1 files changed, 328 insertions, 0 deletions

diff --git a/arch/tile/mm/highmem.c b/arch/tile/mm/highmem.c
new file mode 100644
index 000000000000..ff1cdff5114d
--- /dev/null
+++ b/arch/tile/mm/highmem.c
@@ -0,0 +1,328 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <asm/homecache.h>
+
+#define kmap_get_pte(vaddr) \
+        pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)),\
+                (vaddr)), (vaddr))
+
+
+void *kmap(struct page *page)
+{
+        void *kva;
+        unsigned long flags;
+        pte_t *ptep;
+
+        might_sleep();
+        if (!PageHighMem(page))
+                return page_address(page);
+        kva = kmap_high(page);
+
+        /*
+         * Rewrite the PTE under the lock.  This ensures that the page
+         * is not currently migrating.
+         */
+        ptep = kmap_get_pte((unsigned long)kva);
+        flags = homecache_kpte_lock();
+        set_pte_at(&init_mm, kva, ptep, mk_pte(page, page_to_kpgprot(page)));
+        homecache_kpte_unlock(flags);
+
+        return kva;
+}
+EXPORT_SYMBOL(kmap);
+
+void kunmap(struct page *page)
+{
+        if (in_interrupt())
+                BUG();
+        if (!PageHighMem(page))
+                return;
+        kunmap_high(page);
+}
+EXPORT_SYMBOL(kunmap);
+
+static void debug_kmap_atomic_prot(enum km_type type)
+{
+#ifdef CONFIG_DEBUG_HIGHMEM
+        static unsigned warn_count = 10;
+
+        if (unlikely(warn_count == 0))
+                return;
+
+        if (unlikely(in_interrupt())) {
+                if (in_irq()) {
+                        if (type != KM_IRQ0 && type != KM_IRQ1 &&
+                            type != KM_BIO_SRC_IRQ &&
+                            /* type != KM_BIO_DST_IRQ && */
+                            type != KM_BOUNCE_READ) {
+                                WARN_ON(1);
+                                warn_count--;
+                        }
+                } else if (!irqs_disabled()) {  /* softirq */
+                        if (type != KM_IRQ0 && type != KM_IRQ1 &&
+                            type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
+                            type != KM_SKB_SUNRPC_DATA &&
+                            type != KM_SKB_DATA_SOFTIRQ &&
+                            type != KM_BOUNCE_READ) {
+                                WARN_ON(1);
+                                warn_count--;
+                        }
+                }
+        }
+
+        if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
+            type == KM_BIO_SRC_IRQ /* || type == KM_BIO_DST_IRQ */) {
+                if (!irqs_disabled()) {
+                        WARN_ON(1);
+                        warn_count--;
+                }
+        } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
+                if (irq_count() == 0 && !irqs_disabled()) {
+                        WARN_ON(1);
+                        warn_count--;
+                }
+        }
+#endif
+}
+
+/*
+ * Describe a single atomic mapping of a page on a given cpu at a
+ * given address, and allow it to be linked into a list.
+ */
+struct atomic_mapped_page {
+        struct list_head list;
+        struct page *page;
+        int cpu;
+        unsigned long va;
+};
+
+static spinlock_t amp_lock = __SPIN_LOCK_UNLOCKED(&amp_lock);
+static struct list_head amp_list = LIST_HEAD_INIT(amp_list);
+
+/*
+ * Combining this structure with a per-cpu declaration lets us give
+ * each cpu an atomic_mapped_page structure per type.
+ */
+struct kmap_amps {
+        struct atomic_mapped_page per_type[KM_TYPE_NR];
+};
+static DEFINE_PER_CPU(struct kmap_amps, amps);
+
+/*
+ * Add a page and va, on this cpu, to the list of kmap_atomic pages,
+ * and write the new pte to memory.  Writing the new PTE under the
+ * lock guarantees that it is either on the list before migration starts
+ * (if we won the race), or set_pte() sets the migrating bit in the PTE
+ * (if we lost the race).  And doing it under the lock guarantees
+ * that when kmap_atomic_fix_one_pte() comes along, it finds a valid
+ * PTE in memory, iff the mapping is still on the amp_list.
+ *
+ * Finally, doing it under the lock lets us safely examine the page
+ * to see if it is immutable or not, for the generic kmap_atomic() case.
+ * If we examine it earlier we are exposed to a race where it looks
+ * writable earlier, but becomes immutable before we write the PTE.
+ */
+static void kmap_atomic_register(struct page *page, enum km_type type,
+                                 unsigned long va, pte_t *ptep, pte_t pteval)
+{
+        unsigned long flags;
+        struct atomic_mapped_page *amp;
+
+        flags = homecache_kpte_lock();
+        spin_lock(&amp_lock);
+
+        /* With interrupts disabled, now fill in the per-cpu info. */
+        amp = &__get_cpu_var(amps).per_type[type];
+        amp->page = page;
+        amp->cpu = smp_processor_id();
+        amp->va = va;
+
+        /* For generic kmap_atomic(), choose the PTE writability now. */
+        if (!pte_read(pteval))
+                pteval = mk_pte(page, page_to_kpgprot(page));
+
+        list_add(&amp->list, &amp_list);
+        set_pte(ptep, pteval);
+        arch_flush_lazy_mmu_mode();
+
+        spin_unlock(&amp_lock);
+        homecache_kpte_unlock(flags);
+}
+
+/*
+ * Remove a page and va, on this cpu, from the list of kmap_atomic pages.
+ * Linear-time search, but we count on the lists being short.
+ * We don't need to adjust the PTE under the lock (as opposed to the
+ * kmap_atomic_register() case), since we're just unconditionally
+ * zeroing the PTE after it's off the list.
+ */
+static void kmap_atomic_unregister(struct page *page, unsigned long va)
+{
+        unsigned long flags;
+        struct atomic_mapped_page *amp;
+        int cpu = smp_processor_id();
+        spin_lock_irqsave(&amp_lock, flags);
+        list_for_each_entry(amp, &amp_list, list) {
+                if (amp->page == page && amp->cpu == cpu && amp->va == va)
+                        break;
+        }
+        BUG_ON(&amp->list == &amp_list);
+        list_del(&amp->list);
+        spin_unlock_irqrestore(&amp_lock, flags);
+}
+
+/* Helper routine for kmap_atomic_fix_kpte(), below. */
+static void kmap_atomic_fix_one_kpte(struct atomic_mapped_page *amp,
+                                     int finished)
+{
+        pte_t *ptep = kmap_get_pte(amp->va);
+        if (!finished) {
+                set_pte(ptep, pte_mkmigrate(*ptep));
+                flush_remote(0, 0, NULL, amp->va, PAGE_SIZE, PAGE_SIZE,
+                             cpumask_of(amp->cpu), NULL, 0);
+        } else {
+                /*
+                 * Rewrite a default kernel PTE for this page.
+                 * We rely on the fact that set_pte() writes the
+                 * present+migrating bits last.
+                 */
+                pte_t pte = mk_pte(amp->page, page_to_kpgprot(amp->page));
+                set_pte(ptep, pte);
+        }
+}
+
+/*
+ * This routine is a helper function for homecache_fix_kpte(); see
+ * its comments for more information on the "finished" argument here.
+ *
+ * Note that we hold the lock while doing the remote flushes, which
+ * will stall any unrelated cpus trying to do kmap_atomic operations.
+ * We could just update the PTEs under the lock, and save away copies
+ * of the structs (or just the va+cpu), then flush them after we
+ * release the lock, but it seems easier just to do it all under the lock.
+ */
+void kmap_atomic_fix_kpte(struct page *page, int finished)
+{
+        struct atomic_mapped_page *amp;
+        unsigned long flags;
+        spin_lock_irqsave(&amp_lock, flags);
+        list_for_each_entry(amp, &amp_list, list) {
+                if (amp->page == page)
+                        kmap_atomic_fix_one_kpte(amp, finished);
+        }
+        spin_unlock_irqrestore(&amp_lock, flags);
+}
+
+/*
+ * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap
+ * because the kmap code must perform a global TLB invalidation when
+ * the kmap pool wraps.
+ *
+ * Note that they may be slower than on x86 (etc.) because unlike on
+ * those platforms, we do have to take a global lock to map and unmap
+ * pages on Tile (see above).
+ *
+ * When holding an atomic kmap is is not legal to sleep, so atomic
+ * kmaps are appropriate for short, tight code paths only.
+ */
+void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
+{
+        enum fixed_addresses idx;
+        unsigned long vaddr;
+        pte_t *pte;
+
+        /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+        pagefault_disable();
+
+        /* Avoid icache flushes by disallowing atomic executable mappings. */
+        BUG_ON(pte_exec(prot));
+
+        if (!PageHighMem(page))
+                return page_address(page);
+
+        debug_kmap_atomic_prot(type);
+
+        idx = type + KM_TYPE_NR*smp_processor_id();
+        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+        pte = kmap_get_pte(vaddr);
+        BUG_ON(!pte_none(*pte));
+
+        /* Register that this page is mapped atomically on this cpu. */
+        kmap_atomic_register(page, type, vaddr, pte, mk_pte(page, prot));
+
+        return (void *)vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic_prot);
+
+void *kmap_atomic(struct page *page, enum km_type type)
+{
+        /* PAGE_NONE is a magic value that tells us to check immutability. */
+        return kmap_atomic_prot(page, type, PAGE_NONE);
+}
+EXPORT_SYMBOL(kmap_atomic);
+
+void kunmap_atomic(void *kvaddr, enum km_type type)
+{
+        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+        enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
+
+        /*
+         * Force other mappings to Oops if they try to access this pte without
+         * first remapping it.  Keeping stale mappings around is a bad idea.
+         */
+        if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx)) {
+                pte_t *pte = kmap_get_pte(vaddr);
+                pte_t pteval = *pte;
+                BUG_ON(!pte_present(pteval) && !pte_migrating(pteval));
+                kmap_atomic_unregister(pte_page(pteval), vaddr);
+                kpte_clear_flush(pte, vaddr);
+        } else {
+                /* Must be a lowmem page */
+                BUG_ON(vaddr < PAGE_OFFSET);
+                BUG_ON(vaddr >= (unsigned long)high_memory);
+        }
+
+        arch_flush_lazy_mmu_mode();
+        pagefault_enable();
+}
+EXPORT_SYMBOL(kunmap_atomic);
+
+/*
+ * This API is supposed to allow us to map memory without a "struct page".
+ * Currently we don't support this, though this may change in the future.
+ */
+void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
+{
+        return kmap_atomic(pfn_to_page(pfn), type);
+}
+void *kmap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
+{
+        return kmap_atomic_prot(pfn_to_page(pfn), type, prot);
+}
+
+struct page *kmap_atomic_to_page(void *ptr)
+{
+        pte_t *pte;
+        unsigned long vaddr = (unsigned long)ptr;
+
+        if (vaddr < FIXADDR_START)
+                return virt_to_page(ptr);
+
+        pte = kmap_get_pte(vaddr);
+        return pte_page(*pte);
+}