arch/tile: core support for Tilera 32-bit chips.

This change is the core kernel support for TILEPro and TILE64 chips.
No driver support (except the console driver) is included yet.

This includes the relevant Linux headers in asm/; the low-level
low-level "Tile architecture" headers in arch/, which are
shared with the hypervisor, etc., and are build-system agnostic;
and the relevant hypervisor headers in hv/.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>

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..1fcecc5b9e03
--- /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];
+};
+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);
+}