sh: Move over SH-5 TLB and cache support code.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 1032 insertions, 0 deletions

diff --git a/arch/sh/mm/cache-sh5.c b/arch/sh/mm/cache-sh5.c
new file mode 100644
index 000000000000..421487cfff4c
--- /dev/null
+++ b/arch/sh/mm/cache-sh5.c
@@ -0,0 +1,1032 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * arch/sh64/mm/cache.c
+ *
+ * Original version Copyright (C) 2000, 2001  Paolo Alberelli
+ * Second version Copyright (C) benedict.gaster@superh.com 2002
+ * Third version Copyright Richard.Curnow@superh.com 2003
+ * Hacks to third version Copyright (C) 2003 Paul Mundt
+ */
+
+/****************************************************************************/
+
+#include <linux/init.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/threads.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/cache.h>
+#include <asm/tlb.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/pgalloc.h> /* for flush_itlb_range */
+
+#include <linux/proc_fs.h>
+
+/* This function is in entry.S */
+extern unsigned long switch_and_save_asid(unsigned long new_asid);
+
+/* Wired TLB entry for the D-cache */
+static unsigned long long dtlb_cache_slot;
+
+/**
+ * sh64_cache_init()
+ *
+ * This is pretty much just a straightforward clone of the SH
+ * detect_cpu_and_cache_system().
+ *
+ * This function is responsible for setting up all of the cache
+ * info dynamically as well as taking care of CPU probing and
+ * setting up the relevant subtype data.
+ *
+ * FIXME: For the time being, we only really support the SH5-101
+ * out of the box, and don't support dynamic probing for things
+ * like the SH5-103 or even cut2 of the SH5-101. Implement this
+ * later!
+ */
+int __init sh64_cache_init(void)
+{
+        /*
+         * First, setup some sane values for the I-cache.
+         */
+        cpu_data->icache.ways           = 4;
+        cpu_data->icache.sets           = 256;
+        cpu_data->icache.linesz         = L1_CACHE_BYTES;
+
+        /*
+         * FIXME: This can probably be cleaned up a bit as well.. for example,
+         * do we really need the way shift _and_ the way_step_shift ?? Judging
+         * by the existing code, I would guess no.. is there any valid reason
+         * why we need to be tracking this around?
+         */
+        cpu_data->icache.way_shift      = 13;
+        cpu_data->icache.entry_shift    = 5;
+        cpu_data->icache.set_shift      = 4;
+        cpu_data->icache.way_step_shift = 16;
+        cpu_data->icache.asid_shift     = 2;
+
+        /*
+         * way offset = cache size / associativity, so just don't factor in
+         * associativity in the first place..
+         */
+        cpu_data->icache.way_ofs        = cpu_data->icache.sets *
+                                          cpu_data->icache.linesz;
+
+        cpu_data->icache.asid_mask      = 0x3fc;
+        cpu_data->icache.idx_mask       = 0x1fe0;
+        cpu_data->icache.epn_mask       = 0xffffe000;
+        cpu_data->icache.flags          = 0;
+
+        /*
+         * Next, setup some sane values for the D-cache.
+         *
+         * On the SH5, these are pretty consistent with the I-cache settings,
+         * so we just copy over the existing definitions.. these can be fixed
+         * up later, especially if we add runtime CPU probing.
+         *
+         * Though in the meantime it saves us from having to duplicate all of
+         * the above definitions..
+         */
+        cpu_data->dcache                = cpu_data->icache;
+
+        /*
+         * Setup any cache-related flags here
+         */
+#if defined(CONFIG_DCACHE_WRITE_THROUGH)
+        set_bit(SH_CACHE_MODE_WT, &(cpu_data->dcache.flags));
+#elif defined(CONFIG_DCACHE_WRITE_BACK)
+        set_bit(SH_CACHE_MODE_WB, &(cpu_data->dcache.flags));
+#endif
+
+        /*
+         * We also need to reserve a slot for the D-cache in the DTLB, so we
+         * do this now ..
+         */
+        dtlb_cache_slot                 = sh64_get_wired_dtlb_entry();
+
+        return 0;
+}
+
+#ifdef CONFIG_DCACHE_DISABLED
+#define sh64_dcache_purge_all()                                 do { } while (0)
+#define sh64_dcache_purge_coloured_phy_page(paddr, eaddr)       do { } while (0)
+#define sh64_dcache_purge_user_range(mm, start, end)            do { } while (0)
+#define sh64_dcache_purge_phy_page(paddr)                       do { } while (0)
+#define sh64_dcache_purge_virt_page(mm, eaddr)                  do { } while (0)
+#define sh64_dcache_purge_kernel_range(start, end)              do { } while (0)
+#define sh64_dcache_wback_current_user_range(start, end)        do { } while (0)
+#endif
+
+/*##########################################################################*/
+
+/* From here onwards, a rewrite of the implementation,
+   by Richard.Curnow@superh.com.
+
+   The major changes in this compared to the old version are;
+   1. use more selective purging through OCBP instead of using ALLOCO to purge
+      by natural replacement.  This avoids purging out unrelated cache lines
+      that happen to be in the same set.
+   2. exploit the APIs copy_user_page and clear_user_page better
+   3. be more selective about I-cache purging, in particular use invalidate_all
+      more sparingly.
+
+   */
+
+/*##########################################################################
+                               SUPPORT FUNCTIONS
+  ##########################################################################*/
+
+/****************************************************************************/
+/* The following group of functions deal with mapping and unmapping a temporary
+   page into the DTLB slot that have been set aside for our exclusive use. */
+/* In order to accomplish this, we use the generic interface for adding and
+   removing a wired slot entry as defined in arch/sh64/mm/tlb.c */
+/****************************************************************************/
+
+static unsigned long slot_own_flags;
+
+static inline void sh64_setup_dtlb_cache_slot(unsigned long eaddr, unsigned long asid, unsigned long paddr)
+{
+        local_irq_save(slot_own_flags);
+        sh64_setup_tlb_slot(dtlb_cache_slot, eaddr, asid, paddr);
+}
+
+static inline void sh64_teardown_dtlb_cache_slot(void)
+{
+        sh64_teardown_tlb_slot(dtlb_cache_slot);
+        local_irq_restore(slot_own_flags);
+}
+
+/****************************************************************************/
+
+#ifndef CONFIG_ICACHE_DISABLED
+
+static void __inline__ sh64_icache_inv_all(void)
+{
+        unsigned long long addr, flag, data;
+        unsigned int flags;
+
+        addr=ICCR0;
+        flag=ICCR0_ICI;
+        data=0;
+
+        /* Make this a critical section for safety (probably not strictly necessary.) */
+        local_irq_save(flags);
+
+        /* Without %1 it gets unexplicably wrong */
+        asm volatile("getcfg    %3, 0, %0\n\t"
+                        "or     %0, %2, %0\n\t"
+                        "putcfg %3, 0, %0\n\t"
+                        "synci"
+                        : "=&r" (data)
+                        : "0" (data), "r" (flag), "r" (addr));
+
+        local_irq_restore(flags);
+}
+
+static void sh64_icache_inv_kernel_range(unsigned long start, unsigned long end)
+{
+        /* Invalidate range of addresses [start,end] from the I-cache, where
+         * the addresses lie in the kernel superpage. */
+
+        unsigned long long ullend, addr, aligned_start;
+#if (NEFF == 32)
+        aligned_start = (unsigned long long)(signed long long)(signed long) start;
+#else
+#error "NEFF != 32"
+#endif
+        aligned_start &= L1_CACHE_ALIGN_MASK;
+        addr = aligned_start;
+#if (NEFF == 32)
+        ullend = (unsigned long long) (signed long long) (signed long) end;
+#else
+#error "NEFF != 32"
+#endif
+        while (addr <= ullend) {
+                asm __volatile__ ("icbi %0, 0" : : "r" (addr));
+                addr += L1_CACHE_BYTES;
+        }
+}
+
+static void sh64_icache_inv_user_page(struct vm_area_struct *vma, unsigned long eaddr)
+{
+        /* If we get called, we know that vma->vm_flags contains VM_EXEC.
+           Also, eaddr is page-aligned. */
+
+        unsigned long long addr, end_addr;
+        unsigned long flags = 0;
+        unsigned long running_asid, vma_asid;
+        addr = eaddr;
+        end_addr = addr + PAGE_SIZE;
+
+        /* Check whether we can use the current ASID for the I-cache
+           invalidation.  For example, if we're called via
+           access_process_vm->flush_cache_page->here, (e.g. when reading from
+           /proc), 'running_asid' will be that of the reader, not of the
+           victim.
+
+           Also, note the risk that we might get pre-empted between the ASID
+           compare and blocking IRQs, and before we regain control, the
+           pid->ASID mapping changes.  However, the whole cache will get
+           invalidated when the mapping is renewed, so the worst that can
+           happen is that the loop below ends up invalidating somebody else's
+           cache entries.
+        */
+
+        running_asid = get_asid();
+        vma_asid = (vma->vm_mm->context & MMU_CONTEXT_ASID_MASK);
+        if (running_asid != vma_asid) {
+                local_irq_save(flags);
+                switch_and_save_asid(vma_asid);
+        }
+        while (addr < end_addr) {
+                /* Worth unrolling a little */
+                asm __volatile__("icbi %0,  0" : : "r" (addr));
+                asm __volatile__("icbi %0, 32" : : "r" (addr));
+                asm __volatile__("icbi %0, 64" : : "r" (addr));
+                asm __volatile__("icbi %0, 96" : : "r" (addr));
+                addr += 128;
+        }
+        if (running_asid != vma_asid) {
+                switch_and_save_asid(running_asid);
+                local_irq_restore(flags);
+        }
+}
+
+/****************************************************************************/
+
+static void sh64_icache_inv_user_page_range(struct mm_struct *mm,
+                          unsigned long start, unsigned long end)
+{
+        /* Used for invalidating big chunks of I-cache, i.e. assume the range
+           is whole pages.  If 'start' or 'end' is not page aligned, the code
+           is conservative and invalidates to the ends of the enclosing pages.
+           This is functionally OK, just a performance loss. */
+
+        /* See the comments below in sh64_dcache_purge_user_range() regarding
+           the choice of algorithm.  However, for the I-cache option (2) isn't
+           available because there are no physical tags so aliases can't be
+           resolved.  The icbi instruction has to be used through the user
+           mapping.   Because icbi is cheaper than ocbp on a cache hit, it
+           would be cheaper to use the selective code for a large range than is
+           possible with the D-cache.  Just assume 64 for now as a working
+           figure.
+           */
+
+        int n_pages;
+
+        if (!mm) return;
+
+        n_pages = ((end - start) >> PAGE_SHIFT);
+        if (n_pages >= 64) {
+                sh64_icache_inv_all();
+        } else {
+                unsigned long aligned_start;
+                unsigned long eaddr;
+                unsigned long after_last_page_start;
+                unsigned long mm_asid, current_asid;
+                unsigned long long flags = 0ULL;
+
+                mm_asid = mm->context & MMU_CONTEXT_ASID_MASK;
+                current_asid = get_asid();
+
+                if (mm_asid != current_asid) {
+                        /* Switch ASID and run the invalidate loop under cli */
+                        local_irq_save(flags);
+                        switch_and_save_asid(mm_asid);
+                }
+
+                aligned_start = start & PAGE_MASK;
+                after_last_page_start = PAGE_SIZE + ((end - 1) & PAGE_MASK);
+
+                while (aligned_start < after_last_page_start) {
+                        struct vm_area_struct *vma;
+                        unsigned long vma_end;
+                        vma = find_vma(mm, aligned_start);
+                        if (!vma || (aligned_start <= vma->vm_end)) {
+                                /* Avoid getting stuck in an error condition */
+                                aligned_start += PAGE_SIZE;
+                                continue;
+                        }
+                        vma_end = vma->vm_end;
+                        if (vma->vm_flags & VM_EXEC) {
+                                /* Executable */
+                                eaddr = aligned_start;
+                                while (eaddr < vma_end) {
+                                        sh64_icache_inv_user_page(vma, eaddr);
+                                        eaddr += PAGE_SIZE;
+                                }
+                        }
+                        aligned_start = vma->vm_end; /* Skip to start of next region */
+                }
+                if (mm_asid != current_asid) {
+                        switch_and_save_asid(current_asid);
+                        local_irq_restore(flags);
+                }
+        }
+}
+
+static void sh64_icache_inv_user_small_range(struct mm_struct *mm,
+                                                unsigned long start, int len)
+{
+
+        /* Invalidate a small range of user context I-cache, not necessarily
+           page (or even cache-line) aligned. */
+
+        unsigned long long eaddr = start;
+        unsigned long long eaddr_end = start + len;
+        unsigned long current_asid, mm_asid;
+        unsigned long long flags;
+        unsigned long long epage_start;
+
+        /* Since this is used inside ptrace, the ASID in the mm context
+           typically won't match current_asid.  We'll have to switch ASID to do
+           this.  For safety, and given that the range will be small, do all
+           this under cli.
+
+           Note, there is a hazard that the ASID in mm->context is no longer
+           actually associated with mm, i.e. if the mm->context has started a
+           new cycle since mm was last active.  However, this is just a
+           performance issue: all that happens is that we invalidate lines
+           belonging to another mm, so the owning process has to refill them
+           when that mm goes live again.  mm itself can't have any cache
+           entries because there will have been a flush_cache_all when the new
+           mm->context cycle started. */
+
+        /* Align to start of cache line.  Otherwise, suppose len==8 and start
+           was at 32N+28 : the last 4 bytes wouldn't get invalidated. */
+        eaddr = start & L1_CACHE_ALIGN_MASK;
+        eaddr_end = start + len;
+
+        local_irq_save(flags);
+        mm_asid = mm->context & MMU_CONTEXT_ASID_MASK;
+        current_asid = switch_and_save_asid(mm_asid);
+
+        epage_start = eaddr & PAGE_MASK;
+
+        while (eaddr < eaddr_end)
+        {
+                asm __volatile__("icbi %0, 0" : : "r" (eaddr));
+                eaddr += L1_CACHE_BYTES;
+        }
+        switch_and_save_asid(current_asid);
+        local_irq_restore(flags);
+}
+
+static void sh64_icache_inv_current_user_range(unsigned long start, unsigned long end)
+{
+        /* The icbi instruction never raises ITLBMISS.  i.e. if there's not a
+           cache hit on the virtual tag the instruction ends there, without a
+           TLB lookup. */
+
+        unsigned long long aligned_start;
+        unsigned long long ull_end;
+        unsigned long long addr;
+
+        ull_end = end;
+
+        /* Just invalidate over the range using the natural addresses.  TLB
+           miss handling will be OK (TBC).  Since it's for the current process,
+           either we're already in the right ASID context, or the ASIDs have
+           been recycled since we were last active in which case we might just
+           invalidate another processes I-cache entries : no worries, just a
+           performance drop for him. */
+        aligned_start = start & L1_CACHE_ALIGN_MASK;
+        addr = aligned_start;
+        while (addr < ull_end) {
+                asm __volatile__ ("icbi %0, 0" : : "r" (addr));
+                asm __volatile__ ("nop");
+                asm __volatile__ ("nop");
+                addr += L1_CACHE_BYTES;
+        }
+}
+
+#endif /* !CONFIG_ICACHE_DISABLED */
+
+/****************************************************************************/
+
+#ifndef CONFIG_DCACHE_DISABLED
+
+/* Buffer used as the target of alloco instructions to purge data from cache
+   sets by natural eviction. -- RPC */
+#define DUMMY_ALLOCO_AREA_SIZE L1_CACHE_SIZE_BYTES + (1024 * 4)
+static unsigned char dummy_alloco_area[DUMMY_ALLOCO_AREA_SIZE] __cacheline_aligned = { 0, };
+
+/****************************************************************************/
+
+static void __inline__ sh64_dcache_purge_sets(int sets_to_purge_base, int n_sets)
+{
+        /* Purge all ways in a particular block of sets, specified by the base
+           set number and number of sets.  Can handle wrap-around, if that's
+           needed.  */
+
+        int dummy_buffer_base_set;
+        unsigned long long eaddr, eaddr0, eaddr1;
+        int j;
+        int set_offset;
+
+        dummy_buffer_base_set = ((int)&dummy_alloco_area & cpu_data->dcache.idx_mask) >> cpu_data->dcache.entry_shift;
+        set_offset = sets_to_purge_base - dummy_buffer_base_set;
+
+        for (j=0; j<n_sets; j++, set_offset++) {
+                set_offset &= (cpu_data->dcache.sets - 1);
+                eaddr0 = (unsigned long long)dummy_alloco_area + (set_offset << cpu_data->dcache.entry_shift);
+
+                /* Do one alloco which hits the required set per cache way.  For
+                   write-back mode, this will purge the #ways resident lines.   There's
+                   little point unrolling this loop because the allocos stall more if
+                   they're too close together. */
+                eaddr1 = eaddr0 + cpu_data->dcache.way_ofs * cpu_data->dcache.ways;
+                for (eaddr=eaddr0; eaddr<eaddr1; eaddr+=cpu_data->dcache.way_ofs) {
+                        asm __volatile__ ("alloco %0, 0" : : "r" (eaddr));
+                        asm __volatile__ ("synco"); /* TAKum03020 */
+                }
+
+                eaddr1 = eaddr0 + cpu_data->dcache.way_ofs * cpu_data->dcache.ways;
+                for (eaddr=eaddr0; eaddr<eaddr1; eaddr+=cpu_data->dcache.way_ofs) {
+                        /* Load from each address.  Required because alloco is a NOP if
+                           the cache is write-through.  Write-through is a config option. */
+                        if (test_bit(SH_CACHE_MODE_WT, &(cpu_data->dcache.flags)))
+                                *(volatile unsigned char *)(int)eaddr;
+                }
+        }
+
+        /* Don't use OCBI to invalidate the lines.  That costs cycles directly.
+           If the dummy block is just left resident, it will naturally get
+           evicted as required.  */
+
+        return;
+}
+
+/****************************************************************************/
+
+static void sh64_dcache_purge_all(void)
+{
+        /* Purge the entire contents of the dcache.  The most efficient way to
+           achieve this is to use alloco instructions on a region of unused
+           memory equal in size to the cache, thereby causing the current
+           contents to be discarded by natural eviction.  The alternative,
+           namely reading every tag, setting up a mapping for the corresponding
+           page and doing an OCBP for the line, would be much more expensive.
+           */
+
+        sh64_dcache_purge_sets(0, cpu_data->dcache.sets);
+
+        return;
+
+}
+
+/****************************************************************************/
+
+static void sh64_dcache_purge_kernel_range(unsigned long start, unsigned long end)
+{
+        /* Purge the range of addresses [start,end] from the D-cache.  The
+           addresses lie in the superpage mapping.  There's no harm if we
+           overpurge at either end - just a small performance loss. */
+        unsigned long long ullend, addr, aligned_start;
+#if (NEFF == 32)
+        aligned_start = (unsigned long long)(signed long long)(signed long) start;
+#else
+#error "NEFF != 32"
+#endif
+        aligned_start &= L1_CACHE_ALIGN_MASK;
+        addr = aligned_start;
+#if (NEFF == 32)
+        ullend = (unsigned long long) (signed long long) (signed long) end;
+#else
+#error "NEFF != 32"
+#endif
+        while (addr <= ullend) {
+                asm __volatile__ ("ocbp %0, 0" : : "r" (addr));
+                addr += L1_CACHE_BYTES;
+        }
+        return;
+}
+
+/* Assumes this address (+ (2**n_synbits) pages up from it) aren't used for
+   anything else in the kernel */
+#define MAGIC_PAGE0_START 0xffffffffec000000ULL
+
+static void sh64_dcache_purge_coloured_phy_page(unsigned long paddr, unsigned long eaddr)
+{
+        /* Purge the physical page 'paddr' from the cache.  It's known that any
+           cache lines requiring attention have the same page colour as the the
+           address 'eaddr'.
+
+           This relies on the fact that the D-cache matches on physical tags
+           when no virtual tag matches.  So we create an alias for the original
+           page and purge through that.  (Alternatively, we could have done
+           this by switching ASID to match the original mapping and purged
+           through that, but that involves ASID switching cost + probably a
+           TLBMISS + refill anyway.)
+           */
+
+        unsigned long long magic_page_start;
+        unsigned long long magic_eaddr, magic_eaddr_end;
+
+        magic_page_start = MAGIC_PAGE0_START + (eaddr & CACHE_OC_SYN_MASK);
+
+        /* As long as the kernel is not pre-emptible, this doesn't need to be
+           under cli/sti. */
+
+        sh64_setup_dtlb_cache_slot(magic_page_start, get_asid(), paddr);
+
+        magic_eaddr = magic_page_start;
+        magic_eaddr_end = magic_eaddr + PAGE_SIZE;
+        while (magic_eaddr < magic_eaddr_end) {
+                /* Little point in unrolling this loop - the OCBPs are blocking
+                   and won't go any quicker (i.e. the loop overhead is parallel
+                   to part of the OCBP execution.) */
+                asm __volatile__ ("ocbp %0, 0" : : "r" (magic_eaddr));
+                magic_eaddr += L1_CACHE_BYTES;
+        }
+
+        sh64_teardown_dtlb_cache_slot();
+}
+
+/****************************************************************************/
+
+static void sh64_dcache_purge_phy_page(unsigned long paddr)
+{
+        /* Pure a page given its physical start address, by creating a
+           temporary 1 page mapping and purging across that.  Even if we know
+           the virtual address (& vma or mm) of the page, the method here is
+           more elegant because it avoids issues of coping with page faults on
+           the purge instructions (i.e. no special-case code required in the
+           critical path in the TLB miss handling). */
+
+        unsigned long long eaddr_start, eaddr, eaddr_end;
+        int i;
+
+        /* As long as the kernel is not pre-emptible, this doesn't need to be
+           under cli/sti. */
+
+        eaddr_start = MAGIC_PAGE0_START;
+        for (i=0; i < (1 << CACHE_OC_N_SYNBITS); i++) {
+                sh64_setup_dtlb_cache_slot(eaddr_start, get_asid(), paddr);
+
+                eaddr = eaddr_start;
+                eaddr_end = eaddr + PAGE_SIZE;
+                while (eaddr < eaddr_end) {
+                        asm __volatile__ ("ocbp %0, 0" : : "r" (eaddr));
+                        eaddr += L1_CACHE_BYTES;
+                }
+
+                sh64_teardown_dtlb_cache_slot();
+                eaddr_start += PAGE_SIZE;
+        }
+}
+
+static void sh64_dcache_purge_user_pages(struct mm_struct *mm,
+                                unsigned long addr, unsigned long end)
+{
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        pte_t entry;
+        spinlock_t *ptl;
+        unsigned long paddr;
+
+        if (!mm)
+                return; /* No way to find physical address of page */
+
+        pgd = pgd_offset(mm, addr);
+        if (pgd_bad(*pgd))
+                return;
+
+        pmd = pmd_offset(pgd, addr);
+        if (pmd_none(*pmd) || pmd_bad(*pmd))
+                return;
+
+        pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+        do {
+                entry = *pte;
+                if (pte_none(entry) || !pte_present(entry))
+                        continue;
+                paddr = pte_val(entry) & PAGE_MASK;
+                sh64_dcache_purge_coloured_phy_page(paddr, addr);
+        } while (pte++, addr += PAGE_SIZE, addr != end);
+        pte_unmap_unlock(pte - 1, ptl);
+}
+/****************************************************************************/
+
+static void sh64_dcache_purge_user_range(struct mm_struct *mm,
+                          unsigned long start, unsigned long end)
+{
+        /* There are at least 5 choices for the implementation of this, with
+           pros (+), cons(-), comments(*):
+
+           1. ocbp each line in the range through the original user's ASID
+              + no lines spuriously evicted
+              - tlbmiss handling (must either handle faults on demand => extra
+                special-case code in tlbmiss critical path), or map the page in
+                advance (=> flush_tlb_range in advance to avoid multiple hits)
+              - ASID switching
+              - expensive for large ranges
+
+           2. temporarily map each page in the range to a special effective
+              address and ocbp through the temporary mapping; relies on the
+              fact that SH-5 OCB* always do TLB lookup and match on ptags (they
+              never look at the etags)
+              + no spurious evictions
+              - expensive for large ranges
+              * surely cheaper than (1)
+
+           3. walk all the lines in the cache, check the tags, if a match
+              occurs create a page mapping to ocbp the line through
+              + no spurious evictions
+              - tag inspection overhead
+              - (especially for small ranges)
+              - potential cost of setting up/tearing down page mapping for
+                every line that matches the range
+              * cost partly independent of range size
+
+           4. walk all the lines in the cache, check the tags, if a match
+              occurs use 4 * alloco to purge the line (+3 other probably
+              innocent victims) by natural eviction
+              + no tlb mapping overheads
+              - spurious evictions
+              - tag inspection overhead
+
+           5. implement like flush_cache_all
+              + no tag inspection overhead
+              - spurious evictions
+              - bad for small ranges
+
+           (1) can be ruled out as more expensive than (2).  (2) appears best
+           for small ranges.  The choice between (3), (4) and (5) for large
+           ranges and the range size for the large/small boundary need
+           benchmarking to determine.
+
+           For now use approach (2) for small ranges and (5) for large ones.
+
+           */
+
+        int n_pages;
+
+        n_pages = ((end - start) >> PAGE_SHIFT);
+        if (n_pages >= 64 || ((start ^ (end - 1)) & PMD_MASK)) {
+#if 1
+                sh64_dcache_purge_all();
+#else
+                unsigned long long set, way;
+                unsigned long mm_asid = mm->context & MMU_CONTEXT_ASID_MASK;
+                for (set = 0; set < cpu_data->dcache.sets; set++) {
+                        unsigned long long set_base_config_addr = CACHE_OC_ADDRESS_ARRAY + (set << cpu_data->dcache.set_shift);
+                        for (way = 0; way < cpu_data->dcache.ways; way++) {
+                                unsigned long long config_addr = set_base_config_addr + (way << cpu_data->dcache.way_step_shift);
+                                unsigned long long tag0;
+                                unsigned long line_valid;
+
+                                asm __volatile__("getcfg %1, 0, %0" : "=r" (tag0) : "r" (config_addr));
+                                line_valid = tag0 & SH_CACHE_VALID;
+                                if (line_valid) {
+                                        unsigned long cache_asid;
+                                        unsigned long epn;
+
+                                        cache_asid = (tag0 & cpu_data->dcache.asid_mask) >> cpu_data->dcache.asid_shift;
+                                        /* The next line needs some
+                                           explanation.  The virtual tags
+                                           encode bits [31:13] of the virtual
+                                           address, bit [12] of the 'tag' being
+                                           implied by the cache set index. */
+                                        epn = (tag0 & cpu_data->dcache.epn_mask) | ((set & 0x80) << cpu_data->dcache.entry_shift);
+
+                                        if ((cache_asid == mm_asid) && (start <= epn) && (epn < end)) {
+                                                /* TODO : could optimise this
+                                                   call by batching multiple
+                                                   adjacent sets together. */
+                                                sh64_dcache_purge_sets(set, 1);
+                                                break; /* Don't waste time inspecting other ways for this set */
+                                        }
+                                }
+                        }
+                }
+#endif
+        } else {
+                /* Small range, covered by a single page table page */
+                start &= PAGE_MASK;     /* should already be so */
+                end = PAGE_ALIGN(end);  /* should already be so */
+                sh64_dcache_purge_user_pages(mm, start, end);
+        }
+        return;
+}
+
+static void sh64_dcache_wback_current_user_range(unsigned long start, unsigned long end)
+{
+        unsigned long long aligned_start;
+        unsigned long long ull_end;
+        unsigned long long addr;
+
+        ull_end = end;
+
+        /* Just wback over the range using the natural addresses.  TLB miss
+           handling will be OK (TBC) : the range has just been written to by
+           the signal frame setup code, so the PTEs must exist.
+
+           Note, if we have CONFIG_PREEMPT and get preempted inside this loop,
+           it doesn't matter, even if the pid->ASID mapping changes whilst
+           we're away.  In that case the cache will have been flushed when the
+           mapping was renewed.  So the writebacks below will be nugatory (and
+           we'll doubtless have to fault the TLB entry/ies in again with the
+           new ASID), but it's a rare case.
+           */
+        aligned_start = start & L1_CACHE_ALIGN_MASK;
+        addr = aligned_start;
+        while (addr < ull_end) {
+                asm __volatile__ ("ocbwb %0, 0" : : "r" (addr));
+                addr += L1_CACHE_BYTES;
+        }
+}
+
+/****************************************************************************/
+
+/* These *MUST* lie in an area of virtual address space that's otherwise unused. */
+#define UNIQUE_EADDR_START 0xe0000000UL
+#define UNIQUE_EADDR_END   0xe8000000UL
+
+static unsigned long sh64_make_unique_eaddr(unsigned long user_eaddr, unsigned long paddr)
+{
+        /* Given a physical address paddr, and a user virtual address
+           user_eaddr which will eventually be mapped to it, create a one-off
+           kernel-private eaddr mapped to the same paddr.  This is used for
+           creating special destination pages for copy_user_page and
+           clear_user_page */
+
+        static unsigned long current_pointer = UNIQUE_EADDR_START;
+        unsigned long coloured_pointer;
+
+        if (current_pointer == UNIQUE_EADDR_END) {
+                sh64_dcache_purge_all();
+                current_pointer = UNIQUE_EADDR_START;
+        }
+
+        coloured_pointer = (current_pointer & ~CACHE_OC_SYN_MASK) | (user_eaddr & CACHE_OC_SYN_MASK);
+        sh64_setup_dtlb_cache_slot(coloured_pointer, get_asid(), paddr);
+
+        current_pointer += (PAGE_SIZE << CACHE_OC_N_SYNBITS);
+
+        return coloured_pointer;
+}
+
+/****************************************************************************/
+
+static void sh64_copy_user_page_coloured(void *to, void *from, unsigned long address)
+{
+        void *coloured_to;
+
+        /* Discard any existing cache entries of the wrong colour.  These are
+           present quite often, if the kernel has recently used the page
+           internally, then given it up, then it's been allocated to the user.
+           */
+        sh64_dcache_purge_coloured_phy_page(__pa(to), (unsigned long) to);
+
+        coloured_to = (void *) sh64_make_unique_eaddr(address, __pa(to));
+        sh64_page_copy(from, coloured_to);
+
+        sh64_teardown_dtlb_cache_slot();
+}
+
+static void sh64_clear_user_page_coloured(void *to, unsigned long address)
+{
+        void *coloured_to;
+
+        /* Discard any existing kernel-originated lines of the wrong colour (as
+           above) */
+        sh64_dcache_purge_coloured_phy_page(__pa(to), (unsigned long) to);
+
+        coloured_to = (void *) sh64_make_unique_eaddr(address, __pa(to));
+        sh64_page_clear(coloured_to);
+
+        sh64_teardown_dtlb_cache_slot();
+}
+
+#endif /* !CONFIG_DCACHE_DISABLED */
+
+/****************************************************************************/
+
+/*##########################################################################
+                            EXTERNALLY CALLABLE API.
+  ##########################################################################*/
+
+/* These functions are described in Documentation/cachetlb.txt.
+   Each one of these functions varies in behaviour depending on whether the
+   I-cache and/or D-cache are configured out.
+
+   Note that the Linux term 'flush' corresponds to what is termed 'purge' in
+   the sh/sh64 jargon for the D-cache, i.e. write back dirty data then
+   invalidate the cache lines, and 'invalidate' for the I-cache.
+   */
+
+#undef FLUSH_TRACE
+
+void flush_cache_all(void)
+{
+        /* Invalidate the entire contents of both caches, after writing back to
+           memory any dirty data from the D-cache. */
+        sh64_dcache_purge_all();
+        sh64_icache_inv_all();
+}
+
+/****************************************************************************/
+
+void flush_cache_mm(struct mm_struct *mm)
+{
+        /* Invalidate an entire user-address space from both caches, after
+           writing back dirty data (e.g. for shared mmap etc). */
+
+        /* This could be coded selectively by inspecting all the tags then
+           doing 4*alloco on any set containing a match (as for
+           flush_cache_range), but fork/exit/execve (where this is called from)
+           are expensive anyway. */
+
+        /* Have to do a purge here, despite the comments re I-cache below.
+           There could be odd-coloured dirty data associated with the mm still
+           in the cache - if this gets written out through natural eviction
+           after the kernel has reused the page there will be chaos.
+           */
+
+        sh64_dcache_purge_all();
+
+        /* The mm being torn down won't ever be active again, so any Icache
+           lines tagged with its ASID won't be visible for the rest of the
+           lifetime of this ASID cycle.  Before the ASID gets reused, there
+           will be a flush_cache_all.  Hence we don't need to touch the
+           I-cache.  This is similar to the lack of action needed in
+           flush_tlb_mm - see fault.c. */
+}
+
+/****************************************************************************/
+
+void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
+                       unsigned long end)
+{
+        struct mm_struct *mm = vma->vm_mm;
+
+        /* Invalidate (from both caches) the range [start,end) of virtual
+           addresses from the user address space specified by mm, after writing
+           back any dirty data.
+
+           Note, 'end' is 1 byte beyond the end of the range to flush. */
+
+        sh64_dcache_purge_user_range(mm, start, end);
+        sh64_icache_inv_user_page_range(mm, start, end);
+}
+
+/****************************************************************************/
+
+void flush_cache_page(struct vm_area_struct *vma, unsigned long eaddr, unsigned long pfn)
+{
+        /* Invalidate any entries in either cache for the vma within the user
+           address space vma->vm_mm for the page starting at virtual address
+           'eaddr'.   This seems to be used primarily in breaking COW.  Note,
+           the I-cache must be searched too in case the page in question is
+           both writable and being executed from (e.g. stack trampolines.)
+
+           Note, this is called with pte lock held.
+           */
+
+        sh64_dcache_purge_phy_page(pfn << PAGE_SHIFT);
+
+        if (vma->vm_flags & VM_EXEC) {
+                sh64_icache_inv_user_page(vma, eaddr);
+        }
+}
+
+/****************************************************************************/
+
+#ifndef CONFIG_DCACHE_DISABLED
+
+void copy_user_page(void *to, void *from, unsigned long address, struct page *page)
+{
+        /* 'from' and 'to' are kernel virtual addresses (within the superpage
+           mapping of the physical RAM).  'address' is the user virtual address
+           where the copy 'to' will be mapped after.  This allows a custom
+           mapping to be used to ensure that the new copy is placed in the
+           right cache sets for the user to see it without having to bounce it
+           out via memory.  Note however : the call to flush_page_to_ram in
+           (generic)/mm/memory.c:(break_cow) undoes all this good work in that one
+           very important case!
+
+           TBD : can we guarantee that on every call, any cache entries for
+           'from' are in the same colour sets as 'address' also?  i.e. is this
+           always used just to deal with COW?  (I suspect not). */
+
+        /* There are two possibilities here for when the page 'from' was last accessed:
+           * by the kernel : this is OK, no purge required.
+           * by the/a user (e.g. for break_COW) : need to purge.
+
+           If the potential user mapping at 'address' is the same colour as
+           'from' there is no need to purge any cache lines from the 'from'
+           page mapped into cache sets of colour 'address'.  (The copy will be
+           accessing the page through 'from').
+           */
+
+        if (((address ^ (unsigned long) from) & CACHE_OC_SYN_MASK) != 0) {
+                sh64_dcache_purge_coloured_phy_page(__pa(from), address);
+        }
+
+        if (((address ^ (unsigned long) to) & CACHE_OC_SYN_MASK) == 0) {
+                /* No synonym problem on destination */
+                sh64_page_copy(from, to);
+        } else {
+                sh64_copy_user_page_coloured(to, from, address);
+        }
+
+        /* Note, don't need to flush 'from' page from the cache again - it's
+           done anyway by the generic code */
+}
+
+void clear_user_page(void *to, unsigned long address, struct page *page)
+{
+        /* 'to' is a kernel virtual address (within the superpage
+           mapping of the physical RAM).  'address' is the user virtual address
+           where the 'to' page will be mapped after.  This allows a custom
+           mapping to be used to ensure that the new copy is placed in the
+           right cache sets for the user to see it without having to bounce it
+           out via memory.
+        */
+
+        if (((address ^ (unsigned long) to) & CACHE_OC_SYN_MASK) == 0) {
+                /* No synonym problem on destination */
+                sh64_page_clear(to);
+        } else {
+                sh64_clear_user_page_coloured(to, address);
+        }
+}
+
+#endif /* !CONFIG_DCACHE_DISABLED */
+
+/****************************************************************************/
+
+void flush_dcache_page(struct page *page)
+{
+        sh64_dcache_purge_phy_page(page_to_phys(page));
+        wmb();
+}
+
+/****************************************************************************/
+
+void flush_icache_range(unsigned long start, unsigned long end)
+{
+        /* Flush the range [start,end] of kernel virtual adddress space from
+           the I-cache.  The corresponding range must be purged from the
+           D-cache also because the SH-5 doesn't have cache snooping between
+           the caches.  The addresses will be visible through the superpage
+           mapping, therefore it's guaranteed that there no cache entries for
+           the range in cache sets of the wrong colour.
+
+           Primarily used for cohering the I-cache after a module has
+           been loaded.  */
+
+        /* We also make sure to purge the same range from the D-cache since
+           flush_page_to_ram() won't be doing this for us! */
+
+        sh64_dcache_purge_kernel_range(start, end);
+        wmb();
+        sh64_icache_inv_kernel_range(start, end);
+}
+
+/****************************************************************************/
+
+void flush_icache_user_range(struct vm_area_struct *vma,
+                        struct page *page, unsigned long addr, int len)
+{
+        /* Flush the range of user (defined by vma->vm_mm) address space
+           starting at 'addr' for 'len' bytes from the cache.  The range does
+           not straddle a page boundary, the unique physical page containing
+           the range is 'page'.  This seems to be used mainly for invalidating
+           an address range following a poke into the program text through the
+           ptrace() call from another process (e.g. for BRK instruction
+           insertion). */
+
+        sh64_dcache_purge_coloured_phy_page(page_to_phys(page), addr);
+        mb();
+
+        if (vma->vm_flags & VM_EXEC) {
+                sh64_icache_inv_user_small_range(vma->vm_mm, addr, len);
+        }
+}
+
+/*##########################################################################
+                        ARCH/SH64 PRIVATE CALLABLE API.
+  ##########################################################################*/
+
+void flush_cache_sigtramp(unsigned long start, unsigned long end)
+{
+        /* For the address range [start,end), write back the data from the
+           D-cache and invalidate the corresponding region of the I-cache for
+           the current process.  Used to flush signal trampolines on the stack
+           to make them executable. */
+
+        sh64_dcache_wback_current_user_range(start, end);
+        wmb();
+        sh64_icache_inv_current_user_range(start, end);
+}
+