Messages in this thread | | | Subject | Re: [PATCH 0/6] Don't use BIT() macro in UAPI headers | From | Paolo Bonzini <> | Date | Thu, 20 May 2021 14:09:47 +0200 |
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On 20/05/21 12:43, Joe Richey wrote: > 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, which means that any > UAPI header files must be careful not to use it, or else the user > will get a linker error. For example, 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); > } > > Results in the following likner error: > > /usr/bin/ld: /tmp/cceFpAdR.o: in function `main': > gs.c:(.text+0x21): undefined reference to `BIT' > > This patch series changes all UAPI uses of BIT() to just be open-coded. > However, there really should be a check for this in checkpatch.pl > Currently, the script actually _encourages_ users to use the BIT macro > even if adding things to UAPI. > > Running `rg "BIT\(" **/uapi/**` shows no more usage of BIT() in any > UAPI headers. Tested by building a basic kernel. Changes are trivial. > > Joe Richey (6): > x86/elf: Don't use BIT() macro in UAPI headers > KVM: X86: Don't use BIT() macro in UAPI headers > drivers: firmware: psci: Don't use BIT() macro in UAPI headers > uacce: Don't use BIT() macro in UAPI headers > media: vicodec: Don't use BIT() macro in UAPI headers > tools headers UAPI: Sync pkt_sched.h with the kernel sources > > arch/x86/include/uapi/asm/hwcap2.h | 2 +- > include/uapi/linux/kvm.h | 4 +- > include/uapi/linux/psci.h | 2 +- > include/uapi/linux/v4l2-controls.h | 22 ++--- > include/uapi/misc/uacce/uacce.h | 2 +- > tools/include/uapi/linux/kvm.h | 4 +- > tools/include/uapi/linux/pkt_sched.h | 122 ++++++++++++++++++++++++--- > 7 files changed, 130 insertions(+), 28 deletions(-) >
Will queue the KVM one, thanks!
Paolo
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