powerpc: Move default hash table size calculation to hash_utils_64.c

We weren't computing the size of the hash table correctly on iSeries
because the relevant code in prom.c was #ifdef CONFIG_PPC_PSERIES.
This moves the code to hash_utils_64.c, makes it unconditional, and
cleans it up a bit.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 35dd93eeaf4b..6e9e05cce02c 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -155,6 +155,27 @@ static inline void create_pte_mapping(unsigned long start, unsigned long end,
         }
 }
 
+static unsigned long get_hashtable_size(void)
+{
+        unsigned long rnd_mem_size, pteg_count;
+
+        /* If hash size wasn't obtained in prom.c, we calculate it now based on
+         * the total RAM size
+         */
+        if (ppc64_pft_size)
+                return 1UL << ppc64_pft_size;
+
+        /* round mem_size up to next power of 2 */
+        rnd_mem_size = 1UL << __ilog2(systemcfg->physicalMemorySize);
+        if (rnd_mem_size < systemcfg->physicalMemorySize)
+                rnd_mem_size <<= 1;
+
+        /* # pages / 2 */
+        pteg_count = max(rnd_mem_size >> (12 + 1), 1UL << 11);
+
+        return pteg_count << 7;
+}
+
 void __init htab_initialize(void)
 {
         unsigned long table, htab_size_bytes;
@@ -170,7 +191,7 @@ void __init htab_initialize(void)
          * Calculate the required size of the htab.  We want the number of
          * PTEGs to equal one half the number of real pages.
          */ 
-        htab_size_bytes = 1UL << ppc64_pft_size;
+        htab_size_bytes = get_hashtable_size();
         pteg_count = htab_size_bytes >> 7;
 
         /* For debug, make the HTAB 1/8 as big as it normally would be. */