Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

4 files changed, 635 insertions, 0 deletions

diff --git a/arch/cris/arch-v10/mm/Makefile b/arch/cris/arch-v10/mm/Makefile
new file mode 100644
index 00000000000..588b4baee85
--- /dev/null
+++ b/arch/cris/arch-v10/mm/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for the linux cris-specific parts of the memory manager.
+#
+
+obj-y	 := fault.o init.o tlb.o
+
diff --git a/arch/cris/arch-v10/mm/fault.c b/arch/cris/arch-v10/mm/fault.c
new file mode 100644
index 00000000000..6805cdb25a5
--- /dev/null
+++ b/arch/cris/arch-v10/mm/fault.c
@@ -0,0 +1,117 @@
+/*
+ *  linux/arch/cris/mm/fault.c
+ *
+ *  Low level bus fault handler
+ *
+ *
+ *  Copyright (C) 2000, 2001  Axis Communications AB
+ *
+ *  Authors:  Bjorn Wesen 
+ * 
+ */
+
+#include <linux/mm.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/arch/svinto.h>
+
+/* debug of low-level TLB reload */
+#undef DEBUG
+
+#ifdef DEBUG
+#define D(x) x
+#else
+#define D(x)
+#endif
+
+extern volatile pgd_t *current_pgd;
+
+extern const struct exception_table_entry
+	*search_exception_tables(unsigned long addr);
+
+asmlinkage void do_page_fault(unsigned long address, struct pt_regs *regs,
+                              int protection, int writeaccess);
+
+/* fast TLB-fill fault handler
+ * this is called from entry.S with interrupts disabled
+ */
+
+void
+handle_mmu_bus_fault(struct pt_regs *regs)
+{
+	int cause;
+	int select;
+#ifdef DEBUG
+	int index;
+	int page_id;
+	int acc, inv;
+#endif
+	pgd_t* pgd = (pgd_t*)current_pgd;
+	pmd_t *pmd;
+	pte_t pte;
+	int miss, we, writeac;
+	unsigned long address;
+	unsigned long flags;
+
+	cause = *R_MMU_CAUSE;
+
+	address = cause & PAGE_MASK; /* get faulting address */
+	select = *R_TLB_SELECT;
+
+#ifdef DEBUG
+	page_id = IO_EXTRACT(R_MMU_CAUSE,  page_id,   cause);
+	acc     = IO_EXTRACT(R_MMU_CAUSE,  acc_excp,  cause);
+	inv     = IO_EXTRACT(R_MMU_CAUSE,  inv_excp,  cause);  
+	index   = IO_EXTRACT(R_TLB_SELECT, index,     select);
+#endif
+	miss    = IO_EXTRACT(R_MMU_CAUSE,  miss_excp, cause);
+	we      = IO_EXTRACT(R_MMU_CAUSE,  we_excp,   cause);
+	writeac = IO_EXTRACT(R_MMU_CAUSE,  wr_rd,     cause);
+
+	D(printk("bus_fault from IRP 0x%lx: addr 0x%lx, miss %d, inv %d, we %d, acc %d, dx %d pid %d\n",
+		 regs->irp, address, miss, inv, we, acc, index, page_id));
+
+	/* leave it to the MM system fault handler */
+	if (miss)
+		do_page_fault(address, regs, 0, writeac);
+        else
+		do_page_fault(address, regs, 1, we);
+
+        /* Reload TLB with new entry to avoid an extra miss exception.
+	 * do_page_fault may have flushed the TLB so we have to restore
+	 * the MMU registers.
+	 */
+	local_save_flags(flags);
+	local_irq_disable();
+	pmd = (pmd_t *)(pgd + pgd_index(address));
+	if (pmd_none(*pmd))
+		return;
+	pte = *pte_offset_kernel(pmd, address);
+	if (!pte_present(pte))
+		return;
+	*R_TLB_SELECT = select;
+	*R_TLB_HI = cause;
+	*R_TLB_LO = pte_val(pte);
+	local_irq_restore(flags);
+}
+
+/* Called from arch/cris/mm/fault.c to find fixup code. */
+int
+find_fixup_code(struct pt_regs *regs)
+{
+	const struct exception_table_entry *fixup;
+
+	if ((fixup = search_exception_tables(regs->irp)) != 0) {
+		/* Adjust the instruction pointer in the stackframe. */
+		regs->irp = fixup->fixup;
+		
+		/* 
+		 * Don't return by restoring the CPU state, so switch
+		 * frame-type. 
+		 */
+		regs->frametype = CRIS_FRAME_NORMAL;
+		return 1;
+	}
+
+	return 0;
+}
diff --git a/arch/cris/arch-v10/mm/init.c b/arch/cris/arch-v10/mm/init.c
new file mode 100644
index 00000000000..a9f975a9cfb
--- /dev/null
+++ b/arch/cris/arch-v10/mm/init.c
@@ -0,0 +1,264 @@
+/*
+ *  linux/arch/cris/arch-v10/mm/init.c
+ *
+ */
+#include <linux/config.h>
+#include <linux/mmzone.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/mm.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/types.h>
+#include <asm/mmu.h>
+#include <asm/io.h>
+#include <asm/mmu_context.h>
+#include <asm/arch/svinto.h>
+
+extern void tlb_init(void);
+
+/*
+ * The kernel is already mapped with a kernel segment at kseg_c so 
+ * we don't need to map it with a page table. However head.S also
+ * temporarily mapped it at kseg_4 so we should set up the ksegs again,
+ * clear the TLB and do some other paging setup stuff.
+ */
+
+void __init 
+paging_init(void)
+{
+	int i;
+	unsigned long zones_size[MAX_NR_ZONES];
+
+	printk("Setting up paging and the MMU.\n");
+	
+	/* clear out the init_mm.pgd that will contain the kernel's mappings */
+
+	for(i = 0; i < PTRS_PER_PGD; i++)
+		swapper_pg_dir[i] = __pgd(0);
+	
+	/* make sure the current pgd table points to something sane
+	 * (even if it is most probably not used until the next 
+	 *  switch_mm)
+	 */
+
+	current_pgd = init_mm.pgd;
+
+	/* initialise the TLB (tlb.c) */
+
+	tlb_init();
+
+	/* see README.mm for details on the KSEG setup */
+
+#ifdef CONFIG_CRIS_LOW_MAP
+	/* Etrax-100 LX version 1 has a bug so that we cannot map anything
+	 * across the 0x80000000 boundary, so we need to shrink the user-virtual
+	 * area to 0x50000000 instead of 0xb0000000 and map things slightly
+	 * different. The unused areas are marked as paged so that we can catch
+	 * freak kernel accesses there.
+	 *
+	 * The ARTPEC chip is mapped at 0xa so we pass that segment straight
+	 * through. We cannot vremap it because the vmalloc area is below 0x8
+	 * and Juliette needs an uncached area above 0x8.
+	 *
+	 * Same thing with 0xc and 0x9, which is memory-mapped I/O on some boards.
+	 * We map them straight over in LOW_MAP, but use vremap in LX version 2.
+	 */
+
+#define CACHED_BOOTROM (KSEG_F | 0x08000000UL)
+
+	*R_MMU_KSEG = ( IO_STATE(R_MMU_KSEG, seg_f, seg  ) |  /* bootrom */
+			IO_STATE(R_MMU_KSEG, seg_e, page ) |
+			IO_STATE(R_MMU_KSEG, seg_d, page ) | 
+			IO_STATE(R_MMU_KSEG, seg_c, page ) |   
+			IO_STATE(R_MMU_KSEG, seg_b, seg  ) |  /* kernel reg area */
+#ifdef CONFIG_JULIETTE
+			IO_STATE(R_MMU_KSEG, seg_a, seg  ) |  /* ARTPEC etc. */
+#else
+			IO_STATE(R_MMU_KSEG, seg_a, page ) |
+#endif
+			IO_STATE(R_MMU_KSEG, seg_9, seg  ) |  /* LED's on some boards */
+			IO_STATE(R_MMU_KSEG, seg_8, seg  ) |  /* CSE0/1, flash and I/O */
+			IO_STATE(R_MMU_KSEG, seg_7, page ) |  /* kernel vmalloc area */
+			IO_STATE(R_MMU_KSEG, seg_6, seg  ) |  /* kernel DRAM area */
+			IO_STATE(R_MMU_KSEG, seg_5, seg  ) |  /* cached flash */
+			IO_STATE(R_MMU_KSEG, seg_4, page ) |  /* user area */
+			IO_STATE(R_MMU_KSEG, seg_3, page ) |  /* user area */
+			IO_STATE(R_MMU_KSEG, seg_2, page ) |  /* user area */
+			IO_STATE(R_MMU_KSEG, seg_1, page ) |  /* user area */
+			IO_STATE(R_MMU_KSEG, seg_0, page ) ); /* user area */
+
+	*R_MMU_KBASE_HI = ( IO_FIELD(R_MMU_KBASE_HI, base_f, 0x3 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_e, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_d, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_c, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_b, 0xb ) |
+#ifdef CONFIG_JULIETTE
+			    IO_FIELD(R_MMU_KBASE_HI, base_a, 0xa ) |
+#else
+			    IO_FIELD(R_MMU_KBASE_HI, base_a, 0x0 ) |
+#endif
+			    IO_FIELD(R_MMU_KBASE_HI, base_9, 0x9 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_8, 0x8 ) );
+	
+	*R_MMU_KBASE_LO = ( IO_FIELD(R_MMU_KBASE_LO, base_7, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_6, 0x4 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_5, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_4, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_3, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_2, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_1, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_0, 0x0 ) );
+#else
+	/* This code is for the corrected Etrax-100 LX version 2... */
+
+#define CACHED_BOOTROM (KSEG_A | 0x08000000UL)
+
+	*R_MMU_KSEG = ( IO_STATE(R_MMU_KSEG, seg_f, seg  ) | /* cached flash */
+			IO_STATE(R_MMU_KSEG, seg_e, seg  ) | /* uncached flash */
+			IO_STATE(R_MMU_KSEG, seg_d, page ) | /* vmalloc area */
+			IO_STATE(R_MMU_KSEG, seg_c, seg  ) | /* kernel area */
+			IO_STATE(R_MMU_KSEG, seg_b, seg  ) | /* kernel reg area */
+			IO_STATE(R_MMU_KSEG, seg_a, seg  ) | /* bootrom */
+			IO_STATE(R_MMU_KSEG, seg_9, page ) | /* user area */
+			IO_STATE(R_MMU_KSEG, seg_8, page ) |
+			IO_STATE(R_MMU_KSEG, seg_7, page ) |
+			IO_STATE(R_MMU_KSEG, seg_6, page ) |
+			IO_STATE(R_MMU_KSEG, seg_5, page ) |
+			IO_STATE(R_MMU_KSEG, seg_4, page ) |
+			IO_STATE(R_MMU_KSEG, seg_3, page ) |
+			IO_STATE(R_MMU_KSEG, seg_2, page ) |
+			IO_STATE(R_MMU_KSEG, seg_1, page ) |
+			IO_STATE(R_MMU_KSEG, seg_0, page ) );
+
+	*R_MMU_KBASE_HI = ( IO_FIELD(R_MMU_KBASE_HI, base_f, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_e, 0x8 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_d, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_c, 0x4 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_b, 0xb ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_a, 0x3 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_9, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_HI, base_8, 0x0 ) );
+	
+	*R_MMU_KBASE_LO = ( IO_FIELD(R_MMU_KBASE_LO, base_7, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_6, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_5, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_4, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_3, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_2, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_1, 0x0 ) |
+			    IO_FIELD(R_MMU_KBASE_LO, base_0, 0x0 ) );
+#endif
+
+	*R_MMU_CONTEXT = ( IO_FIELD(R_MMU_CONTEXT, page_id, 0 ) );
+	
+	/* The MMU has been enabled ever since head.S but just to make
+	 * it totally obvious we do it here as well.
+	 */
+
+	*R_MMU_CTRL = ( IO_STATE(R_MMU_CTRL, inv_excp, enable ) |
+			IO_STATE(R_MMU_CTRL, acc_excp, enable ) |
+			IO_STATE(R_MMU_CTRL, we_excp,  enable ) );
+	
+	*R_MMU_ENABLE = IO_STATE(R_MMU_ENABLE, mmu_enable, enable);
+
+	/*
+	 * initialize the bad page table and bad page to point
+	 * to a couple of allocated pages
+	 */
+
+	empty_zero_page = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);
+	memset((void *)empty_zero_page, 0, PAGE_SIZE);
+
+	/* All pages are DMA'able in Etrax, so put all in the DMA'able zone */
+
+	zones_size[0] = ((unsigned long)high_memory - PAGE_OFFSET) >> PAGE_SHIFT;
+
+	for (i = 1; i < MAX_NR_ZONES; i++)
+		zones_size[i] = 0;
+
+	/* Use free_area_init_node instead of free_area_init, because the former
+	 * is designed for systems where the DRAM starts at an address substantially
+	 * higher than 0, like us (we start at PAGE_OFFSET). This saves space in the
+	 * mem_map page array.
+	 */
+
+	free_area_init_node(0, &contig_page_data, zones_size, PAGE_OFFSET >> PAGE_SHIFT, 0);
+}
+
+/* Initialize remaps of some I/O-ports. It is important that this
+ * is called before any driver is initialized.
+ */
+
+static int
+__init init_ioremap(void)
+{
+  
+	/* Give the external I/O-port addresses their values */
+
+#ifdef CONFIG_CRIS_LOW_MAP
+	/* Simply a linear map (see the KSEG map above in paging_init) */
+	port_cse1_addr = (volatile unsigned long *)(MEM_CSE1_START | 
+	                                            MEM_NON_CACHEABLE);
+	port_csp0_addr = (volatile unsigned long *)(MEM_CSP0_START |
+	                                            MEM_NON_CACHEABLE);
+	port_csp4_addr = (volatile unsigned long *)(MEM_CSP4_START |
+	                                            MEM_NON_CACHEABLE);
+#else
+	/* Note that nothing blows up just because we do this remapping 
+	 * it's ok even if the ports are not used or connected 
+	 * to anything (or connected to a non-I/O thing) */        
+	port_cse1_addr = (volatile unsigned long *)
+	  ioremap((unsigned long)(MEM_CSE1_START | MEM_NON_CACHEABLE), 16);
+	port_csp0_addr = (volatile unsigned long *)
+	  ioremap((unsigned long)(MEM_CSP0_START | MEM_NON_CACHEABLE), 16);
+	port_csp4_addr = (volatile unsigned long *)
+	  ioremap((unsigned long)(MEM_CSP4_START | MEM_NON_CACHEABLE), 16);
+#endif	
+	return 0;
+}
+
+__initcall(init_ioremap);
+
+/* Helper function for the two below */
+
+static inline void
+flush_etrax_cacherange(void *startadr, int length)
+{
+	/* CACHED_BOOTROM is mapped to the boot-rom area (cached) which
+	 * we can use to get fast dummy-reads of cachelines
+	 */
+
+	volatile short *flushadr = (volatile short *)(((unsigned long)startadr & ~PAGE_MASK) |
+						      CACHED_BOOTROM);
+
+	length = length > 8192 ? 8192 : length;  /* No need to flush more than cache size */
+
+	while(length > 0) {
+		*flushadr; /* dummy read to flush */
+		flushadr += (32/sizeof(short));  /* a cacheline is 32 bytes */
+		length -= 32;
+	}
+}
+
+/* Due to a bug in Etrax100(LX) all versions, receiving DMA buffers
+ * will occationally corrupt certain CPU writes if the DMA buffers
+ * happen to be hot in the cache.
+ * 
+ * As a workaround, we have to flush the relevant parts of the cache
+ * before (re) inserting any receiving descriptor into the DMA HW.
+ */
+
+void
+prepare_rx_descriptor(struct etrax_dma_descr *desc)
+{
+	flush_etrax_cacherange((void *)desc->buf, desc->sw_len ? desc->sw_len : 65536);
+}
+
+/* Do the same thing but flush the entire cache */
+
+void
+flush_etrax_cache(void)
+{
+	flush_etrax_cacherange(0, 8192);
+}
diff --git a/arch/cris/arch-v10/mm/tlb.c b/arch/cris/arch-v10/mm/tlb.c
new file mode 100644
index 00000000000..9d06125ff5a
--- /dev/null
+++ b/arch/cris/arch-v10/mm/tlb.c
@@ -0,0 +1,248 @@
+/*
+ *  linux/arch/cris/arch-v10/mm/tlb.c
+ *
+ *  Low level TLB handling
+ *
+ *
+ *  Copyright (C) 2000-2002  Axis Communications AB
+ *  
+ *  Authors:   Bjorn Wesen (bjornw@axis.com)
+ *
+ */
+
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+#include <asm/arch/svinto.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'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.
+ *
+ * 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.
+ */
+
+/* invalidate all TLB entries */
+
+void
+flush_tlb_all(void)
+{
+	int i;
+	unsigned long flags;
+
+	/* the vpn of i & 0xf is so we dont write similar TLB entries
+	 * in the same 4-way entry group. details.. 
+	 */
+
+	local_save_flags(flags);
+	local_irq_disable();
+	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        ) );
+	}
+	local_irq_restore(flags);
+	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.page_id;
+	unsigned long flags;
+
+	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 ? 
+	 */
+
+	local_save_flags(flags);
+	local_irq_disable();
+	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   ) );
+		}
+	}
+	local_irq_restore(flags);
+}
+
+/* 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.page_id;
+	int i;
+	unsigned long flags;
+
+	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 
+	 */
+
+	local_save_flags(flags);
+	local_irq_disable();
+	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   ) );
+		}
+	}
+	local_irq_restore(flags);
+}
+
+/* invalidate a page range */
+
+void
+flush_tlb_range(struct vm_area_struct *vma, 
+		unsigned long start,
+		unsigned long end)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int page_id = mm->context.page_id;
+	int i;
+	unsigned long flags;
+
+	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
+	 */
+
+	local_save_flags(flags);
+	local_irq_disable();
+	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   ) );
+		}
+	}
+	local_irq_restore(flags);
+}
+
+/* dump the entire TLB for debug purposes */
+
+#if 0
+void
+dump_tlb_all(void)
+{
+	int i;
+	unsigned long flags;
+	
+	printk("TLB dump. LO is: pfn | reserved | global | valid | kernel | we  |\n");
+
+	local_save_flags(flags);
+	local_irq_disable();
+	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
+		*R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
+		printk("Entry %d: HI 0x%08lx, LO 0x%08lx\n",
+		       i, *R_TLB_HI, *R_TLB_LO);
+	}
+	local_irq_restore(flags);
+}
+#endif
+
+/*
+ * 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.page_id = NO_CONTEXT;
+	return 0;
+}
+
+/* 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)
+{
+	/* make sure we have a context */
+
+	get_mmu_context(next);
+
+	/* 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;
+
+	/* 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.page_id);
+}
+