tracing: Add helpers to create trace remote events

Declaring remote events can be cumbersome let's add a set of macros to
simplify developers life. The declaration of a remote event is very
similar to kernel's events:

 REMOTE_EVENT(name, id,
     RE_STRUCT(
        re_field(u64 foo)
     ),
     RE_PRINTK("foo=%llu", __entry->foo)
 )

Link: https://patch.msgid.link/20260309162516.2623589-12-vdonnefort@google.com
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/include/linux/trace_remote_event.h b/include/linux/trace_remote_event.h
index a4449008a075e862e99c6e14e456b6ec05c4bd5d..c8ae1e1f5e721d0da9b4c9f274958baffe12308e 100644 (file)
--- a/include/linux/trace_remote_event.h
+++ b/include/linux/trace_remote_event.h
@@ -5,6 +5,7 @@
 
 struct trace_remote;
 struct trace_event_fields;
+struct trace_seq;
 
 struct remote_event_hdr {
        unsigned short  id;
@@ -20,4 +21,13 @@ struct remote_event {
        char                            *print_fmt;
        void                            (*print)(void *evt, struct trace_seq *seq);
 };
+
+#define RE_STRUCT(__args...) __args
+#define re_field(__type, __field) __type __field;
+
+#define REMOTE_EVENT_FORMAT(__name, __struct)  \
+       struct remote_event_format_##__name {   \
+               struct remote_event_hdr hdr;    \
+               __struct                        \
+       }
 #endif

diff --git a/include/trace/define_remote_events.h b/include/trace/define_remote_events.h
new file mode 100644 (file)
index 0000000..676e803
--- /dev/null
+++ b/include/trace/define_remote_events.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/trace_events.h>
+#include <linux/trace_remote_event.h>
+#include <linux/trace_seq.h>
+#include <linux/stringify.h>
+
+#define REMOTE_EVENT_INCLUDE(__file) __stringify(../../__file)
+
+#ifdef REMOTE_EVENT_SECTION
+# define __REMOTE_EVENT_SECTION(__name) __used __section(REMOTE_EVENT_SECTION"."#__name)
+#else
+# define __REMOTE_EVENT_SECTION(__name)
+#endif
+
+#define REMOTE_PRINTK_COUNT_ARGS(__args...) \
+       __COUNT_ARGS(, ##__args, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 0)
+
+#define __remote_printk0()                                                             \
+       trace_seq_putc(seq, '\n')
+
+#define __remote_printk1(__fmt)                                                                \
+       trace_seq_puts(seq, " " __fmt "\n")                                             \
+
+#define __remote_printk2(__fmt, __args...)                                             \
+do {                                                                                   \
+       trace_seq_putc(seq, ' ');                                                       \
+       trace_seq_printf(seq, __fmt, __args);                                           \
+       trace_seq_putc(seq, '\n');                                                      \
+} while (0)
+
+/* Apply the appropriate trace_seq sequence according to the number of arguments */
+#define remote_printk(__args...)                                                       \
+       CONCATENATE(__remote_printk, REMOTE_PRINTK_COUNT_ARGS(__args))(__args)
+
+#define RE_PRINTK(__args...) __args
+
+#define REMOTE_EVENT(__name, __id, __struct, __printk)                                 \
+       REMOTE_EVENT_FORMAT(__name, __struct);                                          \
+       static void remote_event_print_##__name(void *evt, struct trace_seq *seq)       \
+       {                                                                               \
+               struct remote_event_format_##__name __maybe_unused *__entry = evt;      \
+               trace_seq_puts(seq, #__name);                                           \
+               remote_printk(__printk);                                                \
+       }
+#include REMOTE_EVENT_INCLUDE(REMOTE_EVENT_INCLUDE_FILE)
+
+#undef REMOTE_EVENT
+#undef RE_PRINTK
+#undef re_field
+#define re_field(__type, __field)                                                      \
+       {                                                                               \
+               .type = #__type, .name = #__field,                                      \
+               .size = sizeof(__type), .align = __alignof__(__type),                   \
+               .is_signed = is_signed_type(__type),                                    \
+       },
+#define __entry REC
+#define RE_PRINTK(__fmt, __args...) "\"" __fmt "\", " __stringify(__args)
+#define REMOTE_EVENT(__name, __id, __struct, __printk)                                 \
+       static struct trace_event_fields remote_event_fields_##__name[] = {             \
+               __struct                                                                \
+               {}                                                                      \
+       };                                                                              \
+       static char remote_event_print_fmt_##__name[] = __printk;                       \
+       static struct remote_event __REMOTE_EVENT_SECTION(__name)                       \
+       remote_event_##__name = {                                                       \
+               .name           = #__name,                                              \
+               .id             = __id,                                                 \
+               .fields         = remote_event_fields_##__name,                         \
+               .print_fmt      = remote_event_print_fmt_##__name,                      \
+               .print          = remote_event_print_##__name,                          \
+       }
+#include REMOTE_EVENT_INCLUDE(REMOTE_EVENT_INCLUDE_FILE)