On Mon, May 14, 2018 at 3:57 PM, Geert Uytterhoeven
<ge...@linux-m68k.org> wrote:
> Revive support for 64-bit get_user(), which was disabled in commit
> d94af931af42152e ("[PATCH] m68k: clean up uaccess.h") due to a "broken"
> typeof in (then brand new) gcc-4.1.
>
> - Keep on using u64 for the temporary, as __typeof__() doesn't drop
> the const qualifier,
> - Move it into a union (like mips32 does) to get rid of the cast, as
> using get_user() to fetch a __user pointer would cause a "cast to
> pointer from integer of different size" warning otherwise.
Can't vouch for the existing asm, but the changes to it look good to
me otherwise.
>
> Signed-off-by: Geert Uytterhoeven <ge...@linux-m68k.org>
Acked-by: Martijn Coenen <m...@android.com>
> ---
> arch/m68k/include/asm/uaccess_mm.h | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/m68k/include/asm/uaccess_mm.h
> b/arch/m68k/include/asm/uaccess_mm.h
> index 75c172e909acdf18..c4cb889660aa0c35 100644
> --- a/arch/m68k/include/asm/uaccess_mm.h
> +++ b/arch/m68k/include/asm/uaccess_mm.h
> @@ -141,10 +141,12 @@ asm volatile ("\n"
> \
> case 4: \
> __get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT); \
> break; \
> -/* case 8: disabled because gcc-4.1 has a broken typeof \
> - { \
> - const void *__gu_ptr = (ptr); \
> - u64 __gu_val; \
> + case 8: { \
> + const void *__gu_ptr = (ptr); \
> + union { \
> + u64 l; \
> + __typeof__(*(ptr)) t; \
> + } __gu_val; \
> asm volatile ("\n" \
> "1: "MOVES".l (%2)+,%1\n" \
> "2: "MOVES".l (%2),%R1\n" \
> @@ -162,13 +164,13 @@ asm volatile ("\n"
> \
> " .long 1b,10b\n" \
> " .long 2b,10b\n" \
> " .previous" \
> - : "+d" (__gu_err), "=&r" (__gu_val), \
> + : "+d" (__gu_err), "=&r" (__gu_val.l), \
> "+a" (__gu_ptr) \
> : "i" (-EFAULT) \
> : "memory"); \
> - (x) = (__force typeof(*(ptr)))__gu_val; \
> + (x) = __gu_val.t; \
> break; \
> - } */ \
> + } \
> default: \
> __gu_err = __get_user_bad(); \
> break; \
> --
> 2.7.4
>
