syscalls: make execve and vfs_read_file_by_path use follow_path, fix vfs_read_file_by_path name, fix execve-related pagefault

grubshit/caller.c

@@ -18,7 +18,7 @@ int main() {
     // The first argument is the path to the executable
     // The second is the array of arguments
     // The third is the array of environment variables
-    execve("callee.", argv, envp);
+    execve("/katau/callee.", argv, envp);
 
     // This part of the code will only be reached if execve fails
     perror("execve failed");