tracing: Add fields format definition for syscall events

Define the format of the syscall trace fields to parse the binary
values from a raw trace using the syscall events "format" file.

This is defined dynamically using the syscalls metadata.
It prepares the export of syscall event raw records to perf
counters.

Example:

$ cat /debug/tracing/events/syscalls/sys_enter_sched_getparam/format
name: sys_enter_sched_getparam
ID: 39
format:
	field:unsigned short common_type;	offset:0;	size:2;
	field:unsigned char common_flags;	offset:2;	size:1;
	field:unsigned char common_preempt_count;	offset:3;	size:1;
	field:int common_pid;	offset:4;	size:4;
	field:int common_tgid;	offset:8;	size:4;

	field:pid_t pid;	offset:12;	size:8;
	field:struct sched_param * param;	offset:20;	size:8;

print fmt: "pid: 0x%08lx, param: 0x%08lx", ((unsigned long)(REC->pid)), ((unsigned long)(REC->param))

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 5541e75e140a..87d06c173ddc 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -189,6 +189,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
                 .system                 = "syscalls",                   \
                 .event                  = &event_syscall_enter,         \
                 .raw_init               = init_enter_##sname,           \
+                .show_format            = ftrace_format_syscall,        \
                 .regfunc                = reg_event_syscall_enter,      \
                 .unregfunc              = unreg_event_syscall_enter,    \
                 .data                   = "sys"#sname,                  \