buildtools: add Python pmdinfogen

Using a high-level, interpreted language simplifies maintenance and
build process. Furthermore, ELF handling is delegated to pyelftools
package. Original logic is kept, the copyright recognizes that.

Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Tested-by: Jie Zhou <jizh@microsoft.com>

buildtools/pmdinfogen.py

@@ -0,0 +1,189 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2016 Neil Horman <nhorman@tuxdriver.com>
+# Copyright (c) 2020 Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
+
+import argparse
+import ctypes
+import json
+import sys
+import tempfile
+
+from elftools.elf.elffile import ELFFile
+from elftools.elf.sections import SymbolTableSection
+
+
+class ELFSymbol:
+    def __init__(self, image, symbol):
+        self._image = image
+        self._symbol = symbol
+
+    @property
+    def size(self):
+        return self._symbol["st_size"]
+
+    @property
+    def value(self):
+        data = self._image.get_section_data(self._symbol["st_shndx"])
+        base = self._symbol["st_value"]
+        return data[base:base + self.size]
+
+    @property
+    def string_value(self):
+        value = self.value
+        return value[:-1].decode() if value else ""
+
+
+class ELFImage:
+    def __init__(self, data):
+        self._image = ELFFile(data)
+        self._symtab = self._image.get_section_by_name(".symtab")
+        if not isinstance(self._symtab, SymbolTableSection):
+            raise Exception(".symtab section is not a symbol table")
+
+    @property
+    def is_big_endian(self):
+        return not self._image.little_endian
+
+    def get_section_data(self, name):
+        return self._image.get_section(name).data()
+
+    def find_by_name(self, name):
+        symbol = self._symtab.get_symbol_by_name(name)
+        return ELFSymbol(self, symbol[0]) if symbol else None
+
+    def find_by_prefix(self, prefix):
+        for i in range(self._symtab.num_symbols()):
+            symbol = self._symtab.get_symbol(i)
+            if symbol.name.startswith(prefix):
+                yield ELFSymbol(self, symbol)
+
+
+def define_rte_pci_id(is_big_endian):
+    base_type = ctypes.LittleEndianStructure
+    if is_big_endian:
+        base_type = ctypes.BigEndianStructure
+
+    class rte_pci_id(base_type):
+        _pack_ = True
+        _fields_ = [
+            ("class_id", ctypes.c_uint32),
+            ("vendor_id", ctypes.c_uint16),
+            ("device_id", ctypes.c_uint16),
+            ("subsystem_vendor_id", ctypes.c_uint16),
+            ("subsystem_device_id", ctypes.c_uint16),
+        ]
+
+    return rte_pci_id
+
+
+class Driver:
+    OPTIONS = [
+        ("params", "_param_string_export"),
+        ("kmod", "_kmod_dep_export"),
+    ]
+
+    def __init__(self, name, options):
+        self.name = name
+        for key, value in options.items():
+            setattr(self, key, value)
+        self.pci_ids = []
+
+    @classmethod
+    def load(cls, image, symbol):
+        name = symbol.string_value
+
+        options = {}
+        for key, suffix in cls.OPTIONS:
+            option_symbol = image.find_by_name("__%s%s" % (name, suffix))
+            if option_symbol:
+                value = option_symbol.string_value
+                options[key] = value
+
+        driver = cls(name, options)
+
+        pci_table_name_symbol = image.find_by_name("__%s_pci_tbl_export" % name)
+        if pci_table_name_symbol:
+            driver.pci_ids = cls._load_pci_ids(image, pci_table_name_symbol)
+
+        return driver
+
+    @staticmethod
+    def _load_pci_ids(image, table_name_symbol):
+        table_name = table_name_symbol.string_value
+        table_symbol = image.find_by_name(table_name)
+        if not table_symbol:
+            raise Exception("PCI table declared but not defined: %d" % table_name)
+
+        rte_pci_id = define_rte_pci_id(image.is_big_endian)
+
+        pci_id_size = ctypes.sizeof(rte_pci_id)
+        pci_ids_desc = rte_pci_id * (table_symbol.size // pci_id_size)
+        pci_ids = pci_ids_desc.from_buffer_copy(table_symbol.value)
+        result = []
+        for pci_id in pci_ids:
+            if not pci_id.device_id:
+                break
+            result.append([
+                pci_id.vendor_id,
+                pci_id.device_id,
+                pci_id.subsystem_vendor_id,
+                pci_id.subsystem_device_id,
+                ])
+        return result
+
+    def dump(self, file):
+        dumped = json.dumps(self.__dict__)
+        escaped = dumped.replace('"', '\\"')
+        print(
+            'const char %s_pmd_info[] __attribute__((used)) = "PMD_INFO_STRING= %s";'
+            % (self.name, escaped),
+            file=file,
+        )
+
+
+def load_drivers(image):
+    drivers = []
+    for symbol in image.find_by_prefix("this_pmd_name"):
+        drivers.append(Driver.load(image, symbol))
+    return drivers
+
+
+def dump_drivers(drivers, file):
+    # Keep legacy order of definitions.
+    for driver in reversed(drivers):
+        driver.dump(file)
+
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("input", help="input object file path or '-' for stdin")
+    parser.add_argument("output", help="output C file path or '-' for stdout")
+    return parser.parse_args()
+
+
+def open_input(path):
+    if path == "-":
+        temp = tempfile.TemporaryFile()
+        temp.write(sys.stdin.buffer.read())
+        return temp
+    return open(path, "rb")
+
+
+def open_output(path):
+    if path == "-":
+        return sys.stdout
+    return open(path, "w")
+
+
+def main():
+    args = parse_args()
+    infile = open_input(args.input)
+    image = ELFImage(infile)
+    drivers = load_drivers(image)
+    output = open_output(args.output)
+    dump_drivers(drivers, output)
+
+
+if __name__ == "__main__":
+    main()