powerpc/mm: Simplify hpte_decode

This patch simplify hpte_decode for easy switching of virtual address to
virtual page number in the later patch

Reviewed-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 28 insertions, 21 deletions

diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
index f21e8ce8db33..ebf685af4af2 100644
--- a/arch/powerpc/mm/hash_native_64.c
+++ b/arch/powerpc/mm/hash_native_64.c
@@ -351,9 +351,10 @@ static void native_hpte_invalidate(unsigned long slot, unsigned long va,
 static void hpte_decode(struct hash_pte *hpte, unsigned long slot,
                         int *psize, int *ssize, unsigned long *va)
 {
+        unsigned long avpn, pteg, vpi;
         unsigned long hpte_r = hpte->r;
         unsigned long hpte_v = hpte->v;
-        unsigned long avpn;
+        unsigned long vsid, seg_off;
         int i, size, shift, penc;
 
         if (!(hpte_v & HPTE_V_LARGE))
@@ -380,32 +381,38 @@ static void hpte_decode(struct hash_pte *hpte, unsigned long slot,
         }
 
         /* This works for all page sizes, and for 256M and 1T segments */
+        *ssize = hpte_v >> HPTE_V_SSIZE_SHIFT;
         shift = mmu_psize_defs[size].shift;
-        avpn = (HPTE_V_AVPN_VAL(hpte_v) & ~mmu_psize_defs[size].avpnm) << 23;
-
-        if (shift < 23) {
-                unsigned long vpi, vsid, pteg;
 
-                pteg = slot / HPTES_PER_GROUP;
-                if (hpte_v & HPTE_V_SECONDARY)
-                        pteg = ~pteg;
-                switch (hpte_v >> HPTE_V_SSIZE_SHIFT) {
-                case MMU_SEGSIZE_256M:
-                        vpi = ((avpn >> 28) ^ pteg) & htab_hash_mask;
-                        break;
-                case MMU_SEGSIZE_1T:
-                        vsid = avpn >> 40;
+        avpn = (HPTE_V_AVPN_VAL(hpte_v) & ~mmu_psize_defs[size].avpnm);
+        pteg = slot / HPTES_PER_GROUP;
+        if (hpte_v & HPTE_V_SECONDARY)
+                pteg = ~pteg;
+
+        switch (*ssize) {
+        case MMU_SEGSIZE_256M:
+                /* We only have 28 - 23 bits of seg_off in avpn */
+                seg_off = (avpn & 0x1f) << 23;
+                vsid    =  avpn >> 5;
+                /* We can find more bits from the pteg value */
+                if (shift < 23) {
+                        vpi = (vsid ^ pteg) & htab_hash_mask;
+                        seg_off |= vpi << shift;
+                }
+                *va = vsid << SID_SHIFT | seg_off;
+        case MMU_SEGSIZE_1T:
+                /* We only have 40 - 23 bits of seg_off in avpn */
+                seg_off = (avpn & 0x1ffff) << 23;
+                vsid    = avpn >> 17;
+                if (shift < 23) {
                         vpi = (vsid ^ (vsid << 25) ^ pteg) & htab_hash_mask;
-                        break;
-                default:
-                        avpn = vpi = size = 0;
+                        seg_off |= vpi << shift;
                 }
-                avpn |= (vpi << mmu_psize_defs[size].shift);
+                *va = vsid << SID_SHIFT_1T | seg_off;
+        default:
+                *va = size = 0;
         }
-
-        *va = avpn;
         *psize = size;
-        *ssize = hpte_v >> HPTE_V_SSIZE_SHIFT;
 }
 
 /*