From mboxrd@z Thu Jan  1 00:00:00 1970
From: catalin.marinas@arm.com (Catalin Marinas)
Date: Mon, 5 Dec 2016 17:12:43 +0000
Subject: [PATCH 11/18] arm64: ilp32: share aarch32 syscall handlers
In-Reply-To: <1477081997-4770-12-git-send-email-ynorov@caviumnetworks.com>
References: <1477081997-4770-1-git-send-email-ynorov@caviumnetworks.com>
 <1477081997-4770-12-git-send-email-ynorov@caviumnetworks.com>
Message-ID: <20161205171242.GH14429@e104818-lin.cambridge.arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, Oct 21, 2016 at 11:33:10PM +0300, Yury Norov wrote:
> off_t is  passed in register pair just like in aarch32.
> In this patch corresponding aarch32 handlers are shared to
> ilp32 code.
[...]
> +/*
> + * Note: off_4k (w5) is always in units of 4K. If we can't do the
> + * requested offset because it is not page-aligned, we return -EINVAL.
> + */
> +ENTRY(compat_sys_mmap2_wrapper)
> +#if PAGE_SHIFT > 12
> +	tst	w5, #~PAGE_MASK >> 12
> +	b.ne	1f
> +	lsr	w5, w5, #PAGE_SHIFT - 12
> +#endif
> +	b	sys_mmap_pgoff
> +1:	mov	x0, #-EINVAL
> +	ret
> +ENDPROC(compat_sys_mmap2_wrapper)

For compat sys_mmap2, the pgoff argument is in multiples of 4K. This was
traditionally used for architectures where off_t is 32-bit to allow
mapping files to 2^44.

Since off_t is 64-bit with AArch64/ILP32, should we just pass the off_t
as a 64-bit value in two different registers (w5 and w6)?

-- 
Catalin