tracing: bpf: use struct trace_entry in struct syscall_tp_t

bpf tracepoint program uses struct trace_event_raw_sys_enter as
argument where trace_entry is the first field. Use the same instead
of unsigned long long since if it's amended (for example by RT
patch) it accesses data with wrong offset.
Signed-off-by: Yauheni Kaliuta <ykaliuta@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230801075222.7717-1-ykaliuta@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/trace/trace_syscalls.c

@@ -555,12 +555,15 @@ static int perf_call_bpf_enter(struct trace_event_call *call, struct pt_regs *re
 			       struct syscall_trace_enter *rec)
 {
 	struct syscall_tp_t {
-		unsigned long long regs;
+		struct trace_entry ent;
 		unsigned long syscall_nr;
 		unsigned long args[SYSCALL_DEFINE_MAXARGS];
-	} param;
+	} __aligned(8) param;
 	int i;
 
+	BUILD_BUG_ON(sizeof(param.ent) < sizeof(void *));
+
+	/* bpf prog requires 'regs' to be the first member in the ctx (a.k.a. &param) */
 	*(struct pt_regs **)&param = regs;
 	param.syscall_nr = rec->nr;
 	for (i = 0; i < sys_data->nb_args; i++)
@@ -657,11 +660,12 @@ static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *reg
 			      struct syscall_trace_exit *rec)
 {
 	struct syscall_tp_t {
-		unsigned long long regs;
+		struct trace_entry ent;
 		unsigned long syscall_nr;
 		unsigned long ret;
-	} param;
+	} __aligned(8) param;
 
+	/* bpf prog requires 'regs' to be the first member in the ctx (a.k.a. &param) */
 	*(struct pt_regs **)&param = regs;
 	param.syscall_nr = rec->nr;
 	param.ret = rec->ret;