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

offwaketime_kern.c (3940B)


      1/* Copyright (c) 2016 Facebook
      2 *
      3 * This program is free software; you can redistribute it and/or
      4 * modify it under the terms of version 2 of the GNU General Public
      5 * License as published by the Free Software Foundation.
      6 */
      7#include <uapi/linux/bpf.h>
      8#include <uapi/linux/ptrace.h>
      9#include <uapi/linux/perf_event.h>
     10#include <linux/version.h>
     11#include <linux/sched.h>
     12#include <bpf/bpf_helpers.h>
     13#include <bpf/bpf_tracing.h>
     14
     15#define _(P)                                                                   \
     16	({                                                                     \
     17		typeof(P) val;                                                 \
     18		bpf_probe_read_kernel(&val, sizeof(val), &(P));                \
     19		val;                                                           \
     20	})
     21
     22#define MINBLOCK_US	1
     23#define MAX_ENTRIES	10000
     24
     25struct key_t {
     26	char waker[TASK_COMM_LEN];
     27	char target[TASK_COMM_LEN];
     28	u32 wret;
     29	u32 tret;
     30};
     31
     32struct {
     33	__uint(type, BPF_MAP_TYPE_HASH);
     34	__type(key, struct key_t);
     35	__type(value, u64);
     36	__uint(max_entries, MAX_ENTRIES);
     37} counts SEC(".maps");
     38
     39struct {
     40	__uint(type, BPF_MAP_TYPE_HASH);
     41	__type(key, u32);
     42	__type(value, u64);
     43	__uint(max_entries, MAX_ENTRIES);
     44} start SEC(".maps");
     45
     46struct wokeby_t {
     47	char name[TASK_COMM_LEN];
     48	u32 ret;
     49};
     50
     51struct {
     52	__uint(type, BPF_MAP_TYPE_HASH);
     53	__type(key, u32);
     54	__type(value, struct wokeby_t);
     55	__uint(max_entries, MAX_ENTRIES);
     56} wokeby SEC(".maps");
     57
     58struct {
     59	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
     60	__uint(key_size, sizeof(u32));
     61	__uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));
     62	__uint(max_entries, MAX_ENTRIES);
     63} stackmap SEC(".maps");
     64
     65#define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
     66
     67SEC("kprobe/try_to_wake_up")
     68int waker(struct pt_regs *ctx)
     69{
     70	struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
     71	struct wokeby_t woke;
     72	u32 pid;
     73
     74	pid = _(p->pid);
     75
     76	bpf_get_current_comm(&woke.name, sizeof(woke.name));
     77	woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
     78
     79	bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);
     80	return 0;
     81}
     82
     83static inline int update_counts(void *ctx, u32 pid, u64 delta)
     84{
     85	struct wokeby_t *woke;
     86	u64 zero = 0, *val;
     87	struct key_t key;
     88
     89	__builtin_memset(&key.waker, 0, sizeof(key.waker));
     90	bpf_get_current_comm(&key.target, sizeof(key.target));
     91	key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
     92	key.wret = 0;
     93
     94	woke = bpf_map_lookup_elem(&wokeby, &pid);
     95	if (woke) {
     96		key.wret = woke->ret;
     97		__builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));
     98		bpf_map_delete_elem(&wokeby, &pid);
     99	}
    100
    101	val = bpf_map_lookup_elem(&counts, &key);
    102	if (!val) {
    103		bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);
    104		val = bpf_map_lookup_elem(&counts, &key);
    105		if (!val)
    106			return 0;
    107	}
    108	(*val) += delta;
    109	return 0;
    110}
    111
    112#if 1
    113/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
    114struct sched_switch_args {
    115	unsigned long long pad;
    116	char prev_comm[TASK_COMM_LEN];
    117	int prev_pid;
    118	int prev_prio;
    119	long long prev_state;
    120	char next_comm[TASK_COMM_LEN];
    121	int next_pid;
    122	int next_prio;
    123};
    124SEC("tracepoint/sched/sched_switch")
    125int oncpu(struct sched_switch_args *ctx)
    126{
    127	/* record previous thread sleep time */
    128	u32 pid = ctx->prev_pid;
    129#else
    130SEC("kprobe/finish_task_switch")
    131int oncpu(struct pt_regs *ctx)
    132{
    133	struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
    134	/* record previous thread sleep time */
    135	u32 pid = _(p->pid);
    136#endif
    137	u64 delta, ts, *tsp;
    138
    139	ts = bpf_ktime_get_ns();
    140	bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);
    141
    142	/* calculate current thread's delta time */
    143	pid = bpf_get_current_pid_tgid();
    144	tsp = bpf_map_lookup_elem(&start, &pid);
    145	if (!tsp)
    146		/* missed start or filtered */
    147		return 0;
    148
    149	delta = bpf_ktime_get_ns() - *tsp;
    150	bpf_map_delete_elem(&start, &pid);
    151	delta = delta / 1000;
    152	if (delta < MINBLOCK_US)
    153		return 0;
    154
    155	return update_counts(ctx, pid, delta);
    156}
    157char _license[] SEC("license") = "GPL";
    158u32 _version SEC("version") = LINUX_VERSION_CODE;