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 { 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 void bpf_task_release(struct task_struct *p) __ksym; 25 struct task_struct *bpf_task_from_pid(s32 pid) __ksym; 26 void bpf_rcu_read_lock(void) __ksym; 27 void bpf_rcu_read_unlock(void) __ksym; 28 29 static 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 41 static 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