1 files changed, 239 insertions, 0 deletions
diff --git a/arch/ppc64/mm/stab.c b/arch/ppc64/mm/stab.c
new file mode 100644
index 00000000000..31491131d5e
--- /dev/null
+++ b/arch/ppc64/mm/stab.c
@@ -0,0 +1,239 @@
+/*
+ * PowerPC64 Segment Translation Support.
+ *
+ * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
+ *    Copyright (c) 2001 Dave Engebretsen
+ *
+ * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <asm/pgtable.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/paca.h>
+#include <asm/cputable.h>
+
+/* Both the segment table and SLB code uses the following cache */
+#define NR_STAB_CACHE_ENTRIES 8
+DEFINE_PER_CPU(long, stab_cache_ptr);
+DEFINE_PER_CPU(long, stab_cache[NR_STAB_CACHE_ENTRIES]);
+
+/*
+ * Create a segment table entry for the given esid/vsid pair.
+ */
+static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
+{
+	unsigned long esid_data, vsid_data;
+	unsigned long entry, group, old_esid, castout_entry, i;
+	unsigned int global_entry;
+	struct stab_entry *ste, *castout_ste;
+	unsigned long kernel_segment = (esid << SID_SHIFT) >= KERNELBASE;
+
+	vsid_data = vsid << STE_VSID_SHIFT;
+	esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V;
+	if (! kernel_segment)
+		esid_data |= STE_ESID_KS;
+
+	/* Search the primary group first. */
+	global_entry = (esid & 0x1f) << 3;
+	ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
+
+	/* Find an empty entry, if one exists. */
+	for (group = 0; group < 2; group++) {
+		for (entry = 0; entry < 8; entry++, ste++) {
+			if (!(ste->esid_data & STE_ESID_V)) {
+				ste->vsid_data = vsid_data;
+				asm volatile("eieio":::"memory");
+				ste->esid_data = esid_data;
+				return (global_entry | entry);
+			}
+		}
+		/* Now search the secondary group. */
+		global_entry = ((~esid) & 0x1f) << 3;
+		ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
+	}
+
+	/*
+	 * Could not find empty entry, pick one with a round robin selection.
+	 * Search all entries in the two groups.
+	 */
+	castout_entry = get_paca()->stab_rr;
+	for (i = 0; i < 16; i++) {
+		if (castout_entry < 8) {
+			global_entry = (esid & 0x1f) << 3;
+			ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
+			castout_ste = ste + castout_entry;
+		} else {
+			global_entry = ((~esid) & 0x1f) << 3;
+			ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
+			castout_ste = ste + (castout_entry - 8);
+		}
+
+		/* Dont cast out the first kernel segment */
+		if ((castout_ste->esid_data & ESID_MASK) != KERNELBASE)
+			break;
+
+		castout_entry = (castout_entry + 1) & 0xf;
+	}
+
+	get_paca()->stab_rr = (castout_entry + 1) & 0xf;
+
+	/* Modify the old entry to the new value. */
+
+	/* Force previous translations to complete. DRENG */
+	asm volatile("isync" : : : "memory");
+
+	old_esid = castout_ste->esid_data >> SID_SHIFT;
+	castout_ste->esid_data = 0;		/* Invalidate old entry */
+
+	asm volatile("sync" : : : "memory");    /* Order update */
+
+	castout_ste->vsid_data = vsid_data;
+	asm volatile("eieio" : : : "memory");   /* Order update */
+	castout_ste->esid_data = esid_data;
+
+	asm volatile("slbie  %0" : : "r" (old_esid << SID_SHIFT));
+	/* Ensure completion of slbie */
+	asm volatile("sync" : : : "memory");
+
+	return (global_entry | (castout_entry & 0x7));
+}
+
+/*
+ * Allocate a segment table entry for the given ea and mm
+ */
+static int __ste_allocate(unsigned long ea, struct mm_struct *mm)
+{
+	unsigned long vsid;
+	unsigned char stab_entry;
+	unsigned long offset;
+
+	/* Kernel or user address? */
+	if (ea >= KERNELBASE) {
+		vsid = get_kernel_vsid(ea);
+	} else {
+		if ((ea >= TASK_SIZE_USER64) || (! mm))
+			return 1;
+
+		vsid = get_vsid(mm->context.id, ea);
+	}
+
+	stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
+
+	if (ea < KERNELBASE) {
+		offset = __get_cpu_var(stab_cache_ptr);
+		if (offset < NR_STAB_CACHE_ENTRIES)
+			__get_cpu_var(stab_cache[offset++]) = stab_entry;
+		else
+			offset = NR_STAB_CACHE_ENTRIES+1;
+		__get_cpu_var(stab_cache_ptr) = offset;
+
+		/* Order update */
+		asm volatile("sync":::"memory");
+	}
+
+	return 0;
+}
+
+int ste_allocate(unsigned long ea)
+{
+	return __ste_allocate(ea, current->mm);
+}
+
+/*
+ * Do the segment table work for a context switch: flush all user
+ * entries from the table, then preload some probably useful entries
+ * for the new task
+ */
+void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
+{
+	struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
+	struct stab_entry *ste;
+	unsigned long offset = __get_cpu_var(stab_cache_ptr);
+	unsigned long pc = KSTK_EIP(tsk);
+	unsigned long stack = KSTK_ESP(tsk);
+	unsigned long unmapped_base;
+
+	/* Force previous translations to complete. DRENG */
+	asm volatile("isync" : : : "memory");
+
+	if (offset <= NR_STAB_CACHE_ENTRIES) {
+		int i;
+
+		for (i = 0; i < offset; i++) {
+			ste = stab + __get_cpu_var(stab_cache[i]);
+			ste->esid_data = 0; /* invalidate entry */
+		}
+	} else {
+		unsigned long entry;
+
+		/* Invalidate all entries. */
+		ste = stab;
+
+		/* Never flush the first entry. */
+		ste += 1;
+		for (entry = 1;
+		     entry < (PAGE_SIZE / sizeof(struct stab_entry));
+		     entry++, ste++) {
+			unsigned long ea;
+			ea = ste->esid_data & ESID_MASK;
+			if (ea < KERNELBASE) {
+				ste->esid_data = 0;
+			}
+		}
+	}
+
+	asm volatile("sync; slbia; sync":::"memory");
+
+	__get_cpu_var(stab_cache_ptr) = 0;
+
+	/* Now preload some entries for the new task */
+	if (test_tsk_thread_flag(tsk, TIF_32BIT))
+		unmapped_base = TASK_UNMAPPED_BASE_USER32;
+	else
+		unmapped_base = TASK_UNMAPPED_BASE_USER64;
+
+	__ste_allocate(pc, mm);
+
+	if (GET_ESID(pc) == GET_ESID(stack))
+		return;
+
+	__ste_allocate(stack, mm);
+
+	if ((GET_ESID(pc) == GET_ESID(unmapped_base))
+	    || (GET_ESID(stack) == GET_ESID(unmapped_base)))
+		return;
+
+	__ste_allocate(unmapped_base, mm);
+
+	/* Order update */
+	asm volatile("sync" : : : "memory");
+}
+
+extern void slb_initialize(void);
+
+/*
+ * Build an entry for the base kernel segment and put it into
+ * the segment table or SLB.  All other segment table or SLB
+ * entries are faulted in.
+ */
+void stab_initialize(unsigned long stab)
+{
+	unsigned long vsid = get_kernel_vsid(KERNELBASE);
+
+	if (cpu_has_feature(CPU_FTR_SLB)) {
+		slb_initialize();
+	} else {
+		asm volatile("isync; slbia; isync":::"memory");
+		make_ste(stab, GET_ESID(KERNELBASE), vsid);
+
+		/* Order update */
+		asm volatile("sync":::"memory");
+	}
+}