text: // SPDX-License-Identifier: GPL-2.0
  
  /*
   * Copyright 2020 Google LLC.
   */
  
  #include <test_progs.h>
  #include "modify_return.skel.h"
  
  #define LOWER(x) ((x) & 0xffff)
  #define UPPER(x) ((x) >> 16)
  
  
  static void run_test(__u32 input_retval, __u16 want_side_effect, __s16 want_ret)
  {
  	struct modify_return *skel = NULL;
  	int err, prog_fd;
  	__u32 duration = 0, retval;
  	__u16 side_effect;
  	__s16 ret;
  
  	skel = modify_return__open_and_load();
  	if (CHECK(!skel, "skel_load", "modify_return skeleton failed\n"))
  		goto cleanup;
  
  	err = modify_return__attach(skel);
  	if (CHECK(err, "modify_return", "attach failed: %d\n", err))
  		goto cleanup;
  
  	skel->bss->input_retval = input_retval;
  	prog_fd = bpf_program__fd(skel->progs.fmod_ret_test);
  	err = bpf_prog_test_run(prog_fd, 1, NULL, 0, NULL, 0,
  				&retval, &duration);
  
  	CHECK(err, "test_run", "err %d errno %d\n", err, errno);
  
  	side_effect = UPPER(retval);
  	ret  = LOWER(retval);
  
  	CHECK(ret != want_ret, "test_run",
  	      "unexpected ret: %d, expected: %d\n", ret, want_ret);
  	CHECK(side_effect != want_side_effect, "modify_return",
  	      "unexpected side_effect: %d\n", side_effect);
  
  	CHECK(skel->bss->fentry_result != 1, "modify_return",
  	      "fentry failed\n");
  	CHECK(skel->bss->fexit_result != 1, "modify_return",
  	      "fexit failed\n");
  	CHECK(skel->bss->fmod_ret_result != 1, "modify_return",
  	      "fmod_ret failed\n");
  
  cleanup:
  	modify_return__destroy(skel);
  }
  
  /* TODO: conflict with get_func_ip_test */
  void serial_test_modify_return(void)
  {
  	run_test(0 /* input_retval */,
  		 1 /* want_side_effect */,
  		 4 /* want_ret */);
  	run_test(-EINVAL /* input_retval */,
  		 0 /* want_side_effect */,
  		 -EINVAL /* want_ret */);
  }
  
  