Re: [PATCH 2/5] arm64: perf: Implement correct cap_user_time

[kbuild test robot <lkp@intel.com>]

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Hi Peter,

I love your patch! Yet something to improve:

[auto build test ERROR on tip/perf/core]
[also build test ERROR on arm64/for-next/core arm-perf/for-next/perf linus/master v5.7-rc5 next-20200512]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Peter-Zijlstra/arm64-perf-Proper-cap_user_time-support/20200512-205141
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 059c6d68cfc5f85ba3ab71d71a6de380016f7936
config: arm64-allyesconfig (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=arm64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

arch/arm64/kernel/perf_event.c: In function 'arch_perf_update_userpage':
>> arch/arm64/kernel/perf_event.c:1205:12: error: 'struct perf_event_mmap_page' has no member named 'shift'
1205 |  if (userpg->shift == 32) {
|            ^~
arch/arm64/kernel/perf_event.c:1206:9: error: 'struct perf_event_mmap_page' has no member named 'shift'
1206 |   userpg->shift = 31;
|         ^~

vim +1205 arch/arm64/kernel/perf_event.c

  1165	
  1166	void arch_perf_update_userpage(struct perf_event *event,
  1167				       struct perf_event_mmap_page *userpg, u64 now)
  1168	{
  1169		struct clock_read_data *rd;
  1170		unsigned int seq;
  1171	
  1172		/*
  1173		 * Internal timekeeping for enabled/running/stopped times
  1174		 * is always computed with the sched_clock.
  1175		 */
  1176		userpg->cap_user_time = 1;
  1177		userpg->cap_user_time_zero = 1;
  1178	
  1179		do {
  1180			rd = sched_clock_read_begin(&seq);
  1181	
  1182			userpg->time_mult = rd->mult;
  1183			userpg->time_shift = rd->shift;
  1184			userpg->time_zero = rd->epoch_ns;
  1185	
  1186			/*
  1187			 * This isn't strictly correct, the ARM64 counter can be
  1188			 * 'short' and then we get funnies when it wraps. The correct
  1189			 * thing would be to extend the perf ABI with a cycle and mask
  1190			 * value, but because wrapping on ARM64 is very rare in
  1191			 * practise this 'works'.
  1192			 */
  1193			userpg->time_zero -= (rd->epoch_cyc * rd->mult) >> rd->shift;
  1194	
  1195		} while (sched_clock_read_retry(seq));
  1196	
  1197		userpg->time_offset = userpg->time_zero - now;
  1198	
  1199		/*
  1200		 * time_shift is not expected to be greater than 31 due to
  1201		 * the original published conversion algorithm shifting a
  1202		 * 32-bit value (now specifies a 64-bit value) - refer
  1203		 * perf_event_mmap_page documentation in perf_event.h.
  1204		 */
> 1205		if (userpg->shift == 32) {
  1206			userpg->shift = 31;
  1207			userpg->time_mult >>= 1;
  1208		}
  1209	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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