summaryrefslogtreecommitdiff
path: root/arch/arm/mm/fault-armv.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mm/fault-armv.c
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/arm/mm/fault-armv.c')
-rw-r--r--arch/arm/mm/fault-armv.c223
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 00000000000..01967ddeef5
--- /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");
+ }
+}