1 files changed, 445 insertions, 0 deletions

diff --git a/arch/tile/mm/homecache.c b/arch/tile/mm/homecache.c
new file mode 100644
index 000000000000..52feb77133ce
--- /dev/null
+++ b/arch/tile/mm/homecache.c
@@ -0,0 +1,445 @@
+/*
+ * 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.
+ *
+ * This code maintains the "home" for each page in the system.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/bootmem.h>
+#include <linux/rmap.h>
+#include <linux/pagemap.h>
+#include <linux/mutex.h>
+#include <linux/interrupt.h>
+#include <linux/sysctl.h>
+#include <linux/pagevec.h>
+#include <linux/ptrace.h>
+#include <linux/timex.h>
+#include <linux/cache.h>
+#include <linux/smp.h>
+
+#include <asm/page.h>
+#include <asm/sections.h>
+#include <asm/tlbflush.h>
+#include <asm/pgalloc.h>
+#include <asm/homecache.h>
+
+#include "migrate.h"
+
+
+#if CHIP_HAS_COHERENT_LOCAL_CACHE()
+
+/*
+ * The noallocl2 option suppresses all use of the L2 cache to cache
+ * locally from a remote home.  There's no point in using it if we
+ * don't have coherent local caching, though.
+ */
+int __write_once noallocl2;
+static int __init set_noallocl2(char *str)
+{
+        noallocl2 = 1;
+        return 0;
+}
+early_param("noallocl2", set_noallocl2);
+
+#else
+
+#define noallocl2 0
+
+#endif
+
+
+
+/* Provide no-op versions of these routines to keep flush_remote() cleaner. */
+#define mark_caches_evicted_start() 0
+#define mark_caches_evicted_finish(mask, timestamp) do {} while (0)
+
+
+
+
+/*
+ * Update the irq_stat for cpus that we are going to interrupt
+ * with TLB or cache flushes.  Also handle removing dataplane cpus
+ * from the TLB flush set, and setting dataplane_tlb_state instead.
+ */
+static void hv_flush_update(const struct cpumask *cache_cpumask,
+                            struct cpumask *tlb_cpumask,
+                            unsigned long tlb_va, unsigned long tlb_length,
+                            HV_Remote_ASID *asids, int asidcount)
+{
+        struct cpumask mask;
+        int i, cpu;
+
+        cpumask_clear(&mask);
+        if (cache_cpumask)
+                cpumask_or(&mask, &mask, cache_cpumask);
+        if (tlb_cpumask && tlb_length) {
+                cpumask_or(&mask, &mask, tlb_cpumask);
+        }
+
+        for (i = 0; i < asidcount; ++i)
+                cpumask_set_cpu(asids[i].y * smp_width + asids[i].x, &mask);
+
+        /*
+         * Don't bother to update atomically; losing a count
+         * here is not that critical.
+         */
+        for_each_cpu(cpu, &mask)
+                ++per_cpu(irq_stat, cpu).irq_hv_flush_count;
+}
+
+/*
+ * This wrapper function around hv_flush_remote() does several things:
+ *
+ *  - Provides a return value error-checking panic path, since
+ *    there's never any good reason for hv_flush_remote() to fail.
+ *  - Accepts a 32-bit PFN rather than a 64-bit PA, which generally
+ *    is the type that Linux wants to pass around anyway.
+ *  - Centralizes the mark_caches_evicted() handling.
+ *  - Canonicalizes that lengths of zero make cpumasks NULL.
+ *  - Handles deferring TLB flushes for dataplane tiles.
+ *  - Tracks remote interrupts in the per-cpu irq_cpustat_t.
+ *
+ * Note that we have to wait until the cache flush completes before
+ * updating the per-cpu last_cache_flush word, since otherwise another
+ * concurrent flush can race, conclude the flush has already
+ * completed, and start to use the page while it's still dirty
+ * remotely (running concurrently with the actual evict, presumably).
+ */
+void flush_remote(unsigned long cache_pfn, unsigned long cache_control,
+                  const struct cpumask *cache_cpumask_orig,
+                  HV_VirtAddr tlb_va, unsigned long tlb_length,
+                  unsigned long tlb_pgsize,
+                  const struct cpumask *tlb_cpumask_orig,
+                  HV_Remote_ASID *asids, int asidcount)
+{
+        int rc;
+        int timestamp = 0;  /* happy compiler */
+        struct cpumask cache_cpumask_copy, tlb_cpumask_copy;
+        struct cpumask *cache_cpumask, *tlb_cpumask;
+        HV_PhysAddr cache_pa;
+        char cache_buf[NR_CPUS*5], tlb_buf[NR_CPUS*5];
+
+        mb();   /* provided just to simplify "magic hypervisor" mode */
+
+        /*
+         * Canonicalize and copy the cpumasks.
+         */
+        if (cache_cpumask_orig && cache_control) {
+                cpumask_copy(&cache_cpumask_copy, cache_cpumask_orig);
+                cache_cpumask = &cache_cpumask_copy;
+        } else {
+                cpumask_clear(&cache_cpumask_copy);
+                cache_cpumask = NULL;
+        }
+        if (cache_cpumask == NULL)
+                cache_control = 0;
+        if (tlb_cpumask_orig && tlb_length) {
+                cpumask_copy(&tlb_cpumask_copy, tlb_cpumask_orig);
+                tlb_cpumask = &tlb_cpumask_copy;
+        } else {
+                cpumask_clear(&tlb_cpumask_copy);
+                tlb_cpumask = NULL;
+        }
+
+        hv_flush_update(cache_cpumask, tlb_cpumask, tlb_va, tlb_length,
+                        asids, asidcount);
+        cache_pa = (HV_PhysAddr)cache_pfn << PAGE_SHIFT;
+        if (cache_control & HV_FLUSH_EVICT_L2)
+                timestamp = mark_caches_evicted_start();
+        rc = hv_flush_remote(cache_pa, cache_control,
+                             cpumask_bits(cache_cpumask),
+                             tlb_va, tlb_length, tlb_pgsize,
+                             cpumask_bits(tlb_cpumask),
+                             asids, asidcount);
+        if (cache_control & HV_FLUSH_EVICT_L2)
+                mark_caches_evicted_finish(cache_cpumask, timestamp);
+        if (rc == 0)
+                return;
+        cpumask_scnprintf(cache_buf, sizeof(cache_buf), &cache_cpumask_copy);
+        cpumask_scnprintf(tlb_buf, sizeof(tlb_buf), &tlb_cpumask_copy);
+
+        printk("hv_flush_remote(%#llx, %#lx, %p [%s],"
+               " %#lx, %#lx, %#lx, %p [%s], %p, %d) = %d\n",
+               cache_pa, cache_control, cache_cpumask, cache_buf,
+               (unsigned long)tlb_va, tlb_length, tlb_pgsize,
+               tlb_cpumask, tlb_buf,
+               asids, asidcount, rc);
+        if (asidcount > 0) {
+                int i;
+                printk(" asids:");
+                for (i = 0; i < asidcount; ++i)
+                        printk(" %d,%d,%d",
+                               asids[i].x, asids[i].y, asids[i].asid);
+                printk("\n");
+        }
+        panic("Unsafe to continue.");
+}
+
+void homecache_evict(const struct cpumask *mask)
+{
+        flush_remote(0, HV_FLUSH_EVICT_L2, mask, 0, 0, 0, NULL, NULL, 0);
+}
+
+/* Return a mask of the cpus whose caches currently own these pages. */
+static void homecache_mask(struct page *page, int pages,
+                           struct cpumask *home_mask)
+{
+        int i;
+        cpumask_clear(home_mask);
+        for (i = 0; i < pages; ++i) {
+                int home = page_home(&page[i]);
+                if (home == PAGE_HOME_IMMUTABLE ||
+                    home == PAGE_HOME_INCOHERENT) {
+                        cpumask_copy(home_mask, cpu_possible_mask);
+                        return;
+                }
+#if CHIP_HAS_CBOX_HOME_MAP()
+                if (home == PAGE_HOME_HASH) {
+                        cpumask_or(home_mask, home_mask, &hash_for_home_map);
+                        continue;
+                }
+#endif
+                if (home == PAGE_HOME_UNCACHED)
+                        continue;
+                BUG_ON(home < 0 || home >= NR_CPUS);
+                cpumask_set_cpu(home, home_mask);
+        }
+}
+
+/*
+ * Return the passed length, or zero if it's long enough that we
+ * believe we should evict the whole L2 cache.
+ */
+static unsigned long cache_flush_length(unsigned long length)
+{
+        return (length >= CHIP_L2_CACHE_SIZE()) ? HV_FLUSH_EVICT_L2 : length;
+}
+
+/* On the simulator, confirm lines have been evicted everywhere. */
+static void validate_lines_evicted(unsigned long pfn, size_t length)
+{
+        sim_syscall(SIM_SYSCALL_VALIDATE_LINES_EVICTED,
+                    (HV_PhysAddr)pfn << PAGE_SHIFT, length);
+}
+
+/* Flush a page out of whatever cache(s) it is in. */
+void homecache_flush_cache(struct page *page, int order)
+{
+        int pages = 1 << order;
+        int length = cache_flush_length(pages * PAGE_SIZE);
+        unsigned long pfn = page_to_pfn(page);
+        struct cpumask home_mask;
+
+        homecache_mask(page, pages, &home_mask);
+        flush_remote(pfn, length, &home_mask, 0, 0, 0, NULL, NULL, 0);
+        validate_lines_evicted(pfn, pages * PAGE_SIZE);
+}
+
+
+/* Report the home corresponding to a given PTE. */
+static int pte_to_home(pte_t pte)
+{
+        if (hv_pte_get_nc(pte))
+                return PAGE_HOME_IMMUTABLE;
+        switch (hv_pte_get_mode(pte)) {
+        case HV_PTE_MODE_CACHE_TILE_L3:
+                return get_remote_cache_cpu(pte);
+        case HV_PTE_MODE_CACHE_NO_L3:
+                return PAGE_HOME_INCOHERENT;
+        case HV_PTE_MODE_UNCACHED:
+                return PAGE_HOME_UNCACHED;
+#if CHIP_HAS_CBOX_HOME_MAP()
+        case HV_PTE_MODE_CACHE_HASH_L3:
+                return PAGE_HOME_HASH;
+#endif
+        }
+        panic("Bad PTE %#llx\n", pte.val);
+}
+
+/* Update the home of a PTE if necessary (can also be used for a pgprot_t). */
+pte_t pte_set_home(pte_t pte, int home)
+{
+        /* Check for non-linear file mapping "PTEs" and pass them through. */
+        if (pte_file(pte))
+                return pte;
+
+#if CHIP_HAS_MMIO()
+        /* Check for MMIO mappings and pass them through. */
+        if (hv_pte_get_mode(pte) == HV_PTE_MODE_MMIO)
+                return pte;
+#endif
+
+
+        /*
+         * Only immutable pages get NC mappings.  If we have a
+         * non-coherent PTE, but the underlying page is not
+         * immutable, it's likely the result of a forced
+         * caching setting running up against ptrace setting
+         * the page to be writable underneath.  In this case,
+         * just keep the PTE coherent.
+         */
+        if (hv_pte_get_nc(pte) && home != PAGE_HOME_IMMUTABLE) {
+                pte = hv_pte_clear_nc(pte);
+                printk("non-immutable page incoherently referenced: %#llx\n",
+                       pte.val);
+        }
+
+        switch (home) {
+
+        case PAGE_HOME_UNCACHED:
+                pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
+                break;
+
+        case PAGE_HOME_INCOHERENT:
+                pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
+                break;
+
+        case PAGE_HOME_IMMUTABLE:
+                /*
+                 * We could home this page anywhere, since it's immutable,
+                 * but by default just home it to follow "hash_default".
+                 */
+                BUG_ON(hv_pte_get_writable(pte));
+                if (pte_get_forcecache(pte)) {
+                        /* Upgrade "force any cpu" to "No L3" for immutable. */
+                        if (hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_TILE_L3
+                            && pte_get_anyhome(pte)) {
+                                pte = hv_pte_set_mode(pte,
+                                                      HV_PTE_MODE_CACHE_NO_L3);
+                        }
+                } else
+#if CHIP_HAS_CBOX_HOME_MAP()
+                if (hash_default)
+                        pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
+                else
+#endif
+                        pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
+                pte = hv_pte_set_nc(pte);
+                break;
+
+#if CHIP_HAS_CBOX_HOME_MAP()
+        case PAGE_HOME_HASH:
+                pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
+                break;
+#endif
+
+        default:
+                BUG_ON(home < 0 || home >= NR_CPUS ||
+                       !cpu_is_valid_lotar(home));
+                pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
+                pte = set_remote_cache_cpu(pte, home);
+                break;
+        }
+
+#if CHIP_HAS_NC_AND_NOALLOC_BITS()
+        if (noallocl2)
+                pte = hv_pte_set_no_alloc_l2(pte);
+
+        /* Simplify "no local and no l3" to "uncached" */
+        if (hv_pte_get_no_alloc_l2(pte) && hv_pte_get_no_alloc_l1(pte) &&
+            hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_NO_L3) {
+                pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
+        }
+#endif
+
+        /* Checking this case here gives a better panic than from the hv. */
+        BUG_ON(hv_pte_get_mode(pte) == 0);
+
+        return pte;
+}
+
+/*
+ * The routines in this section are the "static" versions of the normal
+ * dynamic homecaching routines; they just set the home cache
+ * of a kernel page once, and require a full-chip cache/TLB flush,
+ * so they're not suitable for anything but infrequent use.
+ */
+
+#if CHIP_HAS_CBOX_HOME_MAP()
+static inline int initial_page_home(void) { return PAGE_HOME_HASH; }
+#else
+static inline int initial_page_home(void) { return 0; }
+#endif
+
+int page_home(struct page *page)
+{
+        if (PageHighMem(page)) {
+                return initial_page_home();
+        } else {
+                unsigned long kva = (unsigned long)page_address(page);
+                return pte_to_home(*virt_to_pte(NULL, kva));
+        }
+}
+
+void homecache_change_page_home(struct page *page, int order, int home)
+{
+        int i, pages = (1 << order);
+        unsigned long kva;
+
+        BUG_ON(PageHighMem(page));
+        BUG_ON(page_count(page) > 1);
+        BUG_ON(page_mapcount(page) != 0);
+        kva = (unsigned long) page_address(page);
+        flush_remote(0, HV_FLUSH_EVICT_L2, &cpu_cacheable_map,
+                     kva, pages * PAGE_SIZE, PAGE_SIZE, cpu_online_mask,
+                     NULL, 0);
+
+        for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
+                pte_t *ptep = virt_to_pte(NULL, kva);
+                pte_t pteval = *ptep;
+                BUG_ON(!pte_present(pteval) || pte_huge(pteval));
+                *ptep = pte_set_home(pteval, home);
+        }
+}
+
+struct page *homecache_alloc_pages(gfp_t gfp_mask,
+                                   unsigned int order, int home)
+{
+        struct page *page;
+        BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
+        page = alloc_pages(gfp_mask, order);
+        if (page)
+                homecache_change_page_home(page, order, home);
+        return page;
+}
+
+struct page *homecache_alloc_pages_node(int nid, gfp_t gfp_mask,
+                                        unsigned int order, int home)
+{
+        struct page *page;
+        BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
+        page = alloc_pages_node(nid, gfp_mask, order);
+        if (page)
+                homecache_change_page_home(page, order, home);
+        return page;
+}
+
+void homecache_free_pages(unsigned long addr, unsigned int order)
+{
+        struct page *page;
+
+        if (addr == 0)
+                return;
+
+        VM_BUG_ON(!virt_addr_valid((void *)addr));
+        page = virt_to_page((void *)addr);
+        if (put_page_testzero(page)) {
+                int pages = (1 << order);
+                homecache_change_page_home(page, order, initial_page_home());
+                while (pages--)
+                        __free_page(page++);
+        }
+}