fix: check if libc rseq support is registered

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.

Change-Id: I662e537a6511fd4fd9e0650feb17e9c72ec39ddc
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/src/rseq.c b/src/rseq.c
index adfb62b2ebda53b35cb742a9ee8a898be1241d84..7fafc08b17b7cc396194f82ab1d8d50f6f89d77f 100644 (file)
--- a/src/rseq.c
+++ b/src/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;