When linking the selftests against a libc which does not handle rseq
registration (before 2.35), rseq thread registration silently succeed
even with CONFIG_RSEQ=n because it erroneously thinks that libc is
handling rseq registration.
This is caused by setting the rseq ownership flag only after the
rseq_available() check. It should rather be set before the
rseq_available() check.
Set the rseq_size to 0 (error value) immediately after the
rseq_available() check fails rather than in the thread registration
functions.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-2-mathieu.desnoyers@efficios.com
rseq_flags = *libc_rseq_flags_p;
return;
}
- if (!rseq_available())
- return;
rseq_ownership = 1;
+ if (!rseq_available()) {
+ rseq_size = 0;
+ return;
+ }
rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer();
rseq_size = sizeof(struct rseq_abi);
rseq_flags = 0;