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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runqslower.bpf.c (2396B)

      1// SPDX-License-Identifier: GPL-2.0
      2// Copyright (c) 2019 Facebook
      3#include "vmlinux.h"
      4#include <bpf/bpf_helpers.h>
      5#include "runqslower.h"
      6
      7#define TASK_RUNNING 0
      8#define BPF_F_CURRENT_CPU 0xffffffffULL
      9
     10const volatile __u64 min_us = 0;
     11const volatile pid_t targ_pid = 0;
     12
     13struct {
     14	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
     15	__uint(map_flags, BPF_F_NO_PREALLOC);
     16	__type(key, int);
     17	__type(value, u64);
     18} start SEC(".maps");
     19
     20struct {
     21	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
     22	__uint(key_size, sizeof(u32));
     23	__uint(value_size, sizeof(u32));
     24} events SEC(".maps");
     25
     26/* record enqueue timestamp */
     27__always_inline
     28static int trace_enqueue(struct task_struct *t)
     29{
     30	u32 pid = t->pid;
     31	u64 *ptr;
     32
     33	if (!pid || (targ_pid && targ_pid != pid))
     34		return 0;
     35
     36	ptr = bpf_task_storage_get(&start, t, 0,
     37				   BPF_LOCAL_STORAGE_GET_F_CREATE);
     38	if (!ptr)
     39		return 0;
     40
     41	*ptr = bpf_ktime_get_ns();
     42	return 0;
     43}
     44
     45SEC("tp_btf/sched_wakeup")
     46int handle__sched_wakeup(u64 *ctx)
     47{
     48	/* TP_PROTO(struct task_struct *p) */
     49	struct task_struct *p = (void *)ctx[0];
     50
     51	return trace_enqueue(p);
     52}
     53
     54SEC("tp_btf/sched_wakeup_new")
     55int handle__sched_wakeup_new(u64 *ctx)
     56{
     57	/* TP_PROTO(struct task_struct *p) */
     58	struct task_struct *p = (void *)ctx[0];
     59
     60	return trace_enqueue(p);
     61}
     62
     63SEC("tp_btf/sched_switch")
     64int handle__sched_switch(u64 *ctx)
     65{
     66	/* TP_PROTO(bool preempt, struct task_struct *prev,
     67	 *	    struct task_struct *next)
     68	 */
     69	struct task_struct *prev = (struct task_struct *)ctx[1];
     70	struct task_struct *next = (struct task_struct *)ctx[2];
     71	struct runq_event event = {};
     72	u64 *tsp, delta_us;
     73	long state;
     74	u32 pid;
     75
     76	/* ivcsw: treat like an enqueue event and store timestamp */
     77	if (prev->__state == TASK_RUNNING)
     78		trace_enqueue(prev);
     79
     80	pid = next->pid;
     81
     82	/* For pid mismatch, save a bpf_task_storage_get */
     83	if (!pid || (targ_pid && targ_pid != pid))
     84		return 0;
     85
     86	/* fetch timestamp and calculate delta */
     87	tsp = bpf_task_storage_get(&start, next, 0, 0);
     88	if (!tsp)
     89		return 0;   /* missed enqueue */
     90
     91	delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
     92	if (min_us && delta_us <= min_us)
     93		return 0;
     94
     95	event.pid = pid;
     96	event.delta_us = delta_us;
     97	bpf_get_current_comm(&event.task, sizeof(event.task));
     98
     99	/* output */
    100	bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
    101			      &event, sizeof(event));
    102
    103	bpf_task_storage_delete(&start, next);
    104	return 0;
    105}
    106
    107char LICENSE[] SEC("license") = "GPL";