u-boot/tools/binman/elf_test.py
Simon Glass 1979063264 binman: Support accessing binman tables at run time
Binman construct images consisting of multiple binary files. These files
sometimes need to know (at run timme) where their peers are located. For
example, SPL may want to know where U-Boot is located in the image, so
that it can jump to U-Boot correctly on boot.

In general the positions where the binaries end up after binman has
finished packing them cannot be known at compile time. One reason for
this is that binman does not know the size of the binaries until
everything is compiled, linked and converted to binaries with objcopy.

To make this work, we add a feature to binman which checks each binary
for symbol names starting with '_binman'. These are then decoded to figure
out which entry and property they refer to. Then binman writes the value
of this symbol into the appropriate binary. With this, the symbol will
have the correct value at run time.

Macros are used to make this easier to use. As an example, this declares
a symbol that will access the 'u-boot-spl' entry to find the 'pos' value
(i.e. the position of SPL in the image):

   binman_sym_declare(unsigned long, u_boot_spl, pos);

This converts to a symbol called '_binman_u_boot_spl_prop_pos' in any
binary that includes it. Binman then updates the value in that binary,
ensuring that it can be accessed at runtime with:

   ulong u_boot_pos = binman_sym(ulong, u_boot_spl, pos);

This assigns the variable u_boot_pos to the position of SPL in the image.

Signed-off-by: Simon Glass <sjg@chromium.org>
2017-12-12 19:53:45 -07:00

123 lines
3.9 KiB
Python

#
# Copyright (c) 2017 Google, Inc
# Written by Simon Glass <sjg@chromium.org>
#
# SPDX-License-Identifier: GPL-2.0+
#
# Test for the elf module
from contextlib import contextmanager
import os
import sys
import unittest
try:
from StringIO import StringIO
except ImportError:
from io import StringIO
import elf
binman_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
# Use this to suppress stdout/stderr output:
# with capture_sys_output() as (stdout, stderr)
# ...do something...
@contextmanager
def capture_sys_output():
capture_out, capture_err = StringIO(), StringIO()
old_out, old_err = sys.stdout, sys.stderr
try:
sys.stdout, sys.stderr = capture_out, capture_err
yield capture_out, capture_err
finally:
sys.stdout, sys.stderr = old_out, old_err
class FakeEntry:
def __init__(self, contents_size):
self.contents_size = contents_size
self.data = 'a' * contents_size
def GetPath(self):
return 'entry_path'
class FakeImage:
def __init__(self, sym_value=1):
self.sym_value = sym_value
def GetPath(self):
return 'image_path'
def LookupSymbol(self, name, weak, msg):
return self.sym_value
class TestElf(unittest.TestCase):
def testAllSymbols(self):
fname = os.path.join(binman_dir, 'test', 'u_boot_ucode_ptr')
syms = elf.GetSymbols(fname, [])
self.assertIn('.ucode', syms)
def testRegexSymbols(self):
fname = os.path.join(binman_dir, 'test', 'u_boot_ucode_ptr')
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)
def testMissingFile(self):
entry = FakeEntry(10)
image = FakeImage()
with self.assertRaises(ValueError) as e:
syms = elf.LookupAndWriteSymbols('missing-file', entry, image)
self.assertIn("Filename 'missing-file' not found in input path",
str(e.exception))
def testOutsideFile(self):
entry = FakeEntry(10)
image = FakeImage()
elf_fname = os.path.join(binman_dir, 'test', 'u_boot_binman_syms')
with self.assertRaises(ValueError) as e:
syms = elf.LookupAndWriteSymbols(elf_fname, entry, image)
self.assertIn('entry_path has offset 4 (size 8) but the contents size '
'is a', str(e.exception))
def testMissingImageStart(self):
entry = FakeEntry(10)
image = FakeImage()
elf_fname = os.path.join(binman_dir, 'test', 'u_boot_binman_syms_bad')
self.assertEqual(elf.LookupAndWriteSymbols(elf_fname, entry, image),
None)
def testBadSymbolSize(self):
entry = FakeEntry(10)
image = FakeImage()
elf_fname = os.path.join(binman_dir, 'test', 'u_boot_binman_syms_size')
with self.assertRaises(ValueError) as e:
syms = elf.LookupAndWriteSymbols(elf_fname, entry, image)
self.assertIn('has size 1: only 4 and 8 are supported',
str(e.exception))
def testNoValue(self):
entry = FakeEntry(20)
image = FakeImage(sym_value=None)
elf_fname = os.path.join(binman_dir, 'test', 'u_boot_binman_syms')
syms = elf.LookupAndWriteSymbols(elf_fname, entry, image)
self.assertEqual(chr(255) * 16 + 'a' * 4, entry.data)
def testDebug(self):
elf.debug = True
entry = FakeEntry(20)
image = FakeImage()
elf_fname = os.path.join(binman_dir, 'test', 'u_boot_binman_syms')
with capture_sys_output() as (stdout, stderr):
syms = elf.LookupAndWriteSymbols(elf_fname, entry, image)
elf.debug = False
self.assertTrue(len(stdout.getvalue()) > 0)
if __name__ == '__main__':
unittest.main()