Subject: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it

From: [email-masked] (Arnd Bergmann)
Date: Thu, 05 Nov 2015 14:50:10 +0100

On Tuesday 03 November 2015 02:30:42 Yury Norov wrote:
> From: Andrew Pinski <[email-masked]>
> 
> 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