cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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test_ringbuf.c (1611B)

      1// SPDX-License-Identifier: GPL-2.0
      2// Copyright (c) 2020 Facebook
      3
      4#include <linux/bpf.h>
      5#include <bpf/bpf_helpers.h>
      6#include "bpf_misc.h"
      7
      8char _license[] SEC("license") = "GPL";
      9
     10struct sample {
     11	int pid;
     12	int seq;
     13	long value;
     14	char comm[16];
     15};
     16
     17struct {
     18	__uint(type, BPF_MAP_TYPE_RINGBUF);
     19} ringbuf SEC(".maps");
     20
     21/* inputs */
     22int pid = 0;
     23long value = 0;
     24long flags = 0;
     25
     26/* outputs */
     27long total = 0;
     28long discarded = 0;
     29long dropped = 0;
     30
     31long avail_data = 0;
     32long ring_size = 0;
     33long cons_pos = 0;
     34long prod_pos = 0;
     35
     36/* inner state */
     37long seq = 0;
     38
     39SEC("fentry/" SYS_PREFIX "sys_getpgid")
     40int test_ringbuf(void *ctx)
     41{
     42	int cur_pid = bpf_get_current_pid_tgid() >> 32;
     43	struct sample *sample;
     44	int zero = 0;
     45
     46	if (cur_pid != pid)
     47		return 0;
     48
     49	sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
     50	if (!sample) {
     51		__sync_fetch_and_add(&dropped, 1);
     52		return 0;
     53	}
     54
     55	sample->pid = pid;
     56	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
     57	sample->value = value;
     58
     59	sample->seq = seq++;
     60	__sync_fetch_and_add(&total, 1);
     61
     62	if (sample->seq & 1) {
     63		/* copy from reserved sample to a new one... */
     64		bpf_ringbuf_output(&ringbuf, sample, sizeof(*sample), flags);
     65		/* ...and then discard reserved sample */
     66		bpf_ringbuf_discard(sample, flags);
     67		__sync_fetch_and_add(&discarded, 1);
     68	} else {
     69		bpf_ringbuf_submit(sample, flags);
     70	}
     71
     72	avail_data = bpf_ringbuf_query(&ringbuf, BPF_RB_AVAIL_DATA);
     73	ring_size = bpf_ringbuf_query(&ringbuf, BPF_RB_RING_SIZE);
     74	cons_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_CONS_POS);
     75	prod_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_PROD_POS);
     76
     77	return 0;
     78}