Add namespace contexts

[deliverable/lttng-modules.git] / lttng-context-pid-ns.c

diff --git a/lttng-context-pid-ns.c b/lttng-context-pid-ns.c
new file mode 100644 (file)
index 0000000..f039f26
--- /dev/null
+++ b/lttng-context-pid-ns.c
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * lttng-context-pid-ns.c
+ *
+ * LTTng pid namespace context.
+ *
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *               2019 Michael Jeanson <mjeanson@efficios.com>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/pid_namespace.h>
+#include <lttng-events.h>
+#include <wrapper/ringbuffer/frontend_types.h>
+#include <wrapper/vmalloc.h>
+#include <wrapper/namespace.h>
+#include <lttng-tracer.h>
+
+#if defined(CONFIG_PID_NS) && \
+       (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
+
+static
+size_t pid_ns_get_size(size_t offset)
+{
+       size_t size = 0;
+
+       size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
+       size += sizeof(unsigned int);
+       return size;
+}
+
+static
+void pid_ns_record(struct lttng_ctx_field *field,
+                struct lib_ring_buffer_ctx *ctx,
+                struct lttng_channel *chan)
+{
+       struct pid_namespace *ns;
+       unsigned int pid_ns_inum = 0;
+
+       /*
+        * The pid namespace is an exception -- it's accessed using
+        * task_active_pid_ns. The pid namespace in nsproxy is the
+        * namespace that children will use.
+        */
+       ns = task_active_pid_ns(current);
+
+       if (ns)
+               pid_ns_inum = ns->lttng_ns_inum;
+
+       lib_ring_buffer_align_ctx(ctx, lttng_alignof(pid_ns_inum));
+       chan->ops->event_write(ctx, &pid_ns_inum, sizeof(pid_ns_inum));
+}
+
+static
+void pid_ns_get_value(struct lttng_ctx_field *field,
+               struct lttng_probe_ctx *lttng_probe_ctx,
+               union lttng_ctx_value *value)
+{
+       struct pid_namespace *ns;
+       unsigned int pid_ns_inum = 0;
+
+       /*
+        * The pid namespace is an exception -- it's accessed using
+        * task_active_pid_ns. The pid namespace in nsproxy is the
+        * namespace that children will use.
+        */
+       ns = task_active_pid_ns(current);
+
+       if (ns)
+               pid_ns_inum = ns->lttng_ns_inum;
+
+       value->s64 = pid_ns_inum;
+}
+
+int lttng_add_pid_ns_to_ctx(struct lttng_ctx **ctx)
+{
+       struct lttng_ctx_field *field;
+
+       field = lttng_append_context(ctx);
+       if (!field)
+               return -ENOMEM;
+       if (lttng_find_context(*ctx, "pid_ns")) {
+               lttng_remove_context_field(ctx, field);
+               return -EEXIST;
+       }
+       field->event_field.name = "pid_ns";
+       field->event_field.type.atype = atype_integer;
+       field->event_field.type.u.basic.integer.size = sizeof(unsigned int) * CHAR_BIT;
+       field->event_field.type.u.basic.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
+       field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(unsigned int);
+       field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+       field->event_field.type.u.basic.integer.base = 10;
+       field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+       field->get_size = pid_ns_get_size;
+       field->record = pid_ns_record;
+       field->get_value = pid_ns_get_value;
+       lttng_context_update(*ctx);
+       wrapper_vmalloc_sync_all();
+       return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_pid_ns_to_ctx);
+
+#endif