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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pid_iter.bpf.c (2394B)

      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_core_read.h>
      6#include <bpf/bpf_tracing.h>
      7#include "pid_iter.h"
      8
      9/* keep in sync with the definition in main.h */
     10enum bpf_obj_type {
     11	BPF_OBJ_UNKNOWN,
     12	BPF_OBJ_PROG,
     13	BPF_OBJ_MAP,
     14	BPF_OBJ_LINK,
     15	BPF_OBJ_BTF,
     16};
     17
     18extern const void bpf_link_fops __ksym;
     19extern const void bpf_map_fops __ksym;
     20extern const void bpf_prog_fops __ksym;
     21extern const void btf_fops __ksym;
     22
     23const volatile enum bpf_obj_type obj_type = BPF_OBJ_UNKNOWN;
     24
     25static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type)
     26{
     27	switch (type) {
     28	case BPF_OBJ_PROG:
     29		return BPF_CORE_READ((struct bpf_prog *)ent, aux, id);
     30	case BPF_OBJ_MAP:
     31		return BPF_CORE_READ((struct bpf_map *)ent, id);
     32	case BPF_OBJ_BTF:
     33		return BPF_CORE_READ((struct btf *)ent, id);
     34	case BPF_OBJ_LINK:
     35		return BPF_CORE_READ((struct bpf_link *)ent, id);
     36	default:
     37		return 0;
     38	}
     39}
     40
     41/* could be used only with BPF_LINK_TYPE_PERF_EVENT links */
     42static __u64 get_bpf_cookie(struct bpf_link *link)
     43{
     44	struct bpf_perf_link *perf_link;
     45	struct perf_event *event;
     46
     47	perf_link = container_of(link, struct bpf_perf_link, link);
     48	event = BPF_CORE_READ(perf_link, perf_file, private_data);
     49	return BPF_CORE_READ(event, bpf_cookie);
     50}
     51
     52SEC("iter/task_file")
     53int iter(struct bpf_iter__task_file *ctx)
     54{
     55	struct file *file = ctx->file;
     56	struct task_struct *task = ctx->task;
     57	struct pid_iter_entry e;
     58	const void *fops;
     59
     60	if (!file || !task)
     61		return 0;
     62
     63	switch (obj_type) {
     64	case BPF_OBJ_PROG:
     65		fops = &bpf_prog_fops;
     66		break;
     67	case BPF_OBJ_MAP:
     68		fops = &bpf_map_fops;
     69		break;
     70	case BPF_OBJ_BTF:
     71		fops = &btf_fops;
     72		break;
     73	case BPF_OBJ_LINK:
     74		fops = &bpf_link_fops;
     75		break;
     76	default:
     77		return 0;
     78	}
     79
     80	if (file->f_op != fops)
     81		return 0;
     82
     83	__builtin_memset(&e, 0, sizeof(e));
     84	e.pid = task->tgid;
     85	e.id = get_obj_id(file->private_data, obj_type);
     86
     87	if (obj_type == BPF_OBJ_LINK) {
     88		struct bpf_link *link = (struct bpf_link *) file->private_data;
     89
     90		if (BPF_CORE_READ(link, type) == BPF_LINK_TYPE_PERF_EVENT) {
     91			e.has_bpf_cookie = true;
     92			e.bpf_cookie = get_bpf_cookie(link);
     93		}
     94	}
     95
     96	bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm),
     97				  task->group_leader->comm);
     98	bpf_seq_write(ctx->meta->seq, &e, sizeof(e));
     99
    100	return 0;
    101}
    102
    103char LICENSE[] SEC("license") = "Dual BSD/GPL";