X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=src%2Fprobes%2Flttng-uprobes.c;fp=src%2Fprobes%2Flttng-uprobes.c;h=c0f6e7c31c2a81c749735de4094637a75294b757;hb=cfa6cc1d0f01c2cfcc1a679abf3a6572d411c309;hp=0000000000000000000000000000000000000000;hpb=cd4486798c2b046ea93b89439cd705e93c40b349;p=deliverable%2Flttng-modules.git diff --git a/src/probes/lttng-uprobes.c b/src/probes/lttng-uprobes.c new file mode 100644 index 00000000..c0f6e7c3 --- /dev/null +++ b/src/probes/lttng-uprobes.c @@ -0,0 +1,250 @@ +/* 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 + * Copyright (C) 2009-2012 Mathieu Desnoyers + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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");