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_ksyms_btf_null_check.c (715B)

      1// SPDX-License-Identifier: GPL-2.0
      2/* Copyright (c) 2020 Facebook */
      3
      4#include "vmlinux.h"
      5
      6#include <bpf/bpf_helpers.h>
      7
      8extern const struct rq runqueues __ksym; /* struct type global var. */
      9extern const int bpf_prog_active __ksym; /* int type global var. */
     10
     11SEC("raw_tp/sys_enter")
     12int handler(const void *ctx)
     13{
     14	struct rq *rq;
     15	int *active;
     16	__u32 cpu;
     17
     18	cpu = bpf_get_smp_processor_id();
     19	rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu);
     20	active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
     21	if (active) {
     22		/* READ_ONCE */
     23		*(volatile int *)active;
     24		/* !rq has not been tested, so verifier should reject. */
     25		*(volatile int *)(&rq->cpu);
     26	}
     27
     28	return 0;
     29}
     30
     31char _license[] SEC("license") = "GPL";