--- /dev/null
+/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
+ *
+ * probes/lttng-uprobes.c
+ *
+ * LTTng uprobes integration module.
+ *
+ * Copyright (C) 2013 Yannick Brosseau <yannick.brosseau@gmail.com>
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ */
+
+#include <linux/fdtable.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <lttng/events.h>
+#include <lttng/tracer.h>
+#include <wrapper/irqflags.h>
+#include <ringbuffer/frontend_types.h>
+#include <wrapper/uprobes.h>
+#include <wrapper/vmalloc.h>
+
+static
+int lttng_uprobes_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs)
+{
+ struct lttng_uprobe_handler *uprobe_handler =
+ container_of(uc, struct lttng_uprobe_handler, up_consumer);
+ struct lttng_event *event = uprobe_handler->event;
+ struct lttng_probe_ctx lttng_probe_ctx = {
+ .event = event,
+ .interruptible = !lttng_regs_irqs_disabled(regs),
+ };
+ struct lttng_channel *chan = event->chan;
+ struct lib_ring_buffer_ctx ctx;
+ int ret;
+
+ struct {
+ unsigned long ip;
+ } payload;
+
+ if (unlikely(!READ_ONCE(chan->session->active)))
+ return 0;
+ if (unlikely(!READ_ONCE(chan->enabled)))
+ return 0;
+ if (unlikely(!READ_ONCE(event->enabled)))
+ return 0;
+
+ lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx,
+ sizeof(payload), lttng_alignof(payload), -1);
+
+ ret = chan->ops->event_reserve(&ctx, event->id);
+ if (ret < 0)
+ return 0;
+
+ /* Event payload. */
+ payload.ip = (unsigned long)instruction_pointer(regs);
+
+ lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
+ chan->ops->event_write(&ctx, &payload, sizeof(payload));
+ chan->ops->event_commit(&ctx);
+ return 0;
+}
+
+/*
+ * Create event description.
+ */
+static
+int lttng_create_uprobe_event(const char *name, struct lttng_event *event)
+{
+ struct lttng_event_desc *desc;
+ struct lttng_event_field *fields;
+ int ret;
+
+ desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
+ if (!desc)
+ return -ENOMEM;
+ desc->name = kstrdup(name, GFP_KERNEL);
+ if (!desc->name) {
+ ret = -ENOMEM;
+ goto error_str;
+ }
+
+ desc->nr_fields = 1;
+ desc->fields = fields =
+ kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
+
+ if (!desc->fields) {
+ ret = -ENOMEM;
+ goto error_fields;
+ }
+ fields[0].name = "ip";
+ fields[0].type.atype = atype_integer;
+ fields[0].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
+ fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
+ fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long);
+ fields[0].type.u.integer.reverse_byte_order = 0;
+ fields[0].type.u.integer.base = 16;
+ fields[0].type.u.integer.encoding = lttng_encode_none;
+
+ desc->owner = THIS_MODULE;
+ event->desc = desc;
+
+ return 0;
+
+error_fields:
+ kfree(desc->name);
+error_str:
+ kfree(desc);
+ return ret;
+}
+
+/*
+ * Returns the inode struct from the current task and an fd. The inode is
+ * grabbed by this function and must be put once we are done with it using
+ * iput().
+ */
+static struct inode *get_inode_from_fd(int fd)
+{
+ struct file *file;
+ struct inode *inode;
+
+ rcu_read_lock();
+ /*
+ * Returns the file backing the given fd. Needs to be done inside an RCU
+ * critical section.
+ */
+ file = fcheck(fd);
+ if (file == NULL) {
+ printk(KERN_WARNING "Cannot access file backing the fd(%d)\n", fd);
+ inode = NULL;
+ goto error;
+ }
+
+ /* Grab a reference on the inode. */
+ inode = igrab(file->f_path.dentry->d_inode);
+ if (inode == NULL)
+ printk(KERN_WARNING "Cannot grab a reference on the inode.\n");
+error:
+ rcu_read_unlock();
+ return inode;
+}
+
+int lttng_uprobes_add_callsite(struct lttng_event *event,
+ struct lttng_kernel_event_callsite __user *callsite)
+{
+ int ret = 0;
+ struct lttng_uprobe_handler *uprobe_handler;
+
+ if (!event) {
+ ret = -EINVAL;
+ goto end;
+ }
+
+ uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
+ if (!uprobe_handler) {
+ printk(KERN_WARNING "Error allocating uprobe_uprobe_handlers");
+ ret = -ENOMEM;
+ goto end;
+ }
+
+ /* Ensure the memory we just allocated don't trigger page faults. */
+ wrapper_vmalloc_sync_mappings();
+
+ uprobe_handler->event = event;
+ uprobe_handler->up_consumer.handler = lttng_uprobes_handler_pre;
+
+ ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
+ if (ret) {
+ goto register_error;
+ }
+
+ ret = wrapper_uprobe_register(event->u.uprobe.inode,
+ uprobe_handler->offset, &uprobe_handler->up_consumer);
+ if (ret) {
+ printk(KERN_WARNING "Error registering probe on inode %lu "
+ "and offset 0x%llx\n", event->u.uprobe.inode->i_ino,
+ uprobe_handler->offset);
+ ret = -1;
+ goto register_error;
+ }
+
+ list_add(&uprobe_handler->node, &event->u.uprobe.head);
+
+ return ret;
+
+register_error:
+ kfree(uprobe_handler);
+end:
+ return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_add_callsite);
+
+int lttng_uprobes_register(const char *name, int fd, struct lttng_event *event)
+{
+ int ret = 0;
+ struct inode *inode;
+
+ ret = lttng_create_uprobe_event(name, event);
+ if (ret)
+ goto error;
+
+ inode = get_inode_from_fd(fd);
+ if (!inode) {
+ printk(KERN_WARNING "Cannot get inode from fd\n");
+ ret = -EBADF;
+ goto inode_error;
+ }
+ event->u.uprobe.inode = inode;
+ INIT_LIST_HEAD(&event->u.uprobe.head);
+
+ return 0;
+
+inode_error:
+ kfree(event->desc->name);
+ kfree(event->desc);
+error:
+ return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_register);
+
+void lttng_uprobes_unregister(struct lttng_event *event)
+{
+ struct lttng_uprobe_handler *iter, *tmp;
+
+ /*
+ * Iterate over the list of handler, remove each handler from the list
+ * and free the struct.
+ */
+ list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) {
+ wrapper_uprobe_unregister(event->u.uprobe.inode, iter->offset,
+ &iter->up_consumer);
+ list_del(&iter->node);
+ kfree(iter);
+ }
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_unregister);
+
+void lttng_uprobes_destroy_private(struct lttng_event *event)
+{
+ iput(event->u.uprobe.inode);
+ kfree(event->desc->name);
+ kfree(event->desc);
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Yannick Brosseau");
+MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");
projects / deliverable / lttng-modules.git / blobdiff