[PATCH v2 0/7] Don't use BIT() macro in UAPI headers

From: Joe Richey <joerichey94@gmail.com>
To: trivial@kernel.org
Cc: Joe Richey <joerichey@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Zhangfei Gao <zhangfei.gao@linaro.org>,
	Zhou Wang <wangzhou1@hisilicon.com>,
	Andy Whitcroft <apw@canonical.com>, Joe Perches <joe@perches.com>,
	Dwaipayan Ray <dwaipayanray1@gmail.com>,
	Lukas Bulwahn <lukas.bulwahn@gmail.com>,
	Andi Kleen <ak@linux.intel.com>,
	"Chang S. Bae" <chang.seok.bae@intel.com>,
	Sasha Levin <sashal@kernel.org>, Peter Xu <peterx@redhat.com>,
	Lei Cao <lei.cao@stratus.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Kenneth Lee <liguozhu@hisilicon.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Hans Verkuil <hverkuil-cisco@xs4all.nl>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org, linux-accelerators@lists.ozlabs.org
Subject: [PATCH v2 0/7] Don't use BIT() macro in UAPI headers
Date: Fri, 21 May 2021 01:58:41 -0700	[thread overview]
Message-ID: <20210521085849.37676-1-joerichey94@gmail.com> (raw)
In-Reply-To: <20210520104343.317119-1-joerichey94@gmail.com>

From: Joe Richey <joerichey@google.com>

The BIT(n) macro is used in the kernel as an alias for (1 << n).
However, it is not defined in the UAPI headers, they should instead use
the _BITUL(n) macro. This patch chages all existing usages in UAPI
headers and updates ./scripts/checkpatch.pl to properly reccomend the
correct macro depending on context.

Running the below commands shows no more incorrect macro usages:
    rg "BIT\(" **/uapi/**
    rg "BIT_ULL\(" **/uapi/**

Tested by building a basic kernel. Changes are trivial.

I encountered this issue when compiling the following program:
    #include <sys/auxv.h>
    #include <asm/hwcap2.h>
    // Detect if FSGSBASE instructions are enabled
    int main() {
        unsigned long val = getauxval(AT_HWCAP2);
        return !(val & HWCAP2_FSGSBASE);
    }

Resulting in the following likner error:
    /usr/bin/ld: /tmp/cceFpAdR.o: in function `main':
    gs.c:(.text+0x21): undefined reference to `BIT'

Changes from V1 to V2:
  - Use _BITUL() macro instead of open-coding
  - Fixup HWCAP2_RING3MWAIT as well
  - Shorten commits and added "Fixes" per reviewer comments
  - checkpatch: Broaden UAPI regex
  - checkpatch: Reccomend _BITULL()/_BITUL() for UAPI headers

Joe Richey (7):
  x86/elf: Use _BITUL() macro in UAPI headers
  KVM: X86: Use _BITUL() macro in UAPI headers
  drivers: firmware: psci:  Use _BITUL() macro in UAPI headers
  uacce: Use _BITUL() macro in UAPI headers
  media: vicodec: Use _BITUL() macro in UAPI headers
  tools headers UAPI: Sync pkt_sched.h with the kernel sources
  checkpatch: suggest _BITULL() and _BITUL() for UAPI headers

 arch/x86/include/uapi/asm/hwcap2.h   |   6 +-
 include/uapi/linux/kvm.h             |   5 +-
 include/uapi/linux/psci.h            |   4 +-
 include/uapi/linux/v4l2-controls.h   |  23 ++---
 include/uapi/misc/uacce/uacce.h      |   3 +-
 scripts/checkpatch.pl                |  16 ++--
 tools/include/uapi/linux/kvm.h       |   5 +-
 tools/include/uapi/linux/pkt_sched.h | 122 ++++++++++++++++++++++++---
 8 files changed, 148 insertions(+), 36 deletions(-)

-- 
2.31.1