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Implement futex_wait and futex_wake. #1568

Merged
merged 23 commits into from
Oct 3, 2020
Merged

Implement futex_wait and futex_wake. #1568

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1ffc5bb
Implement futex_wait and futex_wake.
m-ou-se Oct 1, 2020
281a538
Move futex syscall to its own file.
m-ou-se Oct 1, 2020
6c2f36e
Erase tag from futex pointers.
m-ou-se Oct 1, 2020
69cea1d
Only check futex pointer in futex_wait and not in futex_wake.
m-ou-se Oct 1, 2020
1c582e7
Return correct value from futex_wait.
m-ou-se Oct 1, 2020
c2fa27c
Check maximum amount of arguments to SYS_futex.
m-ou-se Oct 2, 2020
712e800
Improve handling of the `addr` argument in SYS_futex.
m-ou-se Oct 2, 2020
ee3eb4b
Add comments that document SYS_futex better.
m-ou-se Oct 2, 2020
dabd980
Update note about number of arguments to SYS_futex.
m-ou-se Oct 2, 2020
422b505
Add note about arguments in futex implementation.
m-ou-se Oct 2, 2020
d5b3f54
Use force_ptr in futex implementation.
m-ou-se Oct 2, 2020
e64ead2
Implement timeouts for FUTEX_WAIT.
m-ou-se Oct 2, 2020
8113882
Add park/park_timeout/unpark test.
m-ou-se Oct 2, 2020
c9627b2
Use correct return type for syscall(SYS_futex).
m-ou-se Oct 2, 2020
924fd56
Only allow FUTEX_WAIT with timeout when isoloation is disabled.
m-ou-se Oct 3, 2020
6628275
Remove backtics from isolation error.
m-ou-se Oct 3, 2020
5880e7d
Update expected error messages in tests.
m-ou-se Oct 3, 2020
6df54c4
Use read_scalar_at_offset in futex_wait instead of memory.get_raw.
m-ou-se Oct 3, 2020
9d764c5
Add FIXME note about variadic syscall().
m-ou-se Oct 3, 2020
dc36988
Add test for futex syscall.
m-ou-se Oct 3, 2020
dfcb46a
Update syscall FIXME to include note about 'wrong' types.
m-ou-se Oct 3, 2020
c268ee2
Add note about use of force_ptr in futex implementation.
m-ou-se Oct 3, 2020
68776d2
Add FIXME about type of `addr` in futex implementation.
m-ou-se Oct 3, 2020
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13 changes: 6 additions & 7 deletions src/shims/posix/linux/sync.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,14 +10,12 @@ pub fn futex<'tcx>(
if args.len() < 4 {
throw_ub_format!("incorrect number of arguments for futex syscall: got {}, expected at least 4", args.len());
}
let addr = this.read_scalar(args[1])?.check_init()?;
let addr = args[1];
let addr_scalar = this.read_scalar(addr)?.check_init()?;
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let futex_ptr = this.force_ptr(addr_scalar)?.erase_tag();
let op = this.read_scalar(args[2])?.to_i32()?;
let val = this.read_scalar(args[3])?.to_i32()?;

this.memory.check_ptr_access(addr, Size::from_bytes(4), Align::from_bytes(4).unwrap())?;

let addr = addr.assert_ptr().erase_tag();

let thread = this.get_active_thread();

let futex_private = this.eval_libc_i32("FUTEX_PRIVATE_FLAG")?;
Expand All @@ -33,10 +31,11 @@ pub fn futex<'tcx>(
if !this.is_null(timeout)? {
throw_ub_format!("miri does not support timeouts for futex operations");
}
this.memory.check_ptr_access(addr_scalar, Size::from_bytes(4), Align::from_bytes(4).unwrap())?;
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let futex_val = this.read_scalar_at_offset(args[1], 0, this.machine.layouts.i32)?.to_i32()?;
if val == futex_val {
this.block_thread(thread);
this.futex_wait(addr, thread);
this.futex_wait(futex_ptr, thread);
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} else {
let eagain = this.eval_libc("EAGAIN")?;
this.set_last_error(eagain)?;
Expand All @@ -45,7 +44,7 @@ pub fn futex<'tcx>(
op if op == futex_wake => {
let mut n = 0;
for _ in 0..val {
if let Some(thread) = this.futex_wake(addr) {
if let Some(thread) = this.futex_wake(futex_ptr) {
this.unblock_thread(thread);
n += 1;
} else {
Expand Down