linux-kernel-module-cheat/path_properties.py

#!/usr/bin/env python3

import os

from shell_helpers import LF

class PathProperties:
    '''
    Encodes properties of userland and baremetal paths.
    For directories, it applies to all files under the directory.
    Used to determine how to build and test the examples.
    '''
    def __init__(
        self,
        **kwargs
    ):
        property_keys = {
            'allowed_archs',
            'c_std',
            'cc_flags',
            'cc_pedantic',
            'cxx_std',
            'exit_status',
            'interactive',
            # We should get rid of this if we ever properly implement dependency graphs.
            'lkmc_common_obj',
            # We were lazy to properly classify why we are skipping these tests.
            # TODO get it done.
            'skip_run_unclassified',
            'more_than_1s',
            # The path does not generate an executable in itself, e.g.
            # it only generates intermediate object files.
            'no_executable',
            'pedantic',
            # the test receives a signal. We skip those tests for now,
            # on userland because we are lazy to figure out the exact semantics
            # of how Python + QEMU + gem5 determine the exit status of signals.
            'receives_signal',
            'requires_kernel_modules',
        }
        for key in kwargs:
            if not key in property_keys:
                raise ValueError('Unknown key: {}'.format(key))
        self.properties = kwargs

    def __getitem__(self, key):
        return self.properties[key]

    def __repr__(self):
        return str(self.properties)

    def update(self, other):
        other_tmp_properties = other.properties.copy()
        if 'cc_flags' in self.properties and 'cc_flags' in other_tmp_properties:
            other_tmp_properties['cc_flags'] = self.properties['cc_flags'] + other_tmp_properties['cc_flags']
        return self.properties.update(other_tmp_properties)

    def should_be_tested(self, arch):
        return \
            not self['interactive'] and \
            not self['more_than_1s'] and \
            not self['no_executable'] and \
            not self['receives_signal'] and \
            not self['requires_kernel_modules'] and \
            not self['skip_run_unclassified'] and \
            (
                self['allowed_archs'] is None or
                arch in self['allowed_archs']
            )

class PrefixTree:
    def __init__(self, path_properties_dict=None, children=None):
        if path_properties_dict is None:
            path_properties_dict = {}
        if children is None:
            children = {}
        self.children = children
        self.path_properties = PathProperties(**path_properties_dict)

    @staticmethod
    def make_from_tuples(tuples):
        def tree_from_tuples(tuple_):
            if not type(tuple_) is tuple:
                tuple_ = (tuple_, {})
            cur_properties, cur_children = tuple_
            return PrefixTree(cur_properties, cur_children)
        top_tree = tree_from_tuples(tuples)
        todo_trees = [top_tree]
        while todo_trees:
            cur_tree = todo_trees.pop()
            cur_children = cur_tree.children
            for child_key in cur_children:
                new_tree = tree_from_tuples(cur_children[child_key])
                cur_children[child_key] = new_tree
                todo_trees.append(new_tree)
        return top_tree

def get(test_path):
    cur_node = path_properties_tree
    path_properties = PathProperties(**cur_node.path_properties.properties)
    for path_component in test_path.split(os.sep):
        if path_component in cur_node.children:
            cur_node = cur_node.children[path_component]
            path_properties.update(cur_node.path_properties)
        else:
            break
    return path_properties

default_c_std = 'c11'
default_cxx_std = 'c++17'
gnu_extensions = {
    'c_std': 'gnu11',
    'cc_pedantic': False,
    'cxx_std': 'gnu++17'
}
path_properties_tuples = (
    {
        'c_std': default_c_std,
        'cxx_std': default_cxx_std,
        'pedantic': True,
        'allowed_archs': None,
        'c_std': None,
        'cc_flags': [],
        'cc_pedantic': True,
        'cxx_std': None,
        'exit_status': 0,
        'interactive': False,
        'lkmc_common_obj': False,
        'skip_run_unclassified': False,
        'more_than_1s': False,
        'no_executable': False,
        'pedantic': False,
        'receives_signal': False,
        'requires_kernel_modules': False,
    },
    {
        'userland': (
            {},
            {
                'arch': (
                    {
                        'cc_flags': [
                            '-fno-pie', LF,
                            '-no-pie', LF,
                        ]
                    },
                    {
                        'arm': (
                            {
                                'allowed_archs': {'arm'},
                                'cc_flags': [
                                    '-Xassembler', '-mcpu=cortex-a72', LF,
                                    # To prevent:
                                    # > vfp.S: Error: selected processor does not support <FPU instruction> in ARM mode
                                    # https://stackoverflow.com/questions/41131432/cross-compiling-error-selected-processor-does-not-support-fmrx-r3-fpexc-in/52875732#52875732
                                    # We aim to take the most extended mode currently available that works on QEMU.
                                    '-Xassembler', '-mfpu=crypto-neon-fp-armv8.1', LF,
                                    '-Xassembler', '-meabi=5', LF,
                                    # Treat inline assembly as arm instead of thumb
                                    # The opposite of -mthumb.
                                    '-marm', LF,
                                    # Make gcc generate .syntax unified for inline assembly.
                                    # However, it gets ignored if -marm is given, which a GCC bug that was recently fixed:
                                    # https://stackoverflow.com/questions/54078112/how-to-write-syntax-unified-ual-armv7-inline-assembly-in-gcc/54132097#54132097
                                    # So we just write divided inline assembly for now.
                                    '-masm-syntax-unified', LF,
                                ]
                            }
                        ),
                        'aarch64': {'allowed_archs': {'aarch64'}},
                        'empty.S': {'no_executable': True},
                        'fail.S': {'no_executable': True},
                        'main.c': {'no_executable': True},
                        'x86_64': (
                            {'allowed_archs': {'x86_64'}},
                            {
                                'c': (
                                    {},
                                    {
                                        'ring0.c': {'receives_signal': True}
                                    }
                                ),
                            }
                        ),
                    }
                ),
                'c': (
                    {},
                    {
                        'false.c': {'exit_status': 1},
                        'getchar.c': {'interactive': True},
                        'infinite_loop.c': {'more_than_1s': True},
                    }
                ),
                'gcc': gnu_extensions,
                'kernel_modules': {**gnu_extensions, **{'requires_kernel_modules': True}},
                'lkmc': (
                    {'lkmc_common_obj': True},
                    {
                        'assert_fail.c': {'exit_status': 1}
                    }
                ),
                'libs': {'skip_run_unclassified': True},
                'linux': {**gnu_extensions, **{'skip_run_unclassified': True}},
                'posix': (
                    {},
                    {
                        'count.c': {'more_than_1s': True},
                        'sleep_forever.c': {'more_than_1s': True},
                        'virt_to_phys_test.c': {'more_than_1s': True},
                    }
                )
            }
        )
    }
)
path_properties_tree = PrefixTree.make_from_tuples(path_properties_tuples)