libbpf-tools/stackcount: Add libbpf-based stackcount tool

libbpf-tools/.gitignore

@@ -54,6 +54,7 @@
 /slabratetop
 /softirqs
 /solisten
+/stackcount
 /statsnoop
 /syncsnoop
 /syscount

libbpf-tools/Makefile

@@ -80,6 +80,7 @@ APPS = \
 	slabratetop \
 	softirqs \
 	solisten \
+	stackcount \
 	statsnoop \
 	syncsnoop \
 	syscount \

libbpf-tools/stackcount.bpf.c

@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2025, Realtek
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "stackcount.h"
+#include "core_fixes.bpf.h"
+
+#define MAX_ENTRIES 10240
+
+const volatile int target_pid = 0;
+const volatile int target_cpu = -1;
+const volatile bool kernel_stacks_only = false;
+const volatile bool user_stacks_only = false;
+const volatile bool per_pid = false;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, MAX_ENTRIES);
+	__type(key, struct key_t);
+	__type(value, u64);
+} counts SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__type(key, u32);
+} stack_traces SEC(".maps");
+
+static int trace_count(void *ctx)
+{
+	if (target_cpu >= 0 && bpf_get_smp_processor_id() != (u32)target_cpu)
+		return 0;
+
+	u32 tgid = bpf_get_current_pid_tgid() >> 32;
+	if (target_pid != 0 && tgid != target_pid)
+		return 0;
+
+	struct key_t key = {};
+	s32 kern_stack_id = -1, user_stack_id = -1;
+
+	if (per_pid) {
+		key.tgid = tgid;
+		bpf_get_current_comm(&key.name, sizeof(key.name));
+	}
+
+	if (!user_stacks_only)
+		kern_stack_id = bpf_get_stackid(ctx, &stack_traces, 0);
+
+	if (!kernel_stacks_only)
+		user_stack_id = bpf_get_stackid(ctx, &stack_traces, BPF_F_USER_STACK);
+
+	key.kernel_stack_id = kern_stack_id;
+	key.user_stack_id = user_stack_id;
+
+	u64 *count;
+
+	count = bpf_map_lookup_elem(&counts, &key);
+	if (count) {
+		__sync_fetch_and_add(count, 1);
+	} else {
+		u64 init_val = 1;
+		bpf_map_update_elem(&counts, &key, &init_val, BPF_ANY);
+	}
+
+	return 0;
+}
+
+SEC("kprobe/dummy")
+int BPF_KPROBE(kprobe_prog)
+{
+	return trace_count(ctx);
+}
+
+SEC("tracepoint/dummy/dummy")
+int BPF_PROG(tp_prog)
+{
+	return trace_count(ctx);
+}
+
+SEC("uprobe/dummy")
+int BPF_KPROBE(uprobe_prog)
+{
+	return trace_count(ctx);
+}
+
+char LICENSE[] SEC("license") = "GPL";