lkml.org 
[lkml]   [2018]   [Aug]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 1/1] rseq/selftests: add __rseq_abi misalignment check
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 <gor@linux.ibm.com>

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> ---
> 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

\
 
 \ /
  Last update: 2018-08-06 16:11    [W:0.071 / U:0.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site