[POWERPC] Fix warning in hpte_decode(), and generalize it

This adds the necessary support to hpte_decode() to handle 1TB
segments and 16GB pages, and removes an uninitialized value
warning on avpn.

We don't have any code to generate HPTEs for 1TB segments or 16GB
pages yet, so this is mostly for completeness, and to fix the
warning.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 17 insertions, 20 deletions

diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
index 7b7fe2d7b9dc..7d722eea4ea8 100644
--- a/arch/powerpc/mm/hash_native_64.c
+++ b/arch/powerpc/mm/hash_native_64.c
@@ -376,31 +376,28 @@ static void hpte_decode(hpte_t *hpte, unsigned long slot,
                 }
         }
 
-        /*
-         * FIXME, the code below works for 16M, 64K, and 4K pages as these
-         * fall under the p<=23 rules for calculating the virtual address.
-         * In the case of 16M pages, an extra bit is stolen from the AVPN
-         * field to achieve the requisite 24 bits.
-         *
-         * Does not work for 16G pages or 1 TB segments.
-         */
+        /* This works for all page sizes, and for 256M and 1T segments */
         shift = mmu_psize_defs[size].shift;
-        if (mmu_psize_defs[size].avpnm)
-                avpnm_bits = __ilog2_u64(mmu_psize_defs[size].avpnm) + 1;
-        else
-                avpnm_bits = 0;
-        if (shift - avpnm_bits <= 23) {
-                avpn = HPTE_V_AVPN_VAL(hpte_v) << 23;
+        avpn = (HPTE_V_AVPN_VAL(hpte_v) & ~mmu_psize_defs[size].avpnm) << 23;
 
-                if (shift < 23) {
-                        unsigned long vpi, pteg;
+        if (shift < 23) {
+                unsigned long vpi, vsid, pteg;
 
-                        pteg = slot / HPTES_PER_GROUP;
-                        if (hpte_v & HPTE_V_SECONDARY)
-                                pteg = ~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;
-                        avpn |= (vpi << mmu_psize_defs[size].shift);
+                        break;
+                case MMU_SEGSIZE_1T:
+                        vsid = avpn >> 40;
+                        vpi = (vsid ^ (vsid << 25) ^ pteg) & htab_hash_mask;
+                        break;
+                default:
+                        avpn = vpi = psize = 0;
                 }
+                avpn |= (vpi << mmu_psize_defs[size].shift);
         }
 
         *va = avpn;