1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ 3 4 #ifndef _TASK_KFUNC_COMMON_H 5 #define _TASK_KFUNC_COMMON_H 6 7 #include <errno.h> 8 #include <vmlinux.h> 9 #include <bpf/bpf_helpers.h> 10 #include <bpf/bpf_tracing.h> 11 12 struct __tasks_kfunc_map_value { 13 struct task_struct __kptr * task; 14 }; 15 16 struct hash_map { 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 23 struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym; 24 struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym; 25 void bpf_task_release(struct task_struct *p) __ksym; 26 struct task_struct *bpf_task_from_pid(s32 pid) __ksym; 27 void bpf_rcu_read_lock(void) __ksym; 28 void bpf_rcu_read_unlock(void) __ksym; 29 30 static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p) 31 { 32 s32 pid; 33 long status; 34 35 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); 36 if (status) 37 return NULL; 38 39 return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); 40 } 41 42 static inline int tasks_kfunc_map_insert(struct task_struct *p) 43 { 44 struct __tasks_kfunc_map_value local, *v; 45 long status; 46 struct task_struct *acquired, *old; 47 s32 pid; 48 49 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); 50 if (status) 51 return status; 52 53 local.task = NULL; 54 status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); 55 if (status) 56 return status; 57 58 v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); 59 if (!v) { 60 bpf_map_delete_elem(&__tasks_kfunc_map, &pid); 61 return -ENOENT; 62 } 63 64 acquired = bpf_task_acquire(p); 65 if (!acquired) 66 return -ENOENT; 67 68 old = bpf_kptr_xchg(&v->task, acquired); 69 if (old) { 70 bpf_task_release(old); 71 return -EEXIST; 72 } 73 74 return 0; 75 } 76 77 #endif /* _TASK_KFUNC_COMMON_H */ 78