Hi Thomas, On 9 okt. 2015, at 11:06, Thomas Gleixner <t...@linutronix.de> wrote: On Mon, 5 Oct 2015, Jaccon Bastiaansen wrote: >> We did some tests with different compilers, kernel versions and kernel >> configs, with the following results:
> You cannot use an explicit 32bit read. We need an access which handles the > fault gracefully. The reason for the explicit read suggestion is to avoid the _builtin_constant_p() in __copy_from_user_nocheck(). The GCC manual says that there may be situations where it returns 0 even though the argument is a constant. Although none of the compiler/kernel combinations we have tried showed this happening, we think it is probably better to be safe than sorry. With kind regards, Hans Zuidam -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
