add REDIRECT

hc

2024-10-09 05e59e5fb0064c97a1c10921ecd549f2d4a58565

 kernel/samples/bpf/tracex6_kern.c
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@@ -2,6 +2,8 @@
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 #include <linux/version.h>
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 #include <uapi/linux/bpf.h>
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 #include <bpf/bpf_helpers.h>
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+#include <bpf/bpf_tracing.h>
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+#include <bpf/bpf_core_read.h>
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 struct {
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 	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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@@ -45,13 +47,24 @@
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 	return 0;
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 }
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-SEC("kprobe/htab_map_lookup_elem")
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-int bpf_prog2(struct pt_regs *ctx)
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+/*
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+ * Since *_map_lookup_elem can't be expected to trigger bpf programs
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+ * due to potential deadlocks (bpf_disable_instrumentation), this bpf
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+ * program will be attached to bpf_map_copy_value (which is called
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+ * from map_lookup_elem) and will only filter the hashtable type.
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+ */
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+SEC("kprobe/bpf_map_copy_value")
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+int BPF_KPROBE(bpf_prog2, struct bpf_map *map)
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 {
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 	u32 key = bpf_get_smp_processor_id();
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 	struct bpf_perf_event_value *val, buf;
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+	enum bpf_map_type type;
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 	int error;
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+	type = BPF_CORE_READ(map, map_type);
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+	if (type != BPF_MAP_TYPE_HASH)
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+		return 0;
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+
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 	error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf));
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 	if (error)
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 		return 0;