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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bpf_prog_profiler.bpf.c (2290B)

      1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
      2// Copyright (c) 2020 Facebook
      3#include "vmlinux.h"
      4#include <bpf/bpf_helpers.h>
      5#include <bpf/bpf_tracing.h>
      6
      7/* map of perf event fds, num_cpu * num_metric entries */
      8struct {
      9	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
     10	__uint(key_size, sizeof(__u32));
     11	__uint(value_size, sizeof(int));
     12} events SEC(".maps");
     13
     14/* readings at fentry */
     15struct {
     16	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
     17	__uint(key_size, sizeof(__u32));
     18	__uint(value_size, sizeof(struct bpf_perf_event_value));
     19	__uint(max_entries, 1);
     20} fentry_readings SEC(".maps");
     21
     22/* accumulated readings */
     23struct {
     24	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
     25	__uint(key_size, sizeof(__u32));
     26	__uint(value_size, sizeof(struct bpf_perf_event_value));
     27	__uint(max_entries, 1);
     28} accum_readings SEC(".maps");
     29
     30const volatile __u32 num_cpu = 1;
     31
     32SEC("fentry/XXX")
     33int BPF_PROG(fentry_XXX)
     34{
     35	__u32 key = bpf_get_smp_processor_id();
     36	struct bpf_perf_event_value *ptr;
     37	__u32 zero = 0;
     38	long err;
     39
     40	/* look up before reading, to reduce error */
     41	ptr = bpf_map_lookup_elem(&fentry_readings, &zero);
     42	if (!ptr)
     43		return 0;
     44
     45	err = bpf_perf_event_read_value(&events, key, ptr, sizeof(*ptr));
     46	if (err)
     47		return 0;
     48
     49	return 0;
     50}
     51
     52static inline void
     53fexit_update_maps(struct bpf_perf_event_value *after)
     54{
     55	struct bpf_perf_event_value *before, diff;
     56	__u32 zero = 0;
     57
     58	before = bpf_map_lookup_elem(&fentry_readings, &zero);
     59	/* only account samples with a valid fentry_reading */
     60	if (before && before->counter) {
     61		struct bpf_perf_event_value *accum;
     62
     63		diff.counter = after->counter - before->counter;
     64		diff.enabled = after->enabled - before->enabled;
     65		diff.running = after->running - before->running;
     66
     67		accum = bpf_map_lookup_elem(&accum_readings, &zero);
     68		if (accum) {
     69			accum->counter += diff.counter;
     70			accum->enabled += diff.enabled;
     71			accum->running += diff.running;
     72		}
     73	}
     74}
     75
     76SEC("fexit/XXX")
     77int BPF_PROG(fexit_XXX)
     78{
     79	struct bpf_perf_event_value reading;
     80	__u32 cpu = bpf_get_smp_processor_id();
     81	int err;
     82
     83	/* read all events before updating the maps, to reduce error */
     84	err = bpf_perf_event_read_value(&events, cpu, &reading, sizeof(reading));
     85	if (err)
     86		return 0;
     87
     88	fexit_update_maps(&reading);
     89	return 0;
     90}
     91
     92char LICENSE[] SEC("license") = "Dual BSD/GPL";