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1/* SPDX-License-Identifier: GPL-2.0 */2/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */3 4#ifndef _TASK_KFUNC_COMMON_H5#define _TASK_KFUNC_COMMON_H6 7#include <errno.h>8#include <vmlinux.h>9#include <bpf/bpf_helpers.h>10#include <bpf/bpf_tracing.h>11 12struct __tasks_kfunc_map_value {13 struct task_struct __kptr * task;14};15 16struct {17 __uint(type, BPF_MAP_TYPE_HASH);18 __type(key, int);19 __type(value, struct __tasks_kfunc_map_value);20 __uint(max_entries, 1);21} __tasks_kfunc_map SEC(".maps");22 23struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;24void bpf_task_release(struct task_struct *p) __ksym;25struct task_struct *bpf_task_from_pid(s32 pid) __ksym;26void bpf_rcu_read_lock(void) __ksym;27void bpf_rcu_read_unlock(void) __ksym;28 29static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)30{31 s32 pid;32 long status;33 34 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);35 if (status)36 return NULL;37 38 return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);39}40 41static inline int tasks_kfunc_map_insert(struct task_struct *p)42{43 struct __tasks_kfunc_map_value local, *v;44 long status;45 struct task_struct *acquired, *old;46 s32 pid;47 48 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);49 if (status)50 return status;51 52 local.task = NULL;53 status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);54 if (status)55 return status;56 57 v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);58 if (!v) {59 bpf_map_delete_elem(&__tasks_kfunc_map, &pid);60 return -ENOENT;61 }62 63 acquired = bpf_task_acquire(p);64 if (!acquired)65 return -ENOENT;66 67 old = bpf_kptr_xchg(&v->task, acquired);68 if (old) {69 bpf_task_release(old);70 return -EEXIST;71 }72 73 return 0;74}75 76#endif /* _TASK_KFUNC_COMMON_H */77