[PATCH] pickles: Add btf-dump.pk BTF utility pickle

[David Faust]

This new pickle has several functions for displaying BTF information in
a convenient and readable manner (displaying type IDs for easy
reference, displaying strings inline, etc.). It is primarily useful for
scripts, for example to quickly verify the BTF contents of an object
file.

2021-02-12  David Faust  <david.faust@oracle.com>

        * pickles/btf-dump.pk: New pickle.
        * pickles/Makefile.am (dist_pickles_DATA): Add `btf-dump.pk`.
---
 ChangeLog           |   5 ++
 pickles/Makefile.am |   2 +-
 pickles/btf-dump.pk | 205 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 211 insertions(+), 1 deletion(-)
 create mode 100644 pickles/btf-dump.pk

diff --git a/pickles/Makefile.am b/pickles/Makefile.am
index 7dada3dd..f42dee92 100644
--- a/pickles/Makefile.am
+++ b/pickles/Makefile.am
@@ -1,5 +1,5 @@
 picklesdir = $(pkgdatadir)/pickles
-dist_pickles_DATA = elf.pk ctf.pk leb128.pk bpf.pk btf.pk bmp.pk \
+dist_pickles_DATA = elf.pk ctf.pk leb128.pk bpf.pk btf.pk btf-dump.pk bmp.pk \
                     color.pk rgb24.pk id3v1.pk \
                     dwarf.pk dwarf-common.pk dwarf-frame.pk dwarf-pubnames.pk \
                     dwarf-types.pk time.pk argp.pk pktest.pk mbr.pk
diff --git a/pickles/btf-dump.pk b/pickles/btf-dump.pk
new file mode 100644
index 00000000..739659a5
--- /dev/null
+++ b/pickles/btf-dump.pk
@@ -0,0 +1,205 @@
+/* btf-dump.pk - Utilities for dumping BTF information.  */
+
+/* Copyright (C) 2021 Oracle, Inc.  */
+
+/* This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+load btf;
+
+/* Dump a BTF integer encoding.  */
+
+fun btf_dump_int = (BTF_Int i) void:
+  {
+    printf (" offset=%v bits=%v %s%s%s",
+            i.offset#b, i.bits#b,
+            i.signed_p ? "SIGNED " : "",
+            i.bool_p ? "BOOL " : "", i.char_p ? "CHAR " : "");
+  }
+
+/* Dump a BTF array encoding.  */
+
+fun btf_dump_array = (BTF_Array arr) void:
+  {
+    printf (" element_type=%u32d index_type=%u32d nelemes=%u32d",
+            arr.elem_type, arr.index_type, arr.nelems);
+  }
+
+/* Dump enumerators.  */
+
+fun btf_dump_enum = (BTF_Section btf, BTF_Enum[] e) void:
+  {
+    for (member in e)
+      printf ("\n\t '%s'(%v) value=%i32d",
+              btf.get_string (member.name),
+              member.name,
+              member.val);
+  }
+
+/* Dump function prototype members.  */
+
+fun btf_dump_proto = (BTF_Section btf, BTF_Param[] ps) void:
+  {
+    for (param in ps)
+      printf ("\n\t param '%s' type=%u32d",
+              btf.get_string (param.name),
+              param.param_type);
+  }
+
+/* Dump BTF Variable information. Currently only linkage.  */
+
+fun btf_dump_var = (BTF_Variable v) void:
+  {
+    printf (" linkage=%u1d (%s)", v.linkage,
+            v.linkage == 0 ? "static" : "global");
+  }
+
+/* Dump members of a struct or union. Note that we take a BTF_Type, because
+   the BTF_Member type is internal to BTF_Type and not visible here.  */
+
+fun btf_dump_sou = (BTF_Section btf, BTF_Type t) void:
+  {
+    var members = t.data.members;
+    for (member in members)
+      {
+        printf ("\n\tmember '%s' type=%u32d ",
+                btf.get_string (member.name),
+                member.type_id);
+
+        if (t.info.kind_flag)
+          printf ("bitfield_size=%v bit_offset=%v",
+                  member.offset.bitfield.bitfield_size,
+                  member.offset.bitfield.bit_offset);
+        else
+          printf ("member_offset=%v", member.offset.member_offset);
+      }
+  }
+
+/* Dump Variable entries following a BTF_KIND_DATASEC.  */
+
+fun btf_dump_datasec = (BTF_Var_SecInfo[] entries) void:
+  {
+    for (entry in entries)
+      printf ("\n\t var type=%u32d offset=%v size=%v",
+              entry.var_type, entry.offset, entry.size);
+  }
+
+/* Dump the variable data portion of a BTF_Type.  */
+
+fun btf_dump_type_vdata = (BTF_Section btf, BTF_Type t) void:
+  {
+    /* Integer */
+    try
+    {
+      btf_dump_int (t.data.integer);
+      return;
+    }
+    catch if E_elem {}
+
+    /* Array */
+    try
+    {
+      btf_dump_array (t.data.array);
+      return;
+    }
+    catch if E_elem {}
+
+    /* Enum */
+    try
+    {
+      btf_dump_enum (btf, t.data.enum);
+      return;
+    }
+    catch if E_elem {}
+
+    /* Func proto */
+    try
+    {
+      btf_dump_proto (btf, t.data.func_proto.params);
+      return;
+    }
+    catch if E_elem {}
+
+    /* Variable.  */
+    try
+    {
+      btf_dump_var (t.data.variable);
+      return;
+    }
+    catch if E_elem {}
+
+    /* Struct or union.  */
+    try
+    {
+      btf_dump_sou (btf, t);
+      return;
+    }
+    catch if E_elem {}
+
+    /* Datasec */
+    try
+    {
+      btf_dump_datasec (t.data.datasec);
+    }
+    catch if E_elem {}
+  }
+
+/* Dump a complete BTF type. Includes lookup and display of any strings
+   referenced by that type (e.g. type name, struct member names, etc.).  */
+
+fun btf_dump_type = (BTF_Section btf, BTF_Type t) void:
+  {
+    var name = btf.get_string (t.name);
+    printf ("%s '%s'(%v) ", btf_kind_names[t.info.kind], name, t.name);
+    try
+    {
+      printf ("size=%v", t.attrs.size);
+    }
+    catch if E_elem
+    {
+      printf ("type=%u32d", t.attrs.type_id);
+    }
+
+    btf_dump_type_vdata (btf, t);
+    print "\n";
+  }
+
+/* Dump all BTF types known by the given header.  */
+
+fun btf_dump = (BTF_Section btf) void:
+  {
+    var i = 1UL;
+    for (t in btf.types)
+      {
+        var name = btf.get_string (t.name);
+        printf ("[%u32d] %s ", i, btf_kind_names[t.info.kind]);
+        if (t.name == 0#B)
+          printf ("<anonymous> ");
+        else
+          printf("'%s'(%v) ", name, t.name);
+        try
+          {
+            printf ("size=%v", t.attrs.size);
+          }
+        catch if E_elem
+          {
+            printf ("type=%u32d", t.attrs.type_id);
+          }
+
+        btf_dump_type_vdata (btf, t);
+
+        print "\n";
+        i = i + 1;
+      }
+  }
-- 
2.30.0