1 files changed, 223 insertions, 0 deletions

diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
new file mode 100644
index 000000000000..01967ddeef53
--- /dev/null
+++ b/arch/arm/mm/fault-armv.c
@@ -0,0 +1,223 @@
+/*
+ *  linux/arch/arm/mm/fault-armv.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Modifications for ARM processor (c) 1995-2002 Russell King
+ *
+ * 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.
+ */
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/bitops.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+
+#include <asm/cacheflush.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+static unsigned long shared_pte_mask = L_PTE_CACHEABLE;
+
+/*
+ * We take the easy way out of this problem - we make the
+ * PTE uncacheable.  However, we leave the write buffer on.
+ */
+static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
+{
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte, entry;
+        int ret = 0;
+
+        pgd = pgd_offset(vma->vm_mm, address);
+        if (pgd_none(*pgd))
+                goto no_pgd;
+        if (pgd_bad(*pgd))
+                goto bad_pgd;
+
+        pmd = pmd_offset(pgd, address);
+        if (pmd_none(*pmd))
+                goto no_pmd;
+        if (pmd_bad(*pmd))
+                goto bad_pmd;
+
+        pte = pte_offset_map(pmd, address);
+        entry = *pte;
+
+        /*
+         * If this page isn't present, or is already setup to
+         * fault (ie, is old), we can safely ignore any issues.
+         */
+        if (pte_present(entry) && pte_val(entry) & shared_pte_mask) {
+                flush_cache_page(vma, address, pte_pfn(entry));
+                pte_val(entry) &= ~shared_pte_mask;
+                set_pte(pte, entry);
+                flush_tlb_page(vma, address);
+                ret = 1;
+        }
+        pte_unmap(pte);
+        return ret;
+
+bad_pgd:
+        pgd_ERROR(*pgd);
+        pgd_clear(pgd);
+no_pgd:
+        return 0;
+
+bad_pmd:
+        pmd_ERROR(*pmd);
+        pmd_clear(pmd);
+no_pmd:
+        return 0;
+}
+
+static void
+make_coherent(struct vm_area_struct *vma, unsigned long addr, struct page *page, int dirty)
+{
+        struct address_space *mapping = page_mapping(page);
+        struct mm_struct *mm = vma->vm_mm;
+        struct vm_area_struct *mpnt;
+        struct prio_tree_iter iter;
+        unsigned long offset;
+        pgoff_t pgoff;
+        int aliases = 0;
+
+        if (!mapping)
+                return;
+
+        pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
+
+        /*
+         * If we have any shared mappings that are in the same mm
+         * space, then we need to handle them specially to maintain
+         * cache coherency.
+         */
+        flush_dcache_mmap_lock(mapping);
+        vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
+                /*
+                 * If this VMA is not in our MM, we can ignore it.
+                 * Note that we intentionally mask out the VMA
+                 * that we are fixing up.
+                 */
+                if (mpnt->vm_mm != mm || mpnt == vma)
+                        continue;
+                if (!(mpnt->vm_flags & VM_MAYSHARE))
+                        continue;
+                offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
+                aliases += adjust_pte(mpnt, mpnt->vm_start + offset);
+        }
+        flush_dcache_mmap_unlock(mapping);
+        if (aliases)
+                adjust_pte(vma, addr);
+        else
+                flush_cache_page(vma, addr, page_to_pfn(page));
+}
+
+/*
+ * Take care of architecture specific things when placing a new PTE into
+ * a page table, or changing an existing PTE.  Basically, there are two
+ * things that we need to take care of:
+ *
+ *  1. If PG_dcache_dirty is set for the page, we need to ensure
+ *     that any cache entries for the kernels virtual memory
+ *     range are written back to the page.
+ *  2. If we have multiple shared mappings of the same space in
+ *     an object, we need to deal with the cache aliasing issues.
+ *
+ * Note that the page_table_lock will be held.
+ */
+void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
+{
+        unsigned long pfn = pte_pfn(pte);
+        struct page *page;
+
+        if (!pfn_valid(pfn))
+                return;
+        page = pfn_to_page(pfn);
+        if (page_mapping(page)) {
+                int dirty = test_and_clear_bit(PG_dcache_dirty, &page->flags);
+
+                if (dirty) {
+                        /*
+                         * This is our first userspace mapping of this page.
+                         * Ensure that the physical page is coherent with
+                         * the kernel mapping.
+                         *
+                         * FIXME: only need to do this on VIVT and aliasing
+                         *        VIPT cache architectures.  We can do that
+                         *        by choosing whether to set this bit...
+                         */
+                        __cpuc_flush_dcache_page(page_address(page));
+                }
+
+                if (cache_is_vivt())
+                        make_coherent(vma, addr, page, dirty);
+        }
+}
+
+/*
+ * Check whether the write buffer has physical address aliasing
+ * issues.  If it has, we need to avoid them for the case where
+ * we have several shared mappings of the same object in user
+ * space.
+ */
+static int __init check_writebuffer(unsigned long *p1, unsigned long *p2)
+{
+        register unsigned long zero = 0, one = 1, val;
+
+        local_irq_disable();
+        mb();
+        *p1 = one;
+        mb();
+        *p2 = zero;
+        mb();
+        val = *p1;
+        mb();
+        local_irq_enable();
+        return val != zero;
+}
+
+void __init check_writebuffer_bugs(void)
+{
+        struct page *page;
+        const char *reason;
+        unsigned long v = 1;
+
+        printk(KERN_INFO "CPU: Testing write buffer coherency: ");
+
+        page = alloc_page(GFP_KERNEL);
+        if (page) {
+                unsigned long *p1, *p2;
+                pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG|
+                                         L_PTE_DIRTY|L_PTE_WRITE|
+                                         L_PTE_BUFFERABLE);
+
+                p1 = vmap(&page, 1, VM_IOREMAP, prot);
+                p2 = vmap(&page, 1, VM_IOREMAP, prot);
+
+                if (p1 && p2) {
+                        v = check_writebuffer(p1, p2);
+                        reason = "enabling work-around";
+                } else {
+                        reason = "unable to map memory\n";
+                }
+
+                vunmap(p1);
+                vunmap(p2);
+                put_page(page);
+        } else {
+                reason = "unable to grab page\n";
+        }
+
+        if (v) {
+                printk("failed, %s\n", reason);
+                shared_pte_mask |= L_PTE_BUFFERABLE;
+        } else {
+                printk("ok\n");
+        }
+}