[lttng-dev] [lttng-modules PATCH] Add uprobes support
Yannick Brosseau
yannick.brosseau at gmail.com
Sun Jan 13 21:40:30 EST 2013
The added support is basic. It create an event with no data associated to the file path + offset
specified.
As per the structures currently used we cannot pass a file path bigger than 256 chars.
Signed-off-by: Yannick Brosseau <yannick.brosseau at gmail.com>
---
README | 5 +-
lttng-abi.c | 3 +
lttng-abi.h | 7 +++
lttng-events.c | 18 ++++++
lttng-events.h | 38 ++++++++++++
probes/Makefile | 5 ++
probes/lttng-uprobes.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++++
7 files changed, 231 insertions(+), 1 deletion(-)
create mode 100644 probes/lttng-uprobes.c
diff --git a/README b/README
index 1bcd5b2..7afdaa3 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).
@@ -86,6 +86,9 @@ 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.c b/lttng-abi.c
index 25a350a..fe428b2 100644
--- a/lttng-abi.c
+++ b/lttng-abi.c
@@ -610,6 +610,9 @@ int lttng_abi_create_event(struct file *channel_file,
case LTTNG_KERNEL_FUNCTION:
event_param->u.ftrace.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
break;
+ case LTTNG_KERNEL_UPROBE:
+ event_param->u.uprobe.path[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
+ break;
default:
break;
}
diff --git a/lttng-abi.h b/lttng-abi.h
index 8d3ecdd..5abdb39 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 path[LTTNG_KERNEL_SYM_NAME_LEN];
+ 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 4f30904..38c901f 100644
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -392,6 +392,16 @@ 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);
}
@@ -443,6 +453,10 @@ 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);
}
@@ -473,6 +487,10 @@ 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 09d5618..e630db0 100644
--- a/lttng-events.h
+++ b/lttng-events.h
@@ -26,6 +26,9 @@
#include <linux/version.h>
#include <linux/list.h>
#include <linux/kprobes.h>
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,5,0))
+#include <linux/uprobes.h>
+#endif
#include "wrapper/uuid.h"
#include "lttng-abi.h"
#include "lttng-abi-old.h"
@@ -203,6 +206,13 @@ struct lttng_event {
struct {
char *symbol_name;
} ftrace;
+ struct {
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,5,0))
+ struct uprobe_consumer up_consumer;
+#endif
+ struct inode *inode;
+ loff_t offset;
+ } uprobe;
} u;
struct list_head list; /* Event list */
unsigned int metadata_dumped:1;
@@ -406,6 +416,34 @@ 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 088cd5f..de0f1a7 100644
--- a/probes/Makefile
+++ b/probes/Makefile
@@ -208,6 +208,11 @@ 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..1d68273
--- /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 <linux/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 *path_name,
+ uint64_t offset,
+ struct lttng_event *event)
+{
+ int ret;
+
+ 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;
+
+ /* TODO Is this also true for uprobes?
+ * 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 = 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)
+{
+ 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");
--
1.7.10.4
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