linux/samples/bpf/xdp_sample_pkts_kern.c
Daniel T. Lee 321f632450 samples: bpf: Refactor XDP kern program maps with BTF-defined map
Most of the samples were converted to use the new BTF-defined MAP as
they moved to libbpf, but some of the samples were missing.

Instead of using the previous BPF MAP definition, this commit refactors
xdp_monitor and xdp_sample_pkts_kern MAP definition with the new
BTF-defined MAP format.

Also, this commit removes the max_entries attribute at PERF_EVENT_ARRAY
map type. The libbpf's bpf_object__create_map() will automatically
set max_entries to the maximum configured number of CPUs on the host.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201010181734.1109-4-danieltimlee@gmail.com
2020-10-11 12:14:36 -07:00

58 lines
1.5 KiB
C

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