1 files changed, 86 insertions, 0 deletions
diff --git a/samples/bpf/tracex2_kern.c b/samples/bpf/tracex2_kern.c
new file mode 100644
index 000000000..19ec1cfc4
--- /dev/null
+++ b/samples/bpf/tracex2_kern.c
@@ -0,0 +1,86 @@
+/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") my_map = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(long),
+	.value_size = sizeof(long),
+	.max_entries = 1024,
+};
+
+/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
+ * example will no longer be meaningful
+ */
+SEC("kprobe/kfree_skb")
+int bpf_prog2(struct pt_regs *ctx)
+{
+	long loc = 0;
+	long init_val = 1;
+	long *value;
+
+	/* x64 specific: read ip of kfree_skb caller.
+	 * non-portable version of __builtin_return_address(0)
+	 */
+	bpf_probe_read(&loc, sizeof(loc), (void *)ctx->sp);
+
+	value = bpf_map_lookup_elem(&my_map, &loc);
+	if (value)
+		*value += 1;
+	else
+		bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
+	return 0;
+}
+
+static unsigned int log2(unsigned int v)
+{
+	unsigned int r;
+	unsigned int shift;
+
+	r = (v > 0xFFFF) << 4; v >>= r;
+	shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
+	shift = (v > 0xF) << 2; v >>= shift; r |= shift;
+	shift = (v > 0x3) << 1; v >>= shift; r |= shift;
+	r |= (v >> 1);
+	return r;
+}
+
+static unsigned int log2l(unsigned long v)
+{
+	unsigned int hi = v >> 32;
+	if (hi)
+		return log2(hi) + 32;
+	else
+		return log2(v);
+}
+
+struct bpf_map_def SEC("maps") my_hist_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(long),
+	.max_entries = 64,
+};
+
+SEC("kprobe/sys_write")
+int bpf_prog3(struct pt_regs *ctx)
+{
+	long write_size = ctx->dx; /* arg3 */
+	long init_val = 1;
+	long *value;
+	u32 index = log2l(write_size);
+
+	value = bpf_map_lookup_elem(&my_hist_map, &index);
+	if (value)
+		__sync_fetch_and_add(value, 1);
+	return 0;
+}
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;