From: Marco Stornelli <marco.stornelli@xxxxxxxxx>
Write protection.
Signed-off-by: Marco Stornelli <marco.stornelli@xxxxxxxxx>
---
diff -uprN linux-2.6.30-orig/fs/pramfs/wprotect.c linux-2.6.30/fs/pramfs/wprotect.c
--- linux-2.6.30-orig/fs/pramfs/wprotect.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.30/fs/pramfs/wprotect.c 2009-06-13 12:54:16.000000000 +0200
@@ -0,0 +1,84 @@
+/*
+ * FILE NAME fs/pramfs/wprotect.c
+ *
+ * BRIEF DESCRIPTION
+ *
+ * Write protection for the filesystem pages.
+ *
+ * Copyright 2009 Marco Stornelli <marco.stornelli@xxxxxxxxx>
+ * Copyright 2003 Sony Corporation
+ * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
+ * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+#include "pram_fs.h"
+
+/* init_mm.page_table_lock must be held before calling! */
+static void pram_page_writeable(unsigned long addr, int rw)
+{
+ pgd_t *pgdp;
+ pud_t *pudp;
+ pmd_t *pmdp;
+ pte_t *ptep;
+
+ pgdp = pgd_offset_k(addr);
+ if (!pgd_none(*pgdp)) {
+ pudp = pud_offset(pgdp, addr);
+ if (!pud_none(*pudp)) {
+ pmdp = pmd_offset(pudp, addr);
+ if (!pmd_none(*pmdp)) {
+ pte_t pte;
+ ptep = pte_offset_kernel(pmdp, addr);
+ pte = *ptep;
+ if (pte_present(pte)) {
+ pte = rw ? pte_mkwrite(pte) :
+ pte_wrprotect(pte);
+ set_pte(ptep, pte);
+ }
+ }
+ }
+ }
+}
+
+/* init_mm.page_table_lock must be held before calling! */
+void pram_writeable(void *vaddr, unsigned long size, int rw)
+{
+ unsigned long addr = (unsigned long)vaddr & PAGE_MASK;
+ unsigned long end = (unsigned long)vaddr + size;
+ unsigned long start = addr;
+
+ do {
+ pram_page_writeable(addr, rw);
+ addr += PAGE_SIZE;
+ } while (addr && (addr < end));
+
+
+ /*
+ * NOTE: we will always flush just one page (one TLB
+ * entry) except possibly in one case: when a new
+ * filesystem is initialized at mount time, when pram_read_super
+ * calls pram_lock_range to make the super block, inode
+ * table, and bitmap writeable.
+ */
+#if defined(CONFIG_ARM) || defined(CONFIG_M68K) || defined(CONFIG_H8300) || \
+ defined(CONFIG_BLACKFIN)
+ /*
+ * FIXME: so far only these archs have flush_tlb_kernel_page(),
+ * for the rest just use flush_tlb_kernel_range(). Not ideal
+ * to use _range() because many archs just flush the whole TLB.
+ */
+ if (end <= start + PAGE_SIZE)
+ flush_tlb_kernel_page(start);
+ else
+#endif
+ flush_tlb_kernel_range(start, end);
+}
--
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