Atlas - list_undefined.py
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1# Prints a list of symbols that are referenced in the Kconfig files of some
2# architecture but not defined by the Kconfig files of any architecture.
3#
4# A Kconfig file might be shared between many architectures and legitimately
5# reference undefined symbols for some of them, but if no architecture defines
6# the symbol, it usually indicates a problem or potential cleanup.
7#
8# This script could be sped up a lot if needed. See the comment near the
9# referencing_nodes() call.
10#
11# Run with the following command in the kernel root:
12#
13#   $ python(3) Kconfiglib/examples/list_undefined.py
14#
15# Example output:
16#
17#   Registering defined and undefined symbols for all arches
18#     Processing mips
19#     Processing ia64
20#     Processing metag
21#     ...
22#
23#   Finding references to each undefined symbol
24#     Processing mips
25#     Processing ia64
26#     Processing metag
27#     ...
28#
29#   The following globally undefined symbols were found, listed here
30#   together with the locations of the items that reference them.
31#   References might come from enclosing menus and ifs.
32#
33#     ARM_ERRATA_753970: arch/arm/mach-mvebu/Kconfig:56, arch/arm/mach-mvebu/Kconfig:39
34#     SUNXI_CCU_MP: drivers/clk/sunxi-ng/Kconfig:14
35#     SUNXI_CCU_DIV: drivers/clk/sunxi-ng/Kconfig:14
36#     AC97: sound/ac97/Kconfig:6
37#     ...
38
39import os
40import subprocess
41
42from kconfiglib import Kconfig
43
44
45# Referenced inside the Kconfig files
46os.environ["KERNELVERSION"] = str(
47    subprocess.check_output(("make", "kernelversion")).decode("utf-8").rstrip()
48)
49
50
51def all_arch_srcarch_pairs():
52    """
53    Generates all valid (ARCH, SRCARCH) tuples for the kernel, corresponding to
54    different architectures. SRCARCH holds the arch/ subdirectory.
55    """
56    for srcarch in os.listdir("arch"):
57        # Each subdirectory of arch/ containing a Kconfig file corresponds to
58        # an architecture
59        if os.path.exists(os.path.join("arch", srcarch, "Kconfig")):
60            yield (srcarch, srcarch)
61
62    # Some architectures define additional ARCH settings with ARCH != SRCARCH
63    # (search for "Additional ARCH settings for" in the top-level Makefile)
64
65    yield ("i386", "x86")
66    yield ("x86_64", "x86")
67
68    yield ("sparc32", "sparc")
69    yield ("sparc64", "sparc")
70
71    yield ("sh64", "sh")
72
73    yield ("um", "um")
74
75
76def all_arch_srcarch_kconfigs():
77    """
78    Generates Kconfig instances for all the architectures in the kernel
79    """
80
81    os.environ["srctree"] = "."
82    os.environ["HOSTCC"] = "gcc"
83    os.environ["HOSTCXX"] = "g++"
84    os.environ["CC"] = "gcc"
85    os.environ["LD"] = "ld"
86
87    for arch, srcarch in all_arch_srcarch_pairs():
88        print("  Processing " + arch)
89
90        os.environ["ARCH"] = arch
91        os.environ["SRCARCH"] = srcarch
92
93        # um (User Mode Linux) uses a different base Kconfig file
94        yield Kconfig("Kconfig" if arch != "um" else "arch/x86/um/Kconfig",
95                      warn=False)
96
97
98print("Registering defined and undefined symbols for all arches")
99
100# Sets holding the names of all defined and undefined symbols, for all
101# architectures
102defined = set()
103undefined = set()
104
105for kconf in all_arch_srcarch_kconfigs():
106    for name, sym in kconf.syms.items():
107        if sym.nodes:
108            # If the symbol has a menu node, it is defined
109            defined.add(name)
110        else:
111            # Undefined symbol. We skip some of the uninteresting ones.
112
113            # Due to how Kconfig works, integer literals show up as symbols
114            # (from e.g. 'default 1'). Skip those.
115            try:
116                int(name, 0)
117                continue
118            except ValueError:
119                # Interesting undefined symbol
120                undefined.add(name)
121
122
123print("\nFinding references to each undefined symbol")
124
125def referencing_nodes(kconf, name):
126    # Returns a list of all menu nodes that reference a symbol named 'name' in
127    # any of their properties or property conditions
128    res = []
129
130    for node in kconf.node_iter():
131        for ref in node.referenced:
132            if ref.name == name:
133                res.append(node)
134
135    return res
136
137
138# Maps each globally undefined symbol to the menu nodes that reference it
139undef_sym_refs = [(name, set()) for name in undefined - defined]
140
141for kconf in all_arch_srcarch_kconfigs():
142    for name, refs in undef_sym_refs:
143        # This means that we search the entire configuration tree for each
144        # undefined symbol, which is terribly inefficient. We could speed
145        # things up by tweaking referencing_nodes() to compare each symbol to
146        # multiple symbols while walking the configuration tree.
147        for node in referencing_nodes(kconf, name):
148            refs.add("{}:{}".format(node.filename, node.linenr))
149
150
151print("\nThe following globally undefined symbols were found, listed here\n"
152      "together with the locations of the items that reference them.\n"
153      "References might come from enclosing menus and ifs.\n")
154
155for name, refs in undef_sym_refs:
156    print("  {}: {}".format(name, ", ".join(refs)))
157
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