selftests/bpf: Fix BPF_KRETPROBE macro and use it in attach_probe test

static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)

#define ___bpf_kretprobe_args0() ctx

#define ___bpf_kretprobe_argsN(x, args...) \

	___bpf_kprobe_args(args), (void *)PT_REGS_RET(ctx)

#define ___bpf_kretprobe_args1(x) \

	___bpf_kretprobe_args0(), (void *)PT_REGS_RET(ctx)

#define ___bpf_kretprobe_args(args...) \

	___bpf_apply(___bpf_kretprobe_args, ___bpf_empty(args))(args)

	___bpf_apply(___bpf_kretprobe_args, ___bpf_narg(args))(args)

/*

 * BPF_KRETPROBE is similar to BPF_KPROBE, except, in addition to listing all

 * input kprobe arguments, one last extra argument has to be specified, which

 * captures kprobe return value.

 * BPF_KRETPROBE is similar to BPF_KPROBE, except, it only provides optional

 * return value (in addition to `struct pt_regs *ctx`), but no input

 * arguments, because they will be clobbered by the time probed function

 * returns.

 */

#define BPF_KRETPROBE(name, args...)					    \

name(struct pt_regs *ctx);						    \

#include <linux/ptrace.h>

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_trace_helpers.h"

int kprobe_res = 0;

int kretprobe_res = 0;

}

SEC("kretprobe/sys_nanosleep")

int handle_kretprobe(struct pt_regs *ctx)

int BPF_KRETPROBE(handle_kretprobe)

{

	kretprobe_res = 2;

	return 0;

}

SEC("kretprobe/__set_task_comm")

int BPF_KRETPROBE(prog2,

		  struct task_struct *tsk, const char *buf, bool exec,

		  int ret)

int BPF_KRETPROBE(prog2, int ret)

{

	return !PT_REGS_PARM1(ctx) && ret;

	return ret;

}

SEC("raw_tp/task_rename")