Hi Ravi, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: fb57b1fabcb28f358901b2df90abd2b48abc1ca8 commit: 29da4f91c0c1fbda12b8a31be0d564930208c92e [10157/10701] powerpc/watchpoint: Don't allow concurrent perf and ptrace events config: arm64-randconfig-r026-20200519 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 135b877874fae96b4372c8a3fbfaa8ff44ff86e3) reproduce: 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 git checkout 29da4f91c0c1fbda12b8a31be0d564930208c92e # 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: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): kernel/events/hw_breakpoint.c:71:12: warning: no previous prototype for function 'hw_breakpoint_weight' [-Wmissing-prototypes] __weak int hw_breakpoint_weight(struct perf_event *bp) ^ kernel/events/hw_breakpoint.c:71:8: note: declare 'static' if the function is not intended to be used outside of this translation unit __weak int hw_breakpoint_weight(struct perf_event *bp) ^ static __weak int arch_reserve_bp_slot(struct perf_event *bp) ^ kernel/events/hw_breakpoint.c:216:8: note: declare 'static' if the function is not intended to be used outside of this translation unit __weak int arch_reserve_bp_slot(struct perf_event *bp) ^ static __weak void arch_release_bp_slot(struct perf_event *bp) ^ kernel/events/hw_breakpoint.c:221:8: note: declare 'static' if the function is not intended to be used outside of this translation unit __weak void arch_release_bp_slot(struct perf_event *bp) ^ static kernel/events/hw_breakpoint.c:228:13: warning: no previous prototype for function 'arch_unregister_hw_breakpoint' [-Wmissing-prototypes] __weak void arch_unregister_hw_breakpoint(struct perf_event *bp) ^ kernel/events/hw_breakpoint.c:228:8: note: declare 'static' if the function is not intended to be used outside of this translation unit __weak void arch_unregister_hw_breakpoint(struct perf_event *bp) ^ static 4 warnings generated. vim +/arch_reserve_bp_slot +216 kernel/events/hw_breakpoint.c 70 72 { 73 return 1; 74 } 75 76 static inline enum bp_type_idx find_slot_idx(u64 bp_type) 77 { 78 if (bp_type & HW_BREAKPOINT_RW) 79 return TYPE_DATA; 80 81 return TYPE_INST; 82 } 83 84 /* 85 * Report the maximum number of pinned breakpoints a task 86 * have in this cpu 87 */ 88 static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) 89 { 90 unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned; 91 int i; 92 93 for (i = nr_slots[type] - 1; i >= 0; i--) { 94 if (tsk_pinned[i] > 0) 95 return i + 1; 96 } 97 98 return 0; 99 } 100 101 /* 102 * Count the number of breakpoints of the same type and same task. 103 * The given event must be not on the list. 104 */ 105 static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type) 106 { 107 struct task_struct *tsk = bp->hw.target; 108 struct perf_event *iter; 109 int count = 0; 110 111 list_for_each_entry(iter, &bp_task_head, hw.bp_list) { 112 if (iter->hw.target == tsk && 113 find_slot_idx(iter->attr.bp_type) == type && 114 (iter->cpu < 0 || cpu == iter->cpu)) 115 count += hw_breakpoint_weight(iter); 116 } 117 118 return count; 119 } 120 121 static const struct cpumask *cpumask_of_bp(struct perf_event *bp) 122 { 123 if (bp->cpu >= 0) 124 return cpumask_of(bp->cpu); 125 return cpu_possible_mask; 126 } 127 128 /* 129 * Report the number of pinned/un-pinned breakpoints we have in 130 * a given cpu (cpu > -1) or in all of them (cpu = -1). 131 */ 132 static void 133 fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp, 134 enum bp_type_idx type) 135 { 136 const struct cpumask *cpumask = cpumask_of_bp(bp); 137 int cpu; 138 139 for_each_cpu(cpu, cpumask) { 140 struct bp_cpuinfo *info = get_bp_info(cpu, type); 141 int nr; 142 143 nr = info->cpu_pinned; 144 if (!bp->hw.target) 145 nr += max_task_bp_pinned(cpu, type); 146 else 147 nr += task_bp_pinned(cpu, bp, type); 148 149 if (nr > slots->pinned) 150 slots->pinned = nr; 151 152 nr = info->flexible; 153 if (nr > slots->flexible) 154 slots->flexible = nr; 155 } 156 } 157 158 /* 159 * For now, continue to consider flexible as pinned, until we can 160 * ensure no flexible event can ever be scheduled before a pinned event 161 * in a same cpu. 162 */ 163 static void 164 fetch_this_slot(struct bp_busy_slots *slots, int weight) 165 { 166 slots->pinned += weight; 167 } 168 169 /* 170 * Add a pinned breakpoint for the given task in our constraint table 171 */ 172 static void toggle_bp_task_slot(struct perf_event *bp, int cpu, 173 enum bp_type_idx type, int weight) 174 { 175 unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned; 176 int old_idx, new_idx; 177 178 old_idx = task_bp_pinned(cpu, bp, type) - 1; 179 new_idx = old_idx + weight; 180 181 if (old_idx >= 0) 182 tsk_pinned[old_idx]--; 183 if (new_idx >= 0) 184 tsk_pinned[new_idx]++; 185 } 186 187 /* 188 * Add/remove the given breakpoint in our constraint table 189 */ 190 static void 191 toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, 192 int weight) 193 { 194 const struct cpumask *cpumask = cpumask_of_bp(bp); 195 int cpu; 196 197 if (!enable) 198 weight = -weight; 199 200 /* Pinned counter cpu profiling */ 201 if (!bp->hw.target) { 202 get_bp_info(bp->cpu, type)->cpu_pinned += weight; 203 return; 204 } 205 206 /* Pinned counter task profiling */ 207 for_each_cpu(cpu, cpumask) 208 toggle_bp_task_slot(bp, cpu, type, weight); 209 210 if (enable) 211 list_add_tail(&bp->hw.bp_list, &bp_task_head); 212 else 213 list_del(&bp->hw.bp_list); 214 } 215 217 { 218 return 0; 219 } 220 222 { 223 } 224 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org