- only if the counter is zero, we have to enable the non-polling mode

the new interface is required for hermitcore/rusty-hermit#117

258: kernel_function: Clear upper bits of register r=stlankes a=mkroening

If the type in a register is smaller than the register, Rust assumes the upper bits in the register to be zero.

For example, checking a `bool` might happen via `test edi, edi`, although the type only occupies `dil`.

Co-authored-by: Martin Kröning <m.kroening@hotmail.de>

If the type in a register is smaller than the register, Rust assumes the upper bits in the register to be zero.

For example, checking a `bool` might happen via `test edi, edi`, although the type only occupies `dil`.

254: update dependencies / lockfile r=stlankes a=striezel

* updating proc-macro2 v1.0.26 -> v1.0.27
* updating raw-cpuid v9.0.0 -> v9.1.1
* updating syn v1.0.72 -> v1.0.73


`proc-macro2` and `syn` should be painless, because these are only patch version updates.

`raw-cpuid` should be no hassle, too, if it follows semver - and its readme says it does. :)

Co-authored-by: Dirk Stolle <striezel-dev@web.de>

* updating proc-macro2 v1.0.26 -> v1.0.27
* updating raw-cpuid v9.0.0 -> v9.1.1
* updating syn v1.0.72 -> v1.0.73

253: fix some typos r=stlankes a=striezel

This pull request fixes some typos.

Co-authored-by: Dirk Stolle <striezel-dev@web.de>

252: Fixup: Relay bigger types over pointers for affected kernel functions r=stlankes a=mkroening

Fixes https://github.com/hermitcore/libhermit-rs/issues/250.

This also improves documentation regarding the design of `kernel_function!`.

Supersedes https://github.com/hermitcore/libhermit-rs/pull/251

.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

246: Fix copyright header placement r=stlankes a=mkroening



248: Remove more instances of hardcoded stack offsets r=stlankes a=mkroening



Co-authored-by: Martin Kröning <mkroening@posteo.net>

247: Fix switching to kernel stack r=stlankes a=mkroening

This fixes https://github.com/hermitcore/libhermit-rs/issues/234 introduced in https://github.com/hermitcore/libhermit-rs/commit/41cf625c33801690f5be566db67e3eec5b372feb.

As described in https://github.com/hermitcore/libhermit-rs/issues/234

, the issue with the old implementation was inlining resulting in wrongly managing stack space after the switch, potentially resulting in a page fault, when writing before the new stack:

```rust
fn sys_foo() {
    // reserves stack space for `a` (`rsp -= 16`)

    switch_rsp();

    // use reserved stack space (`[rsp + 16]`), even though rsp is not the same anymore
    let a = [0_u8; 16];
}
```

To my knowledge, inlining can only be really prevented, by explicitly `call`ing the function in assembly.

I fixed this issue in five steps:

1. Remove `switch_to_kernel!`, `switch_to_user!`, migrate uses to `kernel_function!`
2. Fix a potential stack overflow caused by a typo (unrelated)
3. Improve consistency of kernel functions by adding the prefix `__sys_` to all functions.
4. Make all `__sys_`-functions `extern "C"` to allow calling in assembly.
5. Reimplement `kernel_function!` and call kernel function in assembly.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

To force Rust manage the new stack in the kernel function, we call the
kernel function manually in assembly. That's why we need the kernel
functions to be extern "C".

Switch uses to kernel_function!

243: Complete migration of kernel target r=stlankes a=mkroening

I noticed this due to [failing docs CI](https://github.com/hermitcore/libhermit-rs/runs/2889060428).
The rename began in 18dd15f5

.
It seems that the repository-local json target specifications are not used, so I removed those.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

244: CI: Fix typos r=stlankes a=mkroening



Co-authored-by: Martin Kröning <mkroening@posteo.net>

I noticed this due to failing docs CI [1]
The rename began in 18dd15f5.
It seems that the repository-local json target specifications are not used, so I removed those.

[1] https://github.com/hermitcore/libhermit-rs/runs/2889060428

231: Migrate to naked functions r=stlankes a=mkroening

Fixes https://github.com/hermitcore/libhermit-rs/issues/222

.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

241: Improve macro hygiene r=stlankes a=mkroening

Resolves https://github.com/hermitcore/libhermit-rs/issues/224

.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

230: CI: Rework toolchain setup r=stlankes a=mkroening

This avoids double-installation of rust-toolchains in CI and enables coloring in the output.

Fixes https://github.com/hermitcore/libhermit-rs/issues/226

.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

236: Semaphore: Drop guard explicitly for readability r=stlankes a=mkroening

This is a rather opinionated change regarding code readability.

In my code editor with four spaces per tab, the extra scope looks quite weird. By explicitly dropping the guard instead, I personally find this easier to read. What do you think?

Co-authored-by: Martin Kröning <mkroening@posteo.net>

240: Remove unintended dereference r=stlankes a=mkroening

87a9d3f9

 was wrong.

Instead of calculating an address at one place in `acpi`, it read from that address.
The warning in `apic` was due to an implicit borrow and can be resolved by an explicit copy into a let binding.

Co-authored-by: Martin Kröning <mkroening@posteo.net>

242: Make msb helper function portable r=stlankes a=mkroening

`NonZeroU64::leading_zeros` has recently been stabilized.

Now we can make our `msb` helper function portable, resulting in the same `x86_64` assembly: [Compiler Explorer](https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(fontScale:14,fontUsePx:'0',j:1,lang:rust,selection:(endColumn:8,endLineNumber:3,positionColumn:8,positionLineNumber:3,selectionStartColumn:5,selectionStartLineNumber:3,startColumn:5,startLineNumber:3),source:'%23!!%5Bfeature(asm)%5D%0A%0Ause+std::num::NonZeroU64%3B%0A%0Apub+fn+old_msb(n:+u64)+-%3E+Option%3Cu64%3E+%7B%0A%09if+n+%3E+0+%7B%0A%09%09let+ret%3B%0A%09%09unsafe+%7B%0A%09%09%09asm!!(%22bsr+%7B%7D,+%7B%7D%22,+out(reg)+ret,+in(reg)+n,+options(pure,+nomem,+nostack))%3B%0A%09%09%7D%0A%09%09Some(ret)%0A%09%7D+else+%7B%0A%09%09None%0A%09%7D%0A%7D%0A%0Apub+fn+new_msb(n:+u64)+-%3E+Option%3Cu32%3E+%7B%0A++++NonZeroU64::new(n).map(%7Cn%7C+63+-+n.leading_zeros())%0A%7D%0A'),l:'5',n:'0',o:'Rust+source+%231',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:nightly,filters:(b:'0',binary:'1',commentOnly:'0',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1'),fontScale:14,fontUsePx:'0',j:2,lang:rust,libs:!(),options:'-C+opt-level%3D3',selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1),l:'5',n:'0',o:'rustc+nightly+(Editor+%231,+Compiler+%232)+Rust',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0')),l:'2',n:'0',o:'',t:'0')),version:4

)

Co-authored-by: Martin Kröning <mkroening@posteo.net>