[lttng-dev] [LTTng-modules RFC Patch] Add uprobes support (v2)
Yannick Brosseau
yannick.brosseau at gmail.com
Wed Jul 24 14:07:38 EDT 2013
The added support is basic. It create an event with no data associated to the file path + offset
specified.
update from v1:
- Use a wrapper for uprobe
- Use a userspace pointer for the path
Signed-off-by: Yannick Brosseau <yannick.brosseau at gmail.com>
---
README | 5 +-
lttng-abi.h | 7 +++
lttng-events.c | 18 ++++++
lttng-events.h | 34 +++++++++++
probes/Makefile | 4 ++
probes/lttng-uprobes.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++
wrapper/uprobes.h | 87 +++++++++++++++++++++++++++
7 files changed, 310 insertions(+), 1 deletion(-)
create mode 100644 probes/lttng-uprobes.c
create mode 100644 wrapper/uprobes.h
diff --git a/README b/README
index b7d8b9f..9676a04 100644
--- a/README
+++ b/README
@@ -9,7 +9,7 @@ need for additional patches. Other features:
- Produces CTF (Common Trace Format) natively,
(http://www.efficios.com/ctf)
- Tracepoints, Function tracer, CPU Performance Monitoring Unit (PMU)
- counters, kprobes, and kretprobes support,
+ counters, kprobes, kretprobes and uprobes support,
- Integrated interface for both kernel and userspace tracing,
- Have the ability to attach "context" information to events in the
trace (e.g. any PMU counter, pid, ppid, tid, comm name, etc).
@@ -87,6 +87,9 @@ CONFIG_KPROBES:
CONFIG_KRETPROBES:
Dynamic function entry/return probe.
lttng enable-event -k --function ...
+CONFIG_UPROBES:
+ Dynamic userspace probe.
+ lttng enable-event -k --uprobe ...
* Note about Perf PMU counters support
diff --git a/lttng-abi.h b/lttng-abi.h
index 8d3ecdd..7d43452 100644
--- a/lttng-abi.h
+++ b/lttng-abi.h
@@ -34,6 +34,7 @@ enum lttng_kernel_instrumentation {
LTTNG_KERNEL_KRETPROBE = 3,
LTTNG_KERNEL_NOOP = 4, /* not hooked */
LTTNG_KERNEL_SYSCALL = 5,
+ LTTNG_KERNEL_UPROBE = 6,
};
/*
@@ -79,6 +80,11 @@ struct lttng_kernel_function_tracer {
char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
}__attribute__((packed));
+struct lttng_kernel_uprobe {
+ char __user *path;
+ uint64_t offset;
+}__attribute__((packed));
+
/*
* For syscall tracing, name = '\0' means "enable all".
*/
@@ -94,6 +100,7 @@ struct lttng_kernel_event {
struct lttng_kernel_kretprobe kretprobe;
struct lttng_kernel_kprobe kprobe;
struct lttng_kernel_function_tracer ftrace;
+ struct lttng_kernel_uprobe uprobe;
char padding[LTTNG_KERNEL_EVENT_PADDING2];
} u;
}__attribute__((packed));
diff --git a/lttng-events.c b/lttng-events.c
index 567df65..255618a 100644
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -457,6 +457,16 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
if (!event->desc)
goto register_error;
break;
+ case LTTNG_KERNEL_UPROBE:
+ ret = lttng_uprobes_register(event_param->name,
+ event_param->u.uprobe.path,
+ event_param->u.uprobe.offset,
+ event);
+ if (ret)
+ goto register_error;
+ ret = try_module_get(event->desc->owner);
+ WARN_ON_ONCE(!ret);
+ break;
default:
WARN_ON_ONCE(1);
}
@@ -508,6 +518,10 @@ int _lttng_event_unregister(struct lttng_event *event)
case LTTNG_KERNEL_NOOP:
ret = 0;
break;
+ case LTTNG_KERNEL_UPROBE:
+ lttng_uprobes_unregister(event);
+ ret = 0;
+ break;
default:
WARN_ON_ONCE(1);
}
@@ -538,6 +552,10 @@ void _lttng_event_destroy(struct lttng_event *event)
break;
case LTTNG_KERNEL_NOOP:
break;
+ case LTTNG_KERNEL_UPROBE:
+ module_put(event->desc->owner);
+ lttng_uprobes_destroy_private(event);
+ break;
default:
WARN_ON_ONCE(1);
}
diff --git a/lttng-events.h b/lttng-events.h
index 4c1f322..bd157b0 100644
--- a/lttng-events.h
+++ b/lttng-events.h
@@ -27,6 +27,7 @@
#include <linux/list.h>
#include <linux/kprobes.h>
#include <linux/kref.h>
+#include "wrapper/uprobes.h"
#include "wrapper/uuid.h"
#include "lttng-abi.h"
#include "lttng-abi-old.h"
@@ -209,6 +210,11 @@ struct lttng_event {
struct {
char *symbol_name;
} ftrace;
+ struct {
+ struct uprobe_consumer up_consumer;
+ struct inode *inode;
+ loff_t offset;
+ } uprobe;
} u;
struct list_head list; /* Event list */
unsigned int metadata_dumped:1;
@@ -437,6 +443,34 @@ void lttng_kprobes_destroy_private(struct lttng_event *event)
}
#endif
+#ifdef CONFIG_UPROBES
+int lttng_uprobes_register(const char *name,
+ const char *path,
+ uint64_t offset,
+ struct lttng_event *event);
+void lttng_uprobes_unregister(struct lttng_event *event);
+void lttng_uprobes_destroy_private(struct lttng_event *event);
+#else
+static inline
+int lttng_uprobes_register(const char *name,
+ const char *path,
+ uint64_t offset,
+ struct lttng_event *event)
+{
+ return -ENOSYS;
+}
+
+static inline
+void lttng_uprobes_unregister(struct lttng_event *event)
+{
+}
+
+static inline
+void lttng_uprobes_destroy_private(struct lttng_event *event)
+{
+}
+#endif
+
#ifdef CONFIG_KRETPROBES
int lttng_kretprobes_register(const char *name,
const char *symbol_name,
diff --git a/probes/Makefile b/probes/Makefile
index 63ca7ba..4ca7438 100644
--- a/probes/Makefile
+++ b/probes/Makefile
@@ -220,6 +220,10 @@ ifneq ($(CONFIG_DYNAMIC_FTRACE),)
obj-m += lttng-ftrace.o
endif
+ifneq ($(CONFIG_UPROBES),)
+obj-m += lttng-uprobes.o
+endif
+
endif
else
diff --git a/probes/lttng-uprobes.c b/probes/lttng-uprobes.c
new file mode 100644
index 0000000..080eed3
--- /dev/null
+++ b/probes/lttng-uprobes.c
@@ -0,0 +1,156 @@
+/*
+ * probes/lttng-uprobes.c
+ *
+ * LTTng uprobes integration module.
+ *
+ * Copyright (C) 2013 Yannick Brosseau <yannick.brosseau at gmail.com>
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/module.h>
+#include "../wrapper/uprobes.h"
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
+#include "../lttng-events.h"
+#include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/vmalloc.h"
+#include "../lttng-tracer.h"
+
+static
+int lttng_uprobes_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs)
+{
+ struct lttng_event *event =
+ container_of(uc, struct lttng_event, u.uprobe.up_consumer);
+ struct lttng_channel *chan = event->chan;
+ struct lib_ring_buffer_ctx ctx;
+ int ret;
+
+ 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;
+
+ lib_ring_buffer_ctx_init(&ctx, chan->chan, event, 0,
+ 0, -1);
+ ret = chan->ops->event_reserve(&ctx, event->id);
+ if (ret < 0)
+ return 0;
+ lib_ring_buffer_align_ctx(&ctx, 0);
+ chan->ops->event_write(&ctx, 0, 0);
+ 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;
+ 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->owner = THIS_MODULE;
+ event->desc = desc;
+
+ return 0;
+
+error_str:
+ kfree(desc);
+ return ret;
+}
+
+int lttng_uprobes_register(const char *name,
+ const char __user *path_name,
+ uint64_t offset,
+ struct lttng_event *event)
+{
+ int ret;
+
+
+ if (!access_ok(VERIFY_READ, path_name, 1))
+ return -EFAULT;
+
+ if (path_name[0] == '\0')
+ path_name = NULL;
+
+ ret = lttng_create_uprobe_event(name, event);
+ if (ret)
+ goto error;
+ memset(&event->u.uprobe.up_consumer, 0,
+ sizeof(event->u.uprobe.up_consumer));
+ event->u.uprobe.up_consumer.handler = lttng_uprobes_handler_pre;
+ if (path_name) {
+ struct path path;
+ ret = kern_path(path_name, LOOKUP_FOLLOW, &path);
+ if (ret)
+ goto path_error;
+
+ event->u.uprobe.inode = igrab(path.dentry->d_inode);
+ }
+ event->u.uprobe.offset = offset;
+
+ /* Ensure the memory we just allocated don't trigger page faults. */
+ wrapper_vmalloc_sync_all();
+
+ ret = wrapper_uprobe_register(event->u.uprobe.inode,
+ event->u.uprobe.offset,
+ &event->u.uprobe.up_consumer);
+ if (ret)
+ goto register_error;
+ return 0;
+
+register_error:
+ iput(event->u.uprobe.inode);
+path_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)
+{
+ wrapper_uprobe_unregister(event->u.uprobe.inode,
+ event->u.uprobe.offset,
+ &event->u.uprobe.up_consumer);
+}
+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");
diff --git a/wrapper/uprobes.h b/wrapper/uprobes.h
new file mode 100644
index 0000000..08bce93
--- /dev/null
+++ b/wrapper/uprobes.h
@@ -0,0 +1,87 @@
+#ifndef _LTTNG_WRAPPER_UPROBES_H
+#define _LTTNG_WRAPPER_UPROBES_H
+
+/*
+ * wrapper/uprobes.h
+ *
+ * wrapper around splice_to_pipe. Using KALLSYMS to get its address when
+ * available, else we need to have a kernel that exports this function to GPL
+ * modules.
+ *
+ * Copyright (C) 2013 Yannick Brosseau <yannick.brosseau at gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#include <linux/version.h>
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,5,0))
+#include <linux/uprobes.h>
+
+/* Use kallsym lookup for version before 3.9 */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,9,0))
+
+static inline
+int wrapper_uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
+{
+ return uprobe_register(inode, offset, uc);
+}
+
+static inline
+void wrapper_uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
+{
+ uprobe_unregister(inode, offset, uc);
+}
+
+#else /* Version < 3.9, use kallsym lookup */
+#include "kallsyms.h"
+
+static inline
+int wrapper_uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
+{
+ int (*uprobe_register_sym)(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
+
+ uprobe_register_sym = (void *) kallsyms_lookup_funcptr("uprobe_register");
+
+ if (uprobe_register_sym) {
+ return uprobe_register_sym(inode, offset, uc);
+ } else {
+ printk(KERN_WARNING "LTTng: uprobe_register symbol lookup failed.\n");
+ return -EINVAL;
+ }
+}
+
+static inline
+void wrapper_uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
+{
+ int (*uprobe_unregister_sym)(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
+
+ uprobe_unregister_sym = (void *) kallsyms_lookup_funcptr("uprobe_unregister");
+
+ if (uprobe_unregister_sym) {
+ uprobe_unregister_sym(inode, offset, uc);
+ } else {
+ printk(KERN_WARNING "LTTng: uprobe_unregister symbol lookup failed.\n");
+ WARN_ON(1);
+ }
+}
+#endif
+#else
+/* Version < 3.5, before uprobe was added */
+struct uprobe_consumer {};
+
+#endif
+#endif
--
1.8.1.4
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