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authorJan Glauber <jang@linux.vnet.ibm.com>2011-03-15 17:08:22 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2011-03-15 17:08:23 +0100
commit305b1523250faf9675919def94906775992ce52d (patch)
tree2dcbe253cf463eca3c0dfcc9ee8ac7b97cfa5021 /arch/s390/mm
parentd54cddb620fa493968111f479029dcd910fcb921 (diff)
[S390] Write protect module text and RO data
Implement write protection for kernel modules text and read-only data sections by implementing set_memory_[ro|rw] on s390. Since s390 has no execute bit in the pte's NX is not supported. set_memory_[ro|rw] will only work on normal pages and not on large pages, so in case a large page should be modified bail out with a warning. Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm')
-rw-r--r--arch/s390/mm/Makefile1
-rw-r--r--arch/s390/mm/pageattr.c55
2 files changed, 56 insertions, 0 deletions
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index 6fbc6f3fbdf2..d98fe9004a52 100644
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -6,3 +6,4 @@ obj-y := init.o fault.o extmem.o mmap.o vmem.o pgtable.o maccess.o \
page-states.o gup.o
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
+obj-$(CONFIG_DEBUG_SET_MODULE_RONX) += pageattr.o
diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
new file mode 100644
index 000000000000..122ffbd08ce0
--- /dev/null
+++ b/arch/s390/mm/pageattr.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright IBM Corp. 2011
+ * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
+ */
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <asm/pgtable.h>
+
+static void change_page_attr(unsigned long addr, int numpages,
+ pte_t (*set) (pte_t))
+{
+ pte_t *ptep, pte;
+ pmd_t *pmdp;
+ pud_t *pudp;
+ pgd_t *pgdp;
+ int i;
+
+ for (i = 0; i < numpages; i++) {
+ pgdp = pgd_offset(&init_mm, addr);
+ pudp = pud_offset(pgdp, addr);
+ pmdp = pmd_offset(pudp, addr);
+ if (pmd_huge(*pmdp)) {
+ WARN_ON_ONCE(1);
+ continue;
+ }
+ ptep = pte_offset_kernel(pmdp, addr + i * PAGE_SIZE);
+
+ pte = *ptep;
+ pte = set(pte);
+ ptep_invalidate(&init_mm, addr + i * PAGE_SIZE, ptep);
+ *ptep = pte;
+ }
+}
+
+int set_memory_ro(unsigned long addr, int numpages)
+{
+ change_page_attr(addr, numpages, pte_wrprotect);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(set_memory_ro);
+
+int set_memory_rw(unsigned long addr, int numpages)
+{
+ change_page_attr(addr, numpages, pte_mkwrite);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(set_memory_rw);
+
+/* not possible */
+int set_memory_nx(unsigned long addr, int numpages)
+{
+ return 0;
+}
+EXPORT_SYMBOL_GPL(set_memory_nx);