cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

lathist_kern.c (2142B)

      1/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
      2 * Copyright (c) 2015 BMW Car IT GmbH
      3 *
      4 * This program is free software; you can redistribute it and/or
      5 * modify it under the terms of version 2 of the GNU General Public
      6 * License as published by the Free Software Foundation.
      7 */
      8#include <linux/version.h>
      9#include <linux/ptrace.h>
     10#include <uapi/linux/bpf.h>
     11#include <bpf/bpf_helpers.h>
     12
     13#define MAX_ENTRIES	20
     14#define MAX_CPU		4
     15
     16/* We need to stick to static allocated memory (an array instead of
     17 * hash table) because managing dynamic memory from the
     18 * trace_preempt_[on|off] tracepoints hooks is not supported.
     19 */
     20
     21struct {
     22	__uint(type, BPF_MAP_TYPE_ARRAY);
     23	__type(key, int);
     24	__type(value, u64);
     25	__uint(max_entries, MAX_CPU);
     26} my_map SEC(".maps");
     27
     28SEC("kprobe/trace_preempt_off")
     29int bpf_prog1(struct pt_regs *ctx)
     30{
     31	int cpu = bpf_get_smp_processor_id();
     32	u64 *ts = bpf_map_lookup_elem(&my_map, &cpu);
     33
     34	if (ts)
     35		*ts = bpf_ktime_get_ns();
     36
     37	return 0;
     38}
     39
     40static unsigned int log2(unsigned int v)
     41{
     42	unsigned int r;
     43	unsigned int shift;
     44
     45	r = (v > 0xFFFF) << 4; v >>= r;
     46	shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
     47	shift = (v > 0xF) << 2; v >>= shift; r |= shift;
     48	shift = (v > 0x3) << 1; v >>= shift; r |= shift;
     49	r |= (v >> 1);
     50
     51	return r;
     52}
     53
     54static unsigned int log2l(unsigned long v)
     55{
     56	unsigned int hi = v >> 32;
     57
     58	if (hi)
     59		return log2(hi) + 32;
     60	else
     61		return log2(v);
     62}
     63
     64struct {
     65	__uint(type, BPF_MAP_TYPE_ARRAY);
     66	__type(key, int);
     67	__type(value, long);
     68	__uint(max_entries, MAX_CPU * MAX_ENTRIES);
     69} my_lat SEC(".maps");
     70
     71SEC("kprobe/trace_preempt_on")
     72int bpf_prog2(struct pt_regs *ctx)
     73{
     74	u64 *ts, cur_ts, delta;
     75	int key, cpu;
     76	long *val;
     77
     78	cpu = bpf_get_smp_processor_id();
     79	ts = bpf_map_lookup_elem(&my_map, &cpu);
     80	if (!ts)
     81		return 0;
     82
     83	cur_ts = bpf_ktime_get_ns();
     84	delta = log2l(cur_ts - *ts);
     85
     86	if (delta > MAX_ENTRIES - 1)
     87		delta = MAX_ENTRIES - 1;
     88
     89	key = cpu * MAX_ENTRIES + delta;
     90	val = bpf_map_lookup_elem(&my_lat, &key);
     91	if (val)
     92		__sync_fetch_and_add((long *)val, 1);
     93
     94	return 0;
     95
     96}
     97
     98char _license[] SEC("license") = "GPL";
     99u32 _version SEC("version") = LINUX_VERSION_CODE;