linux-kernel - Re: [PATCH v5 1/7] bits: split the definition of the asm and non-asm GENMASK()

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Message-ID: <fao7tp2y66f7nuep4nl6kz5zenfpzswp3hwqiw325uitgu6u6u@7dipwr3vjui7>
Date: Thu, 6 Mar 2025 08:34:23 -0600
From: Lucas De Marchi <lucas.demarchi@...el.com>
To: <mailhol.vincent@...adoo.fr>
CC: Yury Norov <yury.norov@...il.com>, Rasmus Villemoes
	<linux@...musvillemoes.dk>, Jani Nikula <jani.nikula@...ux.intel.com>,
	"Joonas Lahtinen" <joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi
	<rodrigo.vivi@...el.com>, Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie
	<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Andrew Morton
	<akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
	<intel-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>, "Andi
 Shyti" <andi.shyti@...ux.intel.com>, David Laight <David.Laight@...lab.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Andy Shevchenko
	<andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v5 1/7] bits: split the definition of the asm and non-asm
 GENMASK()

On Thu, Mar 06, 2025 at 08:29:52PM +0900, Vincent Mailhol via B4 Relay wrote:
>From: Vincent Mailhol <mailhol.vincent@...adoo.fr>
>
>In an upcoming change, GENMASK() and its friends will indirectly
>depend on sizeof() which is not available in asm.
>
>Instead of adding further complexity to __GENMASK() to make it work
>for both asm and non asm, just split the definition of the two
>variants.
>
>Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
>---
>Changelog:
>
>  v4 -> v5:
>
>    - Use tab indentations instead of single space to separate the
>      macro name from its body.
>
>  v3 -> v4:
>
>    - New patch in the series
>---
> include/linux/bits.h | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
>diff --git a/include/linux/bits.h b/include/linux/bits.h
>index 14fd0ca9a6cd17339dd2f69e449558312a8a001b..4819cbe7bd48fbae796fc6005c9f92b1c93a034c 100644
>--- a/include/linux/bits.h
>+++ b/include/linux/bits.h
>@@ -19,23 +19,17 @@
>  * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
>  */
> #if !defined(__ASSEMBLY__)
>+
> #include <linux/build_bug.h>
> #include <linux/compiler.h>
>+
> #define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))
>-#else
>-/*
>- * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
>- * disable the input check if that is the case.
>- */

it seems we now have 1 inconsistency that we comment why
GENMASK_U128() is not available in asm, but we don't comment why
GENMASK_INPUT_CHECK() is not available there. Maybe move this comment on
top of GENMASK_INPUT_CHECK().

Anyway,

	Reviewed-by: Lucas De Marchi <lucas.demarchi@...el.com>

thanks for picking up this series.

Lucas De Marchi

>-#define GENMASK_INPUT_CHECK(h, l) 0
>-#endif
>
> #define GENMASK(h, l) \
> 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
> #define GENMASK_ULL(h, l) \
> 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
>
>-#if !defined(__ASSEMBLY__)
> /*
>  * Missing asm support
>  *
>@@ -48,6 +42,12 @@
>  */
> #define GENMASK_U128(h, l) \
> 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l))
>-#endif
>+
>+#else /* defined(__ASSEMBLY__) */
>+
>+#define GENMASK(h, l)		__GENMASK(h, l)
>+#define GENMASK_ULL(h, l)	__GENMASK_ULL(h, l)
>+
>+#endif /* !defined(__ASSEMBLY__) */
>
> #endif	/* __LINUX_BITS_H */
>
>-- 
>2.45.3
>
>