firmware: eliminate most transmutes and document the rest. NFC.

This commit is contained in:
whitequark 2017-10-02 03:09:46 +00:00
parent 7ad54e1dcf
commit 73c76ebb9a
4 changed files with 7 additions and 6 deletions

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@ -409,7 +409,7 @@ static mut INFLIGHT: ExceptionInfo = ExceptionInfo {
#[export_name="__artiq_raise"]
#[unwind]
pub unsafe extern fn raise(exception: *const Exception) -> ! {
// Zing! The Exception<'a> as Exception<'static> cast is not really sound in case
// Zing! The Exception<'a> to Exception<'static> transmute is not really sound in case
// the exception is ever captured. Fortunately, they currently aren't, and we save
// on the hassle of having to allocate exceptions somewhere except on stack.
INFLIGHT.exception = Some(mem::transmute::<Exception, Exception<'static>>(*exception));

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@ -34,7 +34,7 @@ fn send(request: &Message) {
fn recv<R, F: FnOnce(&Message) -> R>(f: F) -> R {
while mailbox::receive() == 0 {}
let result = f(unsafe { mem::transmute::<usize, &Message>(mailbox::receive()) });
let result = f(unsafe { &*(mailbox::receive() as *const Message) });
mailbox::acknowledge();
result
}

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@ -4,7 +4,6 @@ extern crate log;
extern crate log_buffer;
extern crate board;
use core::{mem, ptr};
use core::cell::{Cell, RefCell};
use core::fmt::Write;
use log::{Log, LogMetadata, LogRecord, LogLevelFilter, MaxLogLevelFilter};
@ -43,12 +42,12 @@ impl BufferLogger {
f();
log::shutdown_logger_raw().unwrap();
unsafe {
LOGGER = ptr::null();
LOGGER = 0 as *const _;
}
}
pub fn with<R, F: FnOnce(&BufferLogger) -> R>(f: F) -> R {
f(unsafe { mem::transmute::<*const BufferLogger, &BufferLogger>(LOGGER) })
f(unsafe { &*LOGGER })
}
pub fn clear(&self) {

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@ -150,7 +150,7 @@ fn kern_recv_notrace<R, F>(io: &Io, f: F) -> io::Result<R>
return Err(io::Error::new(io::ErrorKind::InvalidData, message))
}
f(unsafe { mem::transmute::<usize, &kern::Message>(mailbox::receive()) })
f(unsafe { &*(mailbox::receive() as *const kern::Message) })
}
fn kern_recv_dotrace(reply: &kern::Message) {
@ -445,6 +445,8 @@ fn process_kern_message(io: &Io, mut stream: Option<&mut TcpStream>,
&kern::CacheGetRequest { key } => {
let value = session.congress.cache.get(key);
kern_send(io, &kern::CacheGetReply {
// Zing! This transmute is only safe because we dynamically track
// whether the kernel has borrowed any values from the cache.
value: unsafe { mem::transmute::<*const [i32], &'static [i32]>(value) }
})
}