spl: binman: Check at runtime if binman symbols were filled in

Binman lets us declare symbols in SPL/TPL that refer to other entries in
the same binman image as them. These symbols are filled in with the
correct values while binman assembles the images, but this is done
in-memory only. Symbols marked as optional can be filled with
BINMAN_SYM_MISSING as an error value if their referred entry is missing.

However, the unmodified SPL/TPL binaries are still available on disk,
and can be used by people. For these files, nothing ensures that the
symbols are set to this error value, and they will be considered valid
when they are not.

Empirically, all symbols show up as zero in a sandbox_vpl build when we
run e.g. tpl/u-boot-tpl directly. On the other hand, zero is a perfectly
fine value for a binman-written symbol, so we cannot say the symbols
have wrong values based on that.

Declare a magic symbol that binman always fills in with a fixed value.
Check this value as an indicator that symbols were filled in correctly.
Return the error value for all symbols when this magic symbol has the
wrong value.

For binman tests, we need to make room for the new symbol in the mocked
SPL/TPL data by extending them by four bytes. This messes up some test
image layouts. Fix the affected values, and check the magic symbol
wherever it makes sense.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>

1 files changed, 17 insertions, 16 deletions

diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index b5cf549703..fa1f421c05 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -43,8 +43,8 @@ from patman import tout
 # Contents of test files, corresponding to different entry types
 U_BOOT_DATA           = b'1234'
 U_BOOT_IMG_DATA       = b'img'
-U_BOOT_SPL_DATA       = b'56780123456789abcdefghi'
-U_BOOT_TPL_DATA       = b'tpl9876543210fedcbazyw'
+U_BOOT_SPL_DATA       = b'56780123456789abcdefghijklm'
+U_BOOT_TPL_DATA       = b'tpl9876543210fedcbazywvuts'
 BLOB_DATA             = b'89'
 ME_DATA               = b'0abcd'
 VGA_DATA              = b'vga'
@@ -1406,8 +1406,9 @@ class TestFunctional(unittest.TestCase):
         elf_fname = self.ElfTestFile('u_boot_binman_syms')
         syms = elf.GetSymbols(elf_fname, ['binman', 'image'])
         addr = elf.GetSymbolAddress(elf_fname, '__image_copy_start')
+        self.assertEqual(syms['_binman_sym_magic'].address, addr)
         self.assertEqual(syms['_binman_u_boot_spl_any_prop_offset'].address,
-                         addr)
+                         addr + 4)
 
         self._SetupSplElf('u_boot_binman_syms')
         data = self._DoReadFileDtb(dts, entry_args=entry_args,
@@ -1415,17 +1416,17 @@ class TestFunctional(unittest.TestCase):
         # The image should contain the symbols from u_boot_binman_syms.c
         # Note that image_pos is adjusted by the base address of the image,
         # which is 0x10 in our test image
-        sym_values = struct.pack('<LQLL', 0x00,
-                                 u_boot_offset + len(U_BOOT_DATA),
+        sym_values = struct.pack('<LLQLL', elf.BINMAN_SYM_MAGIC_VALUE,
+                                 0x00, u_boot_offset + len(U_BOOT_DATA),
                                  0x10 + u_boot_offset, 0x04)
-        expected = (sym_values + base_data[20:] +
+        expected = (sym_values + base_data[24:] +
                     tools.get_bytes(0xff, 1) + U_BOOT_DATA + sym_values +
-                    base_data[20:])
+                    base_data[24:])
         self.assertEqual(expected, data)
 
     def testSymbols(self):
         """Test binman can assign symbols embedded in U-Boot"""
-        self.checkSymbols('053_symbols.dts', U_BOOT_SPL_DATA, 0x18)
+        self.checkSymbols('053_symbols.dts', U_BOOT_SPL_DATA, 0x1c)
 
     def testSymbolsNoDtb(self):
         """Test binman can assign symbols embedded in U-Boot SPL"""
@@ -3610,20 +3611,20 @@ class TestFunctional(unittest.TestCase):
 
     def _CheckSymbolsTplSection(self, dts, expected_vals):
         data = self._DoReadFile(dts)
-        sym_values = struct.pack('<LQLL', *expected_vals)
+        sym_values = struct.pack('<LLQLL', elf.BINMAN_SYM_MAGIC_VALUE, *expected_vals)
         upto1 = 4 + len(U_BOOT_SPL_DATA)
-        expected1 = tools.get_bytes(0xff, 4) + sym_values + U_BOOT_SPL_DATA[20:]
+        expected1 = tools.get_bytes(0xff, 4) + sym_values + U_BOOT_SPL_DATA[24:]
         self.assertEqual(expected1, data[:upto1])
 
         upto2 = upto1 + 1 + len(U_BOOT_SPL_DATA)
-        expected2 = tools.get_bytes(0xff, 1) + sym_values + U_BOOT_SPL_DATA[20:]
+        expected2 = tools.get_bytes(0xff, 1) + sym_values + U_BOOT_SPL_DATA[24:]
         self.assertEqual(expected2, data[upto1:upto2])
 
-        upto3 = 0x34 + len(U_BOOT_DATA)
+        upto3 = 0x3c + len(U_BOOT_DATA)
         expected3 = tools.get_bytes(0xff, 1) + U_BOOT_DATA
         self.assertEqual(expected3, data[upto2:upto3])
 
-        expected4 = sym_values + U_BOOT_TPL_DATA[20:]
+        expected4 = sym_values + U_BOOT_TPL_DATA[24:]
         self.assertEqual(expected4, data[upto3:upto3 + len(U_BOOT_TPL_DATA)])
 
     def testSymbolsTplSection(self):
@@ -3631,14 +3632,14 @@ class TestFunctional(unittest.TestCase):
         self._SetupSplElf('u_boot_binman_syms')
         self._SetupTplElf('u_boot_binman_syms')
         self._CheckSymbolsTplSection('149_symbols_tpl.dts',
-                                     [0x04, 0x1c, 0x10 + 0x34, 0x04])
+                                     [0x04, 0x20, 0x10 + 0x3c, 0x04])
 
     def testSymbolsTplSectionX86(self):
         """Test binman can assign symbols in a section with end-at-4gb"""
         self._SetupSplElf('u_boot_binman_syms_x86')
         self._SetupTplElf('u_boot_binman_syms_x86')
         self._CheckSymbolsTplSection('155_symbols_tpl_x86.dts',
-                                     [0xffffff04, 0xffffff1c, 0xffffff34,
+                                     [0xffffff04, 0xffffff20, 0xffffff3c,
                                       0x04])
 
     def testPackX86RomIfwiSectiom(self):
@@ -4488,7 +4489,7 @@ class TestFunctional(unittest.TestCase):
 
     def testSymbolsSubsection(self):
         """Test binman can assign symbols from a subsection"""
-        self.checkSymbols('187_symbols_sub.dts', U_BOOT_SPL_DATA, 0x18)
+        self.checkSymbols('187_symbols_sub.dts', U_BOOT_SPL_DATA, 0x1c)
 
     def testReadImageEntryArg(self):
         """Test reading an image that would need an entry arg to generate"""