Cleanup: Move all source files to src/

[lttng-modules.git] / src / lttng-context-preemptible.c

diff --git a/src/lttng-context-preemptible.c b/src/lttng-context-preemptible.c
new file mode 100644 (file)
index 0000000..6130a1a
--- /dev/null
+++ b/src/lttng-context-preemptible.c
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
+ *
+ * lttng-context-preemptible.c
+ *
+ * LTTng preemptible context.
+ *
+ * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/irqflags.h>
+#include <lttng/events.h>
+#include <ringbuffer/frontend_types.h>
+#include <wrapper/vmalloc.h>
+#include <lttng/tracer.h>
+
+/*
+ * We nest twice in preempt disabling within LTTng: one nesting is done
+ * by the instrumentation (tracepoint, kprobes, kretprobes, syscall
+ * tracepoint), and the second is within the lib ring buffer
+ * lib_ring_buffer_get_cpu().
+ */
+#define LTTNG_PREEMPT_DISABLE_NESTING  2
+
+static
+size_t preemptible_get_size(size_t offset)
+{
+       size_t size = 0;
+
+       size += lib_ring_buffer_align(offset, lttng_alignof(uint8_t));
+       size += sizeof(uint8_t);
+       return size;
+}
+
+static
+void preemptible_record(struct lttng_ctx_field *field,
+               struct lib_ring_buffer_ctx *ctx,
+               struct lttng_channel *chan)
+{
+       int pc = preempt_count();
+       uint8_t preemptible = 0;
+
+       WARN_ON_ONCE(pc < LTTNG_PREEMPT_DISABLE_NESTING);
+       if (pc == LTTNG_PREEMPT_DISABLE_NESTING)
+               preemptible = 1;
+       lib_ring_buffer_align_ctx(ctx, lttng_alignof(preemptible));
+       chan->ops->event_write(ctx, &preemptible, sizeof(preemptible));
+}
+
+static
+void preemptible_get_value(struct lttng_ctx_field *field,
+               struct lttng_probe_ctx *lttng_probe_ctx,
+               union lttng_ctx_value *value)
+{
+       int pc = preempt_count();
+
+       WARN_ON_ONCE(pc < LTTNG_PREEMPT_DISABLE_NESTING);
+       if (pc == LTTNG_PREEMPT_DISABLE_NESTING)
+               value->s64 = 1;
+       else
+               value->s64 = 0;
+}
+
+int lttng_add_preemptible_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, "preemptible")) {
+               lttng_remove_context_field(ctx, field);
+               return -EEXIST;
+       }
+       field->event_field.name = "preemptible";
+       field->event_field.type.atype = atype_integer;
+       field->event_field.type.u.integer.size = sizeof(uint8_t) * CHAR_BIT;
+       field->event_field.type.u.integer.alignment = lttng_alignof(uint8_t) * CHAR_BIT;
+       field->event_field.type.u.integer.signedness = lttng_is_signed_type(uint8_t);
+       field->event_field.type.u.integer.reverse_byte_order = 0;
+       field->event_field.type.u.integer.base = 10;
+       field->event_field.type.u.integer.encoding = lttng_encode_none;
+       field->get_size = preemptible_get_size;
+       field->record = preemptible_record;
+       field->get_value = preemptible_get_value;
+       lttng_context_update(*ctx);
+       wrapper_vmalloc_sync_mappings();
+       return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_preemptible_to_ctx);