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> 13fec56f58SAlexei Starovoitov 14be8704ffSAlexei Starovoitov /* dummy _ops. The verifier will operate on target program's ops. */ 15be8704ffSAlexei Starovoitov const struct bpf_verifier_ops bpf_extension_verifier_ops = { 16be8704ffSAlexei Starovoitov }; 17be8704ffSAlexei Starovoitov const struct bpf_prog_ops bpf_extension_prog_ops = { 18be8704ffSAlexei Starovoitov }; 19be8704ffSAlexei Starovoitov 20fec56f58SAlexei Starovoitov /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */ 21fec56f58SAlexei Starovoitov #define TRAMPOLINE_HASH_BITS 10 22fec56f58SAlexei Starovoitov #define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS) 23fec56f58SAlexei Starovoitov 24fec56f58SAlexei Starovoitov static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE]; 25fec56f58SAlexei Starovoitov 267ac88ebaSJiri Olsa /* serializes access to trampoline_table */ 27fec56f58SAlexei Starovoitov static DEFINE_MUTEX(trampoline_mutex); 28fec56f58SAlexei Starovoitov 297ac88ebaSJiri Olsa void *bpf_jit_alloc_exec_page(void) 3098e8627eSBjörn Töpel { 3198e8627eSBjörn Töpel void *image; 3298e8627eSBjörn Töpel 3398e8627eSBjörn Töpel image = bpf_jit_alloc_exec(PAGE_SIZE); 3498e8627eSBjörn Töpel if (!image) 3598e8627eSBjörn Töpel return NULL; 3698e8627eSBjörn Töpel 3798e8627eSBjörn Töpel set_vm_flush_reset_perms(image); 3898e8627eSBjörn Töpel /* Keep image as writeable. The alternative is to keep flipping ro/rw 3998e8627eSBjörn Töpel * everytime new program is attached or detached. 4098e8627eSBjörn Töpel */ 4198e8627eSBjörn Töpel set_memory_x((long)image, 1); 4298e8627eSBjörn Töpel return image; 4398e8627eSBjörn Töpel } 4498e8627eSBjörn Töpel 45a108f7dcSJiri Olsa void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) 46a108f7dcSJiri Olsa { 47a108f7dcSJiri Olsa ksym->start = (unsigned long) data; 487ac88ebaSJiri Olsa ksym->end = ksym->start + PAGE_SIZE; 49a108f7dcSJiri Olsa bpf_ksym_add(ksym); 50a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 517ac88ebaSJiri Olsa PAGE_SIZE, false, ksym->name); 52a108f7dcSJiri Olsa } 53a108f7dcSJiri Olsa 54a108f7dcSJiri Olsa void bpf_image_ksym_del(struct bpf_ksym *ksym) 55a108f7dcSJiri Olsa { 56a108f7dcSJiri Olsa bpf_ksym_del(ksym); 57a108f7dcSJiri Olsa perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, 587ac88ebaSJiri Olsa PAGE_SIZE, true, ksym->name); 59a108f7dcSJiri Olsa } 60a108f7dcSJiri Olsa 61f7b12b6fSToke Høiland-Jørgensen static struct bpf_trampoline *bpf_trampoline_lookup(u64 key) 62fec56f58SAlexei Starovoitov { 63fec56f58SAlexei Starovoitov struct bpf_trampoline *tr; 64fec56f58SAlexei Starovoitov struct hlist_head *head; 65fec56f58SAlexei Starovoitov int i; 66fec56f58SAlexei Starovoitov 67fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 68fec56f58SAlexei Starovoitov head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)]; 69fec56f58SAlexei Starovoitov hlist_for_each_entry(tr, head, hlist) { 70fec56f58SAlexei Starovoitov if (tr->key == key) { 71fec56f58SAlexei Starovoitov refcount_inc(&tr->refcnt); 72fec56f58SAlexei Starovoitov goto out; 73fec56f58SAlexei Starovoitov } 74fec56f58SAlexei Starovoitov } 75fec56f58SAlexei Starovoitov tr = kzalloc(sizeof(*tr), GFP_KERNEL); 76fec56f58SAlexei Starovoitov if (!tr) 77fec56f58SAlexei Starovoitov goto out; 78fec56f58SAlexei Starovoitov 79fec56f58SAlexei Starovoitov tr->key = key; 80fec56f58SAlexei Starovoitov INIT_HLIST_NODE(&tr->hlist); 81fec56f58SAlexei Starovoitov hlist_add_head(&tr->hlist, head); 82fec56f58SAlexei Starovoitov refcount_set(&tr->refcnt, 1); 83fec56f58SAlexei Starovoitov mutex_init(&tr->mutex); 84fec56f58SAlexei Starovoitov for (i = 0; i < BPF_TRAMP_MAX; i++) 85fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&tr->progs_hlist[i]); 86fec56f58SAlexei Starovoitov out: 87fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 88fec56f58SAlexei Starovoitov return tr; 89fec56f58SAlexei Starovoitov } 90fec56f58SAlexei Starovoitov 91861de02eSJiri Olsa static int bpf_trampoline_module_get(struct bpf_trampoline *tr) 92861de02eSJiri Olsa { 93861de02eSJiri Olsa struct module *mod; 94861de02eSJiri Olsa int err = 0; 95861de02eSJiri Olsa 96861de02eSJiri Olsa preempt_disable(); 97861de02eSJiri Olsa mod = __module_text_address((unsigned long) tr->func.addr); 98861de02eSJiri Olsa if (mod && !try_module_get(mod)) 99861de02eSJiri Olsa err = -ENOENT; 100861de02eSJiri Olsa preempt_enable(); 101861de02eSJiri Olsa tr->mod = mod; 102861de02eSJiri Olsa return err; 103861de02eSJiri Olsa } 104861de02eSJiri Olsa 105861de02eSJiri Olsa static void bpf_trampoline_module_put(struct bpf_trampoline *tr) 106861de02eSJiri Olsa { 107861de02eSJiri Olsa module_put(tr->mod); 108861de02eSJiri Olsa tr->mod = NULL; 109861de02eSJiri Olsa } 110861de02eSJiri Olsa 111b91e014fSAlexei Starovoitov static int is_ftrace_location(void *ip) 112b91e014fSAlexei Starovoitov { 113b91e014fSAlexei Starovoitov long addr; 114b91e014fSAlexei Starovoitov 115b91e014fSAlexei Starovoitov addr = ftrace_location((long)ip); 116b91e014fSAlexei Starovoitov if (!addr) 117b91e014fSAlexei Starovoitov return 0; 118b91e014fSAlexei Starovoitov if (WARN_ON_ONCE(addr != (long)ip)) 119b91e014fSAlexei Starovoitov return -EFAULT; 120b91e014fSAlexei Starovoitov return 1; 121b91e014fSAlexei Starovoitov } 122b91e014fSAlexei Starovoitov 123b91e014fSAlexei Starovoitov static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) 124b91e014fSAlexei Starovoitov { 125b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 126b91e014fSAlexei Starovoitov int ret; 127b91e014fSAlexei Starovoitov 128b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 129b91e014fSAlexei Starovoitov ret = unregister_ftrace_direct((long)ip, (long)old_addr); 130b91e014fSAlexei Starovoitov else 131b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); 132861de02eSJiri Olsa 133861de02eSJiri Olsa if (!ret) 134861de02eSJiri Olsa bpf_trampoline_module_put(tr); 135b91e014fSAlexei Starovoitov return ret; 136b91e014fSAlexei Starovoitov } 137b91e014fSAlexei Starovoitov 138b91e014fSAlexei Starovoitov static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr) 139b91e014fSAlexei Starovoitov { 140b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 141b91e014fSAlexei Starovoitov int ret; 142b91e014fSAlexei Starovoitov 143b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 144b91e014fSAlexei Starovoitov ret = modify_ftrace_direct((long)ip, (long)old_addr, (long)new_addr); 145b91e014fSAlexei Starovoitov else 146b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); 147b91e014fSAlexei Starovoitov return ret; 148b91e014fSAlexei Starovoitov } 149b91e014fSAlexei Starovoitov 150b91e014fSAlexei Starovoitov /* first time registering */ 151b91e014fSAlexei Starovoitov static int register_fentry(struct bpf_trampoline *tr, void *new_addr) 152b91e014fSAlexei Starovoitov { 153b91e014fSAlexei Starovoitov void *ip = tr->func.addr; 154b91e014fSAlexei Starovoitov int ret; 155b91e014fSAlexei Starovoitov 156b91e014fSAlexei Starovoitov ret = is_ftrace_location(ip); 157b91e014fSAlexei Starovoitov if (ret < 0) 158b91e014fSAlexei Starovoitov return ret; 159b91e014fSAlexei Starovoitov tr->func.ftrace_managed = ret; 160b91e014fSAlexei Starovoitov 161861de02eSJiri Olsa if (bpf_trampoline_module_get(tr)) 162861de02eSJiri Olsa return -ENOENT; 163861de02eSJiri Olsa 164b91e014fSAlexei Starovoitov if (tr->func.ftrace_managed) 165b91e014fSAlexei Starovoitov ret = register_ftrace_direct((long)ip, (long)new_addr); 166b91e014fSAlexei Starovoitov else 167b91e014fSAlexei Starovoitov ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); 168861de02eSJiri Olsa 169861de02eSJiri Olsa if (ret) 170861de02eSJiri Olsa bpf_trampoline_module_put(tr); 171b91e014fSAlexei Starovoitov return ret; 172b91e014fSAlexei Starovoitov } 173b91e014fSAlexei Starovoitov 17488fd9e53SKP Singh static struct bpf_tramp_progs * 17588fd9e53SKP Singh bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) 17688fd9e53SKP Singh { 17788fd9e53SKP Singh const struct bpf_prog_aux *aux; 17888fd9e53SKP Singh struct bpf_tramp_progs *tprogs; 17988fd9e53SKP Singh struct bpf_prog **progs; 18088fd9e53SKP Singh int kind; 18188fd9e53SKP Singh 18288fd9e53SKP Singh *total = 0; 18388fd9e53SKP Singh tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL); 18488fd9e53SKP Singh if (!tprogs) 18588fd9e53SKP Singh return ERR_PTR(-ENOMEM); 18688fd9e53SKP Singh 18788fd9e53SKP Singh for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { 18888fd9e53SKP Singh tprogs[kind].nr_progs = tr->progs_cnt[kind]; 18988fd9e53SKP Singh *total += tr->progs_cnt[kind]; 19088fd9e53SKP Singh progs = tprogs[kind].progs; 19188fd9e53SKP Singh 19288fd9e53SKP Singh hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) 19388fd9e53SKP Singh *progs++ = aux->prog; 19488fd9e53SKP Singh } 19588fd9e53SKP Singh return tprogs; 19688fd9e53SKP Singh } 197fec56f58SAlexei Starovoitov 198e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_deferred(struct work_struct *work) 199e21aa341SAlexei Starovoitov { 200e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 201e21aa341SAlexei Starovoitov 202e21aa341SAlexei Starovoitov im = container_of(work, struct bpf_tramp_image, work); 203e21aa341SAlexei Starovoitov bpf_image_ksym_del(&im->ksym); 204e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 205e21aa341SAlexei Starovoitov bpf_jit_uncharge_modmem(1); 206e21aa341SAlexei Starovoitov percpu_ref_exit(&im->pcref); 207e21aa341SAlexei Starovoitov kfree_rcu(im, rcu); 208e21aa341SAlexei Starovoitov } 209e21aa341SAlexei Starovoitov 210e21aa341SAlexei Starovoitov /* callback, fexit step 3 or fentry step 2 */ 211e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu) 212e21aa341SAlexei Starovoitov { 213e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 214e21aa341SAlexei Starovoitov 215e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 216e21aa341SAlexei Starovoitov INIT_WORK(&im->work, __bpf_tramp_image_put_deferred); 217e21aa341SAlexei Starovoitov schedule_work(&im->work); 218e21aa341SAlexei Starovoitov } 219e21aa341SAlexei Starovoitov 220e21aa341SAlexei Starovoitov /* callback, fexit step 2. Called after percpu_ref_kill confirms. */ 221e21aa341SAlexei Starovoitov static void __bpf_tramp_image_release(struct percpu_ref *pcref) 222e21aa341SAlexei Starovoitov { 223e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 224e21aa341SAlexei Starovoitov 225e21aa341SAlexei Starovoitov im = container_of(pcref, struct bpf_tramp_image, pcref); 226e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 227e21aa341SAlexei Starovoitov } 228e21aa341SAlexei Starovoitov 229e21aa341SAlexei Starovoitov /* callback, fexit or fentry step 1 */ 230e21aa341SAlexei Starovoitov static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu) 231e21aa341SAlexei Starovoitov { 232e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 233e21aa341SAlexei Starovoitov 234e21aa341SAlexei Starovoitov im = container_of(rcu, struct bpf_tramp_image, rcu); 235e21aa341SAlexei Starovoitov if (im->ip_after_call) 236e21aa341SAlexei Starovoitov /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ 237e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 238e21aa341SAlexei Starovoitov else 239e21aa341SAlexei Starovoitov /* the case of fentry trampoline */ 240e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu); 241e21aa341SAlexei Starovoitov } 242e21aa341SAlexei Starovoitov 243e21aa341SAlexei Starovoitov static void bpf_tramp_image_put(struct bpf_tramp_image *im) 244e21aa341SAlexei Starovoitov { 245e21aa341SAlexei Starovoitov /* The trampoline image that calls original function is using: 246e21aa341SAlexei Starovoitov * rcu_read_lock_trace to protect sleepable bpf progs 247e21aa341SAlexei Starovoitov * rcu_read_lock to protect normal bpf progs 248e21aa341SAlexei Starovoitov * percpu_ref to protect trampoline itself 249e21aa341SAlexei Starovoitov * rcu tasks to protect trampoline asm not covered by percpu_ref 250e21aa341SAlexei Starovoitov * (which are few asm insns before __bpf_tramp_enter and 251e21aa341SAlexei Starovoitov * after __bpf_tramp_exit) 252e21aa341SAlexei Starovoitov * 253e21aa341SAlexei Starovoitov * The trampoline is unreachable before bpf_tramp_image_put(). 254e21aa341SAlexei Starovoitov * 255e21aa341SAlexei Starovoitov * First, patch the trampoline to avoid calling into fexit progs. 256e21aa341SAlexei Starovoitov * The progs will be freed even if the original function is still 257e21aa341SAlexei Starovoitov * executing or sleeping. 258e21aa341SAlexei Starovoitov * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on 259e21aa341SAlexei Starovoitov * first few asm instructions to execute and call into 260e21aa341SAlexei Starovoitov * __bpf_tramp_enter->percpu_ref_get. 261e21aa341SAlexei Starovoitov * Then use percpu_ref_kill to wait for the trampoline and the original 262e21aa341SAlexei Starovoitov * function to finish. 263e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to make sure few asm insns in 264e21aa341SAlexei Starovoitov * the trampoline epilogue are done as well. 265e21aa341SAlexei Starovoitov * 266e21aa341SAlexei Starovoitov * In !PREEMPT case the task that got interrupted in the first asm 267e21aa341SAlexei Starovoitov * insns won't go through an RCU quiescent state which the 268e21aa341SAlexei Starovoitov * percpu_ref_kill will be waiting for. Hence the first 269e21aa341SAlexei Starovoitov * call_rcu_tasks() is not necessary. 270e21aa341SAlexei Starovoitov */ 271e21aa341SAlexei Starovoitov if (im->ip_after_call) { 272e21aa341SAlexei Starovoitov int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, 273e21aa341SAlexei Starovoitov NULL, im->ip_epilogue); 274e21aa341SAlexei Starovoitov WARN_ON(err); 275e21aa341SAlexei Starovoitov if (IS_ENABLED(CONFIG_PREEMPTION)) 276e21aa341SAlexei Starovoitov call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 277e21aa341SAlexei Starovoitov else 278e21aa341SAlexei Starovoitov percpu_ref_kill(&im->pcref); 279e21aa341SAlexei Starovoitov return; 280e21aa341SAlexei Starovoitov } 281e21aa341SAlexei Starovoitov 282e21aa341SAlexei Starovoitov /* The trampoline without fexit and fmod_ret progs doesn't call original 283e21aa341SAlexei Starovoitov * function and doesn't use percpu_ref. 284e21aa341SAlexei Starovoitov * Use call_rcu_tasks_trace() to wait for sleepable progs to finish. 285e21aa341SAlexei Starovoitov * Then use call_rcu_tasks() to wait for the rest of trampoline asm 286e21aa341SAlexei Starovoitov * and normal progs. 287e21aa341SAlexei Starovoitov */ 288e21aa341SAlexei Starovoitov call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); 289e21aa341SAlexei Starovoitov } 290e21aa341SAlexei Starovoitov 291e21aa341SAlexei Starovoitov static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) 292e21aa341SAlexei Starovoitov { 293e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 294e21aa341SAlexei Starovoitov struct bpf_ksym *ksym; 295e21aa341SAlexei Starovoitov void *image; 296e21aa341SAlexei Starovoitov int err = -ENOMEM; 297e21aa341SAlexei Starovoitov 298e21aa341SAlexei Starovoitov im = kzalloc(sizeof(*im), GFP_KERNEL); 299e21aa341SAlexei Starovoitov if (!im) 300e21aa341SAlexei Starovoitov goto out; 301e21aa341SAlexei Starovoitov 302e21aa341SAlexei Starovoitov err = bpf_jit_charge_modmem(1); 303e21aa341SAlexei Starovoitov if (err) 304e21aa341SAlexei Starovoitov goto out_free_im; 305e21aa341SAlexei Starovoitov 306e21aa341SAlexei Starovoitov err = -ENOMEM; 307e21aa341SAlexei Starovoitov im->image = image = bpf_jit_alloc_exec_page(); 308e21aa341SAlexei Starovoitov if (!image) 309e21aa341SAlexei Starovoitov goto out_uncharge; 310e21aa341SAlexei Starovoitov 311e21aa341SAlexei Starovoitov err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); 312e21aa341SAlexei Starovoitov if (err) 313e21aa341SAlexei Starovoitov goto out_free_image; 314e21aa341SAlexei Starovoitov 315e21aa341SAlexei Starovoitov ksym = &im->ksym; 316e21aa341SAlexei Starovoitov INIT_LIST_HEAD_RCU(&ksym->lnode); 317e21aa341SAlexei Starovoitov snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); 318e21aa341SAlexei Starovoitov bpf_image_ksym_add(image, ksym); 319e21aa341SAlexei Starovoitov return im; 320e21aa341SAlexei Starovoitov 321e21aa341SAlexei Starovoitov out_free_image: 322e21aa341SAlexei Starovoitov bpf_jit_free_exec(im->image); 323e21aa341SAlexei Starovoitov out_uncharge: 324e21aa341SAlexei Starovoitov bpf_jit_uncharge_modmem(1); 325e21aa341SAlexei Starovoitov out_free_im: 326e21aa341SAlexei Starovoitov kfree(im); 327e21aa341SAlexei Starovoitov out: 328e21aa341SAlexei Starovoitov return ERR_PTR(err); 329e21aa341SAlexei Starovoitov } 330e21aa341SAlexei Starovoitov 331fec56f58SAlexei Starovoitov static int bpf_trampoline_update(struct bpf_trampoline *tr) 332fec56f58SAlexei Starovoitov { 333e21aa341SAlexei Starovoitov struct bpf_tramp_image *im; 33488fd9e53SKP Singh struct bpf_tramp_progs *tprogs; 335fec56f58SAlexei Starovoitov u32 flags = BPF_TRAMP_F_RESTORE_REGS; 33688fd9e53SKP Singh int err, total; 337fec56f58SAlexei Starovoitov 33888fd9e53SKP Singh tprogs = bpf_trampoline_get_progs(tr, &total); 33988fd9e53SKP Singh if (IS_ERR(tprogs)) 34088fd9e53SKP Singh return PTR_ERR(tprogs); 34188fd9e53SKP Singh 34288fd9e53SKP Singh if (total == 0) { 343e21aa341SAlexei Starovoitov err = unregister_fentry(tr, tr->cur_image->image); 344e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 345e21aa341SAlexei Starovoitov tr->cur_image = NULL; 346fec56f58SAlexei Starovoitov tr->selector = 0; 347fec56f58SAlexei Starovoitov goto out; 348fec56f58SAlexei Starovoitov } 349fec56f58SAlexei Starovoitov 350e21aa341SAlexei Starovoitov im = bpf_tramp_image_alloc(tr->key, tr->selector); 351e21aa341SAlexei Starovoitov if (IS_ERR(im)) { 352e21aa341SAlexei Starovoitov err = PTR_ERR(im); 353e21aa341SAlexei Starovoitov goto out; 354e21aa341SAlexei Starovoitov } 355e21aa341SAlexei Starovoitov 356ae240823SKP Singh if (tprogs[BPF_TRAMP_FEXIT].nr_progs || 357ae240823SKP Singh tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) 358fec56f58SAlexei Starovoitov flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; 359fec56f58SAlexei Starovoitov 360e21aa341SAlexei Starovoitov err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, 36188fd9e53SKP Singh &tr->func.model, flags, tprogs, 362fec56f58SAlexei Starovoitov tr->func.addr); 36385d33df3SMartin KaFai Lau if (err < 0) 364fec56f58SAlexei Starovoitov goto out; 365fec56f58SAlexei Starovoitov 366e21aa341SAlexei Starovoitov WARN_ON(tr->cur_image && tr->selector == 0); 367e21aa341SAlexei Starovoitov WARN_ON(!tr->cur_image && tr->selector); 368e21aa341SAlexei Starovoitov if (tr->cur_image) 369fec56f58SAlexei Starovoitov /* progs already running at this address */ 370e21aa341SAlexei Starovoitov err = modify_fentry(tr, tr->cur_image->image, im->image); 371fec56f58SAlexei Starovoitov else 372fec56f58SAlexei Starovoitov /* first time registering */ 373e21aa341SAlexei Starovoitov err = register_fentry(tr, im->image); 374fec56f58SAlexei Starovoitov if (err) 375fec56f58SAlexei Starovoitov goto out; 376e21aa341SAlexei Starovoitov if (tr->cur_image) 377e21aa341SAlexei Starovoitov bpf_tramp_image_put(tr->cur_image); 378e21aa341SAlexei Starovoitov tr->cur_image = im; 379fec56f58SAlexei Starovoitov tr->selector++; 380fec56f58SAlexei Starovoitov out: 38188fd9e53SKP Singh kfree(tprogs); 382fec56f58SAlexei Starovoitov return err; 383fec56f58SAlexei Starovoitov } 384fec56f58SAlexei Starovoitov 3859e4e01dfSKP Singh static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog) 386fec56f58SAlexei Starovoitov { 3879e4e01dfSKP Singh switch (prog->expected_attach_type) { 388fec56f58SAlexei Starovoitov case BPF_TRACE_FENTRY: 389fec56f58SAlexei Starovoitov return BPF_TRAMP_FENTRY; 390ae240823SKP Singh case BPF_MODIFY_RETURN: 391ae240823SKP Singh return BPF_TRAMP_MODIFY_RETURN; 392be8704ffSAlexei Starovoitov case BPF_TRACE_FEXIT: 393fec56f58SAlexei Starovoitov return BPF_TRAMP_FEXIT; 3949e4e01dfSKP Singh case BPF_LSM_MAC: 3959e4e01dfSKP Singh if (!prog->aux->attach_func_proto->type) 3969e4e01dfSKP Singh /* The function returns void, we cannot modify its 3979e4e01dfSKP Singh * return value. 3989e4e01dfSKP Singh */ 3999e4e01dfSKP Singh return BPF_TRAMP_FEXIT; 4009e4e01dfSKP Singh else 4019e4e01dfSKP Singh return BPF_TRAMP_MODIFY_RETURN; 402be8704ffSAlexei Starovoitov default: 403be8704ffSAlexei Starovoitov return BPF_TRAMP_REPLACE; 404fec56f58SAlexei Starovoitov } 405fec56f58SAlexei Starovoitov } 406fec56f58SAlexei Starovoitov 4073aac1eadSToke Høiland-Jørgensen int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) 408fec56f58SAlexei Starovoitov { 409fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 410fec56f58SAlexei Starovoitov int err = 0; 411be8704ffSAlexei Starovoitov int cnt; 412fec56f58SAlexei Starovoitov 4139e4e01dfSKP Singh kind = bpf_attach_type_to_tramp(prog); 414fec56f58SAlexei Starovoitov mutex_lock(&tr->mutex); 415be8704ffSAlexei Starovoitov if (tr->extension_prog) { 416be8704ffSAlexei Starovoitov /* cannot attach fentry/fexit if extension prog is attached. 417be8704ffSAlexei Starovoitov * cannot overwrite extension prog either. 418be8704ffSAlexei Starovoitov */ 419be8704ffSAlexei Starovoitov err = -EBUSY; 420be8704ffSAlexei Starovoitov goto out; 421be8704ffSAlexei Starovoitov } 422be8704ffSAlexei Starovoitov cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT]; 423be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 424be8704ffSAlexei Starovoitov /* Cannot attach extension if fentry/fexit are in use. */ 425be8704ffSAlexei Starovoitov if (cnt) { 426be8704ffSAlexei Starovoitov err = -EBUSY; 427be8704ffSAlexei Starovoitov goto out; 428be8704ffSAlexei Starovoitov } 429be8704ffSAlexei Starovoitov tr->extension_prog = prog; 430be8704ffSAlexei Starovoitov err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, 431be8704ffSAlexei Starovoitov prog->bpf_func); 432be8704ffSAlexei Starovoitov goto out; 433be8704ffSAlexei Starovoitov } 434be8704ffSAlexei Starovoitov if (cnt >= BPF_MAX_TRAMP_PROGS) { 435fec56f58SAlexei Starovoitov err = -E2BIG; 436fec56f58SAlexei Starovoitov goto out; 437fec56f58SAlexei Starovoitov } 438fec56f58SAlexei Starovoitov if (!hlist_unhashed(&prog->aux->tramp_hlist)) { 439fec56f58SAlexei Starovoitov /* prog already linked */ 440fec56f58SAlexei Starovoitov err = -EBUSY; 441fec56f58SAlexei Starovoitov goto out; 442fec56f58SAlexei Starovoitov } 443fec56f58SAlexei Starovoitov hlist_add_head(&prog->aux->tramp_hlist, &tr->progs_hlist[kind]); 444fec56f58SAlexei Starovoitov tr->progs_cnt[kind]++; 4453aac1eadSToke Høiland-Jørgensen err = bpf_trampoline_update(tr); 446fec56f58SAlexei Starovoitov if (err) { 447f3a95075SJiri Olsa hlist_del_init(&prog->aux->tramp_hlist); 448fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 449fec56f58SAlexei Starovoitov } 450fec56f58SAlexei Starovoitov out: 451fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 452fec56f58SAlexei Starovoitov return err; 453fec56f58SAlexei Starovoitov } 454fec56f58SAlexei Starovoitov 455fec56f58SAlexei Starovoitov /* bpf_trampoline_unlink_prog() should never fail. */ 4563aac1eadSToke Høiland-Jørgensen int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) 457fec56f58SAlexei Starovoitov { 458fec56f58SAlexei Starovoitov enum bpf_tramp_prog_type kind; 459fec56f58SAlexei Starovoitov int err; 460fec56f58SAlexei Starovoitov 4619e4e01dfSKP Singh kind = bpf_attach_type_to_tramp(prog); 462fec56f58SAlexei Starovoitov mutex_lock(&tr->mutex); 463be8704ffSAlexei Starovoitov if (kind == BPF_TRAMP_REPLACE) { 464be8704ffSAlexei Starovoitov WARN_ON_ONCE(!tr->extension_prog); 465be8704ffSAlexei Starovoitov err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, 466be8704ffSAlexei Starovoitov tr->extension_prog->bpf_func, NULL); 467be8704ffSAlexei Starovoitov tr->extension_prog = NULL; 468be8704ffSAlexei Starovoitov goto out; 469be8704ffSAlexei Starovoitov } 470f3a95075SJiri Olsa hlist_del_init(&prog->aux->tramp_hlist); 471fec56f58SAlexei Starovoitov tr->progs_cnt[kind]--; 4723aac1eadSToke Høiland-Jørgensen err = bpf_trampoline_update(tr); 473be8704ffSAlexei Starovoitov out: 474fec56f58SAlexei Starovoitov mutex_unlock(&tr->mutex); 475fec56f58SAlexei Starovoitov return err; 476fec56f58SAlexei Starovoitov } 477fec56f58SAlexei Starovoitov 478f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *bpf_trampoline_get(u64 key, 479f7b12b6fSToke Høiland-Jørgensen struct bpf_attach_target_info *tgt_info) 480f7b12b6fSToke Høiland-Jørgensen { 481f7b12b6fSToke Høiland-Jørgensen struct bpf_trampoline *tr; 482f7b12b6fSToke Høiland-Jørgensen 483f7b12b6fSToke Høiland-Jørgensen tr = bpf_trampoline_lookup(key); 484f7b12b6fSToke Høiland-Jørgensen if (!tr) 485f7b12b6fSToke Høiland-Jørgensen return NULL; 486f7b12b6fSToke Høiland-Jørgensen 487f7b12b6fSToke Høiland-Jørgensen mutex_lock(&tr->mutex); 488f7b12b6fSToke Høiland-Jørgensen if (tr->func.addr) 489f7b12b6fSToke Høiland-Jørgensen goto out; 490f7b12b6fSToke Høiland-Jørgensen 491f7b12b6fSToke Høiland-Jørgensen memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); 492f7b12b6fSToke Høiland-Jørgensen tr->func.addr = (void *)tgt_info->tgt_addr; 493f7b12b6fSToke Høiland-Jørgensen out: 494f7b12b6fSToke Høiland-Jørgensen mutex_unlock(&tr->mutex); 495f7b12b6fSToke Høiland-Jørgensen return tr; 496f7b12b6fSToke Høiland-Jørgensen } 497f7b12b6fSToke Høiland-Jørgensen 498fec56f58SAlexei Starovoitov void bpf_trampoline_put(struct bpf_trampoline *tr) 499fec56f58SAlexei Starovoitov { 500fec56f58SAlexei Starovoitov if (!tr) 501fec56f58SAlexei Starovoitov return; 502fec56f58SAlexei Starovoitov mutex_lock(&trampoline_mutex); 503fec56f58SAlexei Starovoitov if (!refcount_dec_and_test(&tr->refcnt)) 504fec56f58SAlexei Starovoitov goto out; 505fec56f58SAlexei Starovoitov WARN_ON_ONCE(mutex_is_locked(&tr->mutex)); 506fec56f58SAlexei Starovoitov if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FENTRY]))) 507fec56f58SAlexei Starovoitov goto out; 508fec56f58SAlexei Starovoitov if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FEXIT]))) 509fec56f58SAlexei Starovoitov goto out; 510e21aa341SAlexei Starovoitov /* This code will be executed even when the last bpf_tramp_image 511e21aa341SAlexei Starovoitov * is alive. All progs are detached from the trampoline and the 512e21aa341SAlexei Starovoitov * trampoline image is patched with jmp into epilogue to skip 513e21aa341SAlexei Starovoitov * fexit progs. The fentry-only trampoline will be freed via 514e21aa341SAlexei Starovoitov * multiple rcu callbacks. 5151e6c62a8SAlexei Starovoitov */ 516fec56f58SAlexei Starovoitov hlist_del(&tr->hlist); 517fec56f58SAlexei Starovoitov kfree(tr); 518fec56f58SAlexei Starovoitov out: 519fec56f58SAlexei Starovoitov mutex_unlock(&trampoline_mutex); 520fec56f58SAlexei Starovoitov } 521fec56f58SAlexei Starovoitov 522ca06f55bSAlexei Starovoitov #define NO_START_TIME 1 523f2dd3b39SAlexei Starovoitov static u64 notrace bpf_prog_start_time(void) 524f2dd3b39SAlexei Starovoitov { 525f2dd3b39SAlexei Starovoitov u64 start = NO_START_TIME; 526f2dd3b39SAlexei Starovoitov 527ca06f55bSAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key)) { 528f2dd3b39SAlexei Starovoitov start = sched_clock(); 529ca06f55bSAlexei Starovoitov if (unlikely(!start)) 530ca06f55bSAlexei Starovoitov start = NO_START_TIME; 531ca06f55bSAlexei Starovoitov } 532f2dd3b39SAlexei Starovoitov return start; 533f2dd3b39SAlexei Starovoitov } 534f2dd3b39SAlexei Starovoitov 5359ed9e9baSAlexei Starovoitov static void notrace inc_misses_counter(struct bpf_prog *prog) 5369ed9e9baSAlexei Starovoitov { 5379ed9e9baSAlexei Starovoitov struct bpf_prog_stats *stats; 5389ed9e9baSAlexei Starovoitov 5399ed9e9baSAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 5409ed9e9baSAlexei Starovoitov u64_stats_update_begin(&stats->syncp); 5419ed9e9baSAlexei Starovoitov stats->misses++; 5429ed9e9baSAlexei Starovoitov u64_stats_update_end(&stats->syncp); 5439ed9e9baSAlexei Starovoitov } 5449ed9e9baSAlexei Starovoitov 54502ad0596SDavid Miller /* The logic is similar to BPF_PROG_RUN, but with an explicit 54602ad0596SDavid Miller * rcu_read_lock() and migrate_disable() which are required 54702ad0596SDavid Miller * for the trampoline. The macro is split into 548f2dd3b39SAlexei Starovoitov * call __bpf_prog_enter 549fec56f58SAlexei Starovoitov * call prog->bpf_func 550fec56f58SAlexei Starovoitov * call __bpf_prog_exit 551ca06f55bSAlexei Starovoitov * 552ca06f55bSAlexei Starovoitov * __bpf_prog_enter returns: 553ca06f55bSAlexei Starovoitov * 0 - skip execution of the bpf prog 554ca06f55bSAlexei Starovoitov * 1 - execute bpf prog 555*8fb33b60SZhen Lei * [2..MAX_U64] - execute bpf prog and record execution time. 556ca06f55bSAlexei Starovoitov * This is start time. 557fec56f58SAlexei Starovoitov */ 558ca06f55bSAlexei Starovoitov u64 notrace __bpf_prog_enter(struct bpf_prog *prog) 559dcce11d5SJules Irenge __acquires(RCU) 560fec56f58SAlexei Starovoitov { 561fec56f58SAlexei Starovoitov rcu_read_lock(); 56202ad0596SDavid Miller migrate_disable(); 5639ed9e9baSAlexei Starovoitov if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) { 5649ed9e9baSAlexei Starovoitov inc_misses_counter(prog); 565ca06f55bSAlexei Starovoitov return 0; 5669ed9e9baSAlexei Starovoitov } 567f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 568fec56f58SAlexei Starovoitov } 569fec56f58SAlexei Starovoitov 570f2dd3b39SAlexei Starovoitov static void notrace update_prog_stats(struct bpf_prog *prog, 571f2dd3b39SAlexei Starovoitov u64 start) 572fec56f58SAlexei Starovoitov { 573fec56f58SAlexei Starovoitov struct bpf_prog_stats *stats; 574fec56f58SAlexei Starovoitov 575fec56f58SAlexei Starovoitov if (static_branch_unlikely(&bpf_stats_enabled_key) && 576f2dd3b39SAlexei Starovoitov /* static_key could be enabled in __bpf_prog_enter* 577f2dd3b39SAlexei Starovoitov * and disabled in __bpf_prog_exit*. 578fec56f58SAlexei Starovoitov * And vice versa. 579f2dd3b39SAlexei Starovoitov * Hence check that 'start' is valid. 580fec56f58SAlexei Starovoitov */ 581f2dd3b39SAlexei Starovoitov start > NO_START_TIME) { 582700d4796SAlexei Starovoitov stats = this_cpu_ptr(prog->stats); 583fec56f58SAlexei Starovoitov u64_stats_update_begin(&stats->syncp); 584fec56f58SAlexei Starovoitov stats->cnt++; 585fec56f58SAlexei Starovoitov stats->nsecs += sched_clock() - start; 586fec56f58SAlexei Starovoitov u64_stats_update_end(&stats->syncp); 587fec56f58SAlexei Starovoitov } 588f2dd3b39SAlexei Starovoitov } 589f2dd3b39SAlexei Starovoitov 590f2dd3b39SAlexei Starovoitov void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start) 591f2dd3b39SAlexei Starovoitov __releases(RCU) 592f2dd3b39SAlexei Starovoitov { 593f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 594ca06f55bSAlexei Starovoitov __this_cpu_dec(*(prog->active)); 59502ad0596SDavid Miller migrate_enable(); 596fec56f58SAlexei Starovoitov rcu_read_unlock(); 597fec56f58SAlexei Starovoitov } 598fec56f58SAlexei Starovoitov 599ca06f55bSAlexei Starovoitov u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog) 6001e6c62a8SAlexei Starovoitov { 6011e6c62a8SAlexei Starovoitov rcu_read_lock_trace(); 602031d6e02SAlexei Starovoitov migrate_disable(); 603f56407faSAlexei Starovoitov might_fault(); 6049ed9e9baSAlexei Starovoitov if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) { 6059ed9e9baSAlexei Starovoitov inc_misses_counter(prog); 606ca06f55bSAlexei Starovoitov return 0; 6079ed9e9baSAlexei Starovoitov } 608f2dd3b39SAlexei Starovoitov return bpf_prog_start_time(); 6091e6c62a8SAlexei Starovoitov } 6101e6c62a8SAlexei Starovoitov 611f2dd3b39SAlexei Starovoitov void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start) 6121e6c62a8SAlexei Starovoitov { 613f2dd3b39SAlexei Starovoitov update_prog_stats(prog, start); 614ca06f55bSAlexei Starovoitov __this_cpu_dec(*(prog->active)); 615031d6e02SAlexei Starovoitov migrate_enable(); 6161e6c62a8SAlexei Starovoitov rcu_read_unlock_trace(); 6171e6c62a8SAlexei Starovoitov } 6181e6c62a8SAlexei Starovoitov 619e21aa341SAlexei Starovoitov void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr) 620e21aa341SAlexei Starovoitov { 621e21aa341SAlexei Starovoitov percpu_ref_get(&tr->pcref); 622e21aa341SAlexei Starovoitov } 623e21aa341SAlexei Starovoitov 624e21aa341SAlexei Starovoitov void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr) 625e21aa341SAlexei Starovoitov { 626e21aa341SAlexei Starovoitov percpu_ref_put(&tr->pcref); 627e21aa341SAlexei Starovoitov } 628e21aa341SAlexei Starovoitov 629fec56f58SAlexei Starovoitov int __weak 630e21aa341SAlexei Starovoitov arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, 63185d33df3SMartin KaFai Lau const struct btf_func_model *m, u32 flags, 63288fd9e53SKP Singh struct bpf_tramp_progs *tprogs, 633fec56f58SAlexei Starovoitov void *orig_call) 634fec56f58SAlexei Starovoitov { 635fec56f58SAlexei Starovoitov return -ENOTSUPP; 636fec56f58SAlexei Starovoitov } 637fec56f58SAlexei Starovoitov 638fec56f58SAlexei Starovoitov static int __init init_trampolines(void) 639fec56f58SAlexei Starovoitov { 640fec56f58SAlexei Starovoitov int i; 641fec56f58SAlexei Starovoitov 642fec56f58SAlexei Starovoitov for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++) 643fec56f58SAlexei Starovoitov INIT_HLIST_HEAD(&trampoline_table[i]); 644fec56f58SAlexei Starovoitov return 0; 645fec56f58SAlexei Starovoitov } 646fec56f58SAlexei Starovoitov late_initcall(init_trampolines); 647