diff --git a/executer/user/mcexec.c b/executer/user/mcexec.c
index 7f84284..3d65118 100644
--- a/executer/user/mcexec.c
+++ b/executer/user/mcexec.c
@@ -200,6 +200,8 @@ static char *mpol_bind_nodes = NULL;
 static int uti_thread_rank = 0;
 static int uti_use_last_cpu = 0;
 static int enable_uti = 0;
+static const char *signal_injection = "";
+static int injection_signo = 0;
 
 /* Partitioned execution (e.g., for MPI) */
 static int nr_processes = 0;
@@ -892,11 +894,20 @@ int transfer_image(int fd, struct program_load_desc *desc)
 			/* No more left to upload.. */
 			if (lr == 0 && flen == 0) break;
 
+			if (strcmp(signal_injection, "MCEXEC_UP_TRANSFER:before") == 0) {
+				printf("raise\n");
+				raise(injection_signo);
+			}
+			printf("ioctl(MCEXEC_UP_TRANSFER)\n");
 			if (ioctl(fd, MCEXEC_UP_TRANSFER,
 						(unsigned long)&pt)) {
 				perror("dma");
 				break;
 			}
+			if (strcmp(signal_injection, "MCEXEC_UP_TRANSFER:after") == 0) {
+				printf("raise\n");
+				raise(injection_signo);
+			}
 		}
 	}
 
@@ -2092,6 +2103,8 @@ int main(int argc, char **argv)
 	__glob_argv = argv;
 #endif
 
+	printf("signal_injection.patch is applied.\n");
+
 	page_size = sysconf(_SC_PAGESIZE);
 	page_mask = ~(page_size - 1);
 
@@ -2237,6 +2250,21 @@ int main(int argc, char **argv)
 		}
 	}
 
+	while ((opt = getopt_long(argc, argv, "i:s:",
+			mcexec_options, NULL)) != -1) {
+		switch (opt) {
+		case 'i':
+			signal_injection = optarg;
+			break;
+		case 's':
+			injection_signo = strtol(optarg, NULL, 0);
+			break;
+		default: /* '?' */
+			print_usage(argv);
+			exit(EXIT_FAILURE);
+		}
+	}
+
 	if (heap_extension == -1) {
 		heap_extension = sysconf(_SC_PAGESIZE);
 	}
@@ -2653,11 +2681,20 @@ int main(int argc, char **argv)
 	desc->thp_disable = get_thp_disable();
 
 	/* user_start and user_end are set by this call */
+	if (strcmp(signal_injection, "MCEXEC_UP_PREPARE_IMAGE:before") == 0) {
+		printf("raise\n");
+		raise(injection_signo);
+	}
+	printf("ioctl(MCEXEC_UP_PREPARE_IMAGE)\n");
 	if (ioctl(fd, MCEXEC_UP_PREPARE_IMAGE, (unsigned long)desc) != 0) {
 		perror("prepare");
 		close(fd);
 		return 1;
 	}
+	if (strcmp(signal_injection, "MCEXEC_UP_PREPARE_IMAGE:after") == 0) {
+		printf("raise\n");
+		raise(injection_signo);
+	}
 
 	print_desc(desc);
 	if (transfer_image(fd, desc) < 0) {
@@ -2692,7 +2729,16 @@ int main(int argc, char **argv)
 	__dprintf("mccmd server initialized\n");
 #endif
 
+	if (strcmp(signal_injection, "init_sigaction:before") == 0) {
+		printf("raise\n");
+		raise(injection_signo);
+	}
+	printf("init_sigaction\n");
 	init_sigaction();
+	if (strcmp(signal_injection, "init_sigaction:after") == 0) {
+		printf("raise\n");
+		raise(injection_signo);
+	}
 
 	/* Initialize watchdog thread which detects hang of McKernel */
 
@@ -2721,11 +2767,20 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	if (strcmp(signal_injection, "MCEXEC_UP_START_IMAGE:before") == 0) {
+		printf("raise\n");
+		raise(injection_signo);
+	}
+	printf("ioctl(MCEXEC_UP_START_IMAGE)\n");
 	if (ioctl(fd, MCEXEC_UP_START_IMAGE, (unsigned long)desc) != 0) {
 		perror("exec");
 		close(fd);
 		return 1;
 	}
+	if (strcmp(signal_injection, "MCEXEC_UP_START_IMAGE:after") == 0) {
+		printf("raise\n");
+		raise(injection_signo);
+	}
 
 #if 1 /* debug : thread killed by exit_group() are still joinable? */
 	join_all_threads();