On Tue, Jan 13, 2015 at 02:39:05PM -0500, Chris Metcalf wrote:
> Use x86's __inttype macro instead of using the typeof(x-x) trick to
> generate a suitable integer size type. This avoids a sparse warning
> when examining the x-x type with a bitwise type.
>
> Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Reviewed-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> arch/tile/include/asm/uaccess.h | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/arch/tile/include/asm/uaccess.h b/arch/tile/include/asm/uaccess.h
> index b6cde3209b96..b81b24a8489b 100644
> --- a/arch/tile/include/asm/uaccess.h
> +++ b/arch/tile/include/asm/uaccess.h
> @@ -114,14 +114,14 @@ struct exception_table_entry {
> extern int fixup_exception(struct pt_regs *regs);
>
> /*
> + * This is a type: either unsigned long, if the argument fits into
> + * that type, or otherwise unsigned long long.
> + */
> +#define __inttype(x) \
> + __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
> +
> +/*
> * Support macros for __get_user().
> - *
> - * Implementation note: The "case 8" logic of casting to the type of
> - * the result of subtracting the value from itself is basically a way
> - * of keeping all integer types the same, but casting any pointers to
> - * ptrdiff_t, i.e. also an integer type. This way there are no
> - * questionable casts seen by the compiler on an ILP32 platform.
> - *
> * Note that __get_user() and __put_user() assume proper alignment.
> */
>
> @@ -178,7 +178,7 @@ extern int fixup_exception(struct pt_regs *regs);
> "9:" \
> : "=r" (ret), "=r" (__a), "=&r" (__b) \
> : "r" (ptr), "i" (-EFAULT)); \
> - (x) = (__typeof(x))(__typeof((x)-(x))) \
> + (x) = (__force __typeof(x))(__inttype(x)) \
> (((u64)__hi32(__a, __b) << 32) | \
> __lo32(__a, __b)); \
> })
> @@ -246,7 +246,7 @@ extern int __get_user_bad(void)
> #define __put_user_4(x, ptr, ret) __put_user_asm(sw, x, ptr, ret)
> #define __put_user_8(x, ptr, ret) \
> ({ \
> - u64 __x = (__typeof((x)-(x)))(x); \
> + u64 __x = (__force __inttype(x))(x); \
> int __lo = (int) __x, __hi = (int) (__x >> 32); \
> asm volatile("1: { sw %1, %2; addi %0, %1, 4 }\n" \
> "2: { sw %0, %3; movei %0, 0 }\n" \
> --
> 2.1.2
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