commit d862928733ed2b39cd38364710d82715d4f01929
Author: uvos <devnull@uvos.xyz>
Date:   Sat Sep 30 15:28:30 2023 +0200

    inital commit

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..efe50d8
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.5)
+
+project(ksmexec C)
+
+set(SRC_FILES main.c)
+set(LIBS)
+
+add_executable(${PROJECT_NAME} ${SRC_FILES})
+target_link_libraries(${PROJECT_NAME} ${LIBS})
+
+add_executable(${PROJECT_NAME}_test test.c)
+target_link_libraries(${PROJECT_NAME} ${LIBS})
+
+set(CMAKE_INSTALL_PREFIX /usr)
+install(TARGETS ${PROJECT_NAME} RUNTIME DESTINATION bin)
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..1e0f5af
--- /dev/null
+++ b/main.c
@@ -0,0 +1,47 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <sys/prctl.h>
+#include <stdlib.h>
+
+int main(int argc, char** argv)
+{
+	if(argc < 2)
+	{
+		fprintf(stderr, "A process to execute is required\n");
+		return 1;
+	}
+
+	int ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);
+	if(ret != 0)
+	{
+		fprintf(stderr, "Unable to enable KSM for process: %s\n", strerror(errno));
+		return 2;
+	}
+
+	printf("PR_SET_MEMORY_MERGE set to %u\n", prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0));
+
+	pid_t parent_pid = getpid();
+	pid_t pid = fork();
+	if(pid == 0)
+	{
+		printf("PR_SET_MEMORY_MERGE in child is %u\n", prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0));
+		execvp(argv[1], argv+1);
+		fprintf(stderr, "Unable exec process: %s\n", strerror(errno));
+		return 3;
+	}
+	else if(pid == -1)
+	{
+		fprintf(stderr, "Unable fork: %s\n", strerror(errno));
+	}
+	else if(pid == -1)
+	{
+		waitpid(pid, NULL, 0);
+	}
+	return 0;
+}
+
diff --git a/test.c b/test.c
new file mode 100644
index 0000000..017f465
--- /dev/null
+++ b/test.c
@@ -0,0 +1,41 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <sys/prctl.h>
+#include <stdlib.h>
+
+int main(int argc, char** argv)
+{
+	int merge = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);
+	printf("PR_SET_MEMORY_MERGE is %u after exec\n", merge);
+
+	if(merge != 1)
+	{
+		fprintf(stderr, "KSM merging not enabled!\n");
+		return 1;
+	}
+
+	printf("allocating memory\n");
+	char* buf = malloc(100000000);
+
+	printf("writeing memory\n");
+	for(size_t i = 0; i < 100000000; i++)
+		buf[i] = 0x44;
+
+	printf("reading memory\n");
+	volatile char read;
+	while(true)
+	{
+		for(size_t i = 0; i < 100000000; i++)
+		{
+			read = buf[i];
+			if(read != 0x44)
+				return 2;
+		}
+		sleep(1);
+	}
+	return 0;
+}