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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Google */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
extern const int bpf_prog_active __ksym; /* int type global var. */
SEC("raw_tp/sys_enter")
int handler1(const void *ctx)
{
int *active;
__u32 cpu;
cpu = bpf_get_smp_processor_id();
active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
if (active) {
/* Kernel memory obtained from bpf_{per,this}_cpu_ptr
* is read-only, should _not_ pass verification.
*/
/* WRITE_ONCE */
*(volatile int *)active = -1;
}
return 0;
}
__noinline int write_active(int *p)
{
return p ? (*p = 42) : 0;
}
SEC("raw_tp/sys_enter")
int handler2(const void *ctx)
{
int *active;
active = bpf_this_cpu_ptr(&bpf_prog_active);
write_active(active);
return 0;
}
char _license[] SEC("license") = "GPL";
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