From: Marco Stornelli <marco.stornelli@xxxxxxxxx>
Memory write protection.
Signed-off-by: Marco Stornelli <marco.stornelli@xxxxxxxxx>
---
diff -Nurp linux-2.6.36-orig/fs/pramfs/wprotect.c linux-2.6.36/fs/pramfs/wprotect.c
--- linux-2.6.36-orig/fs/pramfs/wprotect.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.36/fs/pramfs/wprotect.c 2010-09-26 18:04:07.000000000 +0200
@@ -0,0 +1,31 @@
+/*
+ * FILE NAME fs/pramfs/wprotect.c
+ *
+ * BRIEF DESCRIPTION
+ *
+ * Write protection for the filesystem pages.
+ *
+ * Copyright 2009-2010 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 <linux/io.h>
+#include "pram.h"
+
+void pram_writeable(void *vaddr, unsigned long size, int rw)
+{
+ int ret = 0;
+
+ ret = rw ? write_on_kernel_pte_range((unsigned long)vaddr, size) :
+ write_off_kernel_pte_range((unsigned long)vaddr, size);
+
+ BUG_ON(ret);
+}
diff -Nurp linux-2.6.36-orig/include/linux/mm.h linux-2.6.36/include/linux/mm.h
--- linux-2.6.36-orig/include/linux/mm.h 2010-09-13 01:07:37.000000000 +0200
+++ linux-2.6.36/include/linux/mm.h 2010-09-14 18:49:52.000000000 +0200
@@ -811,6 +811,11 @@ int follow_phys(struct vm_area_struct *v
unsigned int flags, unsigned long *prot, resource_size_t *phys);
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write);
+int writeable_kernel_pte_range(unsigned long address, unsigned long size,
+ unsigned int rw);
+
+#define write_on_kernel_pte_range(addr, size) writeable_kernel_pte_range(addr, size, 1)
+#define write_off_kernel_pte_range(addr, size) writeable_kernel_pte_range(addr, size, 0)
static inline void unmap_shared_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen)
diff -Nurp linux-2.6.36-orig/mm/memory.c linux-2.6.36/mm/memory.c
--- linux-2.6.36-orig/mm/memory.c 2010-09-13 01:07:37.000000000 +0200
+++ linux-2.6.36/mm/memory.c 2010-09-14 18:49:52.000000000 +0200
@@ -3587,3 +3587,49 @@ void might_fault(void)
}
EXPORT_SYMBOL(might_fault);
#endif
+
+int writeable_kernel_pte_range(unsigned long address, unsigned long size,
+ unsigned int rw)
+{
+
+ unsigned long addr = address & PAGE_MASK;
+ unsigned long end = address + size;
+ unsigned long start = addr;
+ int ret = -EINVAL;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep, pte;
+
+ spin_lock_irq(&init_mm.page_table_lock);
+
+ do {
+ pgd = pgd_offset(&init_mm, address);
+ if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+ goto out;
+
+ pud = pud_offset(pgd, address);
+ if (pud_none(*pud) || unlikely(pud_bad(*pud)))
+ goto out;
+
+ pmd = pmd_offset(pud, address);
+ if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+ goto out;
+
+ ptep = pte_offset_kernel(pmd, addr);
+ pte = *ptep;
+ if (pte_present(pte)) {
+ pte = rw ? pte_mkwrite(pte) : pte_wrprotect(pte);
+ *ptep = pte;
+ }
+ addr += PAGE_SIZE;
+ } while (addr && (addr < end));
+
+ ret = 0;
+
+out:
+ flush_tlb_kernel_range(start, end);
+ spin_unlock_irq(&init_mm.page_table_lock);
+ return ret;
+}
+EXPORT_SYMBOL(writeable_kernel_pte_range);
--
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