tools: add percpu allocator tracing to memleak

Add an ability to trace percpu allocations using the memleak tool.
Example:

./memleak.py --percpu
Attaching to kernel allocators, Ctrl+C to quit.
[14:15:46] Top 10 stacks with outstanding allocations:
	8 bytes in 1 allocations from stack
		pcpu_alloc+0x3d8 [kernel]
		pcpu_alloc+0x3d8 [kernel]
		perf_trace_event_init+0xc9 [kernel]
		perf_trace_init+0x69 [kernel]
		perf_tp_event_init+0x1b [kernel]
		perf_try_init_event+0x42 [kernel]
		perf_event_alloc+0x620 [kernel]
		__do_sys_perf_event_open+0x188 [kernel]
		do_syscall_64+0x48 [kernel]
		entry_SYSCALL_64_after_hwframe+0x44 [kernel]
	16 bytes in 1 allocations from stack
		pcpu_alloc+0x3d8 [kernel]
		pcpu_alloc+0x3d8 [kernel]
		bpf_prog_alloc+0x33 [kernel]
		bpf_prog_load+0xf5 [kernel]
		perf_event_for_each_child+0x34 [kernel]
		_perf_ioctl+0x1d7 [kernel]
		alloc_file_pseudo+0xa7 [kernel]
		__do_sys_bpf+0x953 [kernel]
		perf_ioctl+0x40 [kernel]
		do_vfs_ioctl+0xa5 [kernel]
		do_syscall_64+0x48 [kernel]
		entry_SYSCALL_64_after_hwframe+0x44 [kernel]

tools/memleak.py

@@ -100,6 +100,8 @@ def run_command_get_pid(command):
  help="attach to allocator functions in the specified object")
 parser.add_argument("--ebpf", action="store_true",
  help=argparse.SUPPRESS)
+parser.add_argument("--percpu", default=False, action="store_true",
+ help="trace percpu allocations")
 
 args = parser.parse_args()
 
@@ -365,8 +367,23 @@ def run_command_get_pid(command):
 }
 """
 
+bpf_source_percpu = """
+
+TRACEPOINT_PROBE(percpu, percpu_alloc_percpu) {
+ gen_alloc_enter((struct pt_regs *)args, args->size);
+ return gen_alloc_exit2((struct pt_regs *)args, (size_t)args->ptr);
+}
+
+TRACEPOINT_PROBE(percpu, percpu_free_percpu) {
+ return gen_free_enter((struct pt_regs *)args, (void *)args->ptr);
+}
+"""
+
 if kernel_trace:
- bpf_source += bpf_source_kernel
+ if args.percpu:
+ bpf_source += bpf_source_percpu
+ else:
+ bpf_source += bpf_source_kernel
 
 bpf_source = bpf_source.replace("SHOULD_PRINT", "1" if trace_all else "0")
 bpf_source = bpf_source.replace("SAMPLE_EVERY_N", str(sample_every_n))