1fec56f58SAlexei Starovoitov // SPDX-License-Identifier: GPL-2.0-only 2fec56f58SAlexei Starovoitov /* Copyright (c) 2019 Facebook */ 3fec56f58SAlexei Starovoitov #include <linux/hash.h> 4fec56f58SAlexei Starovoitov #include <linux/bpf.h> 5fec56f58SAlexei Starovoitov #include <linux/filter.h> 6b91e014fSAlexei Starovoitov #include <linux/ftrace.h> 7e9b4e606SJiri Olsa #include <linux/rbtree_latch.h> 8a108f7dcSJiri Olsa #include <linux/perf_event.h> 99e4e01dfSKP Singh #include <linux/btf.h> 101e6c62a8SAlexei Starovoitov #include <linux/rcupdate_trace.h> 111e6c62a8SAlexei Starovoitov #include <linux/rcupdate_wait.h> 12861de02eSJiri Olsa #include <linux/module.h> 13856c02dbSSong Liu #include <linux/static_call.h> 14fec56f58SAlexei Starovoitov 15be8704ffSAlexei Starovoitov /* dummy _ops. The verifier will operate on target program's ops. */ 16be8704ffSAlexei Starovoitov const struct bpf_verifier_ops bpf_extension_verifier_ops = { 17be8704ffSAlexei Starovoitov }; 18be8704ffSAlexei Starovoitov const struct bpf_prog_ops bpf_extension_prog_ops = { 19be8704ffSAlexei Starovoitov }; 20be8704ffSAlexei Starovoitov 21fec56f58SAlexei Starovoitov /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */ 22fec56f58SAlexei Starovoitov #define TRAMPOLINE_HASH_BITS 10 23fec56f58SAlexei Starovoitov #define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS) 24fec56f58SAlexei Starovoitov 25fec56f58SAlexei Starovoitov static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE]; 26fec56f58SAlexei Starovoitov 277ac88ebaSJiri Olsa /* serializes access to trampoline_table */ 28fec56f58SAlexei Starovoitov static DEFINE_MUTEX(trampoline_mutex); 29fec56f58SAlexei Starovoitov 30*f92c1e18SJiri Olsa bool bpf_prog_has_trampoline(const struct bpf_prog *prog) 31*f92c1e18SJiri Olsa { 32*f92c1e18SJiri Olsa enum bpf_attach_type eatype = prog->expected_attach_type; 33*f92c1e18SJiri Olsa 34*f92c1e18SJiri Olsa return eatype == BPF_TRACE_FENTRY || eatype == BPF_TRACE_FEXIT || 35*f92c1e18SJiri Olsa eatype == BPF_MODIFY_RETURN; 36*f92c1e18SJiri Olsa } 37*f92c1e18SJiri Olsa 387ac88ebaSJiri Olsa void *bpf_jit_alloc_exec_page(void) 3998e8627eSBjörn Töpel { 4098e8627eSBjörn Töpel void *image; 4198e8627eSBjörn Töpel 4298e8627eSBjörn Töpel image = bpf_jit_alloc_exec(PAGE_SIZE); 4398e8627eSBjörn Töpel if (!image) 4498e8627eSBjörn Töpel return NULL; 4598e8627eSBjörn Töpel 4698e8627eSBjörn Töpel set_vm_flush_reset_perms(image); 4798e8627eSBjörn Töpel /* Keep image as writeable. The alternative is to keep flipping ro/rw 4898e8627eSBjörn Töpel * everytime new program is attached or detached. 4998e8627eSBjörn Töpel */ 5098e8627eSBjörn Töpel set_memory_x((long)image, 1); 5198e8627eSBjörn Töpel return image; 5298e8627eSBjörn Töpel } 5398e8627eSBjörn Töpel 54a108f7dcSJiri Olsa void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) 55a108f7dcSJiri Olsa { 56a108f7dcSJiri Olsa ksym->start = (unsigned long) data; 577ac88ebaSJiri Olsa ksym->end = ksym->start + PAGE_SIZE; 58a108f7dcSJiri Olsa bpf_ksym_add(ksym); 59a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 607ac88ebaSJiri Olsa PAGE_SIZE, false, ksym->name); 61a108f7dcSJiri Olsa } 62a108f7dcSJiri Olsa 63a108f7dcSJiri Olsa void bpf_image_ksym_del(struct bpf_ksym *ksym) 64a108f7dcSJiri Olsa { 65a108f7dcSJiri Olsa bpf_ksym_del(ksym); 66a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 677ac88ebaSJiri Olsa PAGE_SIZE, true, ksym->name); 68a108f7dcSJiri Olsa } 69a108f7dcSJiri Olsa 70f7b12b6fSToke Høiland-Jørgensen static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) 71fec56f58SAlexei Starovoitov { 72fec56f58SAlexei Starovoitov struct bpf_trampoline *tr; 73fec56f58SAlexei Starovoitov struct hlist_head *head; 74fec56f58SAlexei Starovoitov int i; 75fec56f58SAlexei Starovoitov 76fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 77fec56f58SAlexei Starovoitov head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)]; 78fec56f58SAlexei Starovoitov hlist_for_each_entry(tr, head, hlist) { 79fec56f58SAlexei Starovoitov if (tr->key == key) { 80fec56f58SAlexei Starovoitov refcount_inc(&tr->refcnt); 81fec56f58SAlexei Starovoitov goto out; 82fec56f58SAlexei Starovoitov } 83fec56f58SAlexei Starovoitov } 84fec56f58SAlexei Starovoitov tr = kzalloc(sizeof(*tr), GFP_KERNEL); 85fec56f58SAlexei Starovoitov if (!tr) 86fec56f58SAlexei Starovoitov goto out; 87fec56f58SAlexei Starovoitov 88fec56f58SAlexei Starovoitov tr->key = key; 89fec56f58SAlexei Starovoitov INIT_HLIST_NODE(&tr->hlist); 90fec56f58SAlexei Starovoitov hlist_add_head(&tr->hlist, head); 91fec56f58SAlexei Starovoitov refcount_set(&tr->refcnt, 1); 92fec56f58SAlexei Starovoitov mutex_init(&tr->mutex); 93fec56f58SAlexei Starovoitov for (i = 0; i < BPF_TRAMP_MAX; i++) 94fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&tr->progs_hlist[i]); 95fec56f58SAlexei Starovoitov out: 96fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 97fec56f58SAlexei Starovoitov return tr; 98fec56f58SAlexei Starovoitov } 99fec56f58SAlexei Starovoitov 100861de02eSJiri Olsa static int bpf_trampoline_module_get(struct bpf_trampoline *tr) 101861de02eSJiri Olsa { 102861de02eSJiri Olsa struct module *mod; 103861de02eSJiri Olsa int err = 0; 104861de02eSJiri Olsa 105861de02eSJiri Olsa preempt_disable(); 106861de02eSJiri Olsa mod = __module_text_address((unsigned long) tr->func.addr); 107861de02eSJiri Olsa if (mod && !try_module_get(mod)) 108861de02eSJiri Olsa err = -ENOENT; 109861de02eSJiri Olsa preempt_enable(); 110861de02eSJiri Olsa tr->mod = mod; 111861de02eSJiri Olsa return err; 112861de02eSJiri Olsa } 113861de02eSJiri Olsa 114861de02eSJiri Olsa static void bpf_trampoline_module_put(struct bpf_trampoline *tr) 115861de02eSJiri Olsa { 116861de02eSJiri Olsa module_put(tr->mod); 117861de02eSJiri Olsa tr->mod = NULL; 118861de02eSJiri Olsa } 119861de02eSJiri Olsa 120b91e014fSAlexei Starovoitov static int is_ftrace_location(void *ip) 121b91e014fSAlexei Starovoitov { 122b91e014fSAlexei Starovoitov long addr; 123b91e014fSAlexei Starovoitov 124b91e014fSAlexei Starovoitov addr = ftrace_location((long)ip); 125b91e014fSAlexei Starovoitov if (!addr) 126b91e014fSAlexei Starovoitov return 0; 127b91e014fSAlexei Starovoitov if (WARN_ON_ONCE(addr != (long)ip)) 128b91e014fSAlexei Starovoitov return -EFAULT; 129b91e014fSAlexei Starovoitov return 1; 130b91e014fSAlexei Starovoitov } 131b91e014fSAlexei Starovoitov 132b91e014fSAlexei Starovoitov static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) 133b91e014fSAlexei Starovoitov { 134b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 135b91e014fSAlexei Starovoitov int ret; 136b91e014fSAlexei Starovoitov 137b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 138b91e014fSAlexei Starovoitov ret = unregister_ftrace_direct((long)ip, (long)old_addr); 139b91e014fSAlexei Starovoitov else 140b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); 141861de02eSJiri Olsa 142861de02eSJiri Olsa if (!ret) 143861de02eSJiri Olsa bpf_trampoline_module_put(tr); 144b91e014fSAlexei Starovoitov return ret; 145b91e014fSAlexei Starovoitov } 146b91e014fSAlexei Starovoitov 147b91e014fSAlexei Starovoitov static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr) 148b91e014fSAlexei Starovoitov { 149b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 150b91e014fSAlexei Starovoitov int ret; 151b91e014fSAlexei Starovoitov 152b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 153b91e014fSAlexei Starovoitov ret = modify_ftrace_direct((long)ip, (long)old_addr, (long)new_addr); 154b91e014fSAlexei Starovoitov else 155b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); 156b91e014fSAlexei Starovoitov return ret; 157b91e014fSAlexei Starovoitov } 158b91e014fSAlexei Starovoitov 159b91e014fSAlexei Starovoitov /* first time registering */ 160b91e014fSAlexei Starovoitov static int register_fentry(struct bpf_trampoline *tr, void *new_addr) 161b91e014fSAlexei Starovoitov { 162b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 163b91e014fSAlexei Starovoitov int ret; 164b91e014fSAlexei Starovoitov 165b91e014fSAlexei Starovoitov ret = is_ftrace_location(ip); 166b91e014fSAlexei Starovoitov if (ret < 0) 167b91e014fSAlexei Starovoitov return ret; 168b91e014fSAlexei Starovoitov tr->func.ftrace_managed = ret; 169b91e014fSAlexei Starovoitov 170861de02eSJiri Olsa if (bpf_trampoline_module_get(tr)) 171861de02eSJiri Olsa return -ENOENT; 172861de02eSJiri Olsa 173b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 174b91e014fSAlexei Starovoitov ret = register_ftrace_direct((long)ip, (long)new_addr); 175b91e014fSAlexei Starovoitov else 176b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); 177861de02eSJiri Olsa 178861de02eSJiri Olsa if (ret) 179861de02eSJiri Olsa bpf_trampoline_module_put(tr); 180b91e014fSAlexei Starovoitov return ret; 181b91e014fSAlexei Starovoitov } 182b91e014fSAlexei Starovoitov 18388fd9e53SKP Singh static struct bpf_tramp_progs * 1841e37392cSJiri Olsa bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg) 18588fd9e53SKP Singh { 18688fd9e53SKP Singh const struct bpf_prog_aux *aux; 18788fd9e53SKP Singh struct bpf_tramp_progs *tprogs; 18888fd9e53SKP Singh struct bpf_prog **progs; 18988fd9e53SKP Singh int kind; 19088fd9e53SKP Singh 19188fd9e53SKP Singh *total = 0; 19288fd9e53SKP Singh tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL); 19388fd9e53SKP Singh if (!tprogs) 19488fd9e53SKP Singh return ERR_PTR(-ENOMEM); 19588fd9e53SKP Singh 19688fd9e53SKP Singh for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { 19788fd9e53SKP Singh tprogs[kind].nr_progs = tr->progs_cnt[kind]; 19888fd9e53SKP Singh *total += tr->progs_cnt[kind]; 19988fd9e53SKP Singh progs = tprogs[kind].progs; 20088fd9e53SKP Singh 2011e37392cSJiri Olsa hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) { 2021e37392cSJiri Olsa *ip_arg |= aux->prog->call_get_func_ip; 20388fd9e53SKP Singh *progs++ = aux->prog; 20488fd9e53SKP Singh } 2051e37392cSJiri Olsa } 20688fd9e53SKP Singh return tprogs; 20788fd9e53SKP Singh } 208fec56f58SAlexei Starovoitov 209e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_deferred(struct work_struct *work) 210e21aa341SAlexei Starovoitov { 211e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 212e21aa341SAlexei Starovoitov 213e21aa341SAlexei Starovoitov im = container_of(work, struct bpf_tramp_image, work); 214e21aa341SAlexei Starovoitov bpf_image_ksym_del(&im->ksym); 215e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 216e21aa341SAlexei Starovoitov bpf_jit_uncharge_modmem(1); 217e21aa341SAlexei Starovoitov percpu_ref_exit(&im->pcref); 218e21aa341SAlexei Starovoitov kfree_rcu(im, rcu); 219e21aa341SAlexei Starovoitov } 220e21aa341SAlexei Starovoitov 221e21aa341SAlexei Starovoitov /* callback, fexit step 3 or fentry step 2 */ 222e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu) 223e21aa341SAlexei Starovoitov { 224e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 225e21aa341SAlexei Starovoitov 226e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 227e21aa341SAlexei Starovoitov INIT_WORK(&im->work, __bpf_tramp_image_put_deferred); 228e21aa341SAlexei Starovoitov schedule_work(&im->work); 229e21aa341SAlexei Starovoitov } 230e21aa341SAlexei Starovoitov 231e21aa341SAlexei Starovoitov /* callback, fexit step 2. Called after percpu_ref_kill confirms. */ 232e21aa341SAlexei Starovoitov static void __bpf_tramp_image_release(struct percpu_ref *pcref) 233e21aa341SAlexei Starovoitov { 234e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 235e21aa341SAlexei Starovoitov 236e21aa341SAlexei Starovoitov im = container_of(pcref, struct bpf_tramp_image, pcref); 237e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 238e21aa341SAlexei Starovoitov } 239e21aa341SAlexei Starovoitov 240e21aa341SAlexei Starovoitov /* callback, fexit or fentry step 1 */ 241e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu) 242e21aa341SAlexei Starovoitov { 243e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 244e21aa341SAlexei Starovoitov 245e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 246e21aa341SAlexei Starovoitov if (im->ip_after_call) 247e21aa341SAlexei Starovoitov /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ 248e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 249e21aa341SAlexei Starovoitov else 250e21aa341SAlexei Starovoitov /* the case of fentry trampoline */ 251e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 252e21aa341SAlexei Starovoitov } 253e21aa341SAlexei Starovoitov 254e21aa341SAlexei Starovoitov static void bpf_tramp_image_put(struct bpf_tramp_image *im) 255e21aa341SAlexei Starovoitov { 256e21aa341SAlexei Starovoitov /* The trampoline image that calls original function is using: 257e21aa341SAlexei Starovoitov * rcu_read_lock_trace to protect sleepable bpf progs 258e21aa341SAlexei Starovoitov * rcu_read_lock to protect normal bpf progs 259e21aa341SAlexei Starovoitov * percpu_ref to protect trampoline itself 260e21aa341SAlexei Starovoitov * rcu tasks to protect trampoline asm not covered by percpu_ref 261e21aa341SAlexei Starovoitov * (which are few asm insns before __bpf_tramp_enter and 262e21aa341SAlexei Starovoitov * after __bpf_tramp_exit) 263e21aa341SAlexei Starovoitov * 264e21aa341SAlexei Starovoitov * The trampoline is unreachable before bpf_tramp_image_put(). 265e21aa341SAlexei Starovoitov * 266e21aa341SAlexei Starovoitov * First, patch the trampoline to avoid calling into fexit progs. 267e21aa341SAlexei Starovoitov * The progs will be freed even if the original function is still 268e21aa341SAlexei Starovoitov * executing or sleeping. 269e21aa341SAlexei Starovoitov * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on 270e21aa341SAlexei Starovoitov * first few asm instructions to execute and call into 271e21aa341SAlexei Starovoitov * __bpf_tramp_enter->percpu_ref_get. 272e21aa341SAlexei Starovoitov * Then use percpu_ref_kill to wait for the trampoline and the original 273e21aa341SAlexei Starovoitov * function to finish. 274e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to make sure few asm insns in 275e21aa341SAlexei Starovoitov * the trampoline epilogue are done as well. 276e21aa341SAlexei Starovoitov * 277e21aa341SAlexei Starovoitov * In !PREEMPT case the task that got interrupted in the first asm 278e21aa341SAlexei Starovoitov * insns won't go through an RCU quiescent state which the 279e21aa341SAlexei Starovoitov * percpu_ref_kill will be waiting for. Hence the first 280e21aa341SAlexei Starovoitov * call_rcu_tasks() is not necessary. 281e21aa341SAlexei Starovoitov */ 282e21aa341SAlexei Starovoitov if (im->ip_after_call) { 283e21aa341SAlexei Starovoitov int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, 284e21aa341SAlexei Starovoitov NULL, im->ip_epilogue); 285e21aa341SAlexei Starovoitov WARN_ON(err); 286e21aa341SAlexei Starovoitov if (IS_ENABLED(CONFIG_PREEMPTION)) 287e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 288e21aa341SAlexei Starovoitov else 289e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 290e21aa341SAlexei Starovoitov return; 291e21aa341SAlexei Starovoitov } 292e21aa341SAlexei Starovoitov 293e21aa341SAlexei Starovoitov /* The trampoline without fexit and fmod_ret progs doesn't call original 294e21aa341SAlexei Starovoitov * function and doesn't use percpu_ref. 295e21aa341SAlexei Starovoitov * Use call_rcu_tasks_trace() to wait for sleepable progs to finish. 296e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to wait for the rest of trampoline asm 297e21aa341SAlexei Starovoitov * and normal progs. 298e21aa341SAlexei Starovoitov */ 299e21aa341SAlexei Starovoitov call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 300e21aa341SAlexei Starovoitov } 301e21aa341SAlexei Starovoitov 302e21aa341SAlexei Starovoitov static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) 303e21aa341SAlexei Starovoitov { 304e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 305e21aa341SAlexei Starovoitov struct bpf_ksym *ksym; 306e21aa341SAlexei Starovoitov void *image; 307e21aa341SAlexei Starovoitov int err = -ENOMEM; 308e21aa341SAlexei Starovoitov 309e21aa341SAlexei Starovoitov im = kzalloc(sizeof(*im), GFP_KERNEL); 310e21aa341SAlexei Starovoitov if (!im) 311e21aa341SAlexei Starovoitov goto out; 312e21aa341SAlexei Starovoitov 313e21aa341SAlexei Starovoitov err = bpf_jit_charge_modmem(1); 314e21aa341SAlexei Starovoitov if (err) 315e21aa341SAlexei Starovoitov goto out_free_im; 316e21aa341SAlexei Starovoitov 317e21aa341SAlexei Starovoitov err = -ENOMEM; 318e21aa341SAlexei Starovoitov im->image = image = bpf_jit_alloc_exec_page(); 319e21aa341SAlexei Starovoitov if (!image) 320e21aa341SAlexei Starovoitov goto out_uncharge; 321e21aa341SAlexei Starovoitov 322e21aa341SAlexei Starovoitov err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); 323e21aa341SAlexei Starovoitov if (err) 324e21aa341SAlexei Starovoitov goto out_free_image; 325e21aa341SAlexei Starovoitov 326e21aa341SAlexei Starovoitov ksym = &im->ksym; 327e21aa341SAlexei Starovoitov INIT_LIST_HEAD_RCU(&ksym->lnode); 328e21aa341SAlexei Starovoitov snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); 329e21aa341SAlexei Starovoitov bpf_image_ksym_add(image, ksym); 330e21aa341SAlexei Starovoitov return im; 331e21aa341SAlexei Starovoitov 332e21aa341SAlexei Starovoitov out_free_image: 333e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 334e21aa341SAlexei Starovoitov out_uncharge: 335e21aa341SAlexei Starovoitov bpf_jit_uncharge_modmem(1); 336e21aa341SAlexei Starovoitov out_free_im: 337e21aa341SAlexei Starovoitov kfree(im); 338e21aa341SAlexei Starovoitov out: 339e21aa341SAlexei Starovoitov return ERR_PTR(err); 340e21aa341SAlexei Starovoitov } 341e21aa341SAlexei Starovoitov 342fec56f58SAlexei Starovoitov static int bpf_trampoline_update(struct bpf_trampoline *tr) 343fec56f58SAlexei Starovoitov { 344e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 34588fd9e53SKP Singh struct bpf_tramp_progs *tprogs; 346fec56f58SAlexei Starovoitov u32 flags = BPF_TRAMP_F_RESTORE_REGS; 3471e37392cSJiri Olsa bool ip_arg = false; 34888fd9e53SKP Singh int err, total; 349fec56f58SAlexei Starovoitov 3501e37392cSJiri Olsa tprogs = bpf_trampoline_get_progs(tr, &total, &ip_arg); 35188fd9e53SKP Singh if (IS_ERR(tprogs)) 35288fd9e53SKP Singh return PTR_ERR(tprogs); 35388fd9e53SKP Singh 35488fd9e53SKP Singh if (total == 0) { 355e21aa341SAlexei Starovoitov err = unregister_fentry(tr, tr->cur_image->image); 356e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 357e21aa341SAlexei Starovoitov tr->cur_image = NULL; 358fec56f58SAlexei Starovoitov tr->selector = 0; 359fec56f58SAlexei Starovoitov goto out; 360fec56f58SAlexei Starovoitov } 361fec56f58SAlexei Starovoitov 362e21aa341SAlexei Starovoitov im = bpf_tramp_image_alloc(tr->key, tr->selector); 363e21aa341SAlexei Starovoitov if (IS_ERR(im)) { 364e21aa341SAlexei Starovoitov err = PTR_ERR(im); 365e21aa341SAlexei Starovoitov goto out; 366e21aa341SAlexei Starovoitov } 367e21aa341SAlexei Starovoitov 368ae240823SKP Singh if (tprogs[BPF_TRAMP_FEXIT].nr_progs || 369ae240823SKP Singh tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) 370fec56f58SAlexei Starovoitov flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; 371fec56f58SAlexei Starovoitov 3721e37392cSJiri Olsa if (ip_arg) 3731e37392cSJiri Olsa flags |= BPF_TRAMP_F_IP_ARG; 3741e37392cSJiri Olsa 375e21aa341SAlexei Starovoitov err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, 37688fd9e53SKP Singh &tr->func.model, flags, tprogs, 377fec56f58SAlexei Starovoitov tr->func.addr); 37885d33df3SMartin KaFai Lau if (err < 0) 379fec56f58SAlexei Starovoitov goto out; 380fec56f58SAlexei Starovoitov 381e21aa341SAlexei Starovoitov WARN_ON(tr->cur_image && tr->selector == 0); 382e21aa341SAlexei Starovoitov WARN_ON(!tr->cur_image && tr->selector); 383e21aa341SAlexei Starovoitov if (tr->cur_image) 384fec56f58SAlexei Starovoitov /* progs already running at this address */ 385e21aa341SAlexei Starovoitov err = modify_fentry(tr, tr->cur_image->image, im->image); 386fec56f58SAlexei Starovoitov else 387fec56f58SAlexei Starovoitov /* first time registering */ 388e21aa341SAlexei Starovoitov err = register_fentry(tr, im->image); 389fec56f58SAlexei Starovoitov if (err) 390fec56f58SAlexei Starovoitov goto out; 391e21aa341SAlexei Starovoitov if (tr->cur_image) 392e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 393e21aa341SAlexei Starovoitov tr->cur_image = im; 394fec56f58SAlexei Starovoitov tr->selector++; 395fec56f58SAlexei Starovoitov out: 39688fd9e53SKP Singh kfree(tprogs); 397fec56f58SAlexei Starovoitov return err; 398fec56f58SAlexei Starovoitov } 399fec56f58SAlexei Starovoitov 4009e4e01dfSKP Singh static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog) 401fec56f58SAlexei Starovoitov { 4029e4e01dfSKP Singh switch (prog->expected_attach_type) { 403fec56f58SAlexei Starovoitov case BPF_TRACE_FENTRY: 404fec56f58SAlexei Starovoitov return BPF_TRAMP_FENTRY; 405ae240823SKP Singh case BPF_MODIFY_RETURN: 406ae240823SKP Singh return BPF_TRAMP_MODIFY_RETURN; 407be8704ffSAlexei Starovoitov case BPF_TRACE_FEXIT: 408fec56f58SAlexei Starovoitov return BPF_TRAMP_FEXIT; 4099e4e01dfSKP Singh case BPF_LSM_MAC: 4109e4e01dfSKP Singh if (!prog->aux->attach_func_proto->type) 4119e4e01dfSKP Singh /* The function returns void, we cannot modify its 4129e4e01dfSKP Singh * return value. 4139e4e01dfSKP Singh */ 4149e4e01dfSKP Singh return BPF_TRAMP_FEXIT; 4159e4e01dfSKP Singh else 4169e4e01dfSKP Singh return BPF_TRAMP_MODIFY_RETURN; 417be8704ffSAlexei Starovoitov default: 418be8704ffSAlexei Starovoitov return BPF_TRAMP_REPLACE; 419fec56f58SAlexei Starovoitov } 420fec56f58SAlexei Starovoitov } 421fec56f58SAlexei Starovoitov 4223aac1eadSToke Høiland-Jørgensen int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) 423fec56f58SAlexei Starovoitov { 424fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 425fec56f58SAlexei Starovoitov int err = 0; 426be8704ffSAlexei Starovoitov int cnt; 427fec56f58SAlexei Starovoitov 4289e4e01dfSKP Singh kind = bpf_attach_type_to_tramp(prog); 429fec56f58SAlexei Starovoitov mutex_lock(&tr->mutex); 430be8704ffSAlexei Starovoitov if (tr->extension_prog) { 431be8704ffSAlexei Starovoitov /* cannot attach fentry/fexit if extension prog is attached. 432be8704ffSAlexei Starovoitov * cannot overwrite extension prog either. 433be8704ffSAlexei Starovoitov */ 434be8704ffSAlexei Starovoitov err = -EBUSY; 435be8704ffSAlexei Starovoitov goto out; 436be8704ffSAlexei Starovoitov } 437be8704ffSAlexei Starovoitov cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT]; 438be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 439be8704ffSAlexei Starovoitov /* Cannot attach extension if fentry/fexit are in use. */ 440be8704ffSAlexei Starovoitov if (cnt) { 441be8704ffSAlexei Starovoitov err = -EBUSY; 442be8704ffSAlexei Starovoitov goto out; 443be8704ffSAlexei Starovoitov } 444be8704ffSAlexei Starovoitov tr->extension_prog = prog; 445be8704ffSAlexei Starovoitov err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, 446be8704ffSAlexei Starovoitov prog->bpf_func); 447be8704ffSAlexei Starovoitov goto out; 448be8704ffSAlexei Starovoitov } 449be8704ffSAlexei Starovoitov if (cnt >= BPF_MAX_TRAMP_PROGS) { 450fec56f58SAlexei Starovoitov err = -E2BIG; 451fec56f58SAlexei Starovoitov goto out; 452fec56f58SAlexei Starovoitov } 453fec56f58SAlexei Starovoitov if (!hlist_unhashed(&prog->aux->tramp_hlist)) { 454fec56f58SAlexei Starovoitov /* prog already linked */ 455fec56f58SAlexei Starovoitov err = -EBUSY; 456fec56f58SAlexei Starovoitov goto out; 457fec56f58SAlexei Starovoitov } 458fec56f58SAlexei Starovoitov hlist_add_head(&prog->aux->tramp_hlist, &tr->progs_hlist[kind]); 459fec56f58SAlexei Starovoitov tr->progs_cnt[kind]++; 4603aac1eadSToke Høiland-Jørgensen err = bpf_trampoline_update(tr); 461fec56f58SAlexei Starovoitov if (err) { 462f3a95075SJiri Olsa hlist_del_init(&prog->aux->tramp_hlist); 463fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 464fec56f58SAlexei Starovoitov } 465fec56f58SAlexei Starovoitov out: 466fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 467fec56f58SAlexei Starovoitov return err; 468fec56f58SAlexei Starovoitov } 469fec56f58SAlexei Starovoitov 470fec56f58SAlexei Starovoitov /* bpf_trampoline_unlink_prog() should never fail. */ 4713aac1eadSToke Høiland-Jørgensen int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) 472fec56f58SAlexei Starovoitov { 473fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 474fec56f58SAlexei Starovoitov int err; 475fec56f58SAlexei Starovoitov 4769e4e01dfSKP Singh kind = bpf_attach_type_to_tramp(prog); 477fec56f58SAlexei Starovoitov mutex_lock(&tr->mutex); 478be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 479be8704ffSAlexei Starovoitov WARN_ON_ONCE(!tr->extension_prog); 480be8704ffSAlexei Starovoitov err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, 481be8704ffSAlexei Starovoitov tr->extension_prog->bpf_func, NULL); 482be8704ffSAlexei Starovoitov tr->extension_prog = NULL; 483be8704ffSAlexei Starovoitov goto out; 484be8704ffSAlexei Starovoitov } 485f3a95075SJiri Olsa hlist_del_init(&prog->aux->tramp_hlist); 486fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 4873aac1eadSToke Høiland-Jørgensen err = bpf_trampoline_update(tr); 488be8704ffSAlexei Starovoitov out: 489fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 490fec56f58SAlexei Starovoitov return err; 491fec56f58SAlexei Starovoitov } 492fec56f58SAlexei Starovoitov 493f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *bpf_trampoline_get(u64 key, 494f7b12b6fSToke Høiland-Jørgensen struct bpf_attach_target_info *tgt_info) 495f7b12b6fSToke Høiland-Jørgensen { 496f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *tr; 497f7b12b6fSToke Høiland-Jørgensen 498f7b12b6fSToke Høiland-Jørgensen tr = bpf_trampoline_lookup(key); 499f7b12b6fSToke Høiland-Jørgensen if (!tr) 500f7b12b6fSToke Høiland-Jørgensen return NULL; 501f7b12b6fSToke Høiland-Jørgensen 502f7b12b6fSToke Høiland-Jørgensen mutex_lock(&tr->mutex); 503f7b12b6fSToke Høiland-Jørgensen if (tr->func.addr) 504f7b12b6fSToke Høiland-Jørgensen goto out; 505f7b12b6fSToke Høiland-Jørgensen 506f7b12b6fSToke Høiland-Jørgensen memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); 507f7b12b6fSToke Høiland-Jørgensen tr->func.addr = (void *)tgt_info->tgt_addr; 508f7b12b6fSToke Høiland-Jørgensen out: 509f7b12b6fSToke Høiland-Jørgensen mutex_unlock(&tr->mutex); 510f7b12b6fSToke Høiland-Jørgensen return tr; 511f7b12b6fSToke Høiland-Jørgensen } 512f7b12b6fSToke Høiland-Jørgensen 513fec56f58SAlexei Starovoitov void bpf_trampoline_put(struct bpf_trampoline *tr) 514fec56f58SAlexei Starovoitov { 515fec56f58SAlexei Starovoitov if (!tr) 516fec56f58SAlexei Starovoitov return; 517fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 518fec56f58SAlexei Starovoitov if (!refcount_dec_and_test(&tr->refcnt)) 519fec56f58SAlexei Starovoitov goto out; 520fec56f58SAlexei Starovoitov WARN_ON_ONCE(mutex_is_locked(&tr->mutex)); 521fec56f58SAlexei Starovoitov if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FENTRY]))) 522fec56f58SAlexei Starovoitov goto out; 523fec56f58SAlexei Starovoitov if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FEXIT]))) 524fec56f58SAlexei Starovoitov goto out; 525e21aa341SAlexei Starovoitov /* This code will be executed even when the last bpf_tramp_image 526e21aa341SAlexei Starovoitov * is alive. All progs are detached from the trampoline and the 527e21aa341SAlexei Starovoitov * trampoline image is patched with jmp into epilogue to skip 528e21aa341SAlexei Starovoitov * fexit progs. The fentry-only trampoline will be freed via 529e21aa341SAlexei Starovoitov * multiple rcu callbacks. 5301e6c62a8SAlexei Starovoitov */ 531fec56f58SAlexei Starovoitov hlist_del(&tr->hlist); 532fec56f58SAlexei Starovoitov kfree(tr); 533fec56f58SAlexei Starovoitov out: 534fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 535fec56f58SAlexei Starovoitov } 536fec56f58SAlexei Starovoitov 537ca06f55bSAlexei Starovoitov #define NO_START_TIME 1 538856c02dbSSong Liu static __always_inline u64 notrace bpf_prog_start_time(void) 539f2dd3b39SAlexei Starovoitov { 540f2dd3b39SAlexei Starovoitov u64 start = NO_START_TIME; 541f2dd3b39SAlexei Starovoitov 542ca06f55bSAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key)) { 543f2dd3b39SAlexei Starovoitov start = sched_clock(); 544ca06f55bSAlexei Starovoitov if (unlikely(!start)) 545ca06f55bSAlexei Starovoitov start = NO_START_TIME; 546ca06f55bSAlexei Starovoitov } 547f2dd3b39SAlexei Starovoitov return start; 548f2dd3b39SAlexei Starovoitov } 549f2dd3b39SAlexei Starovoitov 5509ed9e9baSAlexei Starovoitov static void notrace inc_misses_counter(struct bpf_prog *prog) 5519ed9e9baSAlexei Starovoitov { 5529ed9e9baSAlexei Starovoitov struct bpf_prog_stats *stats; 5539ed9e9baSAlexei Starovoitov 5549ed9e9baSAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 5559ed9e9baSAlexei Starovoitov u64_stats_update_begin(&stats->syncp); 55661a0abaeSEric Dumazet u64_stats_inc(&stats->misses); 5579ed9e9baSAlexei Starovoitov u64_stats_update_end(&stats->syncp); 5589ed9e9baSAlexei Starovoitov } 5599ed9e9baSAlexei Starovoitov 560fb7dd8bcSAndrii Nakryiko /* The logic is similar to bpf_prog_run(), but with an explicit 56102ad0596SDavid Miller * rcu_read_lock() and migrate_disable() which are required 56202ad0596SDavid Miller * for the trampoline. The macro is split into 563f2dd3b39SAlexei Starovoitov * call __bpf_prog_enter 564fec56f58SAlexei Starovoitov * call prog->bpf_func 565fec56f58SAlexei Starovoitov * call __bpf_prog_exit 566ca06f55bSAlexei Starovoitov * 567ca06f55bSAlexei Starovoitov * __bpf_prog_enter returns: 568ca06f55bSAlexei Starovoitov * 0 - skip execution of the bpf prog 569ca06f55bSAlexei Starovoitov * 1 - execute bpf prog 5708fb33b60SZhen Lei * [2..MAX_U64] - execute bpf prog and record execution time. 571ca06f55bSAlexei Starovoitov * This is start time. 572fec56f58SAlexei Starovoitov */ 573ca06f55bSAlexei Starovoitov u64 notrace __bpf_prog_enter(struct bpf_prog *prog) 574dcce11d5SJules Irenge __acquires(RCU) 575fec56f58SAlexei Starovoitov { 576fec56f58SAlexei Starovoitov rcu_read_lock(); 57702ad0596SDavid Miller migrate_disable(); 5789ed9e9baSAlexei Starovoitov if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) { 5799ed9e9baSAlexei Starovoitov inc_misses_counter(prog); 580ca06f55bSAlexei Starovoitov return 0; 5819ed9e9baSAlexei Starovoitov } 582f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 583fec56f58SAlexei Starovoitov } 584fec56f58SAlexei Starovoitov 585f2dd3b39SAlexei Starovoitov static void notrace update_prog_stats(struct bpf_prog *prog, 586f2dd3b39SAlexei Starovoitov u64 start) 587fec56f58SAlexei Starovoitov { 588fec56f58SAlexei Starovoitov struct bpf_prog_stats *stats; 589fec56f58SAlexei Starovoitov 590fec56f58SAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key) && 591f2dd3b39SAlexei Starovoitov /* static_key could be enabled in __bpf_prog_enter* 592f2dd3b39SAlexei Starovoitov * and disabled in __bpf_prog_exit*. 593fec56f58SAlexei Starovoitov * And vice versa. 594f2dd3b39SAlexei Starovoitov * Hence check that 'start' is valid. 595fec56f58SAlexei Starovoitov */ 596f2dd3b39SAlexei Starovoitov start > NO_START_TIME) { 597d979617aSEric Dumazet unsigned long flags; 598d979617aSEric Dumazet 599700d4796SAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 600d979617aSEric Dumazet flags = u64_stats_update_begin_irqsave(&stats->syncp); 60161a0abaeSEric Dumazet u64_stats_inc(&stats->cnt); 60261a0abaeSEric Dumazet u64_stats_add(&stats->nsecs, sched_clock() - start); 603d979617aSEric Dumazet u64_stats_update_end_irqrestore(&stats->syncp, flags); 604fec56f58SAlexei Starovoitov } 605f2dd3b39SAlexei Starovoitov } 606f2dd3b39SAlexei Starovoitov 607f2dd3b39SAlexei Starovoitov void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start) 608f2dd3b39SAlexei Starovoitov __releases(RCU) 609f2dd3b39SAlexei Starovoitov { 610f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 611ca06f55bSAlexei Starovoitov __this_cpu_dec(*(prog->active)); 61202ad0596SDavid Miller migrate_enable(); 613fec56f58SAlexei Starovoitov rcu_read_unlock(); 614fec56f58SAlexei Starovoitov } 615fec56f58SAlexei Starovoitov 616ca06f55bSAlexei Starovoitov u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog) 6171e6c62a8SAlexei Starovoitov { 6181e6c62a8SAlexei Starovoitov rcu_read_lock_trace(); 619031d6e02SAlexei Starovoitov migrate_disable(); 620f56407faSAlexei Starovoitov might_fault(); 6219ed9e9baSAlexei Starovoitov if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) { 6229ed9e9baSAlexei Starovoitov inc_misses_counter(prog); 623ca06f55bSAlexei Starovoitov return 0; 6249ed9e9baSAlexei Starovoitov } 625f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 6261e6c62a8SAlexei Starovoitov } 6271e6c62a8SAlexei Starovoitov 628f2dd3b39SAlexei Starovoitov void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start) 6291e6c62a8SAlexei Starovoitov { 630f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 631ca06f55bSAlexei Starovoitov __this_cpu_dec(*(prog->active)); 632031d6e02SAlexei Starovoitov migrate_enable(); 6331e6c62a8SAlexei Starovoitov rcu_read_unlock_trace(); 6341e6c62a8SAlexei Starovoitov } 6351e6c62a8SAlexei Starovoitov 636e21aa341SAlexei Starovoitov void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr) 637e21aa341SAlexei Starovoitov { 638e21aa341SAlexei Starovoitov percpu_ref_get(&tr->pcref); 639e21aa341SAlexei Starovoitov } 640e21aa341SAlexei Starovoitov 641e21aa341SAlexei Starovoitov void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr) 642e21aa341SAlexei Starovoitov { 643e21aa341SAlexei Starovoitov percpu_ref_put(&tr->pcref); 644e21aa341SAlexei Starovoitov } 645e21aa341SAlexei Starovoitov 646fec56f58SAlexei Starovoitov int __weak 647e21aa341SAlexei Starovoitov arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, 64885d33df3SMartin KaFai Lau const struct btf_func_model *m, u32 flags, 64988fd9e53SKP Singh struct bpf_tramp_progs *tprogs, 650fec56f58SAlexei Starovoitov void *orig_call) 651fec56f58SAlexei Starovoitov { 652fec56f58SAlexei Starovoitov return -ENOTSUPP; 653fec56f58SAlexei Starovoitov } 654fec56f58SAlexei Starovoitov 655fec56f58SAlexei Starovoitov static int __init init_trampolines(void) 656fec56f58SAlexei Starovoitov { 657fec56f58SAlexei Starovoitov int i; 658fec56f58SAlexei Starovoitov 659fec56f58SAlexei Starovoitov for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++) 660fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&trampoline_table[i]); 661fec56f58SAlexei Starovoitov return 0; 662fec56f58SAlexei Starovoitov } 663fec56f58SAlexei Starovoitov late_initcall(init_trampolines); 664