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From:   Florian Weimer <fweimer@redhat.com>
To:     Richard Palethorpe <rpalethorpe@suse.com>
Cc:     x86@kernel.org, Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>, rpalethorpe@richiejp.com,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        ltp@lists.linux.it
Subject: Re: [PATCH] x86/entry/ia32: Ensure s32 is sign extended to s64
References: <20210927161955.28494-1-rpalethorpe@suse.com>
Date:   Mon, 27 Sep 2021 20:51:11 +0200
In-Reply-To: <20210927161955.28494-1-rpalethorpe@suse.com> (Richard
        Palethorpe's message of "Mon, 27 Sep 2021 17:19:55 +0100")
Message-ID: <875yuletsw.fsf@oldenburg.str.redhat.com>
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* Richard Palethorpe:

> +#define __SC_COMPAT_CAST(t, a)						\
> +	(__typeof(__builtin_choose_expr(__TYPE_IS_L(t), 0, 0U)))	\
> +	(unsigned int)a

So this casts to int (triggering sign extension) if the type on the
64-bit kernel side is long?  But not in other cases (unsigned long,
pointer)?  Just double-checking.

Thanks,
Florian