patch-2.4.2 linux/arch/cris/mm/tlb.c

• Lines: 302
• Date: Thu Feb 8 16:32:44 2001
• Orig file: v2.4.1/linux/arch/cris/mm/tlb.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.1/linux/arch/cris/mm/tlb.c linux/arch/cris/mm/tlb.c
@@ -0,0 +1,301 @@
+/*
+ *  linux/arch/cris/mm/tlb.c
+ *
+ *  Copyright (C) 2000  Axis Communications AB
+ *  
+ *  Authors:   Bjorn Wesen (bjornw@axis.com)
+ *
+ */
+
+#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/pgtable.h>
+#include <asm/svinto.h>
+
+#define D(x)
+
+/* CRIS in Etrax100LX TLB */
+
+#define NUM_TLB_ENTRIES 64
+#define NUM_PAGEID 64
+#define INVALID_PAGEID 63
+#define NO_CONTEXT -1
+
+/* 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's we have assigned which page_id's, 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.
+ */
+
+struct mm_struct *page_id_map[NUM_PAGEID];
+
+static int map_replace_ptr = 1;  /* which page_id_map entry to replace next */
+
+/* invalidate all TLB entries */
+
+void
+flush_tlb_all()
+{
+	int i;
+
+	/* the vpn of i & 0xf is so we dont write similar TLB entries
+	 * in the same 4-way entry group. details.. 
+	 */
+
+	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
+		*R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
+
+		*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
+			      IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
+		
+		*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no       ) |
+			      IO_STATE(R_TLB_LO, valid, no       ) |
+			      IO_STATE(R_TLB_LO, kernel,no	 ) |
+			      IO_STATE(R_TLB_LO, we,    no       ) |
+			      IO_FIELD(R_TLB_LO, pfn,   0        ) );
+	}
+	D(printk("tlb: flushed all\n"));
+}
+
+/* invalidate the selected mm context only */
+
+void
+flush_tlb_mm(struct mm_struct *mm)
+{
+	int i;
+	int page_id = mm->context;
+
+	D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));
+
+	if(page_id == NO_CONTEXT)
+		return;
+	
+	/* mark the TLB entries that match the page_id as invalid.
+	 * here we could also check the _PAGE_GLOBAL bit and NOT flush
+	 * global pages. is it worth the extra I/O ? 
+	 */
+
+	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
+		*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
+		if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) {
+			*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
+				      IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
+			
+			*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
+				      IO_STATE(R_TLB_LO, valid, no  ) |
+				      IO_STATE(R_TLB_LO, kernel,no  ) |
+				      IO_STATE(R_TLB_LO, we,    no  ) |
+				      IO_FIELD(R_TLB_LO, pfn,   0   ) );
+		}
+	}
+}
+
+/* invalidate a single page */
+
+void
+flush_tlb_page(struct vm_area_struct *vma, 
+	       unsigned long addr)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int page_id = mm->context;
+	int i;
+
+	D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));
+
+	if(page_id == NO_CONTEXT)
+		return;
+
+	addr &= PAGE_MASK; /* perhaps not necessary */
+
+	/* invalidate those TLB entries that match both the mm context
+	 * and the virtual address requested 
+	 */
+
+	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
+		unsigned long tlb_hi;
+		*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
+		tlb_hi = *R_TLB_HI;
+		if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
+		    (tlb_hi & PAGE_MASK) == addr) {
+			*R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
+				addr; /* same addr as before works. */
+			
+			*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
+				      IO_STATE(R_TLB_LO, valid, no  ) |
+				      IO_STATE(R_TLB_LO, kernel,no  ) |
+				      IO_STATE(R_TLB_LO, we,    no  ) |
+				      IO_FIELD(R_TLB_LO, pfn,   0   ) );
+		}
+	}
+}
+
+/* invalidate a page range */
+
+void
+flush_tlb_range(struct mm_struct *mm, 
+		unsigned long start,
+		unsigned long end)
+{
+	int page_id = mm->context;
+	int i;
+
+	D(printk("tlb: flush range %p<->%p in context %d (%p)\n",
+		 start, end, page_id, mm));
+
+	if(page_id == NO_CONTEXT)
+		return;
+
+	start &= PAGE_MASK;  /* probably not necessary */
+	end &= PAGE_MASK;    /* dito */
+
+	/* invalidate those TLB entries that match both the mm context
+	 * and the virtual address range
+	 */
+
+	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
+		unsigned long tlb_hi, vpn;
+		*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
+		tlb_hi = *R_TLB_HI;
+		vpn = tlb_hi & PAGE_MASK;
+		if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
+		    vpn >= start && vpn < end) {
+			*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
+				      IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
+			
+			*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
+				      IO_STATE(R_TLB_LO, valid, no  ) |
+				      IO_STATE(R_TLB_LO, kernel,no  ) |
+				      IO_STATE(R_TLB_LO, we,    no  ) |
+				      IO_FIELD(R_TLB_LO, pfn,   0   ) );
+		}
+	}
+}
+
+/*
+ * 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;
+}
+
+/* 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 = NO_CONTEXT;
+	}
+
+	/* insert it into the page_id_map */
+
+	mm->context = 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 == NO_CONTEXT)
+		alloc_context(mm);
+}
+
+/* called in schedule() just before actually doing the switch_to */
+
+void 
+switch_mm(struct mm_struct *prev, struct mm_struct *next,
+	  struct task_struct *tsk, int cpu)
+{
+	/* make sure we have a context */
+
+	get_mmu_context(next);
+
+	/* switch context in the MMU */
+	
+	D(printk("switching mmu_context to %d (%p)\n", next->context, next));
+
+	*R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT, page_id, next->context);
+}
+
+
+/* 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 != NO_CONTEXT) {
+		D(printk("destroy_context %d (%p)\n", mm->context, mm));
+		flush_tlb_mm(mm);  /* TODO this might be redundant ? */
+		page_id_map[mm->context] = NULL;
+		/* mm->context = NO_CONTEXT; redundant.. mm will be freed */
+	}
+}
+
+/* called once during VM initialization, from init.c */
+
+void __init
+tlb_init(void)
+{
+	int i;
+
+	/* clear the page_id map */
+
+	for(i = 0; i < 64; 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;
+}