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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test_legacy_printk.c (1633B)

      1// SPDX-License-Identifier: GPL-2.0
      2/* Copyright (c) 2021 Facebook */
      3
      4#include <linux/bpf.h>
      5#define BPF_NO_GLOBAL_DATA
      6#include <bpf/bpf_helpers.h>
      7
      8char LICENSE[] SEC("license") = "GPL";
      9
     10struct {
     11	__uint(type, BPF_MAP_TYPE_ARRAY);
     12	__type(key, int);
     13	__type(value, int);
     14	__uint(max_entries, 1);
     15} my_pid_map SEC(".maps");
     16
     17struct {
     18	__uint(type, BPF_MAP_TYPE_ARRAY);
     19	__type(key, int);
     20	__type(value, int);
     21	__uint(max_entries, 1);
     22} res_map SEC(".maps");
     23
     24volatile int my_pid_var = 0;
     25volatile int res_var = 0;
     26
     27SEC("tp/raw_syscalls/sys_enter")
     28int handle_legacy(void *ctx)
     29{
     30	int zero = 0, *my_pid, cur_pid, *my_res;
     31
     32	my_pid = bpf_map_lookup_elem(&my_pid_map, &zero);
     33	if (!my_pid)
     34		return 1;
     35
     36	cur_pid = bpf_get_current_pid_tgid() >> 32;
     37	if (cur_pid != *my_pid)
     38		return 1;
     39
     40	my_res = bpf_map_lookup_elem(&res_map, &zero);
     41	if (!my_res)
     42		return 1;
     43
     44	if (*my_res == 0)
     45		/* use bpf_printk() in combination with BPF_NO_GLOBAL_DATA to
     46		 * force .rodata.str1.1 section that previously caused
     47		 * problems on old kernels due to libbpf always tried to
     48		 * create a global data map for it
     49		 */
     50		bpf_printk("Legacy-case bpf_printk test, pid %d\n", cur_pid);
     51	*my_res = 1;
     52
     53	return *my_res;
     54}
     55
     56SEC("tp/raw_syscalls/sys_enter")
     57int handle_modern(void *ctx)
     58{
     59	int zero = 0, cur_pid;
     60
     61	cur_pid = bpf_get_current_pid_tgid() >> 32;
     62	if (cur_pid != my_pid_var)
     63		return 1;
     64
     65	if (res_var == 0)
     66		/* we need bpf_printk() to validate libbpf logic around unused
     67		 * global maps and legacy kernels; see comment in handle_legacy()
     68		 */
     69		bpf_printk("Modern-case bpf_printk test, pid %d\n", cur_pid);
     70	res_var = 1;
     71
     72	return res_var;
     73}