From 05e59e5fb0064c97a1c10921ecd549f2d4a58565 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 09 Oct 2024 06:14:40 +0000
Subject: [PATCH] add REDIRECT
---
kernel/samples/bpf/tracex6_kern.c | 17 +++++++++++++++--
1 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/kernel/samples/bpf/tracex6_kern.c b/kernel/samples/bpf/tracex6_kern.c
index acad571..fd602c2 100644
--- a/kernel/samples/bpf/tracex6_kern.c
+++ b/kernel/samples/bpf/tracex6_kern.c
@@ -2,6 +2,8 @@
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
@@ -45,13 +47,24 @@
return 0;
}
-SEC("kprobe/htab_map_lookup_elem")
-int bpf_prog2(struct pt_regs *ctx)
+/*
+ * Since *_map_lookup_elem can't be expected to trigger bpf programs
+ * due to potential deadlocks (bpf_disable_instrumentation), this bpf
+ * program will be attached to bpf_map_copy_value (which is called
+ * from map_lookup_elem) and will only filter the hashtable type.
+ */
+SEC("kprobe/bpf_map_copy_value")
+int BPF_KPROBE(bpf_prog2, struct bpf_map *map)
{
u32 key = bpf_get_smp_processor_id();
struct bpf_perf_event_value *val, buf;
+ enum bpf_map_type type;
int error;
+ type = BPF_CORE_READ(map, map_type);
+ if (type != BPF_MAP_TYPE_HASH)
+ return 0;
+
error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf));
if (error)
return 0;
--
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