[PATCH 11/18] arm64: ilp32: share aarch32 syscall handlers

Catalin Marinas
2016-12-05T17:12:43Z

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