PR11015 Support shared library reloading (in different processes)

* runtime/task_finder_vma.c (stap_remove_vma_map_info): Return negative
  status on failure.
  (stap_find_vma_map_info): Likewise.
  (stap_find_vma_map_info_user): New function.
  (stap_drop_vma_maps): New function.
* runtime/sym.h (addr): Renamed to static_addr, to store addresses for
  sections which are always mapped at the same address.
  (_stp_module_relocate): Add extra struct task_struct *tsk argument.
* runtime/sym.c (_stp_tf_exec_cb): New callback, calls stap_drop_vma_maps.
  (_stp_tf_mmap_cb): Don't store address in module.section, but call
  stap_add_vma_map_info() per tsk->group_leader for matched module.
  Don't register empty/null modules.
  (_stp_module_relocate): Take extra struct task_struct *tsk argument,
  cache last tsk used. Only use section->static_addr for none dynamic
  modules. Use stap_find_vma_map_info_user() to locate dynamic modules.
  (_stp_mod_sec_lookup): Add extra argument unsigned long *rel_addr to
  optionally store relative address when module/section found.
  (_stp_kallsyms_lookup): Use _stp_mod_sec_lookup to find relative address.
  (_stp_sym_init): Register _stp_tf_exec_cb in stap_task_finder_target.
  Add error check to see if task finder could be initialized.
* dwflpp.cxx (emit_address): Pass NULL for kernel/modules and current for
  user tasks to _stp_module_relocate.
* runtime/transport/symbols.c (_stp_do_relocation): Set new static_addr
  _stp_section field.
* runtime/unwind.c (adjustStartLoc): Take new struct task_struct *tsk
  argument and pass to stap_find_vma_map_info_user and _stp_module_relocate
  to find adjusted addr.
  (_stp_search_unwind_hdr): Pass through struct task_struct *tsk.
  (unwind_frame): Likewise.
* tapset/context-symbols.stp (probemod): Add NULL to _stp_mod_sec_lookup
  call to indicate we aren't interested in relative address.
* tapsets.cxx (dwarf_derived_probe_group::emit_module_init): Pass NULL to
  _stp_module_relocate to indicate kernel/module address.

1 files changed, 67 insertions, 4 deletions

diff --git a/runtime/task_finder_vma.c b/runtime/task_finder_vma.c
index ed9c6f4f..9a32323f 100644
--- a/runtime/task_finder_vma.c
+++ b/runtime/task_finder_vma.c
@@ -270,6 +270,7 @@ stap_add_vma_map_info(struct task_struct *tsk, unsigned long vm_start,
 
 
 // Remove the vma entry from the vma hash table.
+// Returns -ESRCH if the entry isn't present.
 static int
 stap_remove_vma_map_info(struct task_struct *tsk, unsigned long vm_start,
 			     unsigned long vm_end, unsigned long vm_pgoff)
@@ -277,6 +278,7 @@ stap_remove_vma_map_info(struct task_struct *tsk, unsigned long vm_start,
 	struct hlist_head *head;
 	struct hlist_node *node;
 	struct __stp_tf_vma_entry *entry;
+	int rc = -ESRCH;
 
 	// Take a write lock since we are most likely going to delete
 	// after reading.
@@ -286,13 +288,15 @@ stap_remove_vma_map_info(struct task_struct *tsk, unsigned long vm_start,
 	if (entry != NULL) {
 		hlist_del(&entry->hlist);
 		__stp_tf_vma_put_free_entry(entry);
+                rc = 0;
 	}
 	write_unlock_irqrestore(&__stp_tf_vma_lock, flags);
-	return 0;
+	return rc;
 }
 
-// Finds vma info if the vma is present in the vma map hash table.
-// Returns ESRCH if not present.  The __stp_tf_vma_lock must *not* be
+// Finds vma info if the vma is present in the vma map hash table for
+// a given task and address (between vm_start and vm_end).
+// Returns -ESRCH if not present.  The __stp_tf_vma_lock must *not* be
 // locked before calling this function.
 static int
 stap_find_vma_map_info(struct task_struct *tsk, unsigned long vm_addr,
@@ -303,7 +307,7 @@ stap_find_vma_map_info(struct task_struct *tsk, unsigned long vm_addr,
 	struct hlist_node *node;
 	struct __stp_tf_vma_entry *entry;
 	struct __stp_tf_vma_entry *found_entry = NULL;
-	int rc = ESRCH;
+	int rc = -ESRCH;
 
 	unsigned long flags;
 	read_lock_irqsave(&__stp_tf_vma_lock, flags);
@@ -330,3 +334,62 @@ stap_find_vma_map_info(struct task_struct *tsk, unsigned long vm_addr,
 	read_unlock_irqrestore(&__stp_tf_vma_lock, flags);
 	return rc;
 }
+
+// Finds vma info if the vma is present in the vma map hash table for
+// a given task with the given user handle.
+// Returns -ESRCH if not present.  The __stp_tf_vma_lock must *not* be
+// locked before calling this function.
+static int
+stap_find_vma_map_info_user(struct task_struct *tsk, void *user,
+			    unsigned long *vm_start, unsigned long *vm_end,
+			    unsigned long *vm_pgoff)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct __stp_tf_vma_entry *entry;
+	struct __stp_tf_vma_entry *found_entry = NULL;
+	int rc = -ESRCH;
+
+	unsigned long flags;
+	read_lock_irqsave(&__stp_tf_vma_lock, flags);
+	head = &__stp_tf_vma_map[__stp_tf_vma_map_hash(tsk)];
+	hlist_for_each_entry(entry, node, head, hlist) {
+		if (tsk->pid == entry->pid
+		    && user == entry->user) {
+			found_entry = entry;
+			break;
+		}
+	}
+	if (found_entry != NULL) {
+		if (vm_start != NULL)
+			*vm_start = found_entry->vm_start;
+		if (vm_end != NULL)
+			*vm_end = found_entry->vm_end;
+		if (vm_pgoff != NULL)
+			*vm_pgoff = found_entry->vm_pgoff;
+		rc = 0;
+	}
+	read_unlock_irqrestore(&__stp_tf_vma_lock, flags);
+	return rc;
+}
+
+static int
+stap_drop_vma_maps(struct task_struct *tsk)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct hlist_node *n;
+	struct __stp_tf_vma_entry *entry;
+
+	unsigned long flags;
+	write_lock_irqsave(&__stp_tf_vma_lock, flags);
+	head = &__stp_tf_vma_map[__stp_tf_vma_map_hash(tsk)];
+        hlist_for_each_entry_safe(entry, node, n, head, hlist) {
+            if (tsk->pid == entry->pid) {
+		    hlist_del(&entry->hlist);
+		    __stp_tf_vma_put_free_entry(entry);
+            }
+        }
+	write_unlock_irqrestore(&__stp_tf_vma_lock, flags);
+	return 0;
+}