The rseq selftests should discover whether the kernel implements the
RSEQ_FLAG_RELIABLE_CPU_ID flag, which indicates that the
__rseq_abi.cpu_id field is reliable.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Florian Weimer <fw@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Neel Natu <neelnatu@xxxxxxxxxx>
Cc: linux-api@xxxxxxxxxxxxxxx
Cc: linux-kselftest@xxxxxxxxxxxxxxx
---
tools/testing/selftests/rseq/rseq.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 7159eb777fd3..55f1edb0649c 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -73,6 +73,11 @@ static int sys_rseq(volatile struct rseq *rseq_abi, uint32_t rseq_len,
return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
}
+static bool rseq_reliable_cpu_id(void)
+{
+ return sys_rseq(NULL, 0, RSEQ_FLAG_RELIABLE_CPU_ID, 0) == 0;
+}
+
int rseq_register_current_thread(void)
{
int rc, ret = 0;
@@ -87,7 +92,8 @@ int rseq_register_current_thread(void)
}
if (__rseq_refcount++)
goto end;
- rc = sys_rseq(&__rseq_abi, sizeof(struct rseq), 0, RSEQ_SIG);
+ rc = sys_rseq(&__rseq_abi, sizeof(struct rseq),
+ RSEQ_FLAG_REGISTER | RSEQ_FLAG_RELIABLE_CPU_ID, RSEQ_SIG);
if (!rc) {
assert(rseq_current_cpu_raw() >= 0);
goto end;
@@ -96,6 +102,8 @@ int rseq_register_current_thread(void)
__rseq_abi.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED;
ret = -1;
__rseq_refcount--;
+ if (errno == EINVAL && !rseq_reliable_cpu_id())
+ fprintf(stderr, "Error: rseq does not provide a reliable cpu_id field.\n");
end:
signal_restore(oldset);
return ret;
--
2.17.1
