// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2025 - Google LLC * Author: Vincent Donnefort */ #include #include #include #include #include #include #include #include "trace.h" #define TRACEFS_DIR "remotes" #define TRACEFS_MODE_WRITE 0640 #define TRACEFS_MODE_READ 0440 enum tri_type { TRI_CONSUMING, TRI_NONCONSUMING, }; struct trace_remote_iterator { struct trace_remote *remote; struct trace_seq seq; struct delayed_work poll_work; unsigned long lost_events; u64 ts; struct ring_buffer_iter *rb_iter; struct ring_buffer_iter **rb_iters; struct remote_event_hdr *evt; int cpu; int evt_cpu; loff_t pos; enum tri_type type; }; struct trace_remote { struct trace_remote_callbacks *cbs; void *priv; struct trace_buffer *trace_buffer; struct trace_buffer_desc *trace_buffer_desc; struct dentry *dentry; struct eventfs_inode *eventfs; struct remote_event *events; unsigned long nr_events; unsigned long trace_buffer_size; struct ring_buffer_remote rb_remote; struct mutex lock; struct rw_semaphore reader_lock; struct rw_semaphore *pcpu_reader_locks; unsigned int nr_readers; unsigned int poll_ms; bool tracing_on; }; static bool trace_remote_loaded(struct trace_remote *remote) { return !!remote->trace_buffer; } static int trace_remote_load(struct trace_remote *remote) { struct ring_buffer_remote *rb_remote = &remote->rb_remote; struct trace_buffer_desc *desc; lockdep_assert_held(&remote->lock); if (trace_remote_loaded(remote)) return 0; desc = remote->cbs->load_trace_buffer(remote->trace_buffer_size, remote->priv); if (IS_ERR(desc)) return PTR_ERR(desc); rb_remote->desc = desc; rb_remote->swap_reader_page = remote->cbs->swap_reader_page; rb_remote->priv = remote->priv; rb_remote->reset = remote->cbs->reset; remote->trace_buffer = ring_buffer_alloc_remote(rb_remote); if (!remote->trace_buffer) { remote->cbs->unload_trace_buffer(desc, remote->priv); return -ENOMEM; } remote->trace_buffer_desc = desc; return 0; } static void trace_remote_try_unload(struct trace_remote *remote) { lockdep_assert_held(&remote->lock); if (!trace_remote_loaded(remote)) return; /* The buffer is being read or writable */ if (remote->nr_readers || remote->tracing_on) return; /* The buffer has readable data */ if (!ring_buffer_empty(remote->trace_buffer)) return; ring_buffer_free(remote->trace_buffer); remote->trace_buffer = NULL; remote->cbs->unload_trace_buffer(remote->trace_buffer_desc, remote->priv); } static int trace_remote_enable_tracing(struct trace_remote *remote) { int ret; lockdep_assert_held(&remote->lock); if (remote->tracing_on) return 0; ret = trace_remote_load(remote); if (ret) return ret; ret = remote->cbs->enable_tracing(true, remote->priv); if (ret) { trace_remote_try_unload(remote); return ret; } remote->tracing_on = true; return 0; } static int trace_remote_disable_tracing(struct trace_remote *remote) { int ret; lockdep_assert_held(&remote->lock); if (!remote->tracing_on) return 0; ret = remote->cbs->enable_tracing(false, remote->priv); if (ret) return ret; ring_buffer_poll_remote(remote->trace_buffer, RING_BUFFER_ALL_CPUS); remote->tracing_on = false; trace_remote_try_unload(remote); return 0; } static void trace_remote_reset(struct trace_remote *remote, int cpu) { lockdep_assert_held(&remote->lock); if (!trace_remote_loaded(remote)) return; if (cpu == RING_BUFFER_ALL_CPUS) ring_buffer_reset(remote->trace_buffer); else ring_buffer_reset_cpu(remote->trace_buffer, cpu); trace_remote_try_unload(remote); } static ssize_t tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { struct seq_file *seq = filp->private_data; struct trace_remote *remote = seq->private; unsigned long val; int ret; ret = kstrtoul_from_user(ubuf, cnt, 10, &val); if (ret) return ret; guard(mutex)(&remote->lock); ret = val ? trace_remote_enable_tracing(remote) : trace_remote_disable_tracing(remote); if (ret) return ret; return cnt; } static int tracing_on_show(struct seq_file *s, void *unused) { struct trace_remote *remote = s->private; seq_printf(s, "%d\n", remote->tracing_on); return 0; } DEFINE_SHOW_STORE_ATTRIBUTE(tracing_on); static ssize_t buffer_size_kb_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { struct seq_file *seq = filp->private_data; struct trace_remote *remote = seq->private; unsigned long val; int ret; ret = kstrtoul_from_user(ubuf, cnt, 10, &val); if (ret) return ret; /* KiB to Bytes */ if (!val || check_shl_overflow(val, 10, &val)) return -EINVAL; guard(mutex)(&remote->lock); if (trace_remote_loaded(remote)) return -EBUSY; remote->trace_buffer_size = val; return cnt; } static int buffer_size_kb_show(struct seq_file *s, void *unused) { struct trace_remote *remote = s->private; seq_printf(s, "%lu (%s)\n", remote->trace_buffer_size >> 10, trace_remote_loaded(remote) ? "loaded" : "unloaded"); return 0; } DEFINE_SHOW_STORE_ATTRIBUTE(buffer_size_kb); static int trace_remote_get(struct trace_remote *remote, int cpu) { int ret; if (remote->nr_readers == UINT_MAX) return -EBUSY; ret = trace_remote_load(remote); if (ret) return ret; if (cpu != RING_BUFFER_ALL_CPUS && !remote->pcpu_reader_locks) { int lock_cpu; remote->pcpu_reader_locks = kcalloc(nr_cpu_ids, sizeof(*remote->pcpu_reader_locks), GFP_KERNEL); if (!remote->pcpu_reader_locks) { trace_remote_try_unload(remote); return -ENOMEM; } for_each_possible_cpu(lock_cpu) init_rwsem(&remote->pcpu_reader_locks[lock_cpu]); } remote->nr_readers++; return 0; } static void trace_remote_put(struct trace_remote *remote) { if (WARN_ON(!remote->nr_readers)) return; remote->nr_readers--; if (remote->nr_readers) return; kfree(remote->pcpu_reader_locks); remote->pcpu_reader_locks = NULL; trace_remote_try_unload(remote); } static void __poll_remote(struct work_struct *work) { struct delayed_work *dwork = to_delayed_work(work); struct trace_remote_iterator *iter; iter = container_of(dwork, struct trace_remote_iterator, poll_work); ring_buffer_poll_remote(iter->remote->trace_buffer, iter->cpu); schedule_delayed_work((struct delayed_work *)work, msecs_to_jiffies(iter->remote->poll_ms)); } static void __free_ring_buffer_iter(struct trace_remote_iterator *iter, int cpu) { if (cpu != RING_BUFFER_ALL_CPUS) { ring_buffer_read_finish(iter->rb_iter); return; } for_each_possible_cpu(cpu) { if (iter->rb_iters[cpu]) ring_buffer_read_finish(iter->rb_iters[cpu]); } kfree(iter->rb_iters); } static int __alloc_ring_buffer_iter(struct trace_remote_iterator *iter, int cpu) { if (cpu != RING_BUFFER_ALL_CPUS) { iter->rb_iter = ring_buffer_read_start(iter->remote->trace_buffer, cpu, GFP_KERNEL); return iter->rb_iter ? 0 : -ENOMEM; } iter->rb_iters = kcalloc(nr_cpu_ids, sizeof(*iter->rb_iters), GFP_KERNEL); if (!iter->rb_iters) return -ENOMEM; for_each_possible_cpu(cpu) { iter->rb_iters[cpu] = ring_buffer_read_start(iter->remote->trace_buffer, cpu, GFP_KERNEL); if (!iter->rb_iters[cpu]) { __free_ring_buffer_iter(iter, RING_BUFFER_ALL_CPUS); return -ENOMEM; } } return 0; } static struct trace_remote_iterator *trace_remote_iter(struct trace_remote *remote, int cpu, enum tri_type type) { struct trace_remote_iterator *iter = NULL; int ret; lockdep_assert_held(&remote->lock); if (type == TRI_NONCONSUMING && !trace_remote_loaded(remote)) return NULL; ret = trace_remote_get(remote, cpu); if (ret) return ERR_PTR(ret); /* Test the CPU */ ret = ring_buffer_poll_remote(remote->trace_buffer, cpu); if (ret) goto err; iter = kzalloc_obj(*iter); if (iter) { iter->remote = remote; iter->cpu = cpu; iter->type = type; trace_seq_init(&iter->seq); switch (type) { case TRI_CONSUMING: INIT_DELAYED_WORK(&iter->poll_work, __poll_remote); schedule_delayed_work(&iter->poll_work, msecs_to_jiffies(remote->poll_ms)); break; case TRI_NONCONSUMING: ret = __alloc_ring_buffer_iter(iter, cpu); break; } if (ret) goto err; return iter; } ret = -ENOMEM; err: kfree(iter); trace_remote_put(remote); return ERR_PTR(ret); } static void trace_remote_iter_free(struct trace_remote_iterator *iter) { struct trace_remote *remote; if (!iter) return; remote = iter->remote; lockdep_assert_held(&remote->lock); switch (iter->type) { case TRI_CONSUMING: cancel_delayed_work_sync(&iter->poll_work); break; case TRI_NONCONSUMING: __free_ring_buffer_iter(iter, iter->cpu); break; } kfree(iter); trace_remote_put(remote); } static void trace_remote_iter_read_start(struct trace_remote_iterator *iter) { struct trace_remote *remote = iter->remote; int cpu = iter->cpu; /* Acquire global reader lock */ if (cpu == RING_BUFFER_ALL_CPUS && iter->type == TRI_CONSUMING) down_write(&remote->reader_lock); else down_read(&remote->reader_lock); if (cpu == RING_BUFFER_ALL_CPUS) return; /* * No need for the remote lock here, iter holds a reference on * remote->nr_readers */ /* Get the per-CPU one */ if (WARN_ON_ONCE(!remote->pcpu_reader_locks)) return; if (iter->type == TRI_CONSUMING) down_write(&remote->pcpu_reader_locks[cpu]); else down_read(&remote->pcpu_reader_locks[cpu]); } static void trace_remote_iter_read_finished(struct trace_remote_iterator *iter) { struct trace_remote *remote = iter->remote; int cpu = iter->cpu; /* Release per-CPU reader lock */ if (cpu != RING_BUFFER_ALL_CPUS) { /* * No need for the remote lock here, iter holds a reference on * remote->nr_readers */ if (iter->type == TRI_CONSUMING) up_write(&remote->pcpu_reader_locks[cpu]); else up_read(&remote->pcpu_reader_locks[cpu]); } /* Release global reader lock */ if (cpu == RING_BUFFER_ALL_CPUS && iter->type == TRI_CONSUMING) up_write(&remote->reader_lock); else up_read(&remote->reader_lock); } static struct ring_buffer_iter *__get_rb_iter(struct trace_remote_iterator *iter, int cpu) { return iter->cpu != RING_BUFFER_ALL_CPUS ? iter->rb_iter : iter->rb_iters[cpu]; } static struct ring_buffer_event * __peek_event(struct trace_remote_iterator *iter, int cpu, u64 *ts, unsigned long *lost_events) { struct ring_buffer_event *rb_evt; struct ring_buffer_iter *rb_iter; switch (iter->type) { case TRI_CONSUMING: return ring_buffer_peek(iter->remote->trace_buffer, cpu, ts, lost_events); case TRI_NONCONSUMING: rb_iter = __get_rb_iter(iter, cpu); rb_evt = ring_buffer_iter_peek(rb_iter, ts); if (!rb_evt) return NULL; *lost_events = ring_buffer_iter_dropped(rb_iter); return rb_evt; } return NULL; } static bool trace_remote_iter_read_event(struct trace_remote_iterator *iter) { struct trace_buffer *trace_buffer = iter->remote->trace_buffer; struct ring_buffer_event *rb_evt; int cpu = iter->cpu; if (cpu != RING_BUFFER_ALL_CPUS) { if (ring_buffer_empty_cpu(trace_buffer, cpu)) return false; rb_evt = __peek_event(iter, cpu, &iter->ts, &iter->lost_events); if (!rb_evt) return false; iter->evt_cpu = cpu; iter->evt = ring_buffer_event_data(rb_evt); return true; } iter->ts = U64_MAX; for_each_possible_cpu(cpu) { unsigned long lost_events; u64 ts; if (ring_buffer_empty_cpu(trace_buffer, cpu)) continue; rb_evt = __peek_event(iter, cpu, &ts, &lost_events); if (!rb_evt) continue; if (ts >= iter->ts) continue; iter->ts = ts; iter->evt_cpu = cpu; iter->evt = ring_buffer_event_data(rb_evt); iter->lost_events = lost_events; } return iter->ts != U64_MAX; } static void trace_remote_iter_move(struct trace_remote_iterator *iter) { struct trace_buffer *trace_buffer = iter->remote->trace_buffer; switch (iter->type) { case TRI_CONSUMING: ring_buffer_consume(trace_buffer, iter->evt_cpu, NULL, NULL); break; case TRI_NONCONSUMING: ring_buffer_iter_advance(__get_rb_iter(iter, iter->evt_cpu)); break; } } static struct remote_event *trace_remote_find_event(struct trace_remote *remote, unsigned short id); static int trace_remote_iter_print_event(struct trace_remote_iterator *iter) { struct remote_event *evt; unsigned long usecs_rem; u64 ts = iter->ts; if (iter->lost_events) trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n", iter->evt_cpu, iter->lost_events); do_div(ts, 1000); usecs_rem = do_div(ts, USEC_PER_SEC); trace_seq_printf(&iter->seq, "[%03d]\t%5llu.%06lu: ", iter->evt_cpu, ts, usecs_rem); evt = trace_remote_find_event(iter->remote, iter->evt->id); if (!evt) trace_seq_printf(&iter->seq, "UNKNOWN id=%d\n", iter->evt->id); else evt->print(iter->evt, &iter->seq); return trace_seq_has_overflowed(&iter->seq) ? -EOVERFLOW : 0; } static int trace_pipe_open(struct inode *inode, struct file *filp) { struct trace_remote *remote = inode->i_private; struct trace_remote_iterator *iter; int cpu = tracing_get_cpu(inode); guard(mutex)(&remote->lock); iter = trace_remote_iter(remote, cpu, TRI_CONSUMING); if (IS_ERR(iter)) return PTR_ERR(iter); filp->private_data = iter; return IS_ERR(iter) ? PTR_ERR(iter) : 0; } static int trace_pipe_release(struct inode *inode, struct file *filp) { struct trace_remote_iterator *iter = filp->private_data; struct trace_remote *remote = iter->remote; guard(mutex)(&remote->lock); trace_remote_iter_free(iter); return 0; } static ssize_t trace_pipe_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { struct trace_remote_iterator *iter = filp->private_data; struct trace_buffer *trace_buffer = iter->remote->trace_buffer; int ret; copy_to_user: ret = trace_seq_to_user(&iter->seq, ubuf, cnt); if (ret != -EBUSY) return ret; trace_seq_init(&iter->seq); ret = ring_buffer_wait(trace_buffer, iter->cpu, 0, NULL, NULL); if (ret < 0) return ret; trace_remote_iter_read_start(iter); while (trace_remote_iter_read_event(iter)) { int prev_len = iter->seq.seq.len; if (trace_remote_iter_print_event(iter)) { iter->seq.seq.len = prev_len; break; } trace_remote_iter_move(iter); } trace_remote_iter_read_finished(iter); goto copy_to_user; } static const struct file_operations trace_pipe_fops = { .open = trace_pipe_open, .read = trace_pipe_read, .release = trace_pipe_release, }; static void *trace_next(struct seq_file *m, void *v, loff_t *pos) { struct trace_remote_iterator *iter = m->private; ++*pos; if (!iter || !trace_remote_iter_read_event(iter)) return NULL; trace_remote_iter_move(iter); iter->pos++; return iter; } static void *trace_start(struct seq_file *m, loff_t *pos) { struct trace_remote_iterator *iter = m->private; loff_t i; if (!iter) return NULL; trace_remote_iter_read_start(iter); if (!*pos) { iter->pos = -1; return trace_next(m, NULL, &i); } i = iter->pos; while (i < *pos) { iter = trace_next(m, NULL, &i); if (!iter) return NULL; } return iter; } static int trace_show(struct seq_file *m, void *v) { struct trace_remote_iterator *iter = v; trace_seq_init(&iter->seq); if (trace_remote_iter_print_event(iter)) { seq_printf(m, "[EVENT %d PRINT TOO BIG]\n", iter->evt->id); return 0; } return trace_print_seq(m, &iter->seq); } static void trace_stop(struct seq_file *m, void *v) { struct trace_remote_iterator *iter = m->private; if (iter) trace_remote_iter_read_finished(iter); } static const struct seq_operations trace_sops = { .start = trace_start, .next = trace_next, .show = trace_show, .stop = trace_stop, }; static int trace_open(struct inode *inode, struct file *filp) { struct trace_remote *remote = inode->i_private; struct trace_remote_iterator *iter = NULL; int cpu = tracing_get_cpu(inode); int ret; if (!(filp->f_mode & FMODE_READ)) return 0; guard(mutex)(&remote->lock); iter = trace_remote_iter(remote, cpu, TRI_NONCONSUMING); if (IS_ERR(iter)) return PTR_ERR(iter); ret = seq_open(filp, &trace_sops); if (ret) { trace_remote_iter_free(iter); return ret; } ((struct seq_file *)filp->private_data)->private = (void *)iter; return 0; } static int trace_release(struct inode *inode, struct file *filp) { struct trace_remote_iterator *iter; if (!(filp->f_mode & FMODE_READ)) return 0; iter = ((struct seq_file *)filp->private_data)->private; seq_release(inode, filp); if (!iter) return 0; guard(mutex)(&iter->remote->lock); trace_remote_iter_free(iter); return 0; } static ssize_t trace_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { struct inode *inode = file_inode(filp); struct trace_remote *remote = inode->i_private; int cpu = tracing_get_cpu(inode); guard(mutex)(&remote->lock); trace_remote_reset(remote, cpu); return cnt; } static const struct file_operations trace_fops = { .open = trace_open, .write = trace_write, .read = seq_read, .read_iter = seq_read_iter, .release = trace_release, }; static int trace_remote_init_tracefs(const char *name, struct trace_remote *remote) { struct dentry *remote_d, *percpu_d, *d; static struct dentry *root; static DEFINE_MUTEX(lock); bool root_inited = false; int cpu; guard(mutex)(&lock); if (!root) { root = tracefs_create_dir(TRACEFS_DIR, NULL); if (!root) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"\n"); return -ENOMEM; } root_inited = true; } remote_d = tracefs_create_dir(name, root); if (!remote_d) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/\n", name); goto err; } d = trace_create_file("tracing_on", TRACEFS_MODE_WRITE, remote_d, remote, &tracing_on_fops); if (!d) goto err; d = trace_create_file("buffer_size_kb", TRACEFS_MODE_WRITE, remote_d, remote, &buffer_size_kb_fops); if (!d) goto err; d = trace_create_file("trace_pipe", TRACEFS_MODE_READ, remote_d, remote, &trace_pipe_fops); if (!d) goto err; d = trace_create_file("trace", TRACEFS_MODE_WRITE, remote_d, remote, &trace_fops); if (!d) goto err; percpu_d = tracefs_create_dir("per_cpu", remote_d); if (!percpu_d) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/per_cpu/\n", name); goto err; } for_each_possible_cpu(cpu) { struct dentry *cpu_d; char cpu_name[16]; snprintf(cpu_name, sizeof(cpu_name), "cpu%d", cpu); cpu_d = tracefs_create_dir(cpu_name, percpu_d); if (!cpu_d) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/percpu/cpu%d\n", name, cpu); goto err; } d = trace_create_cpu_file("trace_pipe", TRACEFS_MODE_READ, cpu_d, remote, cpu, &trace_pipe_fops); if (!d) goto err; d = trace_create_cpu_file("trace", TRACEFS_MODE_WRITE, cpu_d, remote, cpu, &trace_fops); if (!d) goto err; } remote->dentry = remote_d; return 0; err: if (root_inited) { tracefs_remove(root); root = NULL; } else { tracefs_remove(remote_d); } return -ENOMEM; } static int trace_remote_register_events(const char *remote_name, struct trace_remote *remote, struct remote_event *events, size_t nr_events); /** * trace_remote_register() - Register a Tracefs remote * @name: Name of the remote, used for the Tracefs remotes/ directory. * @cbs: Set of callbacks used to control the remote. * @priv: Private data, passed to each callback from @cbs. * @events: Array of events. &remote_event.name and &remote_event.id must be * filled by the caller. * @nr_events: Number of events in the @events array. * * A trace remote is an entity, outside of the kernel (most likely firmware or * hypervisor) capable of writing events into a Tracefs compatible ring-buffer. * The kernel would then act as a reader. * * The registered remote will be found under the Tracefs directory * remotes/. * * Return: 0 on success, negative error code on failure. */ int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv, struct remote_event *events, size_t nr_events) { struct trace_remote *remote; int ret; remote = kzalloc_obj(*remote); if (!remote) return -ENOMEM; remote->cbs = cbs; remote->priv = priv; remote->trace_buffer_size = 7 << 10; remote->poll_ms = 100; mutex_init(&remote->lock); init_rwsem(&remote->reader_lock); if (trace_remote_init_tracefs(name, remote)) { kfree(remote); return -ENOMEM; } ret = trace_remote_register_events(name, remote, events, nr_events); if (ret) { pr_err("Failed to register events for trace remote '%s' (%d)\n", name, ret); return ret; } ret = cbs->init ? cbs->init(remote->dentry, priv) : 0; if (ret) pr_err("Init failed for trace remote '%s' (%d)\n", name, ret); return ret; } EXPORT_SYMBOL_GPL(trace_remote_register); /** * trace_remote_free_buffer() - Free trace buffer allocated with trace_remote_alloc_buffer() * @desc: Descriptor of the per-CPU ring-buffers, originally filled by * trace_remote_alloc_buffer() * * Most likely called from &trace_remote_callbacks.unload_trace_buffer. */ void trace_remote_free_buffer(struct trace_buffer_desc *desc) { struct ring_buffer_desc *rb_desc; int cpu; for_each_ring_buffer_desc(rb_desc, cpu, desc) { unsigned int id; free_page(rb_desc->meta_va); for (id = 0; id < rb_desc->nr_page_va; id++) free_page(rb_desc->page_va[id]); } } EXPORT_SYMBOL_GPL(trace_remote_free_buffer); /** * trace_remote_alloc_buffer() - Dynamically allocate a trace buffer * @desc: Uninitialized trace_buffer_desc * @desc_size: Size of the trace_buffer_desc. Must be at least equal to * trace_buffer_desc_size() * @buffer_size: Size in bytes of each per-CPU ring-buffer * @cpumask: CPUs to allocate a ring-buffer for * * Helper to dynamically allocate a set of pages (enough to cover @buffer_size) * for each CPU from @cpumask and fill @desc. Most likely called from * &trace_remote_callbacks.load_trace_buffer. * * Return: 0 on success, negative error code on failure. */ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, size_t buffer_size, const struct cpumask *cpumask) { unsigned int nr_pages = max(DIV_ROUND_UP(buffer_size, PAGE_SIZE), 2UL) + 1; void *desc_end = desc + desc_size; struct ring_buffer_desc *rb_desc; int cpu, ret = -ENOMEM; if (desc_size < struct_size(desc, __data, 0)) return -EINVAL; desc->nr_cpus = 0; desc->struct_len = struct_size(desc, __data, 0); rb_desc = (struct ring_buffer_desc *)&desc->__data[0]; for_each_cpu(cpu, cpumask) { unsigned int id; if ((void *)rb_desc + struct_size(rb_desc, page_va, nr_pages) > desc_end) { ret = -EINVAL; goto err; } rb_desc->cpu = cpu; rb_desc->nr_page_va = 0; rb_desc->meta_va = (unsigned long)__get_free_page(GFP_KERNEL); if (!rb_desc->meta_va) goto err; for (id = 0; id < nr_pages; id++) { rb_desc->page_va[id] = (unsigned long)__get_free_page(GFP_KERNEL); if (!rb_desc->page_va[id]) goto err; rb_desc->nr_page_va++; } desc->nr_cpus++; desc->struct_len += offsetof(struct ring_buffer_desc, page_va); desc->struct_len += struct_size(rb_desc, page_va, rb_desc->nr_page_va); rb_desc = __next_ring_buffer_desc(rb_desc); } return 0; err: trace_remote_free_buffer(desc); return ret; } EXPORT_SYMBOL_GPL(trace_remote_alloc_buffer); static int trace_remote_enable_event(struct trace_remote *remote, struct remote_event *evt, bool enable) { int ret; lockdep_assert_held(&remote->lock); if (evt->enabled == enable) return 0; ret = remote->cbs->enable_event(evt->id, enable, remote->priv); if (ret) return ret; evt->enabled = enable; return 0; } static int remote_event_enable_show(struct seq_file *s, void *unused) { struct remote_event *evt = s->private; seq_printf(s, "%d\n", evt->enabled); return 0; } static ssize_t remote_event_enable_write(struct file *filp, const char __user *ubuf, size_t count, loff_t *ppos) { struct seq_file *seq = filp->private_data; struct remote_event *evt = seq->private; struct trace_remote *remote = evt->remote; u8 enable; int ret; ret = kstrtou8_from_user(ubuf, count, 10, &enable); if (ret) return ret; guard(mutex)(&remote->lock); ret = trace_remote_enable_event(remote, evt, enable); if (ret) return ret; return count; } DEFINE_SHOW_STORE_ATTRIBUTE(remote_event_enable); static int remote_event_id_show(struct seq_file *s, void *unused) { struct remote_event *evt = s->private; seq_printf(s, "%d\n", evt->id); return 0; } DEFINE_SHOW_ATTRIBUTE(remote_event_id); static int remote_event_format_show(struct seq_file *s, void *unused) { size_t offset = sizeof(struct remote_event_hdr); struct remote_event *evt = s->private; struct trace_event_fields *field; seq_printf(s, "name: %s\n", evt->name); seq_printf(s, "ID: %d\n", evt->id); seq_puts(s, "format:\n\tfield:unsigned short common_type;\toffset:0;\tsize:2;\tsigned:0;\n\n"); field = &evt->fields[0]; while (field->name) { seq_printf(s, "\tfield:%s %s;\toffset:%zu;\tsize:%u;\tsigned:%d;\n", field->type, field->name, offset, field->size, field->is_signed); offset += field->size; field++; } if (field != &evt->fields[0]) seq_puts(s, "\n"); seq_printf(s, "print fmt: %s\n", evt->print_fmt); return 0; } DEFINE_SHOW_ATTRIBUTE(remote_event_format); static int remote_event_callback(const char *name, umode_t *mode, void **data, const struct file_operations **fops) { if (!strcmp(name, "enable")) { *mode = TRACEFS_MODE_WRITE; *fops = &remote_event_enable_fops; return 1; } if (!strcmp(name, "id")) { *mode = TRACEFS_MODE_READ; *fops = &remote_event_id_fops; return 1; } if (!strcmp(name, "format")) { *mode = TRACEFS_MODE_READ; *fops = &remote_event_format_fops; return 1; } return 0; } static ssize_t remote_events_dir_enable_write(struct file *filp, const char __user *ubuf, size_t count, loff_t *ppos) { struct trace_remote *remote = file_inode(filp)->i_private; int i, ret; u8 enable; ret = kstrtou8_from_user(ubuf, count, 10, &enable); if (ret) return ret; guard(mutex)(&remote->lock); for (i = 0; i < remote->nr_events; i++) { struct remote_event *evt = &remote->events[i]; trace_remote_enable_event(remote, evt, enable); } return count; } static ssize_t remote_events_dir_enable_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { struct trace_remote *remote = file_inode(filp)->i_private; const char enabled_char[] = {'0', '1', 'X'}; char enabled_str[] = " \n"; int i, enabled = -1; guard(mutex)(&remote->lock); for (i = 0; i < remote->nr_events; i++) { struct remote_event *evt = &remote->events[i]; if (enabled == -1) { enabled = evt->enabled; } else if (enabled != evt->enabled) { enabled = 2; break; } } enabled_str[0] = enabled_char[enabled == -1 ? 0 : enabled]; return simple_read_from_buffer(ubuf, cnt, ppos, enabled_str, 2); } static const struct file_operations remote_events_dir_enable_fops = { .write = remote_events_dir_enable_write, .read = remote_events_dir_enable_read, }; static ssize_t remote_events_dir_header_page_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { struct trace_seq *s; int ret; s = kmalloc(sizeof(*s), GFP_KERNEL); if (!s) return -ENOMEM; trace_seq_init(s); ring_buffer_print_page_header(NULL, s); ret = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, trace_seq_used(s)); kfree(s); return ret; } static const struct file_operations remote_events_dir_header_page_fops = { .read = remote_events_dir_header_page_read, }; static ssize_t remote_events_dir_header_event_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { struct trace_seq *s; int ret; s = kmalloc(sizeof(*s), GFP_KERNEL); if (!s) return -ENOMEM; trace_seq_init(s); ring_buffer_print_entry_header(s); ret = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, trace_seq_used(s)); kfree(s); return ret; } static const struct file_operations remote_events_dir_header_event_fops = { .read = remote_events_dir_header_event_read, }; static int remote_events_dir_callback(const char *name, umode_t *mode, void **data, const struct file_operations **fops) { if (!strcmp(name, "enable")) { *mode = TRACEFS_MODE_WRITE; *fops = &remote_events_dir_enable_fops; return 1; } if (!strcmp(name, "header_page")) { *mode = TRACEFS_MODE_READ; *fops = &remote_events_dir_header_page_fops; return 1; } if (!strcmp(name, "header_event")) { *mode = TRACEFS_MODE_READ; *fops = &remote_events_dir_header_event_fops; return 1; } return 0; } static int trace_remote_init_eventfs(const char *remote_name, struct trace_remote *remote, struct remote_event *evt) { struct eventfs_inode *eventfs = remote->eventfs; static struct eventfs_entry dir_entries[] = { { .name = "enable", .callback = remote_events_dir_callback, }, { .name = "header_page", .callback = remote_events_dir_callback, }, { .name = "header_event", .callback = remote_events_dir_callback, } }; static struct eventfs_entry entries[] = { { .name = "enable", .callback = remote_event_callback, }, { .name = "id", .callback = remote_event_callback, }, { .name = "format", .callback = remote_event_callback, } }; bool eventfs_create = false; if (!eventfs) { eventfs = eventfs_create_events_dir("events", remote->dentry, dir_entries, ARRAY_SIZE(dir_entries), remote); if (IS_ERR(eventfs)) return PTR_ERR(eventfs); /* * Create similar hierarchy as local events even if a single system is supported at * the moment */ eventfs = eventfs_create_dir(remote_name, eventfs, NULL, 0, NULL); if (IS_ERR(eventfs)) return PTR_ERR(eventfs); remote->eventfs = eventfs; eventfs_create = true; } eventfs = eventfs_create_dir(evt->name, eventfs, entries, ARRAY_SIZE(entries), evt); if (IS_ERR(eventfs)) { if (eventfs_create) { eventfs_remove_events_dir(remote->eventfs); remote->eventfs = NULL; } return PTR_ERR(eventfs); } return 0; } static int trace_remote_attach_events(struct trace_remote *remote, struct remote_event *events, size_t nr_events) { int i; for (i = 0; i < nr_events; i++) { struct remote_event *evt = &events[i]; if (evt->remote) return -EEXIST; evt->remote = remote; /* We need events to be sorted for efficient lookup */ if (i && evt->id <= events[i - 1].id) return -EINVAL; } remote->events = events; remote->nr_events = nr_events; return 0; } static int trace_remote_register_events(const char *remote_name, struct trace_remote *remote, struct remote_event *events, size_t nr_events) { int i, ret; ret = trace_remote_attach_events(remote, events, nr_events); if (ret) return ret; for (i = 0; i < nr_events; i++) { struct remote_event *evt = &events[i]; ret = trace_remote_init_eventfs(remote_name, remote, evt); if (ret) pr_warn("Failed to init eventfs for event '%s' (%d)", evt->name, ret); } return 0; } static int __cmp_events(const void *key, const void *data) { const struct remote_event *evt = data; int id = (int)((long)key); return id - (int)evt->id; } static struct remote_event *trace_remote_find_event(struct trace_remote *remote, unsigned short id) { return bsearch((const void *)(unsigned long)id, remote->events, remote->nr_events, sizeof(*remote->events), __cmp_events); }