util/oslib-posix: Forward SIGBUS to MCE handler under Linux
Temporarily modifying the SIGBUS handler is really nasty, as we might be
unlucky and receive an MCE SIGBUS while having our handler registered.
Unfortunately, there is no way around messing with SIGBUS when
MADV_POPULATE_WRITE is not applicable or not around.
Let's forward SIGBUS that don't belong to us to the already registered
handler and document the situation.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20211217134611.31172-8-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 071085f..23bca46 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -352,6 +352,10 @@
{
struct sigaction action;
+ /*
+ * ALERT: when modifying this, take care that SIGBUS forwarding in
+ * os_mem_prealloc() will continue working as expected.
+ */
memset(&action, 0, sizeof(action));
action.sa_flags = SA_SIGINFO;
action.sa_sigaction = sigbus_handler;
