1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
5 * LTTng priority context.
7 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/sched.h>
13 #include <lttng/events.h>
14 #include <lttng/events-internal.h>
15 #include <ringbuffer/frontend_types.h>
16 #include <wrapper/vmalloc.h>
17 #include <wrapper/kallsyms.h>
18 #include <lttng/tracer.h>
21 int (*wrapper_task_prio_sym
)(struct task_struct
*t
);
23 int wrapper_task_prio_init(void)
25 wrapper_task_prio_sym
= (void *) kallsyms_lookup_funcptr("task_prio");
26 if (!wrapper_task_prio_sym
) {
27 printk(KERN_WARNING
"LTTng: task_prio symbol lookup failed.\n");
34 * Canary function to check for 'task_prio()' at compile time.
36 * From 'include/linux/sched.h':
38 * extern int task_prio(const struct task_struct *p);
40 __attribute__((unused
)) static
41 int __canary__task_prio(const struct task_struct
*p
)
47 size_t prio_get_size(void *priv
, struct lttng_kernel_probe_ctx
*probe_ctx
, size_t offset
)
51 size
+= lib_ring_buffer_align(offset
, lttng_alignof(int));
57 void prio_record(void *priv
, struct lttng_kernel_probe_ctx
*probe_ctx
,
58 struct lttng_kernel_ring_buffer_ctx
*ctx
,
59 struct lttng_channel
*chan
)
63 prio
= wrapper_task_prio_sym(current
);
64 lib_ring_buffer_align_ctx(ctx
, lttng_alignof(prio
));
65 chan
->ops
->event_write(ctx
, &prio
, sizeof(prio
));
69 void prio_get_value(void *priv
,
70 struct lttng_kernel_probe_ctx
*lttng_probe_ctx
,
71 struct lttng_ctx_value
*value
)
73 value
->u
.s64
= wrapper_task_prio_sym(current
);
76 static const struct lttng_kernel_ctx_field
*ctx_field
= lttng_kernel_static_ctx_field(
77 lttng_kernel_static_event_field("prio",
78 lttng_kernel_static_type_integer_from_type(int, __BYTE_ORDER
, 10),
85 int lttng_add_prio_to_ctx(struct lttng_kernel_ctx
**ctx
)
89 if (lttng_kernel_find_context(*ctx
, ctx_field
->event_field
->name
))
91 ret
= lttng_kernel_context_append(ctx
, ctx_field
);
92 wrapper_vmalloc_sync_mappings();
95 EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx
);