On Tuesday 03 November 2015 02:30:42 Yury Norov wrote:

From: Andrew Pinski <redacted>

Add a separate syscall-table for ILP32, which dispatches either to native
LP64 system call implementation or to compat-syscalls, as appropriate.

The uapi/asm-generic/unistd.h already contains a list of compat syscalls
that should work by default, I think it would be better to use that
list and override only the ones that differ between normal compat
mode and the new mode, e.g. when you require a wrapper or want to
use the native syscall entry.

+/* We need to make sure the pointer gets copied correctly. */
+asmlinkage long ilp32_sys_mq_notify(mqd_t mqdes, const struct sigevent __user *u_notification)
+{
+	struct sigevent __user *p = NULL;
+	if (u_notification) {
+		struct sigevent n;
+		p = compat_alloc_user_space(sizeof(*p));
+		if (copy_from_user(&n, u_notification, sizeof(*p)))
+			return -EFAULT;
+		if (n.sigev_notify == SIGEV_THREAD)
+			n.sigev_value.sival_ptr = compat_ptr((uintptr_t)n.sigev_value.sival_ptr);
+		if (copy_to_user(p, &n, sizeof(*p)))
+			return -EFAULT;
+	}
+	return sys_mq_notify(mqdes, p);
+}

Could this be avoided by defining sigval_t in a way that is
compatible?

+/* sigevent contains sigval_t which is now 64bit always
+   but need special handling due to padding for SIGEV_THREAD.  */
+#define sys_mq_notify		ilp32_sys_mq_notify
+
+/* sigaltstack needs some special handling as the
+   padding for stack_t might not be non-zero. */
+long ilp32_sys_sigaltstack(const stack_t __user *uss_ptr,
+			   stack_t __user *uoss_ptr)

asmlinkage?

	Arnd