The patch titled
nommu: add support for Memory Protection Units (MPU)
has been added to the -mm tree. Its filename is
nommu-add-support-for-memory-protection-units-mpu.patch
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See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: nommu: add support for Memory Protection Units (MPU)
From: Bernd Schmidt <bernds_cb1@xxxxxxxxxxx>
Some architectures (like the Blackfin arch) implement some of the
"simpler" features that one would expect out of a MMU such as memory
protection.
In our case, we actually get read/write/exec protection down to the page
boundary so processes can't stomp on each other let alone the kernel.
There is a performance decrease (which depends greatly on the workload)
however as the hardware/software interaction was not optimized at design
time.
Signed-off-by: Bernd Schmidt <bernds_cb1@xxxxxxxxxxx>
Signed-off-by: Bryan Wu <cooloney@xxxxxxxxxx>
Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>
Acked-by: David Howells <dhowells@xxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/module.c | 5 +++++
mm/nommu.c | 21 +++++++++++++++++++++
2 files changed, 26 insertions(+)
diff -puN kernel/module.c~nommu-add-support-for-memory-protection-units-mpu kernel/module.c
--- a/kernel/module.c~nommu-add-support-for-memory-protection-units-mpu
+++ a/kernel/module.c
@@ -47,6 +47,7 @@
#include <linux/rculist.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
+#include <asm/mmu_context.h>
#include <linux/license.h>
#include <asm/sections.h>
#include <linux/tracepoint.h>
@@ -1535,6 +1536,10 @@ static void free_module(struct module *m
/* Finally, free the core (containing the module structure) */
module_free(mod, mod->module_core);
+
+#ifdef CONFIG_MPU
+ update_protections(current->mm);
+#endif
}
void *__symbol_get(const char *symbol)
diff -puN mm/nommu.c~nommu-add-support-for-memory-protection-units-mpu mm/nommu.c
--- a/mm/nommu.c~nommu-add-support-for-memory-protection-units-mpu
+++ a/mm/nommu.c
@@ -33,6 +33,7 @@
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
#include "internal.h"
static inline __attribute__((format(printf, 1, 2)))
@@ -583,6 +584,22 @@ static void put_nommu_region(struct vm_r
}
/*
+ * update protection on a vma
+ */
+static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
+{
+#ifdef CONFIG_MPU
+ struct mm_struct *mm = vma->vm_mm;
+ long start = vma->vm_start & PAGE_MASK;
+ while (start < vma->vm_end) {
+ protect_page(mm, start, flags);
+ start += PAGE_SIZE;
+ }
+ update_protections(mm);
+#endif
+}
+
+/*
* add a VMA into a process's mm_struct in the appropriate place in the list
* and tree and add to the address space's page tree also if not an anonymous
* page
@@ -601,6 +618,8 @@ static void add_vma_to_mm(struct mm_stru
mm->map_count++;
vma->vm_mm = mm;
+ protect_vma(vma, vma->vm_flags);
+
/* add the VMA to the mapping */
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
@@ -663,6 +682,8 @@ static void delete_vma_from_mm(struct vm
kenter("%p", vma);
+ protect_vma(vma, 0);
+
mm->map_count--;
if (mm->mmap_cache == vma)
mm->mmap_cache = NULL;
_
Patches currently in -mm which might be from bernds_cb1@xxxxxxxxxxx are
nommu-add-support-for-memory-protection-units-mpu.patch
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