1 files changed, 114 insertions, 0 deletions

diff --git a/kernel/arch/cris/mm/tlb.c b/kernel/arch/cris/mm/tlb.c
new file mode 100644
index 000000000..b7f8de576
--- /dev/null
+++ b/kernel/arch/cris/mm/tlb.c
@@ -0,0 +1,114 @@
+/*
+ *  linux/arch/cris/mm/tlb.c
+ *
+ *  Copyright (C) 2000, 2001  Axis Communications AB
+ *  
+ *  Authors:   Bjorn Wesen (bjornw@axis.com)
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <asm/tlb.h>
+
+#define D(x)
+
+/* The TLB can host up to 64 different mm contexts at the same time.
+ * The running context is R_MMU_CONTEXT, and each TLB entry contains a
+ * page_id that has to match to give a hit. In page_id_map, we keep track
+ * of which mm we have assigned to which page_id, so that we know when
+ * to invalidate TLB entries.
+ *
+ * The last page_id is never running - it is used as an invalid page_id
+ * so we can make TLB entries that will never match.
+ *
+ * Notice that we need to make the flushes atomic, otherwise an interrupt
+ * handler that uses vmalloced memory might cause a TLB load in the middle
+ * of a flush causing.
+ */
+
+struct mm_struct *page_id_map[NUM_PAGEID];
+static int map_replace_ptr = 1;  /* which page_id_map entry to replace next */
+
+/* the following functions are similar to those used in the PPC port */
+
+static inline void
+alloc_context(struct mm_struct *mm)
+{
+	struct mm_struct *old_mm;
+
+	D(printk("tlb: alloc context %d (%p)\n", map_replace_ptr, mm));
+
+	/* did we replace an mm ? */
+
+	old_mm = page_id_map[map_replace_ptr];
+
+	if(old_mm) {
+		/* throw out any TLB entries belonging to the mm we replace
+		 * in the map
+		 */
+		flush_tlb_mm(old_mm);
+
+		old_mm->context.page_id = NO_CONTEXT;
+	}
+
+	/* insert it into the page_id_map */
+
+	mm->context.page_id = map_replace_ptr;
+	page_id_map[map_replace_ptr] = mm;
+
+	map_replace_ptr++;
+
+	if(map_replace_ptr == INVALID_PAGEID)
+		map_replace_ptr = 0;         /* wrap around */	
+}
+
+/* 
+ * if needed, get a new MMU context for the mm. otherwise nothing is done.
+ */
+
+void
+get_mmu_context(struct mm_struct *mm)
+{
+	if(mm->context.page_id == NO_CONTEXT)
+		alloc_context(mm);
+}
+
+/* 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.
+ *
+ * the only thing we really need to do here is mark the used PID slot
+ * as empty.
+ */
+
+void
+destroy_context(struct mm_struct *mm)
+{
+	if(mm->context.page_id != NO_CONTEXT) {
+		D(printk("destroy_context %d (%p)\n", mm->context.page_id, mm));
+		flush_tlb_mm(mm);  /* TODO this might be redundant ? */
+		page_id_map[mm->context.page_id] = NULL;
+	}
+}
+
+/* called once during VM initialization, from init.c */
+
+void __init
+tlb_init(void)
+{
+	int i;
+
+	/* clear the page_id map */
+
+	for (i = 1; i < ARRAY_SIZE(page_id_map); i++)
+		page_id_map[i] = NULL;
+	
+	/* invalidate the entire TLB */
+
+	flush_tlb_all();
+
+	/* the init_mm has context 0 from the boot */
+
+	page_id_map[0] = &init_mm;
+}