67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/ptrace.h>
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#include <linux/version.h>
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#include <uapi/linux/bpf.h>
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#include "bpf_helpers.h"
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#define SAMPLE_SIZE 64ul
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#define MAX_CPUS 128
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#define bpf_printk(fmt, ...) \
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({ \
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char ____fmt[] = fmt; \
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bpf_trace_printk(____fmt, sizeof(____fmt), \
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##__VA_ARGS__); \
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})
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struct bpf_map_def SEC("maps") my_map = {
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.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
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.key_size = sizeof(int),
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.value_size = sizeof(u32),
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.max_entries = MAX_CPUS,
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};
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SEC("xdp_sample")
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int xdp_sample_prog(struct xdp_md *ctx)
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{
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void *data_end = (void *)(long)ctx->data_end;
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void *data = (void *)(long)ctx->data;
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/* Metadata will be in the perf event before the packet data. */
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struct S {
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u16 cookie;
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u16 pkt_len;
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} __packed metadata;
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if (data < data_end) {
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/* The XDP perf_event_output handler will use the upper 32 bits
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* of the flags argument as a number of bytes to include of the
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* packet payload in the event data. If the size is too big, the
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* call to bpf_perf_event_output will fail and return -EFAULT.
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*
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* See bpf_xdp_event_output in net/core/filter.c.
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*
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* The BPF_F_CURRENT_CPU flag means that the event output fd
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* will be indexed by the CPU number in the event map.
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*/
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u64 flags = BPF_F_CURRENT_CPU;
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u16 sample_size;
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int ret;
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metadata.cookie = 0xdead;
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metadata.pkt_len = (u16)(data_end - data);
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sample_size = min(metadata.pkt_len, SAMPLE_SIZE);
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flags |= (u64)sample_size << 32;
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ret = bpf_perf_event_output(ctx, &my_map, flags,
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&metadata, sizeof(metadata));
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if (ret)
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bpf_printk("perf_event_output failed: %d\n", ret);
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}
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return XDP_PASS;
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}
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char _license[] SEC("license") = "GPL";
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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