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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bpf_loop.c (2063B)

      1// SPDX-License-Identifier: GPL-2.0
      2/* Copyright (c) 2021 Facebook */
      3
      4#include "vmlinux.h"
      5#include <bpf/bpf_helpers.h>
      6#include "bpf_misc.h"
      7
      8char _license[] SEC("license") = "GPL";
      9
     10struct callback_ctx {
     11	int output;
     12};
     13
     14/* These should be set by the user program */
     15u32 nested_callback_nr_loops;
     16u32 stop_index = -1;
     17u32 nr_loops;
     18int pid;
     19
     20/* Making these global variables so that the userspace program
     21 * can verify the output through the skeleton
     22 */
     23int nr_loops_returned;
     24int g_output;
     25int err;
     26
     27static int callback(__u32 index, void *data)
     28{
     29	struct callback_ctx *ctx = data;
     30
     31	if (index >= stop_index)
     32		return 1;
     33
     34	ctx->output += index;
     35
     36	return 0;
     37}
     38
     39static int empty_callback(__u32 index, void *data)
     40{
     41	return 0;
     42}
     43
     44static int nested_callback2(__u32 index, void *data)
     45{
     46	nr_loops_returned += bpf_loop(nested_callback_nr_loops, callback, data, 0);
     47
     48	return 0;
     49}
     50
     51static int nested_callback1(__u32 index, void *data)
     52{
     53	bpf_loop(nested_callback_nr_loops, nested_callback2, data, 0);
     54	return 0;
     55}
     56
     57SEC("fentry/" SYS_PREFIX "sys_nanosleep")
     58int test_prog(void *ctx)
     59{
     60	struct callback_ctx data = {};
     61
     62	if (bpf_get_current_pid_tgid() >> 32 != pid)
     63		return 0;
     64
     65	nr_loops_returned = bpf_loop(nr_loops, callback, &data, 0);
     66
     67	if (nr_loops_returned < 0)
     68		err = nr_loops_returned;
     69	else
     70		g_output = data.output;
     71
     72	return 0;
     73}
     74
     75SEC("fentry/" SYS_PREFIX "sys_nanosleep")
     76int prog_null_ctx(void *ctx)
     77{
     78	if (bpf_get_current_pid_tgid() >> 32 != pid)
     79		return 0;
     80
     81	nr_loops_returned = bpf_loop(nr_loops, empty_callback, NULL, 0);
     82
     83	return 0;
     84}
     85
     86SEC("fentry/" SYS_PREFIX "sys_nanosleep")
     87int prog_invalid_flags(void *ctx)
     88{
     89	struct callback_ctx data = {};
     90
     91	if (bpf_get_current_pid_tgid() >> 32 != pid)
     92		return 0;
     93
     94	err = bpf_loop(nr_loops, callback, &data, 1);
     95
     96	return 0;
     97}
     98
     99SEC("fentry/" SYS_PREFIX "sys_nanosleep")
    100int prog_nested_calls(void *ctx)
    101{
    102	struct callback_ctx data = {};
    103
    104	if (bpf_get_current_pid_tgid() >> 32 != pid)
    105		return 0;
    106
    107	nr_loops_returned = 0;
    108	bpf_loop(nr_loops, nested_callback1, &data, 0);
    109
    110	g_output = data.output;
    111
    112	return 0;
    113}