1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
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 <wrapper/ringbuffer/frontend_types.h>
15 #include <wrapper/vmalloc.h>
16 #include <wrapper/kallsyms.h>
17 #include <lttng-tracer.h>
20 int (*wrapper_task_prio_sym
)(struct task_struct
*t
);
22 int wrapper_task_prio_init(void)
24 wrapper_task_prio_sym
= (void *) kallsyms_lookup_funcptr("task_prio");
25 if (!wrapper_task_prio_sym
) {
26 printk(KERN_WARNING
"LTTng: task_prio symbol lookup failed.\n");
33 * Canary function to check for 'task_prio()' at compile time.
35 * From 'include/linux/sched.h':
37 * extern int task_prio(const struct task_struct *p);
39 __attribute__((unused
)) static
40 int __canary__task_prio(const struct task_struct
*p
)
46 size_t prio_get_size(size_t offset
)
50 size
+= lib_ring_buffer_align(offset
, lttng_alignof(int));
56 void prio_record(struct lttng_ctx_field
*field
,
57 struct lib_ring_buffer_ctx
*ctx
,
58 struct lttng_channel
*chan
)
62 prio
= wrapper_task_prio_sym(current
);
63 lib_ring_buffer_align_ctx(ctx
, lttng_alignof(prio
));
64 chan
->ops
->event_write(ctx
, &prio
, sizeof(prio
));
68 void prio_get_value(struct lttng_ctx_field
*field
,
69 struct lttng_probe_ctx
*lttng_probe_ctx
,
70 union lttng_ctx_value
*value
)
72 value
->s64
= wrapper_task_prio_sym(current
);
75 int lttng_add_prio_to_ctx(struct lttng_ctx
**ctx
)
77 struct lttng_ctx_field
*field
;
80 if (!wrapper_task_prio_sym
) {
81 ret
= wrapper_task_prio_init();
86 field
= lttng_append_context(ctx
);
89 if (lttng_find_context(*ctx
, "prio")) {
90 lttng_remove_context_field(ctx
, field
);
93 field
->event_field
.name
= "prio";
94 field
->event_field
.type
.atype
= atype_integer
;
95 field
->event_field
.type
.u
.basic
.integer
.size
= sizeof(int) * CHAR_BIT
;
96 field
->event_field
.type
.u
.basic
.integer
.alignment
= lttng_alignof(int) * CHAR_BIT
;
97 field
->event_field
.type
.u
.basic
.integer
.signedness
= lttng_is_signed_type(int);
98 field
->event_field
.type
.u
.basic
.integer
.reverse_byte_order
= 0;
99 field
->event_field
.type
.u
.basic
.integer
.base
= 10;
100 field
->event_field
.type
.u
.basic
.integer
.encoding
= lttng_encode_none
;
101 field
->get_size
= prio_get_size
;
102 field
->record
= prio_record
;
103 field
->get_value
= prio_get_value
;
104 lttng_context_update(*ctx
);
105 wrapper_vmalloc_sync_mappings();
108 EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx
);
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