On 02/15/2017 05:06 PM, Andrey Ryabinin wrote:
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index 10bca12..5d9dd63 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -301,10 +301,10 @@ static __always_inline void __write_once_size(volatile
> void *p, void *res, int s
> */
>
> #define __READ_ONCE(x, check)
> \
> - __builtin_choose_expr(sizeof(x) == 1, *(volatile typeof(&(x)))&(x), \
> - __builtin_choose_expr(sizeof(x) == 2, *(volatile typeof(&(x)))&(x), \
> - __builtin_choose_expr(sizeof(x) == 4, *(volatile typeof(&(x)))&(x), \
> - __builtin_choose_expr(sizeof(x) == sizeof(long), *(volatile
> typeof(&(x)))&(x), \
> + __builtin_choose_expr(sizeof(x) == 1, (typeof(x))(__u64)*(volatile __u8
> *)&(x), \
> + __builtin_choose_expr(sizeof(x) == 2, (typeof(x))(__u64)*(volatile
> __u16 *)&(x), \
> + __builtin_choose_expr(sizeof(x) == 4, (typeof(x))(__u64)*(volatile
> __u32 *)&(x), \
> + __builtin_choose_expr(sizeof(x) == 8, (typeof(x))(__u64)*(volatile
> __u64 *)&(x), \
> ({union { typeof(x) __val; char __c[1]; } __u; \
> if (check) \
> __read_once_size(&(x), __u.__c, sizeof(x)); \
Scratch this, it doesn't work:
../arch/x86/mm/gup.c:20:2: error: conversion to non-scalar type requested
return READ_ONCE(*ptep);
^
