}
int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
pte_t *ptep, unsigned long trap, unsigned long flags,
@@ -102,7 +131,7 @@
*/
if (!(old_pte & _PAGE_COMBO)) {
flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
- old_pte &= ~_PAGE_HPTE_SUB;
+ old_pte &= ~_PAGE_HASHPTE | _PAGE_F_GIX | _PAGE_F_SECOND;
goto htab_insert_hpte;
}
/*
@@ -192,7 +221,8 @@
/* __real_pte use pte_val() any idea why ? FIXME!! */
rpte.hidx &= ~(0xfUL << (subpg_index << 2));
*hidxp = rpte.hidx | (slot << (subpg_index << 2));
- new_pte |= (_PAGE_HPTE_SUB0 >> subpg_index);
+ new_pte = mark_subptegroup_valid(new_pte, subpg_index);
+ new_pte |= _PAGE_HASHPTE;
/*
* check __real_pte for details on matching smp_rmb()
*/
