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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */
#include <linux/bpf.h>
#define BPF_NO_GLOBAL_DATA
#include <bpf/bpf_helpers.h>
char LICENSE[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, int);
__type(value, int);
__uint(max_entries, 1);
} my_pid_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, int);
__type(value, int);
__uint(max_entries, 1);
} res_map SEC(".maps");
volatile int my_pid_var = 0;
volatile int res_var = 0;
SEC("tp/raw_syscalls/sys_enter")
int handle_legacy(void *ctx)
{
int zero = 0, *my_pid, cur_pid, *my_res;
my_pid = bpf_map_lookup_elem(&my_pid_map, &zero);
if (!my_pid)
return 1;
cur_pid = bpf_get_current_pid_tgid() >> 32;
if (cur_pid != *my_pid)
return 1;
my_res = bpf_map_lookup_elem(&res_map, &zero);
if (!my_res)
return 1;
if (*my_res == 0)
/* use bpf_printk() in combination with BPF_NO_GLOBAL_DATA to
* force .rodata.str1.1 section that previously caused
* problems on old kernels due to libbpf always tried to
* create a global data map for it
*/
bpf_printk("Legacy-case bpf_printk test, pid %d\n", cur_pid);
*my_res = 1;
return *my_res;
}
SEC("tp/raw_syscalls/sys_enter")
int handle_modern(void *ctx)
{
int zero = 0, cur_pid;
cur_pid = bpf_get_current_pid_tgid() >> 32;
if (cur_pid != my_pid_var)
return 1;
if (res_var == 0)
/* we need bpf_printk() to validate libbpf logic around unused
* global maps and legacy kernels; see comment in handle_legacy()
*/
bpf_printk("Modern-case bpf_printk test, pid %d\n", cur_pid);
res_var = 1;
return res_var;
}
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