OpenRISC: Memory management

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 193 insertions, 0 deletions

diff --git a/arch/openrisc/mm/tlb.c b/arch/openrisc/mm/tlb.c
new file mode 100644
index 000000000000..56b0b89624af
--- /dev/null
+++ b/arch/openrisc/mm/tlb.c
@@ -0,0 +1,193 @@
+/*
+ * OpenRISC tlb.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Julius Baxter <julius.baxter@orsoc.se>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      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/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/segment.h>
+#include <asm/tlbflush.h>
+#include <asm/pgtable.h>
+#include <asm/mmu_context.h>
+#include <asm/spr_defs.h>
+
+#define NO_CONTEXT -1
+
+#define NUM_DTLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
+			    SPR_DMMUCFGR_NTS_OFF))
+#define NUM_ITLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
+			    SPR_IMMUCFGR_NTS_OFF))
+#define DTLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_DTLB_SETS-1))
+#define ITLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_ITLB_SETS-1))
+/*
+ * Invalidate all TLB entries.
+ *
+ * This comes down to setting the 'valid' bit for all xTLBMR registers to 0.
+ * Easiest way to accomplish this is to just zero out the xTLBMR register
+ * completely.
+ *
+ */
+
+void flush_tlb_all(void)
+{
+	int i;
+	unsigned long num_tlb_sets;
+
+	/* Determine number of sets for IMMU. */
+	/* FIXME: Assumption is I & D nsets equal. */
+	num_tlb_sets = NUM_ITLB_SETS;
+
+	for (i = 0; i < num_tlb_sets; i++) {
+		mtspr_off(SPR_DTLBMR_BASE(0), i, 0);
+		mtspr_off(SPR_ITLBMR_BASE(0), i, 0);
+	}
+}
+
+#define have_dtlbeir (mfspr(SPR_DMMUCFGR) & SPR_DMMUCFGR_TEIRI)
+#define have_itlbeir (mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_TEIRI)
+
+/*
+ * Invalidate a single page.  This is what the xTLBEIR register is for.
+ *
+ * There's no point in checking the vma for PAGE_EXEC to determine whether it's
+ * the data or instruction TLB that should be flushed... that would take more
+ * than the few instructions that the following compiles down to!
+ *
+ * The case where we don't have the xTLBEIR register really only works for
+ * MMU's with a single way and is hard-coded that way.
+ */
+
+#define flush_dtlb_page_eir(addr) mtspr(SPR_DTLBEIR, addr)
+#define flush_dtlb_page_no_eir(addr) \
+	mtspr_off(SPR_DTLBMR_BASE(0), DTLB_OFFSET(addr), 0);
+
+#define flush_itlb_page_eir(addr) mtspr(SPR_ITLBEIR, addr)
+#define flush_itlb_page_no_eir(addr) \
+	mtspr_off(SPR_ITLBMR_BASE(0), ITLB_OFFSET(addr), 0);
+
+void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
+{
+	if (have_dtlbeir)
+		flush_dtlb_page_eir(addr);
+	else
+		flush_dtlb_page_no_eir(addr);
+
+	if (have_itlbeir)
+		flush_itlb_page_eir(addr);
+	else
+		flush_itlb_page_no_eir(addr);
+}
+
+void flush_tlb_range(struct vm_area_struct *vma,
+		     unsigned long start, unsigned long end)
+{
+	int addr;
+	bool dtlbeir;
+	bool itlbeir;
+
+	dtlbeir = have_dtlbeir;
+	itlbeir = have_itlbeir;
+
+	for (addr = start; addr < end; addr += PAGE_SIZE) {
+		if (dtlbeir)
+			flush_dtlb_page_eir(addr);
+		else
+			flush_dtlb_page_no_eir(addr);
+
+		if (itlbeir)
+			flush_itlb_page_eir(addr);
+		else
+			flush_itlb_page_no_eir(addr);
+	}
+}
+
+/*
+ * Invalidate the selected mm context only.
+ *
+ * FIXME: Due to some bug here, we're flushing everything for now.
+ * This should be changed to loop over over mm and call flush_tlb_range.
+ */
+
+void flush_tlb_mm(struct mm_struct *mm)
+{
+
+	/* Was seeing bugs with the mm struct passed to us. Scrapped most of
+	   this function. */
+	/* Several architctures do this */
+	flush_tlb_all();
+}
+
+/* called in schedule() just before actually doing the switch_to */
+
+void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+	       struct task_struct *next_tsk)
+{
+	/* remember the pgd for the fault handlers
+	 * this is similar to the pgd register in some other CPU's.
+	 * we need our own copy of it because current and active_mm
+	 * might be invalid at points where we still need to derefer
+	 * the pgd.
+	 */
+	current_pgd = next->pgd;
+
+	/* We don't have context support implemented, so flush all
+	 * entries belonging to previous map
+	 */
+
+	if (prev != next)
+		flush_tlb_mm(prev);
+
+}
+
+/*
+ * Initialize the context related info for a new mm_struct
+ * instance.
+ */
+
+int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+	mm->context = NO_CONTEXT;
+	return 0;
+}
+
+/* called by __exit_mm to destroy the used MMU context if any before
+ * destroying the mm itself. this is only called when the last user of the mm
+ * drops it.
+ */
+
+void destroy_context(struct mm_struct *mm)
+{
+	flush_tlb_mm(mm);
+
+}
+
+/* called once during VM initialization, from init.c */
+
+void __init tlb_init(void)
+{
+	/* Do nothing... */
+	/* invalidate the entire TLB */
+	/* flush_tlb_all(); */
+}