[Cbe-oss-dev] [PATCH] 64K support for Kexec

[Luke Browning]

This patch decodes the page size from the pte. This code is used by
kexec, which walks the hash table and issues a tlbie for each 
valid entry. The page size is encoded in the virtual address that
is passed to the tlbie instruction.

Signed-off-by: Luke Browning <lukebrowning at us.ibm.com>

Index: linux-2.6.21-rc4/arch/powerpc/mm/hash_native_64.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/mm/hash_native_64.c	2007-04-06
11:20:38.000000000 -0300
+++ linux-2.6.21-rc4/arch/powerpc/mm/hash_native_64.c	2007-04-06
23:17:16.000000000 -0300
@@ -367,6 +367,34 @@
 	return va;
 }
 
+#define LP_SHIFT	12	
+#define LP_BITS		8	
+#define LP_MASK(i)	((((1 << LP_BITS) - 1) >> (i)) << LP_SHIFT)
+
+static int hpte_decode_lpsize(unsigned long pa)
+{
+	int penc, i;
+
+	if (pa & LP_MASK(0)) {
+		for (i = 0; i < LP_BITS; i++) {
+			if ((pa & LP_MASK(i+1)) == LP_MASK(i+1))
+				break;
+		}
+		penc = LP_MASK(i+1) >> LP_SHIFT;
+		for (i = MMU_PAGE_COUNT - 1; i > 0; i--) {
+			if (!mmu_psize_defs[i].shift)
+				continue;
+			if (penc == mmu_psize_defs[i].penc)
+				break;
+		}
+	}
+	else {
+		i = MMU_PAGE_16M; 
+	}
+
+	return i;
+}
+
 /*
  * clear all mappings on kexec.  All cpus are in real mode (or they
will
  * be when they isi), and we are the only one left.  We rely on our
kernel
@@ -383,6 +411,7 @@
 	hpte_t *hptep = htab_address;
 	unsigned long hpte_v;
 	unsigned long pteg_count;
+	int psize;
 
 	pteg_count = htab_hash_mask + 1;
 
@@ -408,8 +437,12 @@
 		 * already hold the native_tlbie_lock.
 		 */
 		if (hpte_v & HPTE_V_VALID) {
+			if (!(hpte_v & HPTE_V_LARGE))
+                                psize = MMU_PAGE_4K;
+                        else
+                                psize = hpte_decode_lpsize(hptep->r);
 			hptep->v = 0;
-			__tlbie(slot2va(hpte_v, slot), MMU_PAGE_4K);
+			__tlbie(slot2va(hpte_v, slot), psize);
 		}
 	}