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https://github.com/brain-hackers/u-boot-brain
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![Simon Glass](/assets/img/avatar_default.png)
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>
209 lines
7.3 KiB
Python
209 lines
7.3 KiB
Python
# Copyright (c) 2016 Google, Inc
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#
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# SPDX-License-Identifier: GPL-2.0+
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#
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# Base class for all entries
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#
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# importlib was introduced in Python 2.7 but there was a report of it not
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# working in 2.7.12, so we work around this:
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# http://lists.denx.de/pipermail/u-boot/2016-October/269729.html
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try:
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import importlib
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have_importlib = True
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except:
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have_importlib = False
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import fdt_util
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import tools
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modules = {}
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class Entry(object):
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"""An Entry in the image
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An entry corresponds to a single node in the device-tree description
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of the image. Each entry ends up being a part of the final image.
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Entries can be placed either right next to each other, or with padding
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between them. The type of the entry determines the data that is in it.
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This class is not used by itself. All entry objects are subclasses of
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Entry.
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Attributes:
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image: The image containing this entry
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node: The node that created this entry
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pos: Absolute position of entry within the image, None if not known
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size: Entry size in bytes, None if not known
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contents_size: Size of contents in bytes, 0 by default
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align: Entry start position alignment, or None
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align_size: Entry size alignment, or None
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align_end: Entry end position alignment, or None
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pad_before: Number of pad bytes before the contents, 0 if none
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pad_after: Number of pad bytes after the contents, 0 if none
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data: Contents of entry (string of bytes)
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"""
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def __init__(self, image, etype, node, read_node=True):
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self.image = image
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self.etype = etype
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self._node = node
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self.pos = None
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self.size = None
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self.contents_size = 0
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self.align = None
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self.align_size = None
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self.align_end = None
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self.pad_before = 0
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self.pad_after = 0
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self.pos_unset = False
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if read_node:
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self.ReadNode()
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@staticmethod
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def Create(image, node, etype=None):
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"""Create a new entry for a node.
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Args:
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image: Image object containing this node
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node: Node object containing information about the entry to create
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etype: Entry type to use, or None to work it out (used for tests)
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Returns:
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A new Entry object of the correct type (a subclass of Entry)
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"""
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if not etype:
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etype = fdt_util.GetString(node, 'type', node.name)
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module_name = etype.replace('-', '_')
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module = modules.get(module_name)
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# Import the module if we have not already done so.
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if not module:
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try:
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if have_importlib:
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module = importlib.import_module(module_name)
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else:
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module = __import__(module_name)
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except ImportError:
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raise ValueError("Unknown entry type '%s' in node '%s'" %
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(etype, node.path))
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modules[module_name] = module
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# Call its constructor to get the object we want.
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obj = getattr(module, 'Entry_%s' % module_name)
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return obj(image, etype, node)
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def ReadNode(self):
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"""Read entry information from the node
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This reads all the fields we recognise from the node, ready for use.
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"""
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self.pos = fdt_util.GetInt(self._node, 'pos')
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self.size = fdt_util.GetInt(self._node, 'size')
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self.align = fdt_util.GetInt(self._node, 'align')
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if tools.NotPowerOfTwo(self.align):
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raise ValueError("Node '%s': Alignment %s must be a power of two" %
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(self._node.path, self.align))
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self.pad_before = fdt_util.GetInt(self._node, 'pad-before', 0)
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self.pad_after = fdt_util.GetInt(self._node, 'pad-after', 0)
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self.align_size = fdt_util.GetInt(self._node, 'align-size')
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if tools.NotPowerOfTwo(self.align_size):
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raise ValueError("Node '%s': Alignment size %s must be a power "
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"of two" % (self._node.path, self.align_size))
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self.align_end = fdt_util.GetInt(self._node, 'align-end')
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self.pos_unset = fdt_util.GetBool(self._node, 'pos-unset')
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def ObtainContents(self):
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"""Figure out the contents of an entry.
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Returns:
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True if the contents were found, False if another call is needed
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after the other entries are processed.
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"""
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# No contents by default: subclasses can implement this
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return True
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def Pack(self, pos):
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"""Figure out how to pack the entry into the image
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Most of the time the entries are not fully specified. There may be
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an alignment but no size. In that case we take the size from the
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contents of the entry.
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If an entry has no hard-coded position, it will be placed at @pos.
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Once this function is complete, both the position and size of the
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entry will be know.
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Args:
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Current image position pointer
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Returns:
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New image position pointer (after this entry)
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"""
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if self.pos is None:
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if self.pos_unset:
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self.Raise('No position set with pos-unset: should another '
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'entry provide this correct position?')
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self.pos = tools.Align(pos, self.align)
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needed = self.pad_before + self.contents_size + self.pad_after
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needed = tools.Align(needed, self.align_size)
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size = self.size
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if not size:
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size = needed
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new_pos = self.pos + size
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aligned_pos = tools.Align(new_pos, self.align_end)
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if aligned_pos != new_pos:
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size = aligned_pos - self.pos
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new_pos = aligned_pos
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if not self.size:
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self.size = size
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if self.size < needed:
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self.Raise("Entry contents size is %#x (%d) but entry size is "
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"%#x (%d)" % (needed, needed, self.size, self.size))
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# Check that the alignment is correct. It could be wrong if the
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# and pos or size values were provided (i.e. not calculated), but
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# conflict with the provided alignment values
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if self.size != tools.Align(self.size, self.align_size):
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self.Raise("Size %#x (%d) does not match align-size %#x (%d)" %
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(self.size, self.size, self.align_size, self.align_size))
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if self.pos != tools.Align(self.pos, self.align):
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self.Raise("Position %#x (%d) does not match align %#x (%d)" %
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(self.pos, self.pos, self.align, self.align))
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return new_pos
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def Raise(self, msg):
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"""Convenience function to raise an error referencing a node"""
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raise ValueError("Node '%s': %s" % (self._node.path, msg))
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def GetPath(self):
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"""Get the path of a node
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Returns:
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Full path of the node for this entry
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"""
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return self._node.path
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def GetData(self):
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return self.data
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def GetPositions(self):
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return {}
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def SetPositionSize(self, pos, size):
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self.pos = pos
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self.size = size
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def ProcessContents(self):
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pass
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def WriteSymbols(self, image):
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"""Write symbol values into binary files for access at run time
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Args:
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image: Image containing the entry
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"""
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pass
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