On Mon, Aug 06, 2018 at 03:27:23PM +0200, Vasily Gorbik wrote: > The kernel rseq syscall expects that struct rseq is 32 bytes aligned and > returns EINVAL otherwise. Even though __rseq_abi is declared as static > and proper aligned attribute is present __rseq_abi is a part of thread > local storage. It turns out that on some platforms TLS itself is not > properly aligned (at least for threads created), which is a glibc nptl > bug and should be eventually fixed and backported. But in a meanwhile > add __rseq_abi misalignment check, which would detect this situation > and skip rseq test with some user friendly message. > > glibc bug: https://sourceware.org/bugzilla/show_bug.cgi?id=23403 > > Signed-off-by: Vasily Gorbik <[email protected]>
Acked-by: Paul E. McKenney <[email protected]> > --- > tools/testing/selftests/rseq/rseq.c | 20 +++++++++++++++++++ > .../testing/selftests/rseq/run_param_test.sh | 4 ++-- > 2 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/rseq/rseq.c > b/tools/testing/selftests/rseq/rseq.c > index 4847e97ed049..3de7f0e7442e 100644 > --- a/tools/testing/selftests/rseq/rseq.c > +++ b/tools/testing/selftests/rseq/rseq.c > @@ -64,6 +64,24 @@ static int sys_rseq(volatile struct rseq *rseq_abi, > uint32_t rseq_len, > return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig); > } > > +/* > + * rseq syscall might fail on some platforms due to wrong alignment of TLS > + * variables: > + * https://sourceware.org/bugzilla/show_bug.cgi?id=23403 > + * > + * check if glibc bug is present and skip the test in this case > + */ > +static void assert_rseq_abi_aligned(void) > +{ > + if ((unsigned long)&__rseq_abi & (__alignof__(__rseq_abi) - 1)) { > + fputs("__rseq_abi is not properly aligned, which is a known\n" > + "glibc nptl bug > (https://sourceware.org/bugzilla/show_bug.cgi?id=23403).\n" > + "You need a fixed version of glibc to run this test.\n", > + stderr); > + exit(4); /* skip this test */ > + } > +} > + > int rseq_register_current_thread(void) > { > int rc, ret = 0; > @@ -72,6 +90,7 @@ int rseq_register_current_thread(void) > signal_off_save(&oldset); > if (refcount++) > goto end; > + assert_rseq_abi_aligned(); > rc = sys_rseq(&__rseq_abi, sizeof(struct rseq), 0, RSEQ_SIG); > if (!rc) { > assert(rseq_current_cpu_raw() >= 0); > @@ -94,6 +113,7 @@ int rseq_unregister_current_thread(void) > signal_off_save(&oldset); > if (--refcount) > goto end; > + assert_rseq_abi_aligned(); > rc = sys_rseq(&__rseq_abi, sizeof(struct rseq), > RSEQ_FLAG_UNREGISTER, RSEQ_SIG); > if (!rc) > diff --git a/tools/testing/selftests/rseq/run_param_test.sh > b/tools/testing/selftests/rseq/run_param_test.sh > index 3acd6d75ff9f..56caf5e3de3e 100755 > --- a/tools/testing/selftests/rseq/run_param_test.sh > +++ b/tools/testing/selftests/rseq/run_param_test.sh > @@ -34,9 +34,9 @@ function do_tests() > local i=0 > while [ "$i" -lt "${#TEST_LIST[@]}" ]; do > echo "Running test ${TEST_NAME[$i]}" > - ./param_test ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || > exit 1 > + ./param_test ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || > exit $? > echo "Running compare-twice test ${TEST_NAME[$i]}" > - ./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} ${@} > ${EXTRA_ARGS} || exit 1 > + ./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} ${@} > ${EXTRA_ARGS} || exit $? > let "i++" > done > } > -- > 2.18.0.13.gd42ae10
