fix some vDSO bugs.

- vDSO sometimes becomes invalid.
- vDSO is not succeeded for child process.
- vDSO becomes invalid when execve.
refs #744

arch/x86/kernel/syscall.c

@@ -1563,6 +1563,7 @@ static int vdso_get_vdso_info(void)
 	struct ihk_ikc_channel_desc *ch = cpu_local_var(syscall_channel);
 
 	dkprintf("vdso_get_vdso_info()\n");
+	memset(&vdso, '\0', sizeof vdso);
 	vdso.busy = 1;
 	vdso.vdso_npages = 0;
 

executer/kernel/mcctrl/arch/x86_64/archdeps.c

@@ -100,8 +100,6 @@ void get_vdso_info(ihk_os_t os, long vdso_rpa)
 	vdso_pa = ihk_device_map_memory(dev, vdso_rpa, sizeof(*vdso));
 	vdso = ihk_device_map_virtual(dev, vdso_pa, sizeof(*vdso), NULL, 0);
 
-	memset(vdso, 0, sizeof(*vdso));
-
 	/* VDSO pages */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(3,16,0)
 	size = vdso_image->size;

executer/user/mcexec.c

@@ -2198,6 +2198,7 @@ fork_err:
 						strcpy(desc->shell_path, shell_path);
 					}
 
+					desc->enable_vdso = enable_vdso;
 					__dprintf("execve(): load_elf_desc() for %s OK, num sections: %d\n",
 						path, desc->num_sections);
 

kernel/host.c

@@ -332,6 +332,9 @@ int prepare_process_ranges_args_envs(struct thread *thread,
 			goto err;
 		}
 	}
+	else {
+		vm->vdso_addr = NULL;
+	}
 
 	p->rprocess = (unsigned long)thread;
 	p->rpgtable = virt_to_phys(as->page_table);

kernel/process.c

@@ -387,6 +387,8 @@ clone_thread(struct thread *org, unsigned long pc, unsigned long sp,
 			goto err_free_proc;
 		}
 
+		thread->vm->vdso_addr = org->vm->vdso_addr;
+		thread->vm->vvar_addr = org->vm->vvar_addr;
 		thread->proc->maxrss = org->proc->maxrss;
 		thread->vm->currss = org->vm->currss;