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 <[email protected]>
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(&kvm_arm_pmu_available);
60
61 return perf_register_guest_info_callbacks(&kvm_guest_cbs);
62 }
63
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
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 <[email protected]>
>
> 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(&kvm_arm_pmu_available);
> 60
> 61 return perf_register_guest_info_callbacks(&kvm_guest_cbs);
> 62 }
> 63
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/[email protected]
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
On Tue, 13 Apr 2021 21:00:57 +0100,
Nathan Chancellor <[email protected]> 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.
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 <[email protected]>
>>
>> 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(&kvm_arm_pmu_available);
>> 60
>> 61 return perf_register_guest_info_callbacks(&kvm_guest_cbs);
>> 62 }
>> 63
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/[email protected]
> 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