Re: arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function 'perf_num_counters'
Hi, On 4/13/21 9:00 PM, Nathan Chancellor wrote: > On Fri, Mar 26, 2021 at 08:27:13PM +0800, kernel test robot wrote: >> Hi Marc, >> >> FYI, the error/warning still remains. >> >> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >> master >> head: db24726bfefa68c606947a86132591568a06bfb4 >> commit: 6b5b368fccd7109b052e45af8ba1464c8d140a49 KVM: arm64: Turn >> kvm_arm_support_pmu_v3() into a static key >> date: 3 weeks ago >> config: arm64-randconfig-r005-20210326 (attached as .config) >> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project >> f490a5969bd52c8a48586f134ff8f02ccbb295b3) >> reproduce (this is a W=1 build): >> wget >> https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O >> ~/bin/make.cross >> chmod +x ~/bin/make.cross >> # install arm64 cross compiling tool for clang build >> # apt-get install binutils-aarch64-linux-gnu >> # >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6b5b368fccd7109b052e45af8ba1464c8d140a49 >> git remote add linus >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >> git fetch --no-tags linus master >> git checkout 6b5b368fccd7109b052e45af8ba1464c8d140a49 >> # save the attached .config to linux build tree >> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross >> ARCH=arm64 >> >> If you fix the issue, kindly add following tag as appropriate >> Reported-by: kernel test robot >> >> All errors (new ones prefixed by >>): >> arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function 'perf_num_counters' [-Werror,-Wimplicit-function-declaration] >>if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0) >> ^ >>1 error generated. >> >> >> vim +/perf_num_counters +58 arch/arm64/kvm/perf.c >> >> 50 >> 51 int kvm_perf_init(void) >> 52 { >> 53 /* >> 54* Check if HW_PERF_EVENTS are supported by checking >> the number of >> 55* hardware performance counters. This could ensure the >> presence of >> 56* a physical PMU and CONFIG_PERF_EVENT is selected. >> 57*/ >> > 58 if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > >> 0) >> 59 static_branch_enable(_arm_pmu_available); >> 60 >> 61 return >> perf_register_guest_info_callbacks(_guest_cbs); >> 62 } >> 63 >> >> --- >> 0-DAY CI Kernel Test Service, Intel Corporation >> https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org > I just ran into this again. It is not a clang specific issue, it > reproduces quite easily with arm64 defconfig minus CONFIG_PERF_EVENTS > and gcc 10.3.0: > > arch/arm64/kvm/perf.c: In function 'kvm_perf_init': > arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function > 'perf_num_counters'; did you mean 'dec_mm_counter'? > [-Werror=implicit-function-declaration] >58 | if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0) > |^ > |dec_mm_counter > cc1: some warnings being treated as errors I was also able to reproduce it with gcc 10.2.0. I think the problem is that the perf_num_counters() declaration is guarded by CONFIG_PERF_EVENTS (in include/linux/perf_event.h), the implementation is in drivers/perf/arm_pmu.c, which depends on CONFIG_ARM_PMU, but CONFIG_ARM_PMU=y doesn't select CONFIG_PERF_EVENTS. So we end up in a situation where we have the implementation of perf_num_counters(), but no prototype (CONFIG_ARM_PMU=y, CONFIG_PERF_EVENTS is not set). Thanks, Alex > > I am not sure what the cleanest solution would be for providing a static > inline version of perf_num_counters() would be, as only arm64 actually > uses it (sh and s390 define it but it does not appear to be used) but it > is only available through CONFIG_ARM_PMU instead of just > CONFIG_PERF_EVENTS like the other two architectures mentioned above. > > Cheers, > Nathan
Re: arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function 'perf_num_counters'
On Tue, 13 Apr 2021 21:00:57 +0100, Nathan Chancellor wrote: [...] > I just ran into this again. It is not a clang specific issue, it > reproduces quite easily with arm64 defconfig minus CONFIG_PERF_EVENTS > and gcc 10.3.0: > > arch/arm64/kvm/perf.c: In function 'kvm_perf_init': > arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function > 'perf_num_counters'; did you mean 'dec_mm_counter'? > [-Werror=implicit-function-declaration] >58 | if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0) > |^ > |dec_mm_counter > cc1: some warnings being treated as errors > > I am not sure what the cleanest solution would be for providing a static > inline version of perf_num_counters() would be, as only arm64 actually > uses it (sh and s390 define it but it does not appear to be used) but it > is only available through CONFIG_ARM_PMU instead of just > CONFIG_PERF_EVENTS like the other two architectures mentioned above. As you point out, KVM/arm64 is the only user of perf_num_counters() across the whole kernel. The whole oprofile subsystem has been removed, so maybe a a bigger cleanup is in order. I'll post something shortly. Thanks, M. -- Without deviation from the norm, progress is not possible.
Re: arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function 'perf_num_counters'
On Fri, Mar 26, 2021 at 08:27:13PM +0800, kernel test robot wrote: > Hi Marc, > > FYI, the error/warning still remains. > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > master > head: db24726bfefa68c606947a86132591568a06bfb4 > commit: 6b5b368fccd7109b052e45af8ba1464c8d140a49 KVM: arm64: Turn > kvm_arm_support_pmu_v3() into a static key > date: 3 weeks ago > config: arm64-randconfig-r005-20210326 (attached as .config) > compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project > f490a5969bd52c8a48586f134ff8f02ccbb295b3) > reproduce (this is a W=1 build): > wget > https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O > ~/bin/make.cross > chmod +x ~/bin/make.cross > # install arm64 cross compiling tool for clang build > # apt-get install binutils-aarch64-linux-gnu > # > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6b5b368fccd7109b052e45af8ba1464c8d140a49 > git remote add linus > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > git fetch --no-tags linus master > git checkout 6b5b368fccd7109b052e45af8ba1464c8d140a49 > # save the attached .config to linux build tree > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot > > All errors (new ones prefixed by >>): > > >> arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function > >> 'perf_num_counters' [-Werror,-Wimplicit-function-declaration] >if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0) > ^ >1 error generated. > > > vim +/perf_num_counters +58 arch/arm64/kvm/perf.c > > 50 > 51int kvm_perf_init(void) > 52{ > 53/* > 54 * Check if HW_PERF_EVENTS are supported by checking > the number of > 55 * hardware performance counters. This could ensure the > presence of > 56 * a physical PMU and CONFIG_PERF_EVENT is selected. > 57 */ > > 58if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > > 0) > 59static_branch_enable(_arm_pmu_available); > 60 > 61return > perf_register_guest_info_callbacks(_guest_cbs); > 62} > 63 > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org I just ran into this again. It is not a clang specific issue, it reproduces quite easily with arm64 defconfig minus CONFIG_PERF_EVENTS and gcc 10.3.0: arch/arm64/kvm/perf.c: In function 'kvm_perf_init': arch/arm64/kvm/perf.c:58:36: error: implicit declaration of function 'perf_num_counters'; did you mean 'dec_mm_counter'? [-Werror=implicit-function-declaration] 58 | if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0) |^ |dec_mm_counter cc1: some warnings being treated as errors I am not sure what the cleanest solution would be for providing a static inline version of perf_num_counters() would be, as only arm64 actually uses it (sh and s390 define it but it does not appear to be used) but it is only available through CONFIG_ARM_PMU instead of just CONFIG_PERF_EVENTS like the other two architectures mentioned above. Cheers, Nathan