fix sigreturn etc

arch/um/kernel/signal.c

@@ -97,6 +97,9 @@ void do_signal(struct pt_regs *regs)
 	struct ksignal ksig;
 	int handled_sig = 0;
 
+	if (regs->regs.gp[15] == 58)
+		return;
+
 	while (get_signal(&ksig)) {
 		handled_sig = 1;
 		/* Whee!  Actually deliver the signal.  */

arch/x86/um/nommu/entry_64.S

@@ -76,13 +76,25 @@ ENTRY(__kernel_vsyscall)
 
 	POP_REGS
 
+	cmpq	$15, (%rsp)
+	je	sigret
+
 	addq	$8, %rsp	/* skip orig_ax */
 	addq	$8, %rsp	/* skip ip */
 	addq	$8, %rsp	/* skip cs */
 	addq	$8, %rsp	/* skip flags */
 	popq	%rsp
 
 	ret
+sigret:
+	addq	$8, %rsp	/* skip orig_ax */
+	popq	%r11		/* ip */
+	addq	$8, %rsp	/* skip cs */
+	addq	$8, %rsp	/* skip flags */
+	popq	%rsp
+	//jmpq	*%r11
+	pushq	%r11
+	ret
 
 END(__kernel_vsyscall)
 

arch/x86/um/nommu/os-Linux/mcontext.c

@@ -6,10 +6,12 @@
 #include <sysdep/mcontext.h>
 #include <sysdep/syscalls.h>
 
+extern void userspace(struct uml_pt_regs *regs);
 static void userspace_sigreturn(void)
 {
 	__asm__ volatile("movq $15, %rax");
 	__asm__ volatile("call *%0" : : "r"(__kernel_vsyscall) :);
+//	__asm__ volatile("call *%0" : : "r"(userspace) :);
 }
 
 void mc_set_regs_ip_relay(mcontext_t *mc)

arch/x86/um/nommu/signal.c

@@ -11,6 +11,10 @@ int arch_setup_signal_stack_si(struct rt_sigframe __user **frame,
 {
 	int err = 0;
 
+	if (sigismember(&ksig->ka.sa.sa_mask, ksig->sig)) {
+		pr_warn("signal masked");
+		return 0;
+	}
 	/*
 	 * we need to push handler address at top of stack, as
 	 * __kernel_vsyscall, called after this returns with ret with