uprobe: Support multiple call sites for the same uprobe event

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lttng-abi.c b/lttng-abi.c
index 32fa0bfa13011c218c1185caa373fa56efeb9d10..9d3f74240724ca72f5c4db1b93c4d74837b99848 100644 (file)
--- a/lttng-abi.c
+++ b/lttng-abi.c
@@ -1474,6 +1474,15 @@ long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                }
 
                }
+       case LTTNG_KERNEL_ADD_CALLSITE:
+               switch (*evtype) {
+               case LTTNG_TYPE_EVENT:
+                       event = file->private_data;
+                       return lttng_event_add_callsite(event,
+                               (struct lttng_kernel_event_callsite __user *) arg);
+               case LTTNG_TYPE_ENABLER:
+                       return -EINVAL;
+               }
        default:
                return -ENOIOCTLCMD;
        }

diff --git a/lttng-abi.h b/lttng-abi.h
index 762c10b0e44a23e96261680d8ee882731e07608f..db66bf375b74663e30f1b91809746a0bc76147b2 100644 (file)
--- a/lttng-abi.h
+++ b/lttng-abi.h
@@ -76,9 +76,18 @@ struct lttng_kernel_function_tracer {
 
 struct lttng_kernel_uprobe {
        int fd;
+} __attribute__((packed));
+
+struct lttng_kernel_event_callsite_uprobe {
        uint64_t offset;
 } __attribute__((packed));
 
+struct lttng_kernel_event_callsite {
+       union {
+               struct lttng_kernel_event_callsite_uprobe uprobe;
+       } u;
+} __attribute__((packed));
+
 /*
  * For syscall tracing, name = "*" means "enable all".
  */
@@ -220,6 +229,7 @@ struct lttng_kernel_filter_bytecode {
 
 /* Event FD ioctl */
 #define LTTNG_KERNEL_FILTER                    _IO(0xF6, 0x90)
+#define LTTNG_KERNEL_ADD_CALLSITE              _IO(0xF6, 0x91)
 
 /* LTTng-specific ioctls for the lib ringbuffer */
 /* returns the timestamp begin of the current sub-buffer */

diff --git a/lttng-events.c b/lttng-events.c
index 67ed16972a10fbdfe949f4abf8e57bf4a2be0bbd..3964df5fbb2f55b8d98fdb8501023a2c37a2dbab 100644 (file)
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -749,6 +749,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
                 */
                event->enabled = 0;
                event->registered = 1;
+
                /*
                 * Populate lttng_event structure before event
                 * registration.
@@ -757,7 +758,6 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 
                ret = lttng_uprobes_register(event_param->name,
                                event_param->u.uprobe.fd,
-                               event_param->u.uprobe.offset,
                                event);
                if (ret)
                        goto register_error;
@@ -1466,6 +1466,18 @@ error_free:
        return ret;
 }
 
+int lttng_event_add_callsite(struct lttng_event *event,
+               struct lttng_kernel_event_callsite __user *callsite)
+{
+
+       switch (event->instrumentation) {
+       case LTTNG_KERNEL_UPROBE:
+               return lttng_uprobes_add_callsite(event, callsite);
+       default:
+               return -EINVAL;
+       }
+}
+
 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
                struct lttng_kernel_context *context_param)
 {

diff --git a/lttng-events.h b/lttng-events.h
index f6fe151886debe591ff295c800a80b5e5d81e5db..f74f9d52cccb81302b18c242712cb2941009a4e1 100644 (file)
--- a/lttng-events.h
+++ b/lttng-events.h
@@ -285,6 +285,13 @@ struct lttng_enabler_ref {
        struct lttng_enabler *ref;              /* backward ref */
 };
 
+struct lttng_uprobe_handler {
+       struct lttng_event *event;
+       loff_t offset;
+       struct uprobe_consumer up_consumer;
+       struct list_head node;
+};
+
 /*
  * lttng_event structure is referred to by the tracing fast path. It must be
  * kept small.
@@ -311,9 +318,8 @@ struct lttng_event {
                        char *symbol_name;
                } ftrace;
                struct {
-                       struct uprobe_consumer up_consumer;
                        struct inode *inode;
-                       loff_t offset;
+                       struct list_head head;
                } uprobe;
        } u;
        struct list_head list;          /* Event list in session */
@@ -777,19 +783,26 @@ void lttng_kprobes_destroy_private(struct lttng_event *event)
 }
 #endif
 
+int lttng_event_add_callsite(struct lttng_event *event,
+       struct lttng_kernel_event_callsite *callsite);
 #ifdef CONFIG_UPROBES
 int lttng_uprobes_register(const char *name,
-               int fd,
-               uint64_t offset,
-               struct lttng_event *event);
+       int fd, struct lttng_event *event);
+int lttng_uprobes_add_callsite(struct lttng_event *event,
+       struct lttng_kernel_event_callsite *callsite);
 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,
-               int fd,
-               uint64_t offset,
-               struct lttng_event *event)
+       int fd, struct lttng_event *event)
+{
+       return -ENOSYS;
+}
+
+static inline
+int lttng_uprobes_add_callsite(struct lttng_event *event,
+       struct lttng_kernel_callsite_uprobe *callsite)
 {
        return -ENOSYS;
 }

diff --git a/probes/lttng-uprobes.c b/probes/lttng-uprobes.c
index 1f549c2f34bb14660c3513953a5711c9aaddd693..47f3599f2baa336dd6c7e543a81aef5070b67efb 100644 (file)
--- a/probes/lttng-uprobes.c
+++ b/probes/lttng-uprobes.c
@@ -22,9 +22,11 @@
  */
 
 #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>
@@ -35,8 +37,9 @@
 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_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),
@@ -151,12 +154,59 @@ error:
        return inode;
 }
 
-int lttng_uprobes_register(const char *name,
-                          int fd,
-                          uint64_t offset,
-                          struct lttng_event *event)
+int lttng_uprobes_add_callsite(struct lttng_event *event,
+       struct lttng_kernel_event_callsite __user *callsite)
 {
-       int ret;
+       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_all();
+
+       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);
@@ -169,29 +219,11 @@ int lttng_uprobes_register(const char *name,
                ret = -EBADF;
                goto inode_error;
        }
-
-       memset(&event->u.uprobe.up_consumer, 0,
-              sizeof(event->u.uprobe.up_consumer));
-
-       event->u.uprobe.up_consumer.handler = lttng_uprobes_handler_pre;
        event->u.uprobe.inode = inode;
-       event->u.uprobe.offset = offset;
+       INIT_LIST_HEAD(&event->u.uprobe.head);
 
-        /* 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) {
-               printk(KERN_WARNING "Error registering probe on inode %lu "
-                      "and offset %llu\n", event->u.uprobe.inode->i_ino,
-                      event->u.uprobe.offset);
-               goto register_error;
-       }
        return 0;
 
-register_error:
-       iput(event->u.uprobe.inode);
 inode_error:
        kfree(event->desc->name);
        kfree(event->desc);
@@ -202,9 +234,18 @@ 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);
+       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);