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/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
#ifndef _TASK_KFUNC_COMMON_H
#define _TASK_KFUNC_COMMON_H
#include <errno.h>
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
struct __tasks_kfunc_map_value {
struct task_struct __kptr * task;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, int);
__type(value, struct __tasks_kfunc_map_value);
__uint(max_entries, 1);
} __tasks_kfunc_map SEC(".maps");
struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
void bpf_task_release(struct task_struct *p) __ksym;
struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)
{
s32 pid;
long status;
status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
if (status)
return NULL;
return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
}
static inline int tasks_kfunc_map_insert(struct task_struct *p)
{
struct __tasks_kfunc_map_value local, *v;
long status;
struct task_struct *acquired, *old;
s32 pid;
status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
if (status)
return status;
local.task = NULL;
status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);
if (status)
return status;
v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
if (!v) {
bpf_map_delete_elem(&__tasks_kfunc_map, &pid);
return -ENOENT;
}
acquired = bpf_task_acquire(p);
if (!acquired)
return -ENOENT;
old = bpf_kptr_xchg(&v->task, acquired);
if (old) {
bpf_task_release(old);
return -EEXIST;
}
return 0;
}
#endif /* _TASK_KFUNC_COMMON_H */
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