[PATCH 1/6] Make BFD read `.stapsdt' section from binary

[Sergio Durigan Junior <sergiodj at redhat dot com>]

Hi,

The following patch implements the necessary code to make BFD read the
`.stapsdt' note section from the binary file.  It basically allocates a
linked-list where each entry contains information about one SystemTap
probe.

It was regtested on the compile farm.

Thanks,

Sergio.

>From 1f7a8198c27ab823f191b713dae3641d108f1212 Mon Sep 17 00:00:00 2001
From: Sergio Durigan Junior <sergiodj@redhat.com>
Date: Mon, 28 Mar 2011 20:32:20 -0300
Subject: [PATCH 1/6] patch 0: BFD patch

---
 bfd/ChangeLog |    9 +++++++++
 bfd/elf-bfd.h |   14 ++++++++++++++
 bfd/elf.c     |   37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 0 deletions(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 1c34293..cfcffba 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,12 @@
+2011-04-04  Sergio Durigan Junior  <sergiodj@redhat.com>
+
+	* elf-bfd.h (struct sdt_note): New struct.
+	(struct elf_obj_tdata) <sdt_note_head>: New field.
+	* elf.c (elfobj_grok_stapsdt_note_1): New function.
+	(elfobj_grok_stapsdt_note): Likewise.
+	(elf_parse_notes): Added code to treat SystemTap note
+	sections.
+
 2011-04-01  Tristan Gingold  <gingold@adacore.com>
 
 	* elfxx-ia64.c: include bfd_stdint.h
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 21ec38f..d50823a 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1476,6 +1476,15 @@ enum
   Tag_compatibility = 32
 };
 
+/* The following struct stores information about every SystemTap section
+   found in the object file.  */
+struct sdt_note
+{
+  struct sdt_note *next;
+  bfd_size_type size;
+  bfd_byte data[1];
+};
+
 /* Some private data is stashed away for future use using the tdata pointer
    in the bfd structure.  */
 
@@ -1633,6 +1642,11 @@ struct elf_obj_tdata
   bfd_size_type build_id_size;
   bfd_byte *build_id;
 
+  /* Linked-list containing information about every Systemtap section
+     found in the object file.  Each section corresponds to one entry
+     in the list.  */
+  struct sdt_note *sdt_note_head;
+
   /* True if the bfd contains symbols that have the STT_GNU_IFUNC
      symbol type.  Used to set the osabi field in the ELF header
      structure.  */
diff --git a/bfd/elf.c b/bfd/elf.c
index f69abf2..3c038eb 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -8416,6 +8416,37 @@ elfobj_grok_gnu_note (bfd *abfd, Elf_Internal_Note *note)
     }
 }
 
+#define SDT_NOTE_TYPE 3
+
+static bfd_boolean
+elfobj_grok_stapsdt_note_1 (bfd *abfd, Elf_Internal_Note *note)
+{
+  struct sdt_note *cur =
+    (struct sdt_note *) bfd_alloc (abfd, sizeof (struct sdt_note)
+				   + note->descsz);
+
+  cur->next = (struct sdt_note *) (elf_tdata (abfd))->sdt_note_head;
+  cur->size = (bfd_size_type) note->descsz;
+  memcpy (cur->data, note->descdata, note->descsz);
+
+  elf_tdata (abfd)->sdt_note_head = cur;
+
+  return TRUE;
+}
+
+static bfd_boolean
+elfobj_grok_stapsdt_note (bfd *abfd, Elf_Internal_Note *note)
+{
+  switch (note->type)
+    {
+    case SDT_NOTE_TYPE:
+      return elfobj_grok_stapsdt_note_1 (abfd, note);
+
+    default:
+      return TRUE;
+    }
+}
+
 static bfd_boolean
 elfcore_netbsd_get_lwpid (Elf_Internal_Note *note, int *lwpidp)
 {
@@ -9189,6 +9220,12 @@ elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset)
 	      if (! elfobj_grok_gnu_note (abfd, &in))
 		return FALSE;
 	    }
+	  else if (in.namesz == sizeof "stapsdt"
+		   && strcmp (in.namedata, "stapsdt") == 0)
+	    {
+	      if (! elfobj_grok_stapsdt_note (abfd, &in))
+		return FALSE;
+	    }
 	  break;
 	}
 
-- 
1.7.3.4