From: Michael Jeanson <mjeanson@xxxxxxxxxxxx> [ Upstream commit d1a997ba4c1bf65497d956aea90de42a6398f73a ] 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@xxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220614154830.1367382-4-mjeanson@xxxxxxxxxxxx Stable-dep-of: 3bcbc20942db ("selftests/rseq: Play nice with binaries statically linked against glibc 2.35+") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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/selftests/rseq/rseq.c index 986b9458efb26..4177f9507bbee 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 = dlsym(RTLD_NEXT, "__rseq_offset"); libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size"); libc_rseq_flags_p = 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 != 0) { /* rseq registration owned by glibc */ rseq_offset = *libc_rseq_offset_p; rseq_size = *libc_rseq_size_p; -- 2.40.1
