squid 2.0.3

A RISC-V emulator with AOT compilation for fuzzing
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

use std::collections::HashMap;

use crate::frontend::{
    ao::{
        Edge,
        Function,
        CFG,
    },
    ChunkContent,
    HasId,
    Id,
    ProcessImage,
    VAddr,
};

fn find_definition(preds: &[(Id, Id)], defs: &HashMap<Id, Vec<bool>>, var: usize, mut curr: Id, cfg: &CFG) -> VAddr {
    loop {
        let mut found = false;

        for (to, from) in preds {
            if *to == curr {
                curr = *from;
                found = true;
                break;
            }
        }

        if !found {
            unreachable!("Variable import has no matching export");
        }

        let flags = defs.get(&curr).unwrap();

        if flags[var] {
            return cfg.basic_block(curr).unwrap().vaddr().unwrap();
        }
    }
}

pub(crate) struct VariableStorage {
    ids: HashMap<(VAddr, usize), usize>,
    counter: usize,
    num_variables: usize,
}

impl VariableStorage {
    pub(crate) fn new(image: &ProcessImage) -> Self {
        let mut storage = Self {
            ids: HashMap::default(),
            counter: 0,
            num_variables: 0,
        };

        for elf in image.iter_elfs() {
            for section in elf.iter_sections() {
                for symbol in section.iter_symbols() {
                    for chunk in symbol.iter_chunks() {
                        if let ChunkContent::Code(func) = chunk.content() {
                            storage.check_function(func);
                        }
                    }
                }
            }
        }

        storage
    }

    pub(crate) fn num_variables(&self) -> usize {
        self.num_variables
    }

    pub(crate) fn get_static_id(&self, bb: VAddr, var: usize) -> Option<usize> {
        self.ids.get(&(bb, var)).copied()
    }

    fn new_static_id(&mut self, def_bb: VAddr, var: usize) -> usize {
        if let Some(id) = self.get_static_id(def_bb, var) {
            return id;
        }

        let ret = self.counter;
        self.counter += 1;
        ret
    }

    fn check_function(&mut self, func: &Function) {
        self.counter = 0;

        /* First calculate predecessors */
        let mut preds = Vec::new();

        for bb in func.cfg().iter_basic_blocks() {
            for edge in bb.edges() {
                if let Edge::Next(target) = edge {
                    assert_ne!(*target, func.cfg().entry());
                    preds.push((*target, bb.id()));
                }
            }
        }

        /* Then find variable definitions */
        let mut defs = HashMap::new();

        for bb in func.cfg().iter_basic_blocks() {
            let mut flags = vec![false; bb.num_variables()];

            for op in bb.ops() {
                for out_var in op.output_variables() {
                    flags[out_var.id()] = true;
                }
            }

            defs.insert(bb.id(), flags);
        }

        /* Finally, check for variable imports */
        for bb in func.cfg().iter_basic_blocks() {
            let flags = defs.get(&bb.id()).unwrap();

            for op in bb.ops() {
                for in_var in op.input_variables() {
                    if !flags[in_var.id()] {
                        let def_bb = find_definition(&preds, &defs, in_var.id(), bb.id(), func.cfg());
                        let static_id = self.new_static_id(def_bb, in_var.id());
                        self.ids.insert((def_bb, in_var.id()), static_id);
                        self.ids.insert((bb.vaddr().unwrap(), in_var.id()), static_id);
                    }
                }
            }
        }

        self.num_variables = std::cmp::max(self.counter, self.num_variables);
    }
}