[RFC v3 03/23] powerpc: introduce get_hidx_gslot helper

[Ram Pai <linuxram@us.ibm.com>]

Introduce get_hidx_gslot() which returns the slot number of the HPTE
in the global hash table.

This function will come in handy as we work towards re-arranging the
PTE bits in the later patches.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/hash.h |  3 +++
 arch/powerpc/mm/hash_utils_64.c           | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index ac049de..e7cf03a 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -162,6 +162,9 @@ static inline bool hpte_soft_invalid(unsigned long slot)
 	return ((slot & 0xfUL) == 0xfUL);
 }
 
+unsigned long get_hidx_gslot(unsigned long vpn, unsigned long shift,
+		int ssize, real_pte_t rpte, unsigned int subpg_index);
+
 /* This low level function performs the actual PTE insertion
  * Setting the PTE depends on the MMU type and other factors. It's
  * an horrible mess that I'm not going to try to clean up now but
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 1b494d0..99f97754c 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1591,6 +1591,20 @@ static inline void tm_flush_hash_page(int local)
 }
 #endif
 
+unsigned long get_hidx_gslot(unsigned long vpn, unsigned long shift,
+			int ssize, real_pte_t rpte, unsigned int subpg_index)
+{
+	unsigned long hash, slot, hidx;
+
+	hash = hpt_hash(vpn, shift, ssize);
+	hidx = __rpte_to_hidx(rpte, subpg_index);
+	if (hidx & _PTEIDX_SECONDARY)
+		hash = ~hash;
+	slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
+	slot += hidx & _PTEIDX_GROUP_IX;
+	return slot;
+}
+
 /* WARNING: This is called from hash_low_64.S, if you change this prototype,
  *          do not forget to update the assembly call site !
  */
-- 
1.8.3.1