Files
linux/arch/arm64/include/uapi/asm/bitsperlong.h
Thomas Weißschuh 9a6d3ff10f arm64: uapi: Provide correct __BITS_PER_LONG for the compat vDSO
The generic vDSO library uses the UAPI headers. On arm64 __BITS_PER_LONG is
always '64' even when used from the compat vDSO. In that case __GENMASK()
does an illegal bitshift, invoking undefined behaviour.

Change __BITS_PER_LONG to also work when used from the comapt vDSO.
To not confuse real userspace, only do this when building the kernel.

Reported-by: John Stultz <jstultz@google.com>
Closes: https://lore.kernel.org/lkml/CANDhNCqvKOc9JgphQwr0eDyJiyG4oLFS9R8rSFvU0fpurrJFDg@mail.gmail.com/
Fixes: cd3557a761 ("vdso/gettimeofday: Add support for auxiliary clocks")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/20250821-vdso-arm64-compat-bitsperlong-v1-1-700bcabe7732@linutronix.de
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2025-09-03 12:07:23 +01:00

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C

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM_BITSPERLONG_H
#define __ASM_BITSPERLONG_H
#if defined(__KERNEL__) && !defined(__aarch64__)
/* Used by the compat vDSO */
#define __BITS_PER_LONG 32
#else
#define __BITS_PER_LONG 64
#endif
#include <asm-generic/bitsperlong.h>
#endif /* __ASM_BITSPERLONG_H */