Initial import

1 files changed, 780 insertions, 0 deletions

diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
new file mode 100644
index 000000000..7f47d2a56
--- /dev/null
+++ b/arch/arc/mm/tlb.c
@@ -0,0 +1,780 @@
+/*
+ * TLB Management (flush/create/diagnostics) for ARC700
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * vineetg: Aug 2011
+ *  -Reintroduce duplicate PD fixup - some customer chips still have the issue
+ *
+ * vineetg: May 2011
+ *  -No need to flush_cache_page( ) for each call to update_mmu_cache()
+ *   some of the LMBench tests improved amazingly
+ *      = page-fault thrice as fast (75 usec to 28 usec)
+ *      = mmap twice as fast (9.6 msec to 4.6 msec),
+ *      = fork (5.3 msec to 3.7 msec)
+ *
+ * vineetg: April 2011 :
+ *  -MMU v3: PD{0,1} bits layout changed: They don't overlap anymore,
+ *      helps avoid a shift when preparing PD0 from PTE
+ *
+ * vineetg: April 2011 : Preparing for MMU V3
+ *  -MMU v2/v3 BCRs decoded differently
+ *  -Remove TLB_SIZE hardcoding as it's variable now: 256 or 512
+ *  -tlb_entry_erase( ) can be void
+ *  -local_flush_tlb_range( ):
+ *      = need not "ceil" @end
+ *      = walks MMU only if range spans < 32 entries, as opposed to 256
+ *
+ * Vineetg: Sept 10th 2008
+ *  -Changes related to MMU v2 (Rel 4.8)
+ *
+ * Vineetg: Aug 29th 2008
+ *  -In TLB Flush operations (Metal Fix MMU) there is a explict command to
+ *    flush Micro-TLBS. If TLB Index Reg is invalid prior to TLBIVUTLB cmd,
+ *    it fails. Thus need to load it with ANY valid value before invoking
+ *    TLBIVUTLB cmd
+ *
+ * Vineetg: Aug 21th 2008:
+ *  -Reduced the duration of IRQ lockouts in TLB Flush routines
+ *  -Multiple copies of TLB erase code seperated into a "single" function
+ *  -In TLB Flush routines, interrupt disabling moved UP to retrieve ASID
+ *       in interrupt-safe region.
+ *
+ * Vineetg: April 23rd Bug #93131
+ *    Problem: tlb_flush_kernel_range() doesnt do anything if the range to
+ *              flush is more than the size of TLB itself.
+ *
+ * Rahul Trivedi : Codito Technologies 2004
+ */
+
+#include <linux/module.h>
+#include <linux/bug.h>
+#include <asm/arcregs.h>
+#include <asm/setup.h>
+#include <asm/mmu_context.h>
+#include <asm/mmu.h>
+
+/*			Need for ARC MMU v2
+ *
+ * ARC700 MMU-v1 had a Joint-TLB for Code and Data and is 2 way set-assoc.
+ * For a memcpy operation with 3 players (src/dst/code) such that all 3 pages
+ * map into same set, there would be contention for the 2 ways causing severe
+ * Thrashing.
+ *
+ * Although J-TLB is 2 way set assoc, ARC700 caches J-TLB into uTLBS which has
+ * much higher associativity. u-D-TLB is 8 ways, u-I-TLB is 4 ways.
+ * Given this, the thrasing problem should never happen because once the 3
+ * J-TLB entries are created (even though 3rd will knock out one of the prev
+ * two), the u-D-TLB and u-I-TLB will have what is required to accomplish memcpy
+ *
+ * Yet we still see the Thrashing because a J-TLB Write cause flush of u-TLBs.
+ * This is a simple design for keeping them in sync. So what do we do?
+ * The solution which James came up was pretty neat. It utilised the assoc
+ * of uTLBs by not invalidating always but only when absolutely necessary.
+ *
+ * - Existing TLB commands work as before
+ * - New command (TLBWriteNI) for TLB write without clearing uTLBs
+ * - New command (TLBIVUTLB) to invalidate uTLBs.
+ *
+ * The uTLBs need only be invalidated when pages are being removed from the
+ * OS page table. If a 'victim' TLB entry is being overwritten in the main TLB
+ * as a result of a miss, the removed entry is still allowed to exist in the
+ * uTLBs as it is still valid and present in the OS page table. This allows the
+ * full associativity of the uTLBs to hide the limited associativity of the main
+ * TLB.
+ *
+ * During a miss handler, the new "TLBWriteNI" command is used to load
+ * entries without clearing the uTLBs.
+ *
+ * When the OS page table is updated, TLB entries that may be associated with a
+ * removed page are removed (flushed) from the TLB using TLBWrite. In this
+ * circumstance, the uTLBs must also be cleared. This is done by using the
+ * existing TLBWrite command. An explicit IVUTLB is also required for those
+ * corner cases when TLBWrite was not executed at all because the corresp
+ * J-TLB entry got evicted/replaced.
+ */
+
+
+/* A copy of the ASID from the PID reg is kept in asid_cache */
+DEFINE_PER_CPU(unsigned int, asid_cache) = MM_CTXT_FIRST_CYCLE;
+
+/*
+ * Utility Routine to erase a J-TLB entry
+ * Caller needs to setup Index Reg (manually or via getIndex)
+ */
+static inline void __tlb_entry_erase(void)
+{
+	write_aux_reg(ARC_REG_TLBPD1, 0);
+	write_aux_reg(ARC_REG_TLBPD0, 0);
+	write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
+}
+
+static inline unsigned int tlb_entry_lkup(unsigned long vaddr_n_asid)
+{
+	unsigned int idx;
+
+	write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid);
+
+	write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe);
+	idx = read_aux_reg(ARC_REG_TLBINDEX);
+
+	return idx;
+}
+
+static void tlb_entry_erase(unsigned int vaddr_n_asid)
+{
+	unsigned int idx;
+
+	/* Locate the TLB entry for this vaddr + ASID */
+	idx = tlb_entry_lkup(vaddr_n_asid);
+
+	/* No error means entry found, zero it out */
+	if (likely(!(idx & TLB_LKUP_ERR))) {
+		__tlb_entry_erase();
+	} else {
+		/* Duplicate entry error */
+		WARN(idx == TLB_DUP_ERR, "Probe returned Dup PD for %x\n",
+					   vaddr_n_asid);
+	}
+}
+
+/****************************************************************************
+ * ARC700 MMU caches recently used J-TLB entries (RAM) as uTLBs (FLOPs)
+ *
+ * New IVUTLB cmd in MMU v2 explictly invalidates the uTLB
+ *
+ * utlb_invalidate ( )
+ *  -For v2 MMU calls Flush uTLB Cmd
+ *  -For v1 MMU does nothing (except for Metal Fix v1 MMU)
+ *      This is because in v1 TLBWrite itself invalidate uTLBs
+ ***************************************************************************/
+
+static void utlb_invalidate(void)
+{
+#if (CONFIG_ARC_MMU_VER >= 2)
+
+#if (CONFIG_ARC_MMU_VER == 2)
+	/* MMU v2 introduced the uTLB Flush command.
+	 * There was however an obscure hardware bug, where uTLB flush would
+	 * fail when a prior probe for J-TLB (both totally unrelated) would
+	 * return lkup err - because the entry didnt exist in MMU.
+	 * The Workround was to set Index reg with some valid value, prior to
+	 * flush. This was fixed in MMU v3 hence not needed any more
+	 */
+	unsigned int idx;
+
+	/* make sure INDEX Reg is valid */
+	idx = read_aux_reg(ARC_REG_TLBINDEX);
+
+	/* If not write some dummy val */
+	if (unlikely(idx & TLB_LKUP_ERR))
+		write_aux_reg(ARC_REG_TLBINDEX, 0xa);
+#endif
+
+	write_aux_reg(ARC_REG_TLBCOMMAND, TLBIVUTLB);
+#endif
+
+}
+
+static void tlb_entry_insert(unsigned int pd0, unsigned int pd1)
+{
+	unsigned int idx;
+
+	/*
+	 * First verify if entry for this vaddr+ASID already exists
+	 * This also sets up PD0 (vaddr, ASID..) for final commit
+	 */
+	idx = tlb_entry_lkup(pd0);
+
+	/*
+	 * If Not already present get a free slot from MMU.
+	 * Otherwise, Probe would have located the entry and set INDEX Reg
+	 * with existing location. This will cause Write CMD to over-write
+	 * existing entry with new PD0 and PD1
+	 */
+	if (likely(idx & TLB_LKUP_ERR))
+		write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex);
+
+	/* setup the other half of TLB entry (pfn, rwx..) */
+	write_aux_reg(ARC_REG_TLBPD1, pd1);
+
+	/*
+	 * Commit the Entry to MMU
+	 * It doesnt sound safe to use the TLBWriteNI cmd here
+	 * which doesn't flush uTLBs. I'd rather be safe than sorry.
+	 */
+	write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
+}
+
+/*
+ * Un-conditionally (without lookup) erase the entire MMU contents
+ */
+
+noinline void local_flush_tlb_all(void)
+{
+	unsigned long flags;
+	unsigned int entry;
+	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
+
+	local_irq_save(flags);
+
+	/* Load PD0 and PD1 with template for a Blank Entry */
+	write_aux_reg(ARC_REG_TLBPD1, 0);
+	write_aux_reg(ARC_REG_TLBPD0, 0);
+
+	for (entry = 0; entry < mmu->num_tlb; entry++) {
+		/* write this entry to the TLB */
+		write_aux_reg(ARC_REG_TLBINDEX, entry);
+		write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
+	}
+
+	utlb_invalidate();
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Flush the entrie MM for userland. The fastest way is to move to Next ASID
+ */
+noinline void local_flush_tlb_mm(struct mm_struct *mm)
+{
+	/*
+	 * Small optimisation courtesy IA64
+	 * flush_mm called during fork,exit,munmap etc, multiple times as well.
+	 * Only for fork( ) do we need to move parent to a new MMU ctxt,
+	 * all other cases are NOPs, hence this check.
+	 */
+	if (atomic_read(&mm->mm_users) == 0)
+		return;
+
+	/*
+	 * - Move to a new ASID, but only if the mm is still wired in
+	 *   (Android Binder ended up calling this for vma->mm != tsk->mm,
+	 *    causing h/w - s/w ASID to get out of sync)
+	 * - Also get_new_mmu_context() new implementation allocates a new
+	 *   ASID only if it is not allocated already - so unallocate first
+	 */
+	destroy_context(mm);
+	if (current->mm == mm)
+		get_new_mmu_context(mm);
+}
+
+/*
+ * Flush a Range of TLB entries for userland.
+ * @start is inclusive, while @end is exclusive
+ * Difference between this and Kernel Range Flush is
+ *  -Here the fastest way (if range is too large) is to move to next ASID
+ *      without doing any explicit Shootdown
+ *  -In case of kernel Flush, entry has to be shot down explictly
+ */
+void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+			   unsigned long end)
+{
+	const unsigned int cpu = smp_processor_id();
+	unsigned long flags;
+
+	/* If range @start to @end is more than 32 TLB entries deep,
+	 * its better to move to a new ASID rather than searching for
+	 * individual entries and then shooting them down
+	 *
+	 * The calc above is rough, doesn't account for unaligned parts,
+	 * since this is heuristics based anyways
+	 */
+	if (unlikely((end - start) >= PAGE_SIZE * 32)) {
+		local_flush_tlb_mm(vma->vm_mm);
+		return;
+	}
+
+	/*
+	 * @start moved to page start: this alone suffices for checking
+	 * loop end condition below, w/o need for aligning @end to end
+	 * e.g. 2000 to 4001 will anyhow loop twice
+	 */
+	start &= PAGE_MASK;
+
+	local_irq_save(flags);
+
+	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {
+		while (start < end) {
+			tlb_entry_erase(start | hw_pid(vma->vm_mm, cpu));
+			start += PAGE_SIZE;
+		}
+	}
+
+	utlb_invalidate();
+
+	local_irq_restore(flags);
+}
+
+/* Flush the kernel TLB entries - vmalloc/modules (Global from MMU perspective)
+ *  @start, @end interpreted as kvaddr
+ * Interestingly, shared TLB entries can also be flushed using just
+ * @start,@end alone (interpreted as user vaddr), although technically SASID
+ * is also needed. However our smart TLbProbe lookup takes care of that.
+ */
+void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
+{
+	unsigned long flags;
+
+	/* exactly same as above, except for TLB entry not taking ASID */
+
+	if (unlikely((end - start) >= PAGE_SIZE * 32)) {
+		local_flush_tlb_all();
+		return;
+	}
+
+	start &= PAGE_MASK;
+
+	local_irq_save(flags);
+	while (start < end) {
+		tlb_entry_erase(start);
+		start += PAGE_SIZE;
+	}
+
+	utlb_invalidate();
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Delete TLB entry in MMU for a given page (??? address)
+ * NOTE One TLB entry contains translation for single PAGE
+ */
+
+void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
+{
+	const unsigned int cpu = smp_processor_id();
+	unsigned long flags;
+
+	/* Note that it is critical that interrupts are DISABLED between
+	 * checking the ASID and using it flush the TLB entry
+	 */
+	local_irq_save(flags);
+
+	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {
+		tlb_entry_erase((page & PAGE_MASK) | hw_pid(vma->vm_mm, cpu));
+		utlb_invalidate();
+	}
+
+	local_irq_restore(flags);
+}
+
+#ifdef CONFIG_SMP
+
+struct tlb_args {
+	struct vm_area_struct *ta_vma;
+	unsigned long ta_start;
+	unsigned long ta_end;
+};
+
+static inline void ipi_flush_tlb_page(void *arg)
+{
+	struct tlb_args *ta = arg;
+
+	local_flush_tlb_page(ta->ta_vma, ta->ta_start);
+}
+
+static inline void ipi_flush_tlb_range(void *arg)
+{
+	struct tlb_args *ta = arg;
+
+	local_flush_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
+}
+
+static inline void ipi_flush_tlb_kernel_range(void *arg)
+{
+	struct tlb_args *ta = (struct tlb_args *)arg;
+
+	local_flush_tlb_kernel_range(ta->ta_start, ta->ta_end);
+}
+
+void flush_tlb_all(void)
+{
+	on_each_cpu((smp_call_func_t)local_flush_tlb_all, NULL, 1);
+}
+
+void flush_tlb_mm(struct mm_struct *mm)
+{
+	on_each_cpu_mask(mm_cpumask(mm), (smp_call_func_t)local_flush_tlb_mm,
+			 mm, 1);
+}
+
+void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
+{
+	struct tlb_args ta = {
+		.ta_vma = vma,
+		.ta_start = uaddr
+	};
+
+	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_page, &ta, 1);
+}
+
+void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+		     unsigned long end)
+{
+	struct tlb_args ta = {
+		.ta_vma = vma,
+		.ta_start = start,
+		.ta_end = end
+	};
+
+	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_range, &ta, 1);
+}
+
+void flush_tlb_kernel_range(unsigned long start, unsigned long end)
+{
+	struct tlb_args ta = {
+		.ta_start = start,
+		.ta_end = end
+	};
+
+	on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1);
+}
+#endif
+
+/*
+ * Routine to create a TLB entry
+ */
+void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
+{
+	unsigned long flags;
+	unsigned int asid_or_sasid, rwx;
+	unsigned long pd0, pd1;
+
+	/*
+	 * create_tlb() assumes that current->mm == vma->mm, since
+	 * -it ASID for TLB entry is fetched from MMU ASID reg (valid for curr)
+	 * -completes the lazy write to SASID reg (again valid for curr tsk)
+	 *
+	 * Removing the assumption involves
+	 * -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg.
+	 * -Fix the TLB paranoid debug code to not trigger false negatives.
+	 * -More importantly it makes this handler inconsistent with fast-path
+	 *  TLB Refill handler which always deals with "current"
+	 *
+	 * Lets see the use cases when current->mm != vma->mm and we land here
+	 *  1. execve->copy_strings()->__get_user_pages->handle_mm_fault
+	 *     Here VM wants to pre-install a TLB entry for user stack while
+	 *     current->mm still points to pre-execve mm (hence the condition).
+	 *     However the stack vaddr is soon relocated (randomization) and
+	 *     move_page_tables() tries to undo that TLB entry.
+	 *     Thus not creating TLB entry is not any worse.
+	 *
+	 *  2. ptrace(POKETEXT) causes a CoW - debugger(current) inserting a
+	 *     breakpoint in debugged task. Not creating a TLB now is not
+	 *     performance critical.
+	 *
+	 * Both the cases above are not good enough for code churn.
+	 */
+	if (current->active_mm != vma->vm_mm)
+		return;
+
+	local_irq_save(flags);
+
+	tlb_paranoid_check(asid_mm(vma->vm_mm, smp_processor_id()), address);
+
+	address &= PAGE_MASK;
+
+	/* update this PTE credentials */
+	pte_val(*ptep) |= (_PAGE_PRESENT | _PAGE_ACCESSED);
+
+	/* Create HW TLB(PD0,PD1) from PTE  */
+
+	/* ASID for this task */
+	asid_or_sasid = read_aux_reg(ARC_REG_PID) & 0xff;
+
+	pd0 = address | asid_or_sasid | (pte_val(*ptep) & PTE_BITS_IN_PD0);
+
+	/*
+	 * ARC MMU provides fully orthogonal access bits for K/U mode,
+	 * however Linux only saves 1 set to save PTE real-estate
+	 * Here we convert 3 PTE bits into 6 MMU bits:
+	 * -Kernel only entries have Kr Kw Kx 0 0 0
+	 * -User entries have mirrored K and U bits
+	 */
+	rwx = pte_val(*ptep) & PTE_BITS_RWX;
+
+	if (pte_val(*ptep) & _PAGE_GLOBAL)
+		rwx <<= 3;		/* r w x => Kr Kw Kx 0 0 0 */
+	else
+		rwx |= (rwx << 3);	/* r w x => Kr Kw Kx Ur Uw Ux */
+
+	pd1 = rwx | (pte_val(*ptep) & PTE_BITS_NON_RWX_IN_PD1);
+
+	tlb_entry_insert(pd0, pd1);
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Called at the end of pagefault, for a userspace mapped page
+ *  -pre-install the corresponding TLB entry into MMU
+ *  -Finalize the delayed D-cache flush of kernel mapping of page due to
+ *  	flush_dcache_page(), copy_user_page()
+ *
+ * Note that flush (when done) involves both WBACK - so physical page is
+ * in sync as well as INV - so any non-congruent aliases don't remain
+ */
+void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned,
+		      pte_t *ptep)
+{
+	unsigned long vaddr = vaddr_unaligned & PAGE_MASK;
+	unsigned long paddr = pte_val(*ptep) & PAGE_MASK;
+	struct page *page = pfn_to_page(pte_pfn(*ptep));
+
+	create_tlb(vma, vaddr, ptep);
+
+	if (page == ZERO_PAGE(0)) {
+		return;
+	}
+
+	/*
+	 * Exec page : Independent of aliasing/page-color considerations,
+	 *	       since icache doesn't snoop dcache on ARC, any dirty
+	 *	       K-mapping of a code page needs to be wback+inv so that
+	 *	       icache fetch by userspace sees code correctly.
+	 * !EXEC page: If K-mapping is NOT congruent to U-mapping, flush it
+	 *	       so userspace sees the right data.
+	 *  (Avoids the flush for Non-exec + congruent mapping case)
+	 */
+	if ((vma->vm_flags & VM_EXEC) ||
+	     addr_not_cache_congruent(paddr, vaddr)) {
+
+		int dirty = !test_and_set_bit(PG_dc_clean, &page->flags);
+		if (dirty) {
+			/* wback + inv dcache lines */
+			__flush_dcache_page(paddr, paddr);
+
+			/* invalidate any existing icache lines */
+			if (vma->vm_flags & VM_EXEC)
+				__inv_icache_page(paddr, vaddr);
+		}
+	}
+}
+
+/* Read the Cache Build Confuration Registers, Decode them and save into
+ * the cpuinfo structure for later use.
+ * No Validation is done here, simply read/convert the BCRs
+ */
+void read_decode_mmu_bcr(void)
+{
+	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
+	unsigned int tmp;
+	struct bcr_mmu_1_2 {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+		unsigned int ver:8, ways:4, sets:4, u_itlb:8, u_dtlb:8;
+#else
+		unsigned int u_dtlb:8, u_itlb:8, sets:4, ways:4, ver:8;
+#endif
+	} *mmu2;
+
+	struct bcr_mmu_3 {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+	unsigned int ver:8, ways:4, sets:4, osm:1, reserv:3, pg_sz:4,
+		     u_itlb:4, u_dtlb:4;
+#else
+	unsigned int u_dtlb:4, u_itlb:4, pg_sz:4, reserv:3, osm:1, sets:4,
+		     ways:4, ver:8;
+#endif
+	} *mmu3;
+
+	tmp = read_aux_reg(ARC_REG_MMU_BCR);
+	mmu->ver = (tmp >> 24);
+
+	if (mmu->ver <= 2) {
+		mmu2 = (struct bcr_mmu_1_2 *)&tmp;
+		mmu->pg_sz = PAGE_SIZE;
+		mmu->sets = 1 << mmu2->sets;
+		mmu->ways = 1 << mmu2->ways;
+		mmu->u_dtlb = mmu2->u_dtlb;
+		mmu->u_itlb = mmu2->u_itlb;
+	} else {
+		mmu3 = (struct bcr_mmu_3 *)&tmp;
+		mmu->pg_sz = 512 << mmu3->pg_sz;
+		mmu->sets = 1 << mmu3->sets;
+		mmu->ways = 1 << mmu3->ways;
+		mmu->u_dtlb = mmu3->u_dtlb;
+		mmu->u_itlb = mmu3->u_itlb;
+	}
+
+	mmu->num_tlb = mmu->sets * mmu->ways;
+}
+
+char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len)
+{
+	int n = 0;
+	struct cpuinfo_arc_mmu *p_mmu = &cpuinfo_arc700[cpu_id].mmu;
+
+	n += scnprintf(buf + n, len - n,
+		      "MMU [v%x]\t: %dk PAGE, JTLB %d (%dx%d), uDTLB %d, uITLB %d %s\n",
+		       p_mmu->ver, TO_KB(p_mmu->pg_sz),
+		       p_mmu->num_tlb, p_mmu->sets, p_mmu->ways,
+		       p_mmu->u_dtlb, p_mmu->u_itlb,
+		       IS_ENABLED(CONFIG_ARC_MMU_SASID) ? ",SASID" : "");
+
+	return buf;
+}
+
+void arc_mmu_init(void)
+{
+	char str[256];
+	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
+
+	printk(arc_mmu_mumbojumbo(0, str, sizeof(str)));
+
+	/* For efficiency sake, kernel is compile time built for a MMU ver
+	 * This must match the hardware it is running on.
+	 * Linux built for MMU V2, if run on MMU V1 will break down because V1
+	 *  hardware doesn't understand cmds such as WriteNI, or IVUTLB
+	 * On the other hand, Linux built for V1 if run on MMU V2 will do
+	 *   un-needed workarounds to prevent memcpy thrashing.
+	 * Similarly MMU V3 has new features which won't work on older MMU
+	 */
+	if (mmu->ver != CONFIG_ARC_MMU_VER) {
+		panic("MMU ver %d doesn't match kernel built for %d...\n",
+		      mmu->ver, CONFIG_ARC_MMU_VER);
+	}
+
+	if (mmu->pg_sz != PAGE_SIZE)
+		panic("MMU pg size != PAGE_SIZE (%luk)\n", TO_KB(PAGE_SIZE));
+
+	/* Enable the MMU */
+	write_aux_reg(ARC_REG_PID, MMU_ENABLE);
+
+	/* In smp we use this reg for interrupt 1 scratch */
+#ifndef CONFIG_SMP
+	/* swapper_pg_dir is the pgd for the kernel, used by vmalloc */
+	write_aux_reg(ARC_REG_SCRATCH_DATA0, swapper_pg_dir);
+#endif
+}
+
+/*
+ * TLB Programmer's Model uses Linear Indexes: 0 to {255, 511} for 128 x {2,4}
+ * The mapping is Column-first.
+ *		---------------------	-----------
+ *		|way0|way1|way2|way3|	|way0|way1|
+ *		---------------------	-----------
+ * [set0]	|  0 |  1 |  2 |  3 |	|  0 |  1 |
+ * [set1]	|  4 |  5 |  6 |  7 |	|  2 |  3 |
+ *		~		    ~	~	  ~
+ * [set127]	| 508| 509| 510| 511|	| 254| 255|
+ *		---------------------	-----------
+ * For normal operations we don't(must not) care how above works since
+ * MMU cmd getIndex(vaddr) abstracts that out.
+ * However for walking WAYS of a SET, we need to know this
+ */
+#define SET_WAY_TO_IDX(mmu, set, way)  ((set) * mmu->ways + (way))
+
+/* Handling of Duplicate PD (TLB entry) in MMU.
+ * -Could be due to buggy customer tapeouts or obscure kernel bugs
+ * -MMU complaints not at the time of duplicate PD installation, but at the
+ *      time of lookup matching multiple ways.
+ * -Ideally these should never happen - but if they do - workaround by deleting
+ *      the duplicate one.
+ * -Knob to be verbose abt it.(TODO: hook them up to debugfs)
+ */
+volatile int dup_pd_verbose = 1;/* Be slient abt it or complain (default) */
+
+void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
+			  struct pt_regs *regs)
+{
+	int set, way, n;
+	unsigned long flags, is_valid;
+	struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
+	unsigned int pd0[mmu->ways], pd1[mmu->ways];
+
+	local_irq_save(flags);
+
+	/* re-enable the MMU */
+	write_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID));
+
+	/* loop thru all sets of TLB */
+	for (set = 0; set < mmu->sets; set++) {
+
+		/* read out all the ways of current set */
+		for (way = 0, is_valid = 0; way < mmu->ways; way++) {
+			write_aux_reg(ARC_REG_TLBINDEX,
+					  SET_WAY_TO_IDX(mmu, set, way));
+			write_aux_reg(ARC_REG_TLBCOMMAND, TLBRead);
+			pd0[way] = read_aux_reg(ARC_REG_TLBPD0);
+			pd1[way] = read_aux_reg(ARC_REG_TLBPD1);
+			is_valid |= pd0[way] & _PAGE_PRESENT;
+		}
+
+		/* If all the WAYS in SET are empty, skip to next SET */
+		if (!is_valid)
+			continue;
+
+		/* Scan the set for duplicate ways: needs a nested loop */
+		for (way = 0; way < mmu->ways - 1; way++) {
+			if (!pd0[way])
+				continue;
+
+			for (n = way + 1; n < mmu->ways; n++) {
+				if ((pd0[way] & PAGE_MASK) ==
+				    (pd0[n] & PAGE_MASK)) {
+
+					if (dup_pd_verbose) {
+						pr_info("Duplicate PD's @"
+							"[%d:%d]/[%d:%d]\n",
+						     set, way, set, n);
+						pr_info("TLBPD0[%u]: %08x\n",
+						     way, pd0[way]);
+					}
+
+					/*
+					 * clear entry @way and not @n. This is
+					 * critical to our optimised loop
+					 */
+					pd0[way] = pd1[way] = 0;
+					write_aux_reg(ARC_REG_TLBINDEX,
+						SET_WAY_TO_IDX(mmu, set, way));
+					__tlb_entry_erase();
+				}
+			}
+		}
+	}
+
+	local_irq_restore(flags);
+}
+
+/***********************************************************************
+ * Diagnostic Routines
+ *  -Called from Low Level TLB Hanlders if things don;t look good
+ **********************************************************************/
+
+#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
+
+/*
+ * Low Level ASM TLB handler calls this if it finds that HW and SW ASIDS
+ * don't match
+ */
+void print_asid_mismatch(int mm_asid, int mmu_asid, int is_fast_path)
+{
+	pr_emerg("ASID Mismatch in %s Path Handler: sw-pid=0x%x hw-pid=0x%x\n",
+	       is_fast_path ? "Fast" : "Slow", mm_asid, mmu_asid);
+
+	__asm__ __volatile__("flag 1");
+}
+
+void tlb_paranoid_check(unsigned int mm_asid, unsigned long addr)
+{
+	unsigned int mmu_asid;
+
+	mmu_asid = read_aux_reg(ARC_REG_PID) & 0xff;
+
+	/*
+	 * At the time of a TLB miss/installation
+	 *   - HW version needs to match SW version
+	 *   - SW needs to have a valid ASID
+	 */
+	if (addr < 0x70000000 &&
+	    ((mm_asid == MM_CTXT_NO_ASID) ||
+	      (mmu_asid != (mm_asid & MM_CTXT_ASID_MASK))))
+		print_asid_mismatch(mm_asid, mmu_asid, 0);
+}
+#endif