From: Mark Wielaard <mark@klomp.org>
Date: Thu, 28 Dec 2017 16:44:06 +0000 (+0100)
Subject: libdw: Add support for DWARF5 DW_FORM_data16.
X-Git-Tag: elfutils-0.171~72
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8e5e78927ee319816eb7a74f870671d21e762bfc;p=thirdparty%2Felfutils.git

libdw: Add support for DWARF5 DW_FORM_data16.

The DWARF5 spec says DW_FORM_data16 is constant class (128bit value).
But we treat it as if it is block class. So to use a attribute that is
encoded as DW_FORM_data16 use dwarf_formblock, not dwarf_form[us]data.

We cannot use dwarf_form[us]data since they return a Dwarf_Word/Sword,
which are only 64bits.

This does mean we don't try to convert the value but just return it as
a block of 16 raw bytes.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 888e50967..b86fb13fd 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,8 @@
+2018-02-09  Mark Wielaard  <mark@klomp.org>
+
+	* dwarf_formblock.c (dwarf_formblock): Handle DW_FORM_data16 as a
+	16 byte block.
+
 2018-02-09  Mark Wielaard  <mark@klomp.org>
 
 	* dwarf_child.c (__libdw_find_attr): Handle DW_FORM_implicit_const.
diff --git a/libdw/dwarf_formblock.c b/libdw/dwarf_formblock.c
index 13f9e72a2..924baf458 100644
--- a/libdw/dwarf_formblock.c
+++ b/libdw/dwarf_formblock.c
@@ -1,5 +1,5 @@
 /* Return block represented by attribute.
-   Copyright (C) 2004-2010, 2014 Red Hat, Inc.
+   Copyright (C) 2004-2010, 2014, 2018 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <drepper@redhat.com>, 2004.
 
@@ -75,6 +75,16 @@ dwarf_formblock (Dwarf_Attribute *attr, Dwarf_Block *return_block)
       return_block->data = (unsigned char *) datap;
       break;
 
+    case DW_FORM_data16:
+      /* The DWARFv5 spec calls this constant class, but we interpret
+	 it as a block that the user will need to interpret when
+	 converting to a value.  */
+      if (unlikely (endp - datap < 16))
+	goto invalid;
+      return_block->length = 16;
+      return_block->data = (unsigned char *) datap;
+      break;
+
     default:
       __libdw_seterrno (DWARF_E_NO_BLOCK);
       return -1;
diff --git a/src/ChangeLog b/src/ChangeLog
index 282736636..0ae01e926 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2018-02-09  Mark Wielaard  <mark@klomp.org>
+
+	* readelf.c (attr_callback): Handle DW_FORM_data16 as Dwarf_Block.
+
 2018-02-09  Mark Wielaard  <mark@klomp.org>
 
 	* readelf.c (print_debug_abbrev_section): Print the value of a
diff --git a/src/readelf.c b/src/readelf.c
index bdeba4b6b..2d49af346 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -6083,7 +6083,7 @@ attr_callback (Dwarf_Attribute *attrp, void *arg)
     case DW_FORM_implicit_const:
     case DW_FORM_udata:
     case DW_FORM_sdata:
-    case DW_FORM_data8:
+    case DW_FORM_data8: /* Note no data16 here, we see that as block. */
     case DW_FORM_data4:
     case DW_FORM_data2:
     case DW_FORM_data1:;
@@ -6276,6 +6276,7 @@ attr_callback (Dwarf_Attribute *attrp, void *arg)
     case DW_FORM_block2:
     case DW_FORM_block1:
     case DW_FORM_block:
+    case DW_FORM_data16: /* DWARF5 calls this a constant class.  */
       if (cbargs->silent)
 	break;
       Dwarf_Block block;