liblttng-ust-ctl: Implement SIGBUS handling

[lttng-ust.git] / include / lttng / ust-sigbus.h

diff --git a/include/lttng/ust-sigbus.h b/include/lttng/ust-sigbus.h
new file mode 100644 (file)
index 0000000..7cdc1c1
--- /dev/null
+++ b/include/lttng/ust-sigbus.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2020 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License only.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _LTTNG_UST_SIGBUS_H
+#define _LTTNG_UST_SIGBUS_H
+
+#include <urcu/list.h>
+#include <setjmp.h>
+
+struct lttng_ust_sigbus_range {
+       void *start;    /* inclusive */
+       void *end;      /* exclusive */
+       struct cds_list_head node;
+};
+
+struct lttng_ust_sigbus_state {
+       int jmp_ready;
+       struct cds_list_head head;      /* struct lttng_ust_sigbus_range */
+       sigjmp_buf sj_env;
+};
+
+/*
+ * Define the lttng_ust_sigbus_state TLS variable as initial-exec model
+ * to allow using it from the SIGBUS signal handler. This variable must
+ * be defined by the executable using DEFINE_LTTNG_UST_SIGBUS_STATE()
+ * rather than internally within liblttng-ust-ctl.so to ensure we don't
+ * contribute to reach glibc limits of pre-allocated TLS IE model space
+ * for shared objects.
+ */
+#define DEFINE_LTTNG_UST_SIGBUS_STATE()        \
+       __thread __attribute__((tls_model("initial-exec"))) struct lttng_ust_sigbus_state lttng_ust_sigbus_state
+
+extern __thread __attribute__((tls_model("initial-exec"))) struct lttng_ust_sigbus_state lttng_ust_sigbus_state;
+
+#endif /* _LTTNG_UST_SIGBUS_H */