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From: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
To: Yury Norov <yury.norov@gmail.com>,
	 I Hsin Cheng <richard120310@gmail.com>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	"Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
Subject: [PATCH] uapi: bitops: use UAPI-safe variant of BITS_PER_LONG again
Date: Fri, 06 Jun 2025 10:23:57 +0200	[thread overview]
Message-ID: <20250606-uapi-genmask-v1-1-e05cdc2e14c5@linutronix.de> (raw)

Commit 1e7933a575ed ("uapi: Revert "bitops: avoid integer overflow in GENMASK(_ULL)"")
did not take in account that the usage of BITS_PER_LONG in __GENMASK() was
changed to __BITS_PER_LONG for UAPI-safety in
commit 3c7a8e190bc5 ("uapi: introduce uapi-friendly macros for GENMASK").
BITS_PER_LONG can not be used in UAPI headers as it derives from the kernel
configuration and not from the current compiler invocation.
When building compat userspace code or a compat vDSO its value will be
incorrect.

Switch back to __BITS_PER_LONG.

Fixes: 1e7933a575ed ("uapi: Revert "bitops: avoid integer overflow in GENMASK(_ULL)"")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 include/uapi/linux/bits.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bits.h b/include/uapi/linux/bits.h
index 682b406e10679dc8baa188830ab0811e7e3e13e3..a04afef9efca42f062e142fcb33f5d267512b1e5 100644
--- a/include/uapi/linux/bits.h
+++ b/include/uapi/linux/bits.h
@@ -4,9 +4,9 @@
 #ifndef _UAPI_LINUX_BITS_H
 #define _UAPI_LINUX_BITS_H
 
-#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (BITS_PER_LONG - 1 - (h))))
+#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (__BITS_PER_LONG - 1 - (h))))
 
-#define __GENMASK_ULL(h, l) (((~_ULL(0)) << (l)) & (~_ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
+#define __GENMASK_ULL(h, l) (((~_ULL(0)) << (l)) & (~_ULL(0) >> (__BITS_PER_LONG_LONG - 1 - (h))))
 
 #define __GENMASK_U128(h, l) \
 	((_BIT128((h)) << 1) - (_BIT128(l)))

---
base-commit: e271ed52b344ac02d4581286961d0c40acc54c03
change-id: 20250606-uapi-genmask-e07667de69ec

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@linutronix.de>


             reply	other threads:[~2025-06-06  8:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-06  8:23 Thomas Weißschuh [this message]
2025-06-06 14:20 ` Yury Norov
2025-06-06 14:32   ` Thomas Weißschuh
2025-06-09  7:47     ` I Hsin Cheng
2025-06-10  7:19       ` Thomas Weißschuh

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