Create enclave with additional heap that consumes all physical SGX
memory and then remove it.
Depending on the available SGX memory this test could take a
significant time to run (several minutes) as it (1) creates the
enclave, (2) changes the type of every page to be trimmed,
(3) enters the enclave once per page to run EACCEPT, before
(4) the pages are finally removed.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/e7c6aa2ab30cb1c41e52b776958409c06970d168.1652137848.git.reinette.chatre@intel.com
Removing a page from an initialized enclave involves three steps:
(1) the user requests changing the page type to PT_TRIM via the
SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl()
(2) on success the ENCLU[EACCEPT] instruction is run from within
the enclave to accept the page removal
(3) the user initiates the actual removal of the page via the
SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl().
Remove a page that has never been accessed. This means that when the
first ioctl() requesting page removal arrives, there will be no page
table entry, yet a valid page table entry needs to exist for the
ENCLU[EACCEPT] function to succeed. In this test it is verified that
a page table entry can still be installed for a page that is in the
process of being removed.
Suggested-by: Haitao Huang <haitao.huang@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/45e1b2a2fcd8c14597d04e40af5d8a9c1c5b017e.1652137848.git.reinette.chatre@intel.com
Removing a page from an initialized enclave involves three steps:
(1) the user requests changing the page type to SGX_PAGE_TYPE_TRIM
via the SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl(), (2) on success the
ENCLU[EACCEPT] instruction is run from within the enclave to accept
the page removal, (3) the user initiates the actual removal of the
page via the SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl().
Test two possible invalid accesses during the page removal flow:
* Test the behavior when a request to remove the page by changing its
type to SGX_PAGE_TYPE_TRIM completes successfully but instead of
executing ENCLU[EACCEPT] from within the enclave the enclave attempts
to read from the page. Even though the page is accessible from the
page table entries its type is SGX_PAGE_TYPE_TRIM and thus not
accessible according to SGX. The expected behavior is a page fault
with the SGX flag set in the error code.
* Test the behavior when the page type is changed successfully and
ENCLU[EACCEPT] was run from within the enclave. The final ioctl(),
SGX_IOC_ENCLAVE_REMOVE_PAGES, is omitted and replaced with an
attempt to access the page. Even though the page is accessible
from the page table entries its type is SGX_PAGE_TYPE_TRIM and
thus not accessible according to SGX. The expected behavior is
a page fault with the SGX flag set in the error code.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/189a86c25d6d62da7cfdd08ee97abc1a06fcc179.1652137848.git.reinette.chatre@intel.com
Removing a page from an initialized enclave involves three steps:
first the user requests changing the page type to SGX_PAGE_TYPE_TRIM
via an ioctl(), on success the ENCLU[EACCEPT] instruction needs to be
run from within the enclave to accept the page removal, finally the
user requests page removal to be completed via an ioctl(). Only after
acceptance (ENCLU[EACCEPT]) from within the enclave can the kernel
remove the page from a running enclave.
Test the behavior when the user's request to change the page type
succeeds, but the ENCLU[EACCEPT] instruction is not run before the
ioctl() requesting page removal is run. This should not be permitted.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/fa5da30ebac108b7517194c3038b52995602b996.1652137848.git.reinette.chatre@intel.com
Support for changing an enclave page's type enables an initialized
enclave to be expanded with support for more threads by changing the
type of a regular enclave page to that of a Thread Control Structure
(TCS). Additionally, being able to change a TCS or regular enclave
page's type to be trimmed (SGX_PAGE_TYPE_TRIM) initiates the removal
of the page from the enclave.
Test changing page type to TCS as well as page removal flows
in two phases: In the first phase support for a new thread is
dynamically added to an initialized enclave and in the second phase
the pages associated with the new thread are removed from the enclave.
As an additional sanity check after the second phase the page used as
a TCS page during the first phase is added back as a regular page and
ensured that it can be written to (which is not possible if it was a
TCS page).
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/d05b48b00338683a94dcaef9f478540fc3d6d5f9.1652137848.git.reinette.chatre@intel.com
Enclave pages can be added to an initialized enclave when an address
belonging to the enclave but without a backing page is accessed from
within the enclave.
Accessing memory without a backing enclave page from within an enclave
can be in different ways:
1) Pre-emptively run ENCLU[EACCEPT]. Since the addition of a page
always needs to be accepted by the enclave via ENCLU[EACCEPT] this
flow is efficient since the first execution of ENCLU[EACCEPT]
triggers the addition of the page and when execution returns to the
same instruction the second execution would be successful as an
acceptance of the page.
2) A direct read or write. The flow where a direct read or write
triggers the page addition execution cannot resume from the
instruction (read/write) that triggered the fault but instead
the enclave needs to be entered at a different entry point to
run needed ENCLU[EACCEPT] before execution can return to the
original entry point and the read/write instruction that faulted.
Add tests for both flows.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/0c321e0e32790ac1de742ce5017a331e6d902ac1.1652137848.git.reinette.chatre@intel.com
EPCM permission changes could be made from within (to relax
permissions) or out (to restrict permissions) the enclave. Kernel
support is needed when permissions are restricted to be able to
call the privileged ENCLS[EMODPR] instruction. EPCM permissions
can be relaxed via ENCLU[EMODPE] from within the enclave but the
enclave still depends on the kernel to install PTEs with the needed
permissions.
Add a test that exercises a few of the enclave page permission flows:
1) Test starts with a RW (from enclave and kernel perspective)
enclave page that is mapped via a RW VMA.
2) Use the SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS ioctl() to restrict
the enclave (EPCM) page permissions to read-only.
3) Run ENCLU[EACCEPT] from within the enclave to accept the new page
permissions.
4) Attempt to write to the enclave page from within the enclave - this
should fail with a page fault on the EPCM permissions since the page
table entry continues to allow RW access.
5) Restore EPCM permissions to RW by running ENCLU[EMODPE] from within
the enclave.
6) Attempt to write to the enclave page from within the enclave - this
should succeed since both EPCM and PTE permissions allow this access.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/2617bf2b2d1e27ca1d0096e1192ae5896baf3f80.1652137848.git.reinette.chatre@intel.com
The TH_LOG() macro is an optional debug logging function made
available by kselftest itself. When TH_LOG_ENABLED is set it
prints the provided message with additional information and
formatting that already includes a newline.
Providing a newline to the message printed by TH_LOG() results
in a double newline that produces irregular test output.
Remove the unnecessary newlines from the text provided to
TH_LOG().
Fixes: 1b35eb7195 ("selftests/sgx: Encpsulate the test enclave creation")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lkml.kernel.org/r/6fd171ba622aed172a7c5b129d34d50bd0482f24.1644355600.git.reinette.chatre@intel.com
In support of debugging the SGX tests print details from
the enclave and its memory mappings if any failure is encountered
during enclave loading.
When a failure is encountered no data is printed because the
printing of the data is preceded by cleanup of the data.
Move the data cleanup after the data print.
Fixes: 1471721489 ("selftests/sgx: Dump segments and /proc/self/maps only on failure")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lkml.kernel.org/r/dab672f771e9b99e50c17ae2a75dc0b020cb0ce9.1644355600.git.reinette.chatre@intel.com
It is not possible to build an enclave if it was not possible to load
the binary from which it should be constructed. Do not attempt
to make further progress but instead return with failure. A
"return false" from setup_test_encl() is expected to trip an
ASSERT_TRUE() and abort the rest of the test.
Fixes: 1b35eb7195 ("selftests/sgx: Encpsulate the test enclave creation")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lkml.kernel.org/r/e3778c77f95e6dca348c732b12f155051d2899b4.1644355600.git.reinette.chatre@intel.com
The SGX selftest fails to build on tip/x86/sgx:
main.c: In function ‘get_total_epc_mem’:
main.c:296:17: error: implicit declaration of function ‘__cpuid’ [-Werror=implicit-function-declaration]
296 | __cpuid(&eax, &ebx, &ecx, &edx);
| ^~~~~~~
Include cpuid.h and use __cpuid_count() macro in order to fix the
compilation issue.
[ dhansen: tweak commit message ]
Fixes: f0ff2447b8 ("selftests/sgx: Add a new kselftest: Unclobbered_vdso_oversubscribed")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211204202355.23005-1-jarkko@kernel.org
Cc: Shuah Khan <shuah@kernel.org>
Each thread executing in an enclave is associated with a Thread Control
Structure (TCS). The SGX test enclave contains two hardcoded TCS, thus
supporting two threads in the enclave.
Add a test to ensure it is possible to enter enclave at both entrypoints.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/7be151a57b4c7959a2364753b995e0006efa3da1.1636997631.git.reinette.chatre@intel.com
The Enclave Page Cache Map (EPCM) is a secure structure used by the
processor to track the contents of the enclave page cache. The EPCM
contains permissions with which enclave pages can be accessed. SGX
support allows EPCM and PTE page permissions to differ - as long as
the PTE permissions do not exceed the EPCM permissions.
Add a test that:
(1) Creates an SGX enclave page with writable EPCM permission.
(2) Changes the PTE permission on the page to read-only. This should
be permitted because the permission does not exceed the EPCM
permission.
(3) Attempts a write to the page. This should generate a page fault
(#PF) because of the read-only PTE even though the EPCM
permissions allow the page to be written to.
This introduces the first test of SGX exception handling. In this test
the issue that caused the exception (PTE page permissions) can be fixed
from outside the enclave and after doing so it is possible to re-enter
enclave at original entrypoint with ERESUME.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/3bcc73a4b9fe8780bdb40571805e7ced59e01df7.1636997631.git.reinette.chatre@intel.com
SGX selftests prepares a data structure outside of the enclave with
the type of and data for the operation that needs to be run within
the enclave. At this time only two complementary operations are supported
by the enclave: copying a value from outside the enclave into a default
buffer within the enclave and reading a value from the enclave's default
buffer into a variable accessible outside the enclave.
In preparation for more operations supported by the enclave the names of the
current enclave operations are changed to more accurately reflect the
operations and more easily distinguish it from future operations:
* The enums ENCL_OP_PUT and ENCL_OP_GET are renamed to ENCL_OP_PUT_TO_BUFFER
and ENCL_OP_GET_FROM_BUFFER respectively.
* The structs encl_op_put and encl_op_get are renamed to encl_op_put_to_buf
and encl_op_get_from_buf respectively.
* The enclave functions do_encl_op_put and do_encl_op_get are renamed to
do_encl_op_put_to_buf and do_encl_op_get_from_buf respectively.
No functional changes.
Suggested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/023fda047c787cf330b88ed9337705edae6a0078.1636997631.git.reinette.chatre@intel.com
To add more operations to the test enclave, the protocol needs to allow
to have operations with varying parameters. Create a separate parameter
struct for each existing operation, with the shared parameters in struct
encl_op_header.
[reinette: rebased to apply on top of oversubscription test series]
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/f9a4a8c436b538003b8ebddaa66083992053cef1.1636997631.git.reinette.chatre@intel.com
Add a variation of the unclobbered_vdso test.
In the new test, create a heap for the test enclave, which has the same
size as all available Enclave Page Cache (EPC) pages in the system. This
will guarantee that all test_encl.elf pages *and* SGX Enclave Control
Structure (SECS) have been swapped out by the page reclaimer during the
load time.
This test will trigger both the page reclaimer and the page fault handler.
The page reclaimer triggered, while the heap is being created during the
load time. The page fault handler is triggered for all the required pages,
while the test case is executing.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/41f7c508eea79a3198b5014d7691903be08f9ff1.1636997631.git.reinette.chatre@intel.com
Create the test enclave inside each TEST_F(), instead of FIXTURE_SETUP(),
so that the heap size can be defined per test.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/70ca264535d2ca0dc8dcaf2281e7d6965f8d4a24.1636997631.git.reinette.chatre@intel.com
Introduce setup_test_encl() so that the enclave creation can be moved to
TEST_F()'s. This is required for a reclaimer test where the heap size needs
to be set large enough to triger the page reclaimer.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/bee0ca867a95828a569c1ba2a8e443a44047dc71.1636997631.git.reinette.chatre@intel.com
Logging is always a compromise between clarity and detail. The main use
case for dumping VMA's is when FIXTURE_SETUP() fails, and is less important
for enclaves that do initialize correctly. Therefore, print the segments
and /proc/self/maps only in the error case.
Finally, if a single test ever creates multiple enclaves, the amount of
log lines would become enormous.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/23cef0ae1de3a8a74cbfbbe74eca48ca3f300fde.1636997631.git.reinette.chatre@intel.com
Create a heap for the test enclave, which is allocated from /dev/null,
and left unmeasured. This is beneficial by its own because it verifies
that an enclave built from multiple choices, works properly. If LSM
hooks are added for SGX some day, a multi source enclave has higher
probability to trigger bugs on access control checks.
The immediate need comes from the need to implement page reclaim tests.
In order to trigger the page reclaimer, one can just set the size of
the heap to high enough.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/e070c5f23578c29608051cab879b1d276963a27a.1636997631.git.reinette.chatre@intel.com
Extend the enclave to have two operations: ENCL_OP_PUT and ENCL_OP_GET.
ENCL_OP_PUT stores value inside the enclave address space and
ENCL_OP_GET reads it. The internal buffer can be later extended to be
variable size, and allow reclaimer tests.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Add EXPECT_EEXIT() macro, which will conditionally print the exception
information, in addition to
EXPECT_EQ(self->run.function, EEXIT);
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Often, it's useful to check whether /proc/self/maps looks sane when
dealing with memory mapped objects, especially when they are JIT'ish
dynamically constructed objects. Therefore, dump "/dev/sgx_enclave"
matching lines from the memory map in FIXTURE_SETUP().
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Migrate to kselftest harness. Use a fixture test with enclave initialized
and de-initialized for each of the existing three tests, in other words:
1. One FIXTURE() for managing the enclave life-cycle.
2. Three TEST_F()'s, one for each test case.
Dump lines of /proc/self/maps matching "sgx" in FIXTURE_SETUP() as this
can be very useful debugging information later on.
Amended commit log:
This migration changes the output of this test. Instead of skipping
the tests if open /dev/sgx_enclave fails, it will run all the tests
and report failures on all of them.
Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Rename symbols for better clarity:
* 'eenter' might be confused for directly calling ENCLU[EENTER]. It does
not. It calls into the VDSO, which actually has the EENTER instruction.
* 'sgx_call_vdso' is *only* used for entering the enclave. It's not some
generic SGX call into the VDSO.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Use the library function getauxval() instead of a custom function to get
the base address of the vDSO.
[ bp: Massage commit message. ]
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20210314111621.68428-1-tianjia.zhang@linux.alibaba.com
The SGX device file (/dev/sgx_enclave) is unusual in that it requires
execute permissions. It has to be both "chmod +x" *and* be on a
filesystem without 'noexec'.
In the future, udev and systemd should get updates to set up systems
automatically. But, for now, nobody's systems do this automatically,
and everybody gets error messages like this when running ./test_sgx:
0x0000000000000000 0x0000000000002000 0x03
0x0000000000002000 0x0000000000001000 0x05
0x0000000000003000 0x0000000000003000 0x03
mmap() failed, errno=1.
That isn't very user friendly, even for forgetful kernel developers.
Further, the test case is rather haphazard about its use of fprintf()
versus perror().
Improve the error messages. Use perror() where possible. Lastly,
do some sanity checks on opening and mmap()ing the device file so
that we can get a decent error message out to the user.
Now, if your user doesn't have permission, you'll get the following:
$ ls -l /dev/sgx_enclave
crw------- 1 root root 10, 126 Mar 18 11:29 /dev/sgx_enclave
$ ./test_sgx
Unable to open /dev/sgx_enclave: Permission denied
If you then 'chown dave:dave /dev/sgx_enclave' (or whatever), but
you leave execute permissions off, you'll get:
$ ls -l /dev/sgx_enclave
crw------- 1 dave dave 10, 126 Mar 18 11:29 /dev/sgx_enclave
$ ./test_sgx
no execute permissions on device file
If you fix that with "chmod ug+x /dev/sgx" but you leave /dev as
noexec, you'll get this:
$ mount | grep "/dev .*noexec"
udev on /dev type devtmpfs (rw,nosuid,noexec,...)
$ ./test_sgx
ERROR: mmap for exec: Operation not permitted
mmap() succeeded for PROT_READ, but failed for PROT_EXEC
check that user has execute permissions on /dev/sgx_enclave and
that /dev does not have noexec set: 'mount | grep "/dev .*noexec"'
That can be fixed with:
mount -o remount,noexec /devESC
Hopefully, the combination of better error messages and the search
engines indexing this message will help people fix their systems
until we do this properly.
[ bp: Improve error messages more. ]
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20210318194301.11D9A984@viggo.jf.intel.com
Add a selftest for SGX. It is a trivial test where a simple enclave
copies one 64-bit word of memory between two memory locations,
but ensures that all SGX hardware and software infrastructure is
functioning.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Cc: linux-kselftest@vger.kernel.org
Link: https://lkml.kernel.org/r/20201112220135.165028-21-jarkko@kernel.org
