Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Michael Jeanson <mjeanson@efficios.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Boqun Feng <boqun.feng@gmail.com>,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
        Michael Jeanson <mjeanson@efficios.com>
Subject: [PATCH 3/3] selftests/rseq: check if libc rseq support is registered
Date:   Tue, 14 Jun 2022 11:48:30 -0400
Message-Id: <20220614154830.1367382-4-mjeanson@efficios.com>
In-Reply-To: <20220614154830.1367382-1-mjeanson@efficios.com>
References: <20220614154830.1367382-1-mjeanson@efficios.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

When checking for libc rseq support in the library constructor, don't
only depend on the symbols presence, check that the registration was
completed.

This targets a scenario where the libc has rseq support but it is not
wired for the current architecture in 'bits/rseq.h', we want to fallback
to our internal registration mechanism.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
 tools/testing/selftests/rseq/rseq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftest=
s/rseq/rseq.c
index 986b9458efb2..4177f9507bbe 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -111,7 +111,8 @@ void rseq_init(void)
 	libc_rseq_offset_p =3D dlsym(RTLD_NEXT, "__rseq_offset");
 	libc_rseq_size_p =3D dlsym(RTLD_NEXT, "__rseq_size");
 	libc_rseq_flags_p =3D dlsym(RTLD_NEXT, "__rseq_flags");
-	if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p) {
+	if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p &&
+			*libc_rseq_size_p !=3D 0) {
 		/* rseq registration owned by glibc */
 		rseq_offset =3D *libc_rseq_offset_p;
 		rseq_size =3D *libc_rseq_size_p;
--=20
2.34.1