linux-kernel - [PATCH v12 17/22] selftests/vm: associate key on a mapped page and detect access violation

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Message-Id: <1519264541-7621-18-git-send-email-linuxram@us.ibm.com>
Date:   Wed, 21 Feb 2018 17:55:36 -0800
From:   Ram Pai <linuxram@...ibm.com>
To:     shuahkh@....samsung.com, linux-kselftest@...r.kernel.org
Cc:     mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
        linux-mm@...ck.org, x86@...nel.org, linux-arch@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, akpm@...ux-foundation.org, dave.hansen@...el.com,
        benh@...nel.crashing.org, paulus@...ba.org,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, hbabu@...ibm.com, mhocko@...nel.org,
        bauerman@...ux.vnet.ibm.com, ebiederm@...ssion.com,
        linuxram@...ibm.com, arnd@...db.de
Subject: [PATCH v12 17/22] selftests/vm: associate key on a mapped page and detect access violation

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

cc: Dave Hansen <dave.hansen@...el.com>
cc: Florian Weimer <fweimer@...hat.com>
Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 tools/testing/selftests/vm/protection_keys.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index aae6771..dba9162 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -1016,6 +1016,24 @@ 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);
+	rdpkey_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);
@@ -1310,6 +1328,7 @@ 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,
-- 
1.7.1