sel4_panicking/
lib.rs

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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
//
// Copyright 2023, Colias Group, LLC
//
// SPDX-License-Identifier: BSD-2-Clause
//

#![no_std]
#![feature(cfg_target_thread_local)]
#![feature(core_intrinsics)]
#![feature(lang_items)]
#![feature(panic_can_unwind)]
#![feature(thread_local)]
#![cfg_attr(not(panic_info_message_stable), feature(panic_info_message))]
#![allow(internal_features)]

#[cfg(feature = "alloc")]
extern crate alloc;

use core::fmt;
use core::mem::ManuallyDrop;
use core::panic::Location;
use core::panic::{PanicInfo, UnwindSafe};

#[cfg(panic_info_message_stable)]
pub use core::panic::PanicMessage;

use cfg_if::cfg_if;

use sel4_panicking_env::abort;

mod count;
mod hook;
mod payload;
mod strategy;

use count::{count_panic, count_panic_caught};
use hook::get_hook;
use payload::NoPayload;
use strategy::{panic_cleanup, start_panic};

pub use hook::{set_hook, PanicHook};
pub use payload::{Payload, SmallPayload, UpcastIntoPayload, SMALL_PAYLOAD_MAX_SIZE};

#[cfg(not(panic_info_message_stable))]
pub type PanicMessage<'a> = &'a fmt::Arguments<'a>;

/// Information passed to a [`PanicHook`].
///
/// Analogous to `std::panic::PanicHookInfo`.
pub struct ExternalPanicInfo<'a> {
    payload: Payload,
    message: Option<PanicMessage<'a>>,
    location: Option<&'a Location<'a>>,
    can_unwind: bool,
}

impl ExternalPanicInfo<'_> {
    pub fn payload(&self) -> &Payload {
        &self.payload
    }

    pub fn message(&self) -> Option<&PanicMessage> {
        self.message.as_ref()
    }

    pub fn location(&self) -> Option<&Location> {
        self.location
    }

    pub fn can_unwind(&self) -> bool {
        self.can_unwind
    }
}

impl fmt::Display for ExternalPanicInfo<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.write_str("panicked at ")?;
        if let Some(location) = self.location() {
            location.fmt(f)?;
        } else {
            f.write_str("unknown location")?;
        }
        if let Some(message) = self.message() {
            f.write_str(":\n")?;
            message.fmt(f)?;
        }
        Ok(())
    }
}

#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    do_panic(ExternalPanicInfo {
        payload: NoPayload.upcast_into_payload(),
        #[cfg(panic_info_message_stable)]
        message: Some(info.message()),
        #[cfg(not(panic_info_message_stable))]
        message: info.message(),
        location: info.location(),
        can_unwind: info.can_unwind(),
    })
}

/// Like `std::panic::panic_any`.
#[track_caller]
pub fn panic_any<M: UpcastIntoPayload>(msg: M) -> ! {
    do_panic(ExternalPanicInfo {
        payload: msg.upcast_into_payload(),
        message: None,
        location: Some(Location::caller()),
        can_unwind: true,
    })
}

fn do_panic(info: ExternalPanicInfo) -> ! {
    count_panic();
    (get_hook())(&info);
    if info.can_unwind() {
        let code = start_panic(info.payload);
        abort!("failed to initiate panic, error {}", code)
    } else {
        abort!("can't unwind this panic")
    }
}

cfg_if! {
    if #[cfg(catch_unwind_intrinsic_still_named_try)] {
        use core::intrinsics::r#try as catch_unwind_intrinsic;
    } else {
        use core::intrinsics::catch_unwind as catch_unwind_intrinsic;
    }
}

/// Like `std::panic::catch_unwind`.
pub fn catch_unwind<R, F: FnOnce() -> R + UnwindSafe>(f: F) -> Result<R, Payload> {
    union Data<F, R> {
        f: ManuallyDrop<F>,
        r: ManuallyDrop<R>,
        p: ManuallyDrop<Payload>,
    }

    let mut data = Data {
        f: ManuallyDrop::new(f),
    };

    let data_ptr = &mut data as *mut _ as *mut u8;
    unsafe {
        return if catch_unwind_intrinsic(do_call::<F, R>, data_ptr, do_catch::<F, R>) == 0 {
            Ok(ManuallyDrop::into_inner(data.r))
        } else {
            Err(ManuallyDrop::into_inner(data.p))
        };
    }

    #[inline]
    fn do_call<F: FnOnce() -> R, R>(data: *mut u8) {
        unsafe {
            let data = data as *mut Data<F, R>;
            let data = &mut (*data);
            let f = ManuallyDrop::take(&mut data.f);
            data.r = ManuallyDrop::new(f());
        }
    }

    #[inline]
    fn do_catch<F: FnOnce() -> R, R>(data: *mut u8, exception: *mut u8) {
        unsafe {
            let data = data as *mut Data<F, R>;
            let data = &mut (*data);
            let payload = panic_cleanup(exception);
            count_panic_caught();
            data.p = ManuallyDrop::new(payload);
        }
    }
}