ppc64 power4 SLB optimisations:

set the class bit for kernel segments.
preload all 16 segments for 32 bit tasks, pc and sp segments for
64 bit tasks.
add commented out code to only invalidate 16 user segments for
32 bit tasks, we need to pass in the previous task to use this.

arch/ppc64/kernel/head.S

@@ -993,6 +993,7 @@ SLB_NUM_ENTRIES = 64
 	li      r21,0
 	rldimi  r21,r20,12,0
 	ori     r20,r21,1024
+	ori	r20,r20,128    /* set class bit for kernel region */
 #ifndef CONFIG_PPC_ISERIES
 	ori	r20,r20,256    /* map kernel region with large ptes */
 #endif

arch/ppc64/kernel/stab.c

@@ -18,10 +18,10 @@
 #include <asm/Naca.h>
 #include <asm/pmc.h>
 
-inline int make_ste(unsigned long stab, 
-		    unsigned long esid, unsigned long vsid);
-inline void make_slbe(unsigned long esid, unsigned long vsid,
-		      int large);
+int make_ste(unsigned long stab, 
+	     unsigned long esid, unsigned long vsid);
+void make_slbe(unsigned long esid, unsigned long vsid,
+	       int large);
 extern struct Naca *naca;
 
 /*
@@ -56,8 +56,7 @@ void stab_initialize(unsigned long stab)
 /*
  * Create a segment table entry for the given esid/vsid pair.
  */ 
-inline int
-make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
+int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
 {
 	unsigned long entry, group, old_esid, castout_entry, i;
 	unsigned int global_entry;
@@ -146,11 +145,11 @@ make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
 
 /*
  * Create a segment buffer entry for the given esid/vsid pair.
- */ 
-inline void make_slbe(unsigned long esid, unsigned long vsid, int large)
+ */
+void make_slbe(unsigned long esid, unsigned long vsid, int large)
 {
+	int kernel_segment = 0;
 	unsigned long entry, castout_entry;
-	slb_dword0 castout_esid_data;
 	union {
 		unsigned long word0;
 		slb_dword0    data;
@@ -159,7 +158,10 @@ inline void make_slbe(unsigned long esid, unsigned long vsid, int large)
 		unsigned long word0;
 		slb_dword1    data;
 	} vsid_data;
-	
+
+	if (REGION_ID(esid << SID_SHIFT) >= KERNEL_REGION_ID)
+		kernel_segment = 1;
+
 	/*
 	 * Find an empty entry, if one exists.
 	 */
@@ -175,6 +177,8 @@ inline void make_slbe(unsigned long esid, unsigned long vsid, int large)
 			vsid_data.data.kp = 1;
 			if (large)
 				vsid_data.data.l = 1;
+			if (kernel_segment)
+				vsid_data.data.c = 1;
 
 			esid_data.word0 = 0;
 			esid_data.data.esid = esid;
@@ -200,21 +204,13 @@ inline void make_slbe(unsigned long esid, unsigned long vsid, int large)
 	PMC_SW_PROCESSOR(stab_capacity_castouts); 
 
 	castout_entry = get_paca()->xStab_data.next_round_robin;
-	__asm__ __volatile__("slbmfee  %0,%1" 
-			     : "=r" (castout_esid_data) 
-			     : "r" (castout_entry)); 
-
 	entry = castout_entry; 
 	castout_entry++; 
-	if(castout_entry >= naca->slb_size) {
+	if (castout_entry >= naca->slb_size)
 		castout_entry = 1; 
-	}
 	get_paca()->xStab_data.next_round_robin = castout_entry;
 
-	/* Invalidate the old entry. */
-	castout_esid_data.v = 0; /* Set the class to 0 */
 	/* slbie not needed as the previous mapping is still valid. */
-	__asm__ __volatile__("slbie  %0" : : "r" (castout_esid_data)); 
 	
 	/* 
 	 * Write the new SLB entry.
@@ -224,6 +220,8 @@ inline void make_slbe(unsigned long esid, unsigned long vsid, int large)
 	vsid_data.data.kp = 1;
 	if (large)
 		vsid_data.data.l = 1;
+	if (kernel_segment)
+		vsid_data.data.c = 1;
 	
 	esid_data.word0 = 0;
 	esid_data.data.esid = esid;
@@ -300,7 +298,7 @@ int ste_allocate ( unsigned long ea,
 
 #define STAB_PRESSURE 0
 
-void flush_stab(void)
+void flush_stab(struct task_struct *tsk, struct mm_struct *mm)
 {
 	STE *stab = (STE *) get_paca()->xStab_data.virt;
 	unsigned char *segments = get_paca()->xSegments;
@@ -349,12 +347,57 @@ void flush_stab(void)
 		/* Force flush to complete.  */
 		__asm__ __volatile__ ("sync" : : : "memory");  
 	} else {
+/* XXX The commented out code will only work for 32 bit tasks */
+#if 1
 		unsigned long flags;
-
-		PMC_SW_PROCESSOR(stab_invalidations); 
-
 		__save_and_cli(flags);
 		__asm__ __volatile__("isync; slbia; isync":::"memory");
 		__restore_flags(flags);
+#else
+		union {
+			unsigned long word0;
+			slb_dword0 data;
+		} esid_data;
+		unsigned long esid;
+
+		__asm__ __volatile__("isync" : : : "memory");
+		for (esid = 0; esid < 16; esid++) {
+			esid_data.word0 = 0;
+			esid_data.data.esid = esid;
+			__asm__ __volatile__("slbie %0" : : "r" (esid_data));
+		}
+		__asm__ __volatile__("isync" : : : "memory");
+#endif
+
+		PMC_SW_PROCESSOR(stab_invalidations);
+
+		if (test_tsk_thread_flag(tsk, TIF_32BIT)) {
+			unsigned long esid, vsid;
+
+			for (esid = 0; esid < 16; esid++) {
+				vsid = get_vsid(mm->context, esid << SID_SHIFT);
+				make_slbe(esid, vsid, 0);
+			}
+		} else {
+			unsigned long pc = KSTK_EIP(tsk);
+			unsigned long stack = KSTK_ESP(tsk);
+			unsigned long pc_segment = pc & ~SID_MASK;
+			unsigned long stack_segment = stack & ~SID_MASK;
+			unsigned long vsid;
+
+			if (pc) {
+				if (REGION_ID(pc) >= KERNEL_REGION_ID)
+					BUG();
+				vsid = get_vsid(mm->context, pc);
+				make_slbe(GET_ESID(pc), vsid, 0);
+			}
+
+			if (stack && (pc_segment != stack_segment)) {
+				if (REGION_ID(stack) >= KERNEL_REGION_ID)
+					BUG();
+				vsid = get_vsid(mm->context, stack);
+				make_slbe(GET_ESID(stack), vsid, 0);
+			}
+		}
 	}
 }