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Auto merge of #3653 - tiif:bug/futex_ice, r=RalfJung

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Fix futex with large timeout ICE

Fixes #3647.

This PR changed the type of ``nanoseconds`` from ``u64`` to ``u128``. In ``duration_since``, nanoseconds is manually converted to second by dividing it with 1e9. But overflow is still possible.
This commit is contained in:
bors 2024-06-09 10:18:56 +00:00
commit 509eec19c4
1 changed files with 20 additions and 8 deletions
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28
src/tools/miri/src/clock.rs
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@ -6,7 +6,7 @@ use std::time::{Duration, Instant as StdInstant};
/// This number is pretty random, but it has been shown to approximately cause
/// some sample programs to run within an order of magnitude of real time on desktop CPUs.
/// (See `tests/pass/shims/time-with-isolation*.rs`.)
const NANOSECONDS_PER_BASIC_BLOCK: u64 = 5000;
const NANOSECONDS_PER_BASIC_BLOCK: u128 = 5000;
#[derive(Debug)]
pub struct Instant {
@ -16,7 +16,7 @@ pub struct Instant {
#[derive(Debug)]
enum InstantKind {
Host(StdInstant),
Virtual { nanoseconds: u64 },
Virtual { nanoseconds: u128 },
}
impl Instant {
@ -25,9 +25,8 @@ impl Instant {
InstantKind::Host(instant) =>
instant.checked_add(duration).map(|i| Instant { kind: InstantKind::Host(i) }),
InstantKind::Virtual { nanoseconds } =>
u128::from(nanoseconds)
nanoseconds
.checked_add(duration.as_nanos())
.and_then(|n| u64::try_from(n).ok())
.map(|nanoseconds| Instant { kind: InstantKind::Virtual { nanoseconds } }),
}
}
@ -39,7 +38,17 @@ impl Instant {
(
InstantKind::Virtual { nanoseconds },
InstantKind::Virtual { nanoseconds: earlier },
) => Duration::from_nanos(nanoseconds.saturating_sub(earlier)),
) => {
let duration = nanoseconds.saturating_sub(earlier);
// `Duration` does not provide a nice constructor from a `u128` of nanoseconds,
// so we have to implement this ourselves.
// It is possible for second to overflow because u64::MAX < (u128::MAX / 1e9).
// It will be saturated to u64::MAX seconds if the value after division exceeds u64::MAX.
let seconds = u64::try_from(duration / 1_000_000_000).unwrap_or(u64::MAX);
// It is impossible for nanosecond to overflow because u32::MAX > 1e9.
let nanosecond = u32::try_from(duration.wrapping_rem(1_000_000_000)).unwrap();
Duration::new(seconds, nanosecond)
}
_ => panic!("all `Instant` must be of the same kind"),
}
}
@ -59,7 +68,7 @@ enum ClockKind {
},
Virtual {
/// The "current virtual time".
nanoseconds: Cell<u64>,
nanoseconds: Cell<u128>,
},
}
@ -93,8 +102,11 @@ impl Clock {
ClockKind::Host { .. } => std::thread::sleep(duration),
ClockKind::Virtual { nanoseconds } => {
// Just pretend that we have slept for some time.
let nanos: u64 = duration.as_nanos().try_into().unwrap();
nanoseconds.update(|x| x + nanos);
let nanos: u128 = duration.as_nanos();
nanoseconds.update(|x| {
x.checked_add(nanos)
.expect("Miri's virtual clock cannot represent an execution this long")
});
}
}
}