diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index 9585c81..ce0b2b4 100644
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -269,14 +269,19 @@
 
 long do_syscall_trace_enter(struct pt_regs *regs)
 {
-	long ret = 0;
-
 	/* Do the secure computing check first. */
 	secure_computing_strict(regs->gr[20]);
 
 	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
-	    tracehook_report_syscall_entry(regs))
-		ret = -1L;
+	    tracehook_report_syscall_entry(regs)) {
+		/*
+		 * Tracing decided this syscall should not happen or the
+		 * debugger stored an invalid system call number. Skip
+		 * the system call and the system call restart handling.
+		 */
+		regs->gr[20] = -1UL;
+		goto out;
+	}
 
 #ifdef CONFIG_64BIT
 	if (!is_compat_task())
@@ -290,7 +295,8 @@
 			regs->gr[24] & 0xffffffff,
 			regs->gr[23] & 0xffffffff);
 
-	return ret ? : regs->gr[20];
+out:
+	return regs->gr[20];
 }
 
 void do_syscall_trace_exit(struct pt_regs *regs)
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 3fbd725..fbafa0d 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -343,7 +343,7 @@
 #endif
 
 	comiclr,>>=	__NR_Linux_syscalls, %r20, %r0
-	b,n	.Lsyscall_nosys
+	b,n	.Ltracesys_nosys
 
 	LDREGX  %r20(%r19), %r19
 
@@ -359,6 +359,9 @@
 	be      0(%sr7,%r19)
 	ldo	R%tracesys_exit(%r2),%r2
 
+.Ltracesys_nosys:
+	ldo	-ENOSYS(%r0),%r28		/* set errno */
+
 	/* Do *not* call this function on the gateway page, because it
 	makes a direct call to syscall_trace. */