[PATCH v17 18/24] selftests/vm/pkeys: Associate key on a mapped page and detect access violation

[Sandipan Das]

From: Ram Pai <linuxram at us.ibm.com>

Detect access-violation on a page to which access-disabled
key is associated much after the page is mapped.

cc: Dave Hansen <dave.hansen at intel.com>
cc: Florian Weimer <fweimer at redhat.com>
Signed-off-by: Ram Pai <linuxram at us.ibm.com>
Acked-by: Dave Hansen <dave.hansen at intel.com>
Signed-off: Sandipan Das <sandipan at linux.ibm.com>
---
 tools/testing/selftests/vm/protection_keys.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index 95f173049f43..f65d384ef6a0 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -984,6 +984,24 @@ void test_read_of_access_disabled_region(int *ptr, u16 pkey)
 	dprintf1("*ptr: %d\n", ptr_contents);
 	expected_pkey_fault(pkey);
 }
+
+void test_read_of_access_disabled_region_with_page_already_mapped(int *ptr,
+		u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling access to PKEY[%02d], doing read @ %p\n",
+				pkey, ptr);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("reading ptr before disabling the read : %d\n",
+			ptr_contents);
+	read_pkey_reg();
+	pkey_access_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	expected_pkey_fault(pkey);
+}
+
 void test_write_of_write_disabled_region(int *ptr, u16 pkey)
 {
 	dprintf1("disabling write access to PKEY[%02d], doing write\n", pkey);
@@ -1390,6 +1408,7 @@ void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
 void (*pkey_tests[])(int *ptr, u16 pkey) = {
 	test_read_of_write_disabled_region,
 	test_read_of_access_disabled_region,
+	test_read_of_access_disabled_region_with_page_already_mapped,
 	test_write_of_write_disabled_region,
 	test_write_of_access_disabled_region,
 	test_kernel_write_of_access_disabled_region,
-- 
2.17.1