--- /dev/null
+/*
+ * (C) Copyright 2009-2011 -
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng kretprobes integration module.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/slab.h>
+#include <linux/kref.h>
+#include "../ltt-events.h"
+#include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/vmalloc.h"
+#include "../ltt-tracer.h"
+
+enum lttng_kretprobe_type {
+ EVENT_ENTRY = 0,
+ EVENT_RETURN = 1,
+};
+
+struct lttng_krp {
+ struct kretprobe krp;
+ struct ltt_event *event[2]; /* ENTRY and RETURN */
+ struct kref kref_register;
+ struct kref kref_alloc;
+};
+
+static
+int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
+ struct pt_regs *regs,
+ enum lttng_kretprobe_type type)
+{
+ struct lttng_krp *lttng_krp =
+ container_of(krpi->rp, struct lttng_krp, krp);
+ struct ltt_event *event =
+ lttng_krp->event[type];
+ struct ltt_channel *chan = event->chan;
+ struct lib_ring_buffer_ctx ctx;
+ int ret;
+ struct {
+ unsigned long ip;
+ unsigned long parent_ip;
+ } payload;
+
+ if (unlikely(!ACCESS_ONCE(chan->session->active)))
+ return 0;
+ if (unlikely(!ACCESS_ONCE(chan->enabled)))
+ return 0;
+ if (unlikely(!ACCESS_ONCE(event->enabled)))
+ return 0;
+
+ payload.ip = (unsigned long) krpi->rp->kp.addr;
+ payload.parent_ip = (unsigned long) krpi->ret_addr;
+
+ lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(payload),
+ ltt_alignof(payload), -1);
+ ret = chan->ops->event_reserve(&ctx, event->id);
+ if (ret < 0)
+ return 0;
+ lib_ring_buffer_align_ctx(&ctx, ltt_alignof(payload));
+ chan->ops->event_write(&ctx, &payload, sizeof(payload));
+ chan->ops->event_commit(&ctx);
+ return 0;
+}
+
+static
+int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi,
+ struct pt_regs *regs)
+{
+ return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY);
+}
+
+static
+int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi,
+ struct pt_regs *regs)
+{
+ return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN);
+}
+
+/*
+ * Create event description
+ */
+static
+int lttng_create_kprobe_event(const char *name, struct ltt_event *event,
+ enum lttng_kretprobe_type type)
+{
+ struct lttng_event_field *fields;
+ struct lttng_event_desc *desc;
+ int ret;
+ char *alloc_name;
+ size_t name_len;
+ const char *suffix = NULL;
+
+ desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
+ if (!desc)
+ return -ENOMEM;
+ name_len = strlen(name);
+ switch (type) {
+ case EVENT_ENTRY:
+ suffix = "_entry";
+ break;
+ case EVENT_RETURN:
+ suffix = "_return";
+ break;
+ }
+ name_len += strlen(suffix);
+ alloc_name = kmalloc(name_len + 1, GFP_KERNEL);
+ if (!alloc_name) {
+ ret = -ENOMEM;
+ goto error_str;
+ }
+ strcpy(alloc_name, name);
+ strcat(alloc_name, suffix);
+ desc->name = alloc_name;
+ desc->nr_fields = 2;
+ desc->fields = fields =
+ kzalloc(2 * 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.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+ fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+ fields[0].type.u.basic.integer.signedness = is_signed_type(unsigned long);
+ fields[0].type.u.basic.integer.reverse_byte_order = 0;
+ fields[0].type.u.basic.integer.base = 16;
+ fields[0].type.u.basic.integer.encoding = lttng_encode_none;
+
+ fields[1].name = "parent_ip";
+ fields[1].type.atype = atype_integer;
+ fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+ fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+ fields[1].type.u.basic.integer.signedness = is_signed_type(unsigned long);
+ fields[1].type.u.basic.integer.reverse_byte_order = 0;
+ fields[1].type.u.basic.integer.base = 16;
+ fields[1].type.u.basic.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;
+}
+
+int lttng_kretprobes_register(const char *name,
+ const char *symbol_name,
+ uint64_t offset,
+ uint64_t addr,
+ struct ltt_event *event_entry,
+ struct ltt_event *event_return)
+{
+ int ret;
+ struct lttng_krp *lttng_krp;
+
+ /* Kprobes expects a NULL symbol name if unused */
+ if (symbol_name[0] == '\0')
+ symbol_name = NULL;
+
+ ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY);
+ if (ret)
+ goto error;
+ ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN);
+ if (ret)
+ goto event_return_error;
+ lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
+ if (!lttng_krp)
+ goto krp_error;
+ lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
+ lttng_krp->krp.handler = lttng_kretprobes_handler_return;
+ if (symbol_name) {
+ char *alloc_symbol;
+
+ alloc_symbol = kstrdup(symbol_name, GFP_KERNEL);
+ if (!alloc_symbol) {
+ ret = -ENOMEM;
+ goto name_error;
+ }
+ lttng_krp->krp.kp.symbol_name =
+ alloc_symbol;
+ event_entry->u.kretprobe.symbol_name =
+ alloc_symbol;
+ event_return->u.kretprobe.symbol_name =
+ alloc_symbol;
+ }
+ lttng_krp->krp.kp.offset = offset;
+ lttng_krp->krp.kp.addr = (void *) addr;
+
+ /* Allow probe handler to find event structures */
+ lttng_krp->event[EVENT_ENTRY] = event_entry;
+ lttng_krp->event[EVENT_RETURN] = event_return;
+ event_entry->u.kretprobe.lttng_krp = lttng_krp;
+ event_return->u.kretprobe.lttng_krp = lttng_krp;
+
+ /*
+ * Both events must be unregistered before the kretprobe is
+ * unregistered. Same for memory allocation.
+ */
+ kref_init(<tng_krp->kref_alloc);
+ kref_get(<tng_krp->kref_alloc); /* inc refcount to 2 */
+ kref_init(<tng_krp->kref_register);
+ kref_get(<tng_krp->kref_register); /* inc refcount to 2 */
+
+ /*
+ * Ensure the memory we just allocated don't trigger page faults.
+ * Well.. kprobes itself puts the page fault handler on the blacklist,
+ * but we can never be too careful.
+ */
+ wrapper_vmalloc_sync_all();
+
+ ret = register_kretprobe(<tng_krp->krp);
+ if (ret)
+ goto register_error;
+ return 0;
+
+register_error:
+ kfree(lttng_krp->krp.kp.symbol_name);
+name_error:
+ kfree(lttng_krp);
+krp_error:
+ kfree(event_return->desc->fields);
+ kfree(event_return->desc->name);
+ kfree(event_return->desc);
+event_return_error:
+ kfree(event_entry->desc->fields);
+ kfree(event_entry->desc->name);
+ kfree(event_entry->desc);
+error:
+ return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_register);
+
+static
+void _lttng_kretprobes_unregister_release(struct kref *kref)
+{
+ struct lttng_krp *lttng_krp =
+ container_of(kref, struct lttng_krp, kref_register);
+ unregister_kretprobe(<tng_krp->krp);
+}
+
+void lttng_kretprobes_unregister(struct ltt_event *event)
+{
+ kref_put(&event->u.kretprobe.lttng_krp->kref_register,
+ _lttng_kretprobes_unregister_release);
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister);
+
+static
+void _lttng_kretprobes_release(struct kref *kref)
+{
+ struct lttng_krp *lttng_krp =
+ container_of(kref, struct lttng_krp, kref_alloc);
+ kfree(lttng_krp->krp.kp.symbol_name);
+}
+
+void lttng_kretprobes_destroy_private(struct ltt_event *event)
+{
+ kfree(event->desc->fields);
+ kfree(event->desc->name);
+ kfree(event->desc);
+ kref_put(&event->u.kretprobe.lttng_krp->kref_alloc,
+ _lttng_kretprobes_release);
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support");
projects / lttng-modules.git / blobdiff