On Mon, 9 Mar 2026 11:54:34 +0000 Pratyush Yadav <[email protected]> wrote:
> From: "Pratyush Yadav (Google)" <[email protected]> > > Currently memfd preservation using LUO is only tested indirectly via the > luo_multi_session or luo_kexec_simple tests. Their main purpose is to > test other live update functionality. > > Add a framework for writing memfd tests. The framework hooks into the > kselftest harness, but adds some things on top to make it suitable for > live update. > > The LUO FD (/dev/liveupdate) can only be opened by one process at a > time. Each test runs in its own process. This means the LUO FD must be > owned by the main process and shared to children. main() opens the LUO > FD and shares it to child runners using a global variable. > > Live update tests run in two stages. One before kexec and one after. > Detect the stage using a special state session. If the session is > present, it means the test is in post-kexec state. > > Additionally, take in an optional --stage argument that lets callers > specify expected stage. This is useful as a safety net to catch LUO core > failures. If LUO core fails to preserve the state session properly, this > option can help detect this and fail early. Since the option is not > recognized by the kselftest harness, remove it from argv before calling > test_harness_run(). > > Signed-off-by: Pratyush Yadav (Google) <[email protected]> > --- > tools/testing/selftests/liveupdate/Makefile | 1 + > .../testing/selftests/liveupdate/luo_memfd.c | 77 +++++++++++++++++++ > 2 files changed, 78 insertions(+) > create mode 100644 tools/testing/selftests/liveupdate/luo_memfd.c > > diff --git a/tools/testing/selftests/liveupdate/Makefile > b/tools/testing/selftests/liveupdate/Makefile > index 080754787ede..051daae55eec 100644 > --- a/tools/testing/selftests/liveupdate/Makefile > +++ b/tools/testing/selftests/liveupdate/Makefile > @@ -6,6 +6,7 @@ TEST_GEN_PROGS += liveupdate > > TEST_GEN_PROGS_EXTENDED += luo_kexec_simple > TEST_GEN_PROGS_EXTENDED += luo_multi_session > +TEST_GEN_PROGS_EXTENDED += luo_memfd > > TEST_FILES += do_kexec.sh > > diff --git a/tools/testing/selftests/liveupdate/luo_memfd.c > b/tools/testing/selftests/liveupdate/luo_memfd.c > new file mode 100644 > index 000000000000..b779eee18387 > --- /dev/null > +++ b/tools/testing/selftests/liveupdate/luo_memfd.c > @@ -0,0 +1,77 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +/* > + * Copyright (c) 2026, Google LLC. > + * Pratyush Yadav (Google) <[email protected]> > + */ > + > +/* > + * Selftests for memfd preservation via LUO. > + */ > + > +#include <errno.h> > +#include <fcntl.h> > +#include <string.h> > +#include <sys/ioctl.h> > +#include <unistd.h> > + > +#include <linux/liveupdate.h> > + > +#include "../kselftest.h" > +#include "../kselftest_harness.h" > + > +#include "luo_test_utils.h" > + > +#define STATE_SESSION_NAME "luo-state" > +#define STATE_MEMFD_TOKEN 1 > + > +#define LIVEUPDATE_DEV "/dev/liveupdate" Hello! LIVEUPDATE_DEV doesn't seem to be used anywhere? > +static int luo_fd = -1, stage; > + > +int main(int argc, char *argv[]) > +{ > + int session, expected_stage = 0; > + > + /* > + * The test takes an optional --stage argument. This lets callers > + * provide the expected stage, and if that doesn't match the test errors > + * out. > + * > + * Look for the stage. Since test_harness_run() doesn't recognize it, > + * once found, remove it from argv. > + */ > + for (int i = 1; i < argc; i++) { > + if (strcmp(argv[i], "--stage") == 0) { > + if (i + 1 < argc) { > + expected_stage = atoi(argv[i + 1]); > + memmove(&argv[i], &argv[i + 2], (argc - i - 1) > * sizeof(char *)); > + argc -= 2; > + i--; > + } else { > + ksft_exit_fail_msg("Option --stage requires an > argument\n"); > + } > + } > + } > + > + luo_fd = luo_open_device(); > + if (luo_fd < 0) > + ksft_exit_skip("Failed to open %s (%s). Is the luo module > loaded?\n", > + strerror(errno), LUO_DEVICE); Need to reverse strerror(errno) and LUO_DEVICE? > + > + session = luo_retrieve_session(luo_fd, STATE_SESSION_NAME); > + if (session == -ENOENT) > + stage = 1; > + else if (session >= 0) > + stage = 2; > + else > + fail_exit("Failed to check for state session"); > + > + if (expected_stage && expected_stage != stage) > + ksft_exit_fail_msg("Stage mismatch: expected %d, got %d\n", > + expected_stage, stage); > + > + if (stage == 1) > + create_state_file(luo_fd, STATE_SESSION_NAME, > STATE_MEMFD_TOKEN, 2); > + > + test_harness_run(argc, argv); > +} > -- > 2.53.0.473.g4a7958ca14-goog > >
