ptrace: Fix the timing of save_fp_regs, and Add copy fp_regs to child in clone_thread

refs #702

arch/x86/kernel/cpu.c

@@ -1648,13 +1648,11 @@ release_fp_regs(struct thread *thread)
 	thread->fp_regs = NULL;
 }
 
-/*@
+static int
-  @ requires \valid(thread);
+check_and_allocate_fp_regs(struct thread *thread)
-  @*/
-void
-save_fp_regs(struct thread *thread)
 {
-	int	pages;
+	int pages;
+	int result = 0;
 
 	if (!thread->fp_regs) {
 		pages = (xsave_size + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
@@ -1663,12 +1661,26 @@ save_fp_regs(struct thread *thread)
 
 		if (!thread->fp_regs) {
 			kprintf("error: allocating fp_regs pages\n");
-			return;
+			result = 1;
+			goto out;
 		}
 
-		memset(thread->fp_regs, 0, sizeof(fp_regs_struct));
 		memset(thread->fp_regs, 0, pages * PAGE_SIZE);
 	}
+out:
+	return result;
+}
+
+/*@
+  @ requires \valid(thread);
+  @*/
+void
+save_fp_regs(struct thread *thread)
+{
+	if (check_and_allocate_fp_regs(thread) != 0) {
+		// alloc error
+		return;
+	}
 
 	if (xsave_available) {
 		unsigned int low, high;
@@ -1684,6 +1696,13 @@ save_fp_regs(struct thread *thread)
 	}
 }
 
+void copy_fp_regs(struct thread *from, struct thread *to)
+{
+	if ((from->fp_regs != NULL) && (check_and_allocate_fp_regs(to) == 0)) {
+		memcpy(to->fp_regs, from->fp_regs, sizeof(fp_regs_struct));
+	}
+}
+
 #ifdef POSTK_DEBUG_TEMP_FIX_19
 void
 clear_fp_regs(struct thread *thread)

arch/x86/kernel/syscall.c

@@ -33,7 +33,6 @@
 void terminate(int, int);
 extern long do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact);
 long syscall(int num, ihk_mc_user_context_t *ctx);
-extern void save_fp_regs(struct thread *proc);
 void set_signal(int sig, void *regs0, siginfo_t *info);
 void check_signal(unsigned long rc, void *regs0, int num);
 extern unsigned long do_fork(int, unsigned long, unsigned long, unsigned long,
@@ -460,7 +459,6 @@ void set_single_step(struct thread *thread)
 
 long ptrace_read_fpregs(struct thread *thread, void *fpregs)
 {
-	save_fp_regs(thread);
 	if (thread->fp_regs == NULL) {
 		return -ENOMEM;
 	}
@@ -470,7 +468,6 @@ long ptrace_read_fpregs(struct thread *thread, void *fpregs)
 
 long ptrace_write_fpregs(struct thread *thread, void *fpregs)
 {
-	save_fp_regs(thread);
 	if (thread->fp_regs == NULL) {
 		return -ENOMEM;
 	}

kernel/process.c

@@ -62,6 +62,7 @@ static void insert_vm_range_list(struct process_vm *vm,
 static int copy_user_ranges(struct process_vm *vm, struct process_vm *orgvm);
 extern void release_fp_regs(struct thread *proc);
 extern void save_fp_regs(struct thread *proc);
+extern void copy_fp_regs(struct thread *from, struct thread *to);
 extern void restore_fp_regs(struct thread *proc);
 extern void __runq_add_proc(struct thread *proc, int cpu_id);
 extern void terminate_host(int pid);
@@ -389,6 +390,10 @@ clone_thread(struct thread *org, unsigned long pc, unsigned long sp,
 	/* NOTE: sp is the user mode stack! */
 	ihk_mc_init_user_process(&thread->ctx, &thread->uctx, ((char *)thread) +
 				 KERNEL_STACK_NR_PAGES * PAGE_SIZE, pc, sp);
+
+	/* copy fp_regs from parent */
+	save_fp_regs(org);
+	copy_fp_regs(org, thread);
 #ifdef POSTK_DEBUG_ARCH_DEP_23 /* add arch dep. clone_process() function */
 	arch_clone_thread(org, pc, sp, thread);
 #endif /* POSTK_DEBUG_ARCH_DEP_23 */