binman: Add a function to read ELF symbols

In some cases we need to read symbols from U-Boot. At present we have a
a few cases which does this via 'nm' and 'grep'.

It is better to use objdump since that tells us the size of the symbols
and also whether it is weak or not.

Add a new module which reads ELF information from files. Update existing
uses of 'nm' to use this module.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/binman.py

@@ -33,6 +33,7 @@ import control
 
 def RunTests():
     """Run the functional tests and any embedded doctests"""
+    import elf_test
     import entry_test
     import fdt_test
     import ftest
@@ -50,7 +51,7 @@ def RunTests():
     # 'entry' module.
     suite = unittest.TestLoader().loadTestsFromTestCase(entry_test.TestEntry)
     suite.run(result)
-    for module in (ftest.TestFunctional, fdt_test.TestFdt):
+    for module in (ftest.TestFunctional, fdt_test.TestFdt, elf_test.TestElf):
         suite = unittest.TestLoader().loadTestsFromTestCase(module)
         suite.run(result)
 

tools/binman/elf.py

@@ -0,0 +1,77 @@
+# Copyright (c) 2016 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# SPDX-License-Identifier:      GPL-2.0+
+#
+# Handle various things related to ELF images
+#
+
+from collections import namedtuple, OrderedDict
+import command
+import os
+import re
+import struct
+
+import tools
+
+Symbol = namedtuple('Symbol', ['section', 'address', 'size', 'weak'])
+
+# Used for tests which don't have an ELF file to read
+ignore_missing_files = False
+
+
+def GetSymbols(fname, patterns):
+    """Get the symbols from an ELF file
+
+    Args:
+        fname: Filename of the ELF file to read
+        patterns: List of regex patterns to search for, each a string
+
+    Returns:
+        None, if the file does not exist, or Dict:
+          key: Name of symbol
+          value: Hex value of symbol
+    """
+    stdout = command.Output('objdump', '-t', fname, raise_on_error=False)
+    lines = stdout.splitlines()
+    if patterns:
+        re_syms = re.compile('|'.join(patterns))
+    else:
+        re_syms = None
+    syms = {}
+    syms_started = False
+    for line in lines:
+        if not line or not syms_started:
+            if 'SYMBOL TABLE' in line:
+                syms_started = True
+            line = None  # Otherwise code coverage complains about 'continue'
+            continue
+        if re_syms and not re_syms.search(line):
+            continue
+
+        space_pos = line.find(' ')
+        value, rest = line[:space_pos], line[space_pos + 1:]
+        flags = rest[:7]
+        parts = rest[7:].split()
+        section, size =  parts[:2]
+        if len(parts) > 2:
+            name = parts[2]
+            syms[name] = Symbol(section, int(value, 16), int(size,16),
+                                flags[1] == 'w')
+    return syms
+
+def GetSymbolAddress(fname, sym_name):
+    """Get a value of a symbol from an ELF file
+
+    Args:
+        fname: Filename of the ELF file to read
+        patterns: List of regex patterns to search for, each a string
+
+    Returns:
+        Symbol value (as an integer) or None if not found
+    """
+    syms = GetSymbols(fname, [sym_name])
+    sym = syms.get(sym_name)
+    if not sym:
+        return None
+    return sym.address

tools/binman/elf_test.py

@@ -0,0 +1,32 @@
+#
+# Copyright (c) 2017 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# SPDX-License-Identifier:      GPL-2.0+
+#
+# Test for the elf module
+
+import os
+import sys
+import unittest
+
+import elf
+
+binman_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
+fname = os.path.join(binman_dir, 'test', 'u_boot_ucode_ptr')
+
+class TestElf(unittest.TestCase):
+    def testAllSymbols(self):
+        syms = elf.GetSymbols(fname, [])
+        self.assertIn('.ucode', syms)
+
+    def testRegexSymbols(self):
+        syms = elf.GetSymbols(fname, ['ucode'])
+        self.assertIn('.ucode', syms)
+        syms = elf.GetSymbols(fname, ['missing'])
+        self.assertNotIn('.ucode', syms)
+        syms = elf.GetSymbols(fname, ['missing', 'ucode'])
+        self.assertIn('.ucode', syms)
+
+if __name__ == '__main__':
+    unittest.main()

tools/binman/etype/u_boot_spl_bss_pad.py

@@ -9,6 +9,7 @@
 #
 
 import command
+import elf
 from entry import Entry
 from blob import Entry_blob
 import tools
@@ -19,8 +20,8 @@ class Entry_u_boot_spl_bss_pad(Entry_blob):
 
     def ObtainContents(self):
         fname = tools.GetInputFilename('spl/u-boot-spl')
-        args = [['nm', fname], ['grep', '__bss_size']]
-        out = command.RunPipe(args, capture=True).stdout.splitlines()
-        bss_size = int(out[0].split()[0], 16)
+        bss_size = elf.GetSymbolAddress(fname, '__bss_size')
+        if not bss_size:
+            self.Raise('Expected __bss_size symbol in spl/u-boot-spl')
         self.data = chr(0) * bss_size
         self.contents_size = bss_size

tools/binman/etype/u_boot_with_ucode_ptr.py

@@ -9,6 +9,7 @@
 import struct
 
 import command
+import elf
 from entry import Entry
 from blob import Entry_blob
 import fdt_util
@@ -31,11 +32,9 @@ class Entry_u_boot_with_ucode_ptr(Entry_blob):
     def ObtainContents(self):
         # Figure out where to put the microcode pointer
         fname = tools.GetInputFilename(self.elf_fname)
-        args = [['nm', fname], ['grep', '-w', '_dt_ucode_base_size']]
-        out = (command.RunPipe(args, capture=True, raise_on_error=False).
-               stdout.splitlines())
-        if len(out) == 1:
-            self.target_pos = int(out[0].split()[0], 16)
+        sym = elf.GetSymbolAddress(fname, '_dt_ucode_base_size')
+        if sym:
+           self.target_pos = sym
         elif not fdt_util.GetBool(self._node, 'optional-ucode'):
             self.Raise('Cannot locate _dt_ucode_base_size symbol in u-boot')
 

tools/binman/ftest.py

@@ -835,6 +835,13 @@ class TestFunctional(unittest.TestCase):
         data = self._DoReadFile('47_spl_bss_pad.dts')
         self.assertEqual(U_BOOT_SPL_DATA + (chr(0) * 10) + U_BOOT_DATA, data)
 
+        with open(self.TestFile('u_boot_ucode_ptr')) as fd:
+            TestFunctional._MakeInputFile('spl/u-boot-spl', fd.read())
+        with self.assertRaises(ValueError) as e:
+            data = self._DoReadFile('47_spl_bss_pad.dts')
+        self.assertIn('Expected __bss_size symbol in spl/u-boot-spl',
+                      str(e.exception))
+
     def testPackStart16Spl(self):
         """Test that an image with an x86 start16 region can be created"""
         data = self._DoReadFile('48_x86-start16-spl.dts')

tools/binman/test/bss_data.c

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier:     GPL-2.0+
  *
  * Simple program to create a _dt_ucode_base_size symbol which can be read
- * by 'nm'. This is used by binman tests.
+ * by binutils. This is used by binman tests.
  */
 
 int bss_data[10];

tools/binman/test/u_boot_ucode_ptr.c

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier:     GPL-2.0+
  *
  * Simple program to create a _dt_ucode_base_size symbol which can be read
- * by 'nm'. This is used by binman tests.
+ * by binutils. This is used by binman tests.
  */
 
 static unsigned long _dt_ucode_base_size[2]