Commit Graph

377 Commits

Author SHA1 Message Date
Nick Fitzgerald
ff0e84ecf4 Wasmtime: fix stack walking across frames from different stores (#4779)
We were previously implicitly assuming that all Wasm frames in a stack used the
same `VMRuntimeLimits` as the previous frame we walked, but this is not true
when Wasm in store A calls into the host which then calls into Wasm in store B:

    | ...             |
    | Host            |  |
    +-----------------+  | stack
    | Wasm in store A |  | grows
    +-----------------+  | down
    | Host            |  |
    +-----------------+  |
    | Wasm in store B |  V
    +-----------------+

Trying to walk this stack would previously result in a runtime panic.

The solution is to push the maintenance of our list of saved Wasm FP/SP/PC
registers that allow us to identify contiguous regions of Wasm frames on the
stack deeper into `CallThreadState`. The saved registers list is now maintained
whenever updating the `CallThreadState` linked list by making the
`CallThreadState::prev` field private and only accessible via a getter and
setter, where the setter always maintains our invariants.
2022-08-30 18:28:00 +00:00
Alex Crichton
5add267b87 Fix a soundness issue with lowering variants (#4723)
* Fix a compile error on nightly Rust

It looks like Rust nightly has gotten a bit more strict about
attributes-on-expressions and previously accepted code is no longer
accepted. This commit updates the generated code for a macro to a form
which is accepted by rustc.

* Fix a soundness issue with lowering variants

This commit fixes a soundness issue lowering variants in the component
model where host memory could be leaked to the guest module by accident.
In reviewing code recently for `Val::lower` I noticed that the variant
lowering was extending the payload with `ValRaw::u32(0)` to
appropriately fit the size of the variant. In reading this it appeared
incorrect to me due to the fact that it should be `ValRaw::u64(0)` since
up to 64-bits can be read. Additionally this implementation was also
incorrect because the lowered representation of the payload itself was
not possibly zero-extended to 64-bits to accommodate other variants.

It turned out these issues were benign because with the dynamic
surface area to the component model the arguments were all initialized
to 0 anyway. The static version of the API, however, does not initialize
arguments to 0 and I wanted to initially align these two implementations
so I updated the variant implementation of lowering for dynamic values
and removed the zero-ing of arguments.

To test this change I updated the `debug` mode of adapter module
generation to assert that the upper bits of values in wasm are always
zero when the value is casted down (during `stack_get` which only
happens with variants). I then threaded through the `debug` boolean
configuration parameter into the dynamic and static fuzzers.

To my surprise this new assertion tripped even after the fix was
applied. It turns out, though, that there was other leakage of bits
through other means that I was previously unaware of. At the primitive
level lowerings of types like `u32` will have a `Lower` representation
of `ValRaw` and the lowering is simply `dst.write(ValRaw::i32(self))`,
or the equivalent thereof. The problem, that the fuzzers detected, with
this pattern is that the `ValRaw` type is 16-bytes, and
`ValRaw::i32(X)` only initializes the first 4. This meant that all the
lowerings for all primitives were writing up to 12 bytes of garbage from
the host for the wasm module to read.

It turned out that this write of a `ValRaw` was sometimes 16 bytes and
sometimes the appropriate size depending on the number of optimizations
in play. With enough inlining for example `dst.write(ValRaw::i32(self))`
would only write 4 bytes, as expected. In debug mode though without
inlining 16 bytes would be written, including the garbage from the upper
bits.

To solve this issue I ended up taking a somewhat different approach. I
primarily updated the `ValRaw` constructors to simply always extend the
values internally to 64-bits, meaning that the low 8 bytes of a `ValRaw`
is always initialized. This prevents any undefined data from leaking
from the host into a wasm module, and means that values are also
zero-extended even if they're only used in 32-bit contexts outside of a
variant. This felt like the best fix for now, though, in terms of
not really having a performance impact while additionally not requiring
a rewrite of all lowerings.

This solution ended up also neatly removing the "zero out the entire
payload" logic that was previously require. Now after a payload is
lowered only the tail end of the payload, up to the size of the variant,
is zeroed out. This means that each lowered argument is written to at
most once which should hopefully be a small performance boost for
calling into functions as well.
2022-08-16 22:33:24 +00:00
Alex Crichton
cc955e4e7e Rename MmapVec::drain to split_off (#4673)
* Rename `MmapVec::drain` to `split_off`

As suggested on #4609

* Fix tests

* Make MmapVec::split_off work like Vec::split_off

Co-authored-by: Jamey Sharp <jsharp@fastly.com>
2022-08-15 21:00:12 +00:00
Alex Crichton
c1c48b4386 Don't be clever about representing non-CoW images (#4691)
This commit fixes a build warning on Rust 1.63 when the `memory-init-cow`
feature is disabled in the `wasmtime-runtime` crate. Some "tricks" were
used prior to have the `MemoryImage` type be an empty `enum {}` but that
wreaks havoc with warnings so this commit instead just makes it a unit
struct and makes all methods panic (as they shouldn't be hit anyway).
2022-08-11 18:16:28 +00:00
Nick Fitzgerald
0b1f51f804 Remove unnecessary parens around expression (#4647)
Fixes a compiler warning.
2022-08-08 15:48:03 -07:00
Alex Crichton
650979ae40 Implement strings in adapter modules (#4623)
* Implement strings in adapter modules

This commit is a hefty addition to Wasmtime's support for the component
model. This implements the final remaining type (in the current type
hierarchy) unimplemented in adapter module trampolines: strings. Strings
are the most complicated type to implement in adapter trampolines
because they are highly structured chunks of data in memory (according
to specific encodings). Additionally each lift/lower operation can
choose its own encoding for strings meaning that Wasmtime, the host, may
have to convert between any pairwise ordering of string encodings.

The `CanonicalABI.md` in the component-model repo in general specifies
all the fiddly bits of string encoding so there's not a ton of wiggle
room for Wasmtime to get creative. This PR largely "just" implements
that. The high-level architecture of this implementation is:

* Fused adapters are first identified to determine src/dst string
  encodings. This statically fixes what transcoding operation is being
  performed.

* The generated adapter will be responsible for managing calls to
  `realloc` and performing bounds checks. The adapter itself does not
  perform memory copies or validation of string contents, however.
  Instead each transcoding operation is modeled as an imported function
  into the adapter module.  This means that the adapter module
  dynamically, during compile time, determines what string transcoders
  are needed. Note that an imported transcoder is not only parameterized
  over the transcoding operation but additionally which memory is the
  source and which is the destination.

* The imported core wasm functions are modeled as a new
  `CoreDef::Transcoder` structure. These transcoders end up being small
  Cranelift-compiled trampolines. The Cranelift-compiled trampoline will
  load the actual base pointer of memory and add it to the relative
  pointers passed as function arguments. This trampoline then calls a
  transcoder "libcall" which enters Rust-defined functions for actual
  transcoding operations.

* Each possible transcoding operation is implemented in Rust with a
  unique name and a unique signature depending on the needs of the
  transcoder. I've tried to document inline what each transcoder does.

This means that the `Module::translate_string` in adapter modules is by
far the largest translation method. The main reason for this is due to
the management around calling the imported transcoder functions in the
face of validating string pointer/lengths and performing the dance of
`realloc`-vs-transcode at the right time. I've tried to ensure that each
individual case in transcoding is documented well enough to understand
what's going on as well.

Additionally in this PR is a full implementation in the host for the
`latin1+utf16` encoding which means that both lifting and lowering host
strings now works with this encoding.

Currently the implementation of each transcoder function is likely far
from optimal. Where possible I've leaned on the standard library itself
and for latin1-related things I'm leaning on the `encoding_rs` crate. I
initially tried to implement everything with `encoding_rs` but was
unable to uniformly do so easily. For now I settled on trying to get a
known-correct (even in the face of endianness) implementation for all of
these transcoders. If an when performance becomes an issue it should be
possible to implement more optimized versions of each of these
transcoding operations.

Testing this commit has been somewhat difficult and my general plan,
like with the `(list T)` type, is to rely heavily on fuzzing to cover
the various cases here. In this PR though I've added a simple test that
pushes some statically known strings through all the pairs of encodings
between source and destination. I've attempted to pick "interesting"
strings that one way or another stress the various paths in each
transcoding operation to ideally get full branch coverage there.
Additionally a suite of "negative" tests have also been added to ensure
that validity of encoding is actually checked.

* Fix a temporarily commented out case

* Fix wasmtime-runtime tests

* Update deny.toml configuration

* Add `BSD-3-Clause` for the `encoding_rs` crate
* Remove some unused licenses

* Add an exemption for `encoding_rs` for now

* Split up the `translate_string` method

Move out all the closures and package up captured state into smaller
lists of arguments.

* Test out-of-bounds for zero-length strings
2022-08-08 16:01:57 +00:00
wasmtime-publish
412fa04911 Bump Wasmtime to 0.41.0 (#4620)
Co-authored-by: Wasmtime Publish <wasmtime-publish@users.noreply.github.com>
2022-08-04 20:02:19 -05:00
Nick Fitzgerald
70ce288dc7 Save exit Wasm FP and PC in component-to-host trampolines (#4601)
* Wasmtime: Add a pointer to `VMRuntimeLimits` in component contexts

* Save exit Wasm FP and PC in component-to-host trampolines

Fixes #4535

* Add comment about why we deref the trampoline's FP

* Update some tests to use new `vmruntime_limits_*` methods
2022-08-04 10:27:30 -05:00
Anton Kirilov
a897742593 Initial back-edge CFI implementation (#3606)
Give the user the option to sign and to authenticate function
return addresses with the operations introduced by the Pointer
Authentication extension to the Arm instruction set architecture.

Copyright (c) 2021, Arm Limited.
2022-08-03 11:08:29 -07:00
Alex Crichton
9f82644cc3 Some minor cleanups/refactorings in components (#4582)
This is a collection of some minor renamings, refactorings, sharing of
code, etc. This was all discovered during my addition of string support
to adapter functions and I figured it'd be best to frontload this and
land it ahead of the full patch since it's getting complex.
2022-08-03 11:21:55 -05:00
Nick Fitzgerald
edf7f9f2bb wasmtime: Add lots of logging for externrefs and table_ops fuzz target (#4583)
I essentially add these same logs back in every time I'm debugging something
related to this fuzz target or `externref`s in general. Probably like 5 times
I've added roughly these logs. We should just make them available whenever we
need them via `RUST_LOG=wasmtime_runtime=trace`.

This also changes a couple `if let`s to `unwrap`s that are now infallible after
2022-08-02 15:06:44 -07:00
Alex Crichton
04631ad0af Unconditionally enable component-model tests (#4556)
* Unconditionally enable component-model tests

* Remove an outdated test that wasn't previously being compiled

* Fix a component model doc test

* Try to decrease memory usage in qemu
2022-08-01 15:43:37 +00:00
Nick Fitzgerald
46782b18c2 wasmtime: Implement fast Wasm stack walking (#4431)
* Always preserve frame pointers in Wasmtime

This allows us to efficiently and simply capture Wasm stacks without maintaining
and synchronizing any safety-critical side tables between the compiler and the
runtime.

* wasmtime: Implement fast Wasm stack walking

Why do we want Wasm stack walking to be fast? Because we capture stacks whenever
there is a trap and traps actually happen fairly frequently with short-lived
programs and WASI's `exit`.

Previously, we would rely on generating the system unwind info (e.g.
`.eh_frame`) and using the system unwinder (via the `backtrace`crate) to walk
the full stack and filter out any non-Wasm stack frames. This can,
unfortunately, be slow for two primary reasons:

1. The system unwinder is doing `O(all-kinds-of-frames)` work rather than
`O(wasm-frames)` work.

2. System unwind info and the system unwinder need to be much more general than
a purpose-built stack walker for Wasm needs to be. It has to handle any kind of
stack frame that any compiler might emit where as our Wasm frames are emitted by
Cranelift and always have frame pointers. This translates into implementation
complexity and general overhead. There can also be unnecessary-for-our-use-cases
global synchronization and locks involved, further slowing down stack walking in
the presence of multiple threads trying to capture stacks in parallel.

This commit introduces a purpose-built stack walker for traversing just our Wasm
frames. To find all the sequences of Wasm-to-Wasm stack frames, and ignore
non-Wasm stack frames, we keep a linked list of `(entry stack pointer, exit
frame pointer)` pairs. This linked list is maintained via Wasm-to-host and
host-to-Wasm trampolines. Within a sequence of Wasm-to-Wasm calls, we can use
frame pointers (which Cranelift preserves) to find the next older Wasm frame on
the stack, and we keep doing this until we reach the entry stack pointer,
meaning that the next older frame will be a host frame.

The trampolines need to avoid a couple stumbling blocks. First, they need to be
compiled ahead of time, since we may not have access to a compiler at
runtime (e.g. if the `cranelift` feature is disabled) but still want to be able
to call functions that have already been compiled and get stack traces for those
functions. Usually this means we would compile the appropriate trampolines
inside `Module::new` and the compiled module object would hold the
trampolines. However, we *also* need to support calling host functions that are
wrapped into `wasmtime::Func`s and there doesn't exist *any* ahead-of-time
compiled module object to hold the appropriate trampolines:

```rust
// Define a host function.
let func_type = wasmtime::FuncType::new(
    vec![wasmtime::ValType::I32],
    vec![wasmtime::ValType::I32],
);
let func = Func::new(&mut store, func_type, |_, params, results| {
    // ...
    Ok(())
});

// Call that host function.
let mut results = vec![wasmtime::Val::I32(0)];
func.call(&[wasmtime::Val::I32(0)], &mut results)?;
```

Therefore, we define one host-to-Wasm trampoline and one Wasm-to-host trampoline
in assembly that work for all Wasm and host function signatures. These
trampolines are careful to only use volatile registers, avoid touching any
register that is an argument in the calling convention ABI, and tail call to the
target callee function. This allows forwarding any set of arguments and any
returns to and from the callee, while also allowing us to maintain our linked
list of Wasm stack and frame pointers before transferring control to the
callee. These trampolines are not used in Wasm-to-Wasm calls, only when crossing
the host-Wasm boundary, so they do not impose overhead on regular calls. (And if
using one trampoline for all host-Wasm boundary crossing ever breaks branch
prediction enough in the CPU to become any kind of bottleneck, we can do fun
things like have multiple copies of the same trampoline and choose a random copy
for each function, sharding the functions across branch predictor entries.)

Finally, this commit also ends the use of a synthetic `Module` and allocating a
stubbed out `VMContext` for host functions. Instead, we define a
`VMHostFuncContext` with its own magic value, similar to `VMComponentContext`,
specifically for host functions.

<h2>Benchmarks</h2>

<h3>Traps and Stack Traces</h3>

Large improvements to taking stack traces on traps, ranging from shaving off 64%
to 99.95% of the time it used to take.

<details>

```
multi-threaded-traps/0  time:   [2.5686 us 2.5808 us 2.5934 us]
                        thrpt:  [0.0000  elem/s 0.0000  elem/s 0.0000  elem/s]
                 change:
                        time:   [-85.419% -85.153% -84.869%] (p = 0.00 < 0.05)
                        thrpt:  [+560.90% +573.56% +585.84%]
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  4 (4.00%) high mild
  4 (4.00%) high severe
multi-threaded-traps/1  time:   [2.9021 us 2.9167 us 2.9322 us]
                        thrpt:  [341.04 Kelem/s 342.86 Kelem/s 344.58 Kelem/s]
                 change:
                        time:   [-91.455% -91.294% -91.096%] (p = 0.00 < 0.05)
                        thrpt:  [+1023.1% +1048.6% +1070.3%]
                        Performance has improved.
Found 6 outliers among 100 measurements (6.00%)
  1 (1.00%) high mild
  5 (5.00%) high severe
multi-threaded-traps/2  time:   [2.9996 us 3.0145 us 3.0295 us]
                        thrpt:  [660.18 Kelem/s 663.47 Kelem/s 666.76 Kelem/s]
                 change:
                        time:   [-94.040% -93.910% -93.762%] (p = 0.00 < 0.05)
                        thrpt:  [+1503.1% +1542.0% +1578.0%]
                        Performance has improved.
Found 5 outliers among 100 measurements (5.00%)
  5 (5.00%) high severe
multi-threaded-traps/4  time:   [5.5768 us 5.6052 us 5.6364 us]
                        thrpt:  [709.68 Kelem/s 713.63 Kelem/s 717.25 Kelem/s]
                 change:
                        time:   [-93.193% -93.121% -93.052%] (p = 0.00 < 0.05)
                        thrpt:  [+1339.2% +1353.6% +1369.1%]
                        Performance has improved.
multi-threaded-traps/8  time:   [8.6408 us 9.1212 us 9.5438 us]
                        thrpt:  [838.24 Kelem/s 877.08 Kelem/s 925.84 Kelem/s]
                 change:
                        time:   [-94.754% -94.473% -94.202%] (p = 0.00 < 0.05)
                        thrpt:  [+1624.7% +1709.2% +1806.1%]
                        Performance has improved.
multi-threaded-traps/16 time:   [10.152 us 10.840 us 11.545 us]
                        thrpt:  [1.3858 Melem/s 1.4760 Melem/s 1.5761 Melem/s]
                 change:
                        time:   [-97.042% -96.823% -96.577%] (p = 0.00 < 0.05)
                        thrpt:  [+2821.5% +3048.1% +3281.1%]
                        Performance has improved.
Found 1 outliers among 100 measurements (1.00%)
  1 (1.00%) high mild

many-modules-registered-traps/1
                        time:   [2.6278 us 2.6361 us 2.6447 us]
                        thrpt:  [378.11 Kelem/s 379.35 Kelem/s 380.55 Kelem/s]
                 change:
                        time:   [-85.311% -85.108% -84.909%] (p = 0.00 < 0.05)
                        thrpt:  [+562.65% +571.51% +580.76%]
                        Performance has improved.
Found 9 outliers among 100 measurements (9.00%)
  3 (3.00%) high mild
  6 (6.00%) high severe
many-modules-registered-traps/8
                        time:   [2.6294 us 2.6460 us 2.6623 us]
                        thrpt:  [3.0049 Melem/s 3.0235 Melem/s 3.0425 Melem/s]
                 change:
                        time:   [-85.895% -85.485% -85.022%] (p = 0.00 < 0.05)
                        thrpt:  [+567.63% +588.95% +608.95%]
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  3 (3.00%) high mild
  5 (5.00%) high severe
many-modules-registered-traps/64
                        time:   [2.6218 us 2.6329 us 2.6452 us]
                        thrpt:  [24.195 Melem/s 24.308 Melem/s 24.411 Melem/s]
                 change:
                        time:   [-93.629% -93.551% -93.470%] (p = 0.00 < 0.05)
                        thrpt:  [+1431.4% +1450.6% +1469.5%]
                        Performance has improved.
Found 3 outliers among 100 measurements (3.00%)
  3 (3.00%) high mild
many-modules-registered-traps/512
                        time:   [2.6569 us 2.6737 us 2.6923 us]
                        thrpt:  [190.17 Melem/s 191.50 Melem/s 192.71 Melem/s]
                 change:
                        time:   [-99.277% -99.268% -99.260%] (p = 0.00 < 0.05)
                        thrpt:  [+13417% +13566% +13731%]
                        Performance has improved.
Found 4 outliers among 100 measurements (4.00%)
  4 (4.00%) high mild
many-modules-registered-traps/4096
                        time:   [2.7258 us 2.7390 us 2.7535 us]
                        thrpt:  [1.4876 Gelem/s 1.4955 Gelem/s 1.5027 Gelem/s]
                 change:
                        time:   [-99.956% -99.955% -99.955%] (p = 0.00 < 0.05)
                        thrpt:  [+221417% +223380% +224881%]
                        Performance has improved.
Found 2 outliers among 100 measurements (2.00%)
  1 (1.00%) high mild
  1 (1.00%) high severe

many-stack-frames-traps/1
                        time:   [1.4658 us 1.4719 us 1.4784 us]
                        thrpt:  [676.39 Kelem/s 679.38 Kelem/s 682.21 Kelem/s]
                 change:
                        time:   [-90.368% -89.947% -89.586%] (p = 0.00 < 0.05)
                        thrpt:  [+860.23% +894.72% +938.21%]
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  5 (5.00%) high mild
  3 (3.00%) high severe
many-stack-frames-traps/8
                        time:   [2.4772 us 2.4870 us 2.4973 us]
                        thrpt:  [3.2034 Melem/s 3.2167 Melem/s 3.2294 Melem/s]
                 change:
                        time:   [-85.550% -85.370% -85.199%] (p = 0.00 < 0.05)
                        thrpt:  [+575.65% +583.51% +592.03%]
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  4 (4.00%) high mild
  4 (4.00%) high severe
many-stack-frames-traps/64
                        time:   [10.109 us 10.171 us 10.236 us]
                        thrpt:  [6.2525 Melem/s 6.2925 Melem/s 6.3309 Melem/s]
                 change:
                        time:   [-78.144% -77.797% -77.336%] (p = 0.00 < 0.05)
                        thrpt:  [+341.22% +350.38% +357.55%]
                        Performance has improved.
Found 7 outliers among 100 measurements (7.00%)
  5 (5.00%) high mild
  2 (2.00%) high severe
many-stack-frames-traps/512
                        time:   [126.16 us 126.54 us 126.96 us]
                        thrpt:  [4.0329 Melem/s 4.0461 Melem/s 4.0583 Melem/s]
                 change:
                        time:   [-65.364% -64.933% -64.453%] (p = 0.00 < 0.05)
                        thrpt:  [+181.32% +185.17% +188.71%]
                        Performance has improved.
Found 4 outliers among 100 measurements (4.00%)
  4 (4.00%) high severe
```

</details>

<h3>Calls</h3>

There is, however, a small regression in raw Wasm-to-host and host-to-Wasm call
performance due the new trampolines. It seems to be on the order of about 2-10
nanoseconds per call, depending on the benchmark.

I believe this regression is ultimately acceptable because

1. this overhead will be vastly dominated by whatever work a non-nop callee
actually does,

2. we will need these trampolines, or something like them, when implementing the
Wasm exceptions proposal to do things like translate Wasm's exceptions into
Rust's `Result`s,

3. and because the performance improvements to trapping and capturing stack
traces are of such a larger magnitude than this call regressions.

<details>

```
sync/no-hook/host-to-wasm - typed - nop
                        time:   [28.683 ns 28.757 ns 28.844 ns]
                        change: [+16.472% +17.183% +17.904%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  1 (1.00%) low mild
  4 (4.00%) high mild
  5 (5.00%) high severe
sync/no-hook/host-to-wasm - untyped - nop
                        time:   [42.515 ns 42.652 ns 42.841 ns]
                        change: [+12.371% +14.614% +17.462%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  1 (1.00%) high mild
  10 (10.00%) high severe
sync/no-hook/host-to-wasm - unchecked - nop
                        time:   [33.936 ns 34.052 ns 34.179 ns]
                        change: [+25.478% +26.938% +28.369%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  7 (7.00%) high mild
  2 (2.00%) high severe
sync/no-hook/host-to-wasm - typed - nop-params-and-results
                        time:   [34.290 ns 34.388 ns 34.502 ns]
                        change: [+40.802% +42.706% +44.526%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 13 outliers among 100 measurements (13.00%)
  5 (5.00%) high mild
  8 (8.00%) high severe
sync/no-hook/host-to-wasm - untyped - nop-params-and-results
                        time:   [62.546 ns 62.721 ns 62.919 ns]
                        change: [+2.5014% +3.6319% +4.8078%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  2 (2.00%) high mild
  10 (10.00%) high severe
sync/no-hook/host-to-wasm - unchecked - nop-params-and-results
                        time:   [42.609 ns 42.710 ns 42.831 ns]
                        change: [+20.966% +22.282% +23.475%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  4 (4.00%) high mild
  7 (7.00%) high severe

sync/hook-sync/host-to-wasm - typed - nop
                        time:   [29.546 ns 29.675 ns 29.818 ns]
                        change: [+20.693% +21.794% +22.836%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 5 outliers among 100 measurements (5.00%)
  3 (3.00%) high mild
  2 (2.00%) high severe
sync/hook-sync/host-to-wasm - untyped - nop
                        time:   [45.448 ns 45.699 ns 45.961 ns]
                        change: [+17.204% +18.514% +19.590%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 14 outliers among 100 measurements (14.00%)
  4 (4.00%) high mild
  10 (10.00%) high severe
sync/hook-sync/host-to-wasm - unchecked - nop
                        time:   [34.334 ns 34.437 ns 34.558 ns]
                        change: [+23.225% +24.477% +25.886%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  5 (5.00%) high mild
  7 (7.00%) high severe
sync/hook-sync/host-to-wasm - typed - nop-params-and-results
                        time:   [36.594 ns 36.763 ns 36.974 ns]
                        change: [+41.967% +47.261% +52.086%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  3 (3.00%) high mild
  9 (9.00%) high severe
sync/hook-sync/host-to-wasm - untyped - nop-params-and-results
                        time:   [63.541 ns 63.831 ns 64.194 ns]
                        change: [-4.4337% -0.6855% +2.7134%] (p = 0.73 > 0.05)
                        No change in performance detected.
Found 8 outliers among 100 measurements (8.00%)
  6 (6.00%) high mild
  2 (2.00%) high severe
sync/hook-sync/host-to-wasm - unchecked - nop-params-and-results
                        time:   [43.968 ns 44.169 ns 44.437 ns]
                        change: [+18.772% +21.802% +24.623%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 15 outliers among 100 measurements (15.00%)
  3 (3.00%) high mild
  12 (12.00%) high severe

async/no-hook/host-to-wasm - typed - nop
                        time:   [4.9612 us 4.9743 us 4.9889 us]
                        change: [+9.9493% +11.911% +13.502%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  6 (6.00%) high mild
  4 (4.00%) high severe
async/no-hook/host-to-wasm - untyped - nop
                        time:   [5.0030 us 5.0211 us 5.0439 us]
                        change: [+10.841% +11.873% +12.977%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  3 (3.00%) high mild
  7 (7.00%) high severe
async/no-hook/host-to-wasm - typed - nop-params-and-results
                        time:   [4.9273 us 4.9468 us 4.9700 us]
                        change: [+4.7381% +6.8445% +8.8238%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 14 outliers among 100 measurements (14.00%)
  5 (5.00%) high mild
  9 (9.00%) high severe
async/no-hook/host-to-wasm - untyped - nop-params-and-results
                        time:   [5.1151 us 5.1338 us 5.1555 us]
                        change: [+9.5335% +11.290% +13.044%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  3 (3.00%) high mild
  13 (13.00%) high severe

async/hook-sync/host-to-wasm - typed - nop
                        time:   [4.9330 us 4.9394 us 4.9467 us]
                        change: [+10.046% +11.038% +12.035%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  5 (5.00%) high mild
  7 (7.00%) high severe
async/hook-sync/host-to-wasm - untyped - nop
                        time:   [5.0073 us 5.0183 us 5.0310 us]
                        change: [+9.3828% +10.565% +11.752%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
  3 (3.00%) high mild
  5 (5.00%) high severe
async/hook-sync/host-to-wasm - typed - nop-params-and-results
                        time:   [4.9610 us 4.9839 us 5.0097 us]
                        change: [+9.0857% +11.513% +14.359%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 13 outliers among 100 measurements (13.00%)
  7 (7.00%) high mild
  6 (6.00%) high severe
async/hook-sync/host-to-wasm - untyped - nop-params-and-results
                        time:   [5.0995 us 5.1272 us 5.1617 us]
                        change: [+9.3600% +11.506% +13.809%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  6 (6.00%) high mild
  4 (4.00%) high severe

async-pool/no-hook/host-to-wasm - typed - nop
                        time:   [2.4242 us 2.4316 us 2.4396 us]
                        change: [+7.8756% +8.8803% +9.8346%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
  5 (5.00%) high mild
  3 (3.00%) high severe
async-pool/no-hook/host-to-wasm - untyped - nop
                        time:   [2.5102 us 2.5155 us 2.5210 us]
                        change: [+12.130% +13.194% +14.270%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  4 (4.00%) high mild
  8 (8.00%) high severe
async-pool/no-hook/host-to-wasm - typed - nop-params-and-results
                        time:   [2.4203 us 2.4310 us 2.4440 us]
                        change: [+4.0380% +6.3623% +8.7534%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 14 outliers among 100 measurements (14.00%)
  5 (5.00%) high mild
  9 (9.00%) high severe
async-pool/no-hook/host-to-wasm - untyped - nop-params-and-results
                        time:   [2.5501 us 2.5593 us 2.5700 us]
                        change: [+8.8802% +10.976% +12.937%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  5 (5.00%) high mild
  11 (11.00%) high severe

async-pool/hook-sync/host-to-wasm - typed - nop
                        time:   [2.4135 us 2.4190 us 2.4254 us]
                        change: [+8.3640% +9.3774% +10.435%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  6 (6.00%) high mild
  5 (5.00%) high severe
async-pool/hook-sync/host-to-wasm - untyped - nop
                        time:   [2.5172 us 2.5248 us 2.5357 us]
                        change: [+11.543% +12.750% +13.982%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
  1 (1.00%) high mild
  7 (7.00%) high severe
async-pool/hook-sync/host-to-wasm - typed - nop-params-and-results
                        time:   [2.4214 us 2.4353 us 2.4532 us]
                        change: [+1.5158% +5.0872% +8.6765%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 15 outliers among 100 measurements (15.00%)
  2 (2.00%) high mild
  13 (13.00%) high severe
async-pool/hook-sync/host-to-wasm - untyped - nop-params-and-results
                        time:   [2.5499 us 2.5607 us 2.5748 us]
                        change: [+10.146% +12.459% +14.919%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 18 outliers among 100 measurements (18.00%)
  3 (3.00%) high mild
  15 (15.00%) high severe

sync/no-hook/wasm-to-host - nop - typed
                        time:   [6.6135 ns 6.6288 ns 6.6452 ns]
                        change: [+37.927% +38.837% +39.869%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 7 outliers among 100 measurements (7.00%)
  2 (2.00%) high mild
  5 (5.00%) high severe
sync/no-hook/wasm-to-host - nop-params-and-results - typed
                        time:   [15.930 ns 15.993 ns 16.067 ns]
                        change: [+3.9583% +5.6286% +7.2430%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  11 (11.00%) high mild
  1 (1.00%) high severe
sync/no-hook/wasm-to-host - nop - untyped
                        time:   [20.596 ns 20.640 ns 20.690 ns]
                        change: [+4.3293% +5.2047% +6.0935%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  5 (5.00%) high mild
  5 (5.00%) high severe
sync/no-hook/wasm-to-host - nop-params-and-results - untyped
                        time:   [42.659 ns 42.882 ns 43.159 ns]
                        change: [-2.1466% -0.5079% +1.2554%] (p = 0.58 > 0.05)
                        No change in performance detected.
Found 15 outliers among 100 measurements (15.00%)
  1 (1.00%) high mild
  14 (14.00%) high severe
sync/no-hook/wasm-to-host - nop - unchecked
                        time:   [10.671 ns 10.691 ns 10.713 ns]
                        change: [+83.911% +87.620% +92.062%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  2 (2.00%) high mild
  7 (7.00%) high severe
sync/no-hook/wasm-to-host - nop-params-and-results - unchecked
                        time:   [11.136 ns 11.190 ns 11.263 ns]
                        change: [-29.719% -28.446% -27.029%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  4 (4.00%) high mild
  10 (10.00%) high severe

sync/hook-sync/wasm-to-host - nop - typed
                        time:   [6.7964 ns 6.8087 ns 6.8226 ns]
                        change: [+21.531% +24.206% +27.331%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 14 outliers among 100 measurements (14.00%)
  4 (4.00%) high mild
  10 (10.00%) high severe
sync/hook-sync/wasm-to-host - nop-params-and-results - typed
                        time:   [15.865 ns 15.921 ns 15.985 ns]
                        change: [+4.8466% +6.3330% +7.8317%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  3 (3.00%) high mild
  13 (13.00%) high severe
sync/hook-sync/wasm-to-host - nop - untyped
                        time:   [21.505 ns 21.587 ns 21.677 ns]
                        change: [+8.0908% +9.1943% +10.254%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
  4 (4.00%) high mild
  4 (4.00%) high severe
sync/hook-sync/wasm-to-host - nop-params-and-results - untyped
                        time:   [44.018 ns 44.128 ns 44.261 ns]
                        change: [-1.4671% -0.0458% +1.2443%] (p = 0.94 > 0.05)
                        No change in performance detected.
Found 14 outliers among 100 measurements (14.00%)
  5 (5.00%) high mild
  9 (9.00%) high severe
sync/hook-sync/wasm-to-host - nop - unchecked
                        time:   [11.264 ns 11.326 ns 11.387 ns]
                        change: [+80.225% +81.659% +83.068%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 6 outliers among 100 measurements (6.00%)
  3 (3.00%) high mild
  3 (3.00%) high severe
sync/hook-sync/wasm-to-host - nop-params-and-results - unchecked
                        time:   [11.816 ns 11.865 ns 11.920 ns]
                        change: [-29.152% -28.040% -26.957%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  8 (8.00%) high mild
  6 (6.00%) high severe

async/no-hook/wasm-to-host - nop - typed
                        time:   [6.6221 ns 6.6385 ns 6.6569 ns]
                        change: [+43.618% +44.755% +45.965%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 13 outliers among 100 measurements (13.00%)
  6 (6.00%) high mild
  7 (7.00%) high severe
async/no-hook/wasm-to-host - nop-params-and-results - typed
                        time:   [15.884 ns 15.929 ns 15.983 ns]
                        change: [+3.5987% +5.2053% +6.7846%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  3 (3.00%) high mild
  13 (13.00%) high severe
async/no-hook/wasm-to-host - nop - untyped
                        time:   [20.615 ns 20.702 ns 20.821 ns]
                        change: [+6.9799% +8.1212% +9.2819%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  2 (2.00%) high mild
  8 (8.00%) high severe
async/no-hook/wasm-to-host - nop-params-and-results - untyped
                        time:   [41.956 ns 42.207 ns 42.521 ns]
                        change: [-4.3057% -2.7730% -1.2428%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  3 (3.00%) high mild
  11 (11.00%) high severe
async/no-hook/wasm-to-host - nop - unchecked
                        time:   [10.440 ns 10.474 ns 10.513 ns]
                        change: [+83.959% +85.826% +87.541%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  5 (5.00%) high mild
  6 (6.00%) high severe
async/no-hook/wasm-to-host - nop-params-and-results - unchecked
                        time:   [11.476 ns 11.512 ns 11.554 ns]
                        change: [-29.857% -28.383% -26.978%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 12 outliers among 100 measurements (12.00%)
  1 (1.00%) low mild
  6 (6.00%) high mild
  5 (5.00%) high severe
async/no-hook/wasm-to-host - nop - async-typed
                        time:   [26.427 ns 26.478 ns 26.532 ns]
                        change: [+6.5730% +7.4676% +8.3983%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  2 (2.00%) high mild
  7 (7.00%) high severe
async/no-hook/wasm-to-host - nop-params-and-results - async-typed
                        time:   [28.557 ns 28.693 ns 28.880 ns]
                        change: [+1.9099% +3.7332% +5.9731%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 15 outliers among 100 measurements (15.00%)
  1 (1.00%) high mild
  14 (14.00%) high severe

async/hook-sync/wasm-to-host - nop - typed
                        time:   [6.7488 ns 6.7630 ns 6.7784 ns]
                        change: [+19.935% +22.080% +23.683%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  4 (4.00%) high mild
  5 (5.00%) high severe
async/hook-sync/wasm-to-host - nop-params-and-results - typed
                        time:   [15.928 ns 16.031 ns 16.149 ns]
                        change: [+5.5188% +6.9567% +8.3839%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  9 (9.00%) high mild
  2 (2.00%) high severe
async/hook-sync/wasm-to-host - nop - untyped
                        time:   [21.930 ns 22.114 ns 22.296 ns]
                        change: [+4.6674% +7.7588% +10.375%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 4 outliers among 100 measurements (4.00%)
  3 (3.00%) high mild
  1 (1.00%) high severe
async/hook-sync/wasm-to-host - nop-params-and-results - untyped
                        time:   [42.684 ns 42.858 ns 43.081 ns]
                        change: [-5.2957% -3.4693% -1.6217%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  2 (2.00%) high mild
  12 (12.00%) high severe
async/hook-sync/wasm-to-host - nop - unchecked
                        time:   [11.026 ns 11.053 ns 11.086 ns]
                        change: [+70.751% +72.378% +73.961%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 10 outliers among 100 measurements (10.00%)
  5 (5.00%) high mild
  5 (5.00%) high severe
async/hook-sync/wasm-to-host - nop-params-and-results - unchecked
                        time:   [11.840 ns 11.900 ns 11.982 ns]
                        change: [-27.977% -26.584% -24.887%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 18 outliers among 100 measurements (18.00%)
  3 (3.00%) high mild
  15 (15.00%) high severe
async/hook-sync/wasm-to-host - nop - async-typed
                        time:   [27.601 ns 27.709 ns 27.882 ns]
                        change: [+8.1781% +9.1102% +10.030%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  2 (2.00%) low mild
  3 (3.00%) high mild
  6 (6.00%) high severe
async/hook-sync/wasm-to-host - nop-params-and-results - async-typed
                        time:   [28.955 ns 29.174 ns 29.413 ns]
                        change: [+1.1226% +3.0366% +5.1126%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 13 outliers among 100 measurements (13.00%)
  7 (7.00%) high mild
  6 (6.00%) high severe

async-pool/no-hook/wasm-to-host - nop - typed
                        time:   [6.5626 ns 6.5733 ns 6.5851 ns]
                        change: [+40.561% +42.307% +44.514%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  5 (5.00%) high mild
  4 (4.00%) high severe
async-pool/no-hook/wasm-to-host - nop-params-and-results - typed
                        time:   [15.820 ns 15.886 ns 15.969 ns]
                        change: [+4.1044% +5.7928% +7.7122%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 17 outliers among 100 measurements (17.00%)
  4 (4.00%) high mild
  13 (13.00%) high severe
async-pool/no-hook/wasm-to-host - nop - untyped
                        time:   [20.481 ns 20.521 ns 20.566 ns]
                        change: [+6.7962% +7.6950% +8.7612%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  6 (6.00%) high mild
  5 (5.00%) high severe
async-pool/no-hook/wasm-to-host - nop-params-and-results - untyped
                        time:   [41.834 ns 41.998 ns 42.189 ns]
                        change: [-3.8185% -2.2687% -0.7541%] (p = 0.01 < 0.05)
                        Change within noise threshold.
Found 13 outliers among 100 measurements (13.00%)
  3 (3.00%) high mild
  10 (10.00%) high severe
async-pool/no-hook/wasm-to-host - nop - unchecked
                        time:   [10.353 ns 10.380 ns 10.414 ns]
                        change: [+82.042% +84.591% +87.205%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 7 outliers among 100 measurements (7.00%)
  4 (4.00%) high mild
  3 (3.00%) high severe
async-pool/no-hook/wasm-to-host - nop-params-and-results - unchecked
                        time:   [11.123 ns 11.168 ns 11.228 ns]
                        change: [-30.813% -29.285% -27.874%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 12 outliers among 100 measurements (12.00%)
  11 (11.00%) high mild
  1 (1.00%) high severe
async-pool/no-hook/wasm-to-host - nop - async-typed
                        time:   [27.442 ns 27.528 ns 27.638 ns]
                        change: [+7.5215% +9.9795% +12.266%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 18 outliers among 100 measurements (18.00%)
  3 (3.00%) high mild
  15 (15.00%) high severe
async-pool/no-hook/wasm-to-host - nop-params-and-results - async-typed
                        time:   [29.014 ns 29.148 ns 29.312 ns]
                        change: [+2.0227% +3.4722% +4.9047%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 7 outliers among 100 measurements (7.00%)
  6 (6.00%) high mild
  1 (1.00%) high severe

async-pool/hook-sync/wasm-to-host - nop - typed
                        time:   [6.7916 ns 6.8116 ns 6.8325 ns]
                        change: [+20.937% +22.050% +23.281%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
  5 (5.00%) high mild
  6 (6.00%) high severe
async-pool/hook-sync/wasm-to-host - nop-params-and-results - typed
                        time:   [15.917 ns 15.975 ns 16.051 ns]
                        change: [+4.6404% +6.4217% +8.3075%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  5 (5.00%) high mild
  11 (11.00%) high severe
async-pool/hook-sync/wasm-to-host - nop - untyped
                        time:   [21.558 ns 21.612 ns 21.679 ns]
                        change: [+8.1158% +9.1409% +10.217%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  2 (2.00%) high mild
  7 (7.00%) high severe
async-pool/hook-sync/wasm-to-host - nop-params-and-results - untyped
                        time:   [42.475 ns 42.614 ns 42.775 ns]
                        change: [-6.3613% -4.4709% -2.7647%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 18 outliers among 100 measurements (18.00%)
  3 (3.00%) high mild
  15 (15.00%) high severe
async-pool/hook-sync/wasm-to-host - nop - unchecked
                        time:   [11.150 ns 11.195 ns 11.247 ns]
                        change: [+74.424% +77.056% +79.811%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 14 outliers among 100 measurements (14.00%)
  3 (3.00%) high mild
  11 (11.00%) high severe
async-pool/hook-sync/wasm-to-host - nop-params-and-results - unchecked
                        time:   [11.639 ns 11.695 ns 11.760 ns]
                        change: [-30.212% -29.023% -27.954%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 15 outliers among 100 measurements (15.00%)
  7 (7.00%) high mild
  8 (8.00%) high severe
async-pool/hook-sync/wasm-to-host - nop - async-typed
                        time:   [27.480 ns 27.712 ns 27.984 ns]
                        change: [+2.9764% +6.5061% +9.8914%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
  6 (6.00%) high mild
  2 (2.00%) high severe
async-pool/hook-sync/wasm-to-host - nop-params-and-results - async-typed
                        time:   [29.218 ns 29.380 ns 29.600 ns]
                        change: [+5.2283% +7.7247% +10.822%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 16 outliers among 100 measurements (16.00%)
  2 (2.00%) high mild
  14 (14.00%) high severe
```

</details>

* Add s390x support for frame pointer-based stack walking

* wasmtime: Allow `Caller::get_export` to get all exports

* fuzzing: Add a fuzz target to check that our stack traces are correct

We generate Wasm modules that keep track of their own stack as they call and
return between functions, and then we periodically check that if the host
captures a backtrace, it matches what the Wasm module has recorded.

* Remove VM offsets for `VMHostFuncContext` since it isn't used by JIT code

* Add doc comment with stack walking implementation notes

* Document the extra state that can be passed to `wasmtime_runtime::Backtrace` methods

* Add extensive comments for stack walking function

* Factor architecture-specific bits of stack walking out into modules

* Initialize store-related fields in a vmctx to null when there is no store yet

Rather than leaving them as uninitialized data.

* Use `set_callee` instead of manually setting the vmctx field

* Use a more informative compile error message for unsupported architectures

* Document unsafety of `prepare_host_to_wasm_trampoline`

* Use `bti c` instead of `hint #34` in inline aarch64 assembly

* Remove outdated TODO comment

* Remove setting of `last_wasm_exit_fp` in `set_jit_trap`

This is no longer needed as the value is plumbed through to the backtrace code
directly now.

* Only set the stack limit once, in the face of re-entrancy into Wasm

* Add comments for s390x-specific stack walking bits

* Use the helper macro for all libcalls

If we forget to use it, and then trigger a GC from the libcall, that means we
could miss stack frames when walking the stack, fail to find live GC refs, and
then get use after free bugs. Much less risky to always use the helper macro
that takes care of all of that for us.

* Use the `asm_sym!` macro in Wasm-to-libcall trampolines

This macro handles the macOS-specific underscore prefix stuff for us.

* wasmtime: add size and align to `externref` assertion error message

* Extend the `stacks` fuzzer to have host frames in between Wasm frames

This way we get one or more contiguous sequences of Wasm frames on the stack,
instead of exactly one.

* Add documentation for aarch64-specific backtrace helpers

* Clarify that we only support little-endian aarch64 in trampoline comment

* Use `.machine z13` in s390x assembly file

Since apparently our CI machines have pretty old assemblers that don't have
`.machine z14`. This should be fine though since these trampolines don't make
use of anything that is introduced in z14.

* Fix aarch64 build

* Fix macOS build

* Document the `asm_sym!` macro

* Add windows support to the `wasmtime-asm-macros` crate

* Add windows support to host<--->Wasm trampolines

* Fix trap handler build on windows

* Run `rustfmt` on s390x trampoline source file

* Temporarily disable some assertions about a trap's backtrace in the component model tests

Follow up to re-enable this and fix the associated issue:
https://github.com/bytecodealliance/wasmtime/issues/4535

* Refactor libcall definitions with less macros

This refactors the `libcall!` macro to use the
`foreach_builtin_function!` macro to define all of the trampolines.
Additionally the macro surrounding each libcall itself is no longer
necessary and helps avoid too many macros.

* Use `VMOpaqueContext::from_vm_host_func_context` in `VMHostFuncContext::new`

* Move `backtrace` module to be submodule of `traphandlers`

This avoids making some things `pub(crate)` in `traphandlers` that really
shouldn't be.

* Fix macOS aarch64 build

* Use "i64" instead of "word" in aarch64-specific file

* Save/restore entry SP and exit FP/return pointer in the face of panicking imported host functions

Also clean up assertions surrounding our saved entry/exit registers.

* Put "typed" vs "untyped" in the same position of call benchmark names

Regardless if we are doing wasm-to-host or host-to-wasm

* Fix stacks test case generator build for new `wasm-encoder`

* Fix build for s390x

* Expand libcalls in s390x asm

* Disable more parts of component tests now that backtrace assertions are a bit tighter

* Remove assertion that can maybe fail on s390x

Co-authored-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Co-authored-by: Alex Crichton <alex@alexcrichton.com>
2022-07-28 15:46:14 -07:00
Alex Crichton
1321c234e5 Remove dependency on more-asserts (#4408)
* Remove dependency on `more-asserts`

In my recent adventures to do a bit of gardening on our dependencies I
noticed that there's a new major version for the `more-asserts` crate.
Instead of updating to this though I've opted to instead remove the
dependency since I don't think we heavily lean on this crate and
otherwise one-off prints are probably sufficient to avoid the need for
pulling in a whole crate for this.

* Remove exemption for `more-asserts`
2022-07-26 16:47:33 +00:00
Alex Crichton
97894bc65e Add initial support for fused adapter trampolines (#4501)
* Add initial support for fused adapter trampolines

This commit lands a significant new piece of functionality to Wasmtime's
implementation of the component model in the form of the implementation
of fused adapter trampolines. Internally within a component core wasm
modules can communicate with each other by having their exports
`canon lift`'d to get `canon lower`'d into a different component. This
signifies that two components are communicating through a statically
known interface via the canonical ABI at this time. Previously Wasmtime
was able to identify that this communication was happening but it simply
panicked with `unimplemented!` upon seeing it. This commit is the
beginning of filling out this panic location with an actual
implementation.

The implementation route chosen here for fused adapters is to use a
WebAssembly module itself for the implementation. This means that, at
compile time of a component, Wasmtime is generating core WebAssembly
modules which then get recursively compiled within Wasmtime as well. The
choice to use WebAssembly itself as the implementation of fused adapters
stems from a few motivations:

* This does not represent a significant increase in the "trusted
  compiler base" of Wasmtime. Getting the Wasm -> CLIF translation
  correct once is hard enough much less for an entirely different IR to
  CLIF. By generating WebAssembly no new interactions with Cranelift are
  added which drastically reduces the possibilities for mistakes.

* Using WebAssembly means that component adapters are insulated from
  miscompilations and mistakes. If something goes wrong it's defined
  well within the WebAssembly specification how it goes wrong and what
  happens as a result. This means that the "blast zone" for a wrong
  adapter is the component instance but not the entire host itself.
  Accesses to linear memory are guaranteed to be in-bounds and otherwise
  handled via well-defined traps.

* A fully-finished fused adapter compiler is expected to be a
  significant and quite complex component of Wasmtime. Functionality
  along these lines is expected to be needed for Web-based polyfills of
  the component model and by using core WebAssembly it provides the
  opportunity to share code between Wasmtime and these polyfills for the
  component model.

* Finally the runtime implementation of managing WebAssembly modules is
  already implemented and quite easy to integrate with, so representing
  fused adapters with WebAssembly results in very little extra support
  necessary for the runtime implementation of instantiating and managing
  a component.

The compiler added in this commit is dubbed Wasmtime's Fused Adapter
Compiler of Trampolines (FACT) because who doesn't like deriving a name
from an acronym. Currently the trampoline compiler is limited in its
support for interface types and only supports a few primitives. I plan
on filing future PRs to flesh out the support here for all the variants
of `InterfaceType`. For now this PR is primarily focused on all of the
other infrastructure for the addition of a trampoline compiler.

With the choice to use core WebAssembly to implement fused adapters it
means that adapters need to be inserted into a module. Unfortunately
adapters cannot all go into a single WebAssembly module because adapters
themselves have dependencies which may be provided transitively through
instances that were instantiated with other adapters. This means that a
significant chunk of this PR (`adapt.rs`) is dedicated to determining
precisely which adapters go into precisely which adapter modules. This
partitioning process attempts to make large modules wherever it can to
cut down on core wasm instantiations but is likely not optimal as
it's just a simple heuristic today.

With all of this added together it's now possible to start writing
`*.wast` tests that internally have adapted modules communicating with
one another. A `fused.wast` test suite was added as part of this PR
which is the beginning of tests for the support of the fused adapter
compiler added in this PR. Currently this is primarily testing some
various topologies of adapters along with direct/indirect modes. This
will grow many more tests over time as more types are supported.

Overall I'm not 100% satisfied with the testing story of this PR. When a
test fails it's very difficult to debug since everything is written in
the text format of WebAssembly meaning there's no "conveniences" to
print out the state of the world when things go wrong and easily debug.
I think this will become even more apparent as more tests are written
for more types in subsequent PRs. At this time though I know of no
better alternative other than leaning pretty heavily on fuzz-testing to
ensure this is all exercised.

* Fix an unused field warning

* Fix tests in `wasmtime-runtime`

* Add some more tests for compiled trampolines

* Remap exports when injecting adapters

The exports of a component were accidentally left unmapped which meant
that they indexed the instance indexes pre-adapter module insertion.

* Fix typo

* Rebase conflicts
2022-07-25 23:13:26 +00:00
Nick Fitzgerald
35b750ab9a Implement std::fmt::Pointer for ExternRef (#4504) 2022-07-21 16:16:23 -07:00
Nick Fitzgerald
6e099720af wasmtime-runtime: Remove old libcalls that aren't used anymore (#4470)
These were for x86 (32-bit) where the ISA didn't have instructions for these
things, but now that we don't support that, and always have SSE2 for x86_64, we
never need or use these libcalls anymore.
2022-07-20 09:42:25 -05:00
Alex Crichton
33312c5380 Fix a possible panic with null-containing element segments (#4455)
This commit fixes an issue with the initialization of element segments
when one of the elements in the element segment is `ref.func null`.
Previously the contents of a table were accidentally initialized with
the raw value of the `*mut VMCallerCheckedAnyfunc` which bypassed the
"this is initialized" encoding of function table entries that Wasmtime
uses for lazy table initialization. The fix here was to ensure that the
encoded form is used.

The impact of this issue is that a module could panic at runtime when
accessing a table element that was initialized with an element segment
containing a `ref.null func` entry. This only happens with imported
tables in a WebAssembly module where the table itself was defined on the
host. If the table was defined in another wasm module or in the local
wasm module this bug would not occur. Additionally this bug requires
enabling the reference types proposal for WebAssembly (which is enabled
by default) due to the usage of encodings for null funcrefs in element
segments.
2022-07-15 20:14:53 +00:00
Alex Crichton
601e8f3094 Remove dependency on the region crate (#4407)
This commit removes Wasmtime's dependency on the `region` crate. The
motivation for this came about when I was updating dependencies and saw
that `region` had a new major version at 3.0.0 as opposed to our
currently used 2.3 track. In reviewing the use cases of `region` within
Wasmtime I found two trends in particular which motivated this commit:

* Some unix-specific areas of `wasmtime_runtime` use
  `rustix::mm::mprotect` instead of `region::protect` already. This
  means that the usage of `region::protect` for changing virtual memory
  protections was already inconsistent.

* Many uses of `region::protect` were already in unix-specific regions
  which could make use of `rustix`.

Overall I opted to remove the dependency on the `region` crate to avoid
chasing its versions over time. Unix-specific changes of protections
were easily changed to `rustix::mm::mprotect`. There were two locations
where a windows/unix split is now required and I subjectively ruled
"that seems ok". Finally removing `region` also meant that the "what is
the current page size" query needed to be inlined into
`wasmtime_runtime`, which I have also subjectively ruled "that seems
fine".

Finally one final refactoring here was that the `unix.rs` and `linux.rs`
split for the pooling allocator was merged. These two files already only
differed in one function so I slapped a `cfg_if!` in there to help
reduce the duplication.
2022-07-07 21:28:25 +00:00
wasmtime-publish
7c428bbd62 Bump Wasmtime to 0.40.0 (#4378)
Co-authored-by: Wasmtime Publish <wasmtime-publish@users.noreply.github.com>
2022-07-05 09:10:52 -05:00
Dan Gohman
a2197ebbeb Do one add_seals call, rather than one per flag. (#4366)
When setting up a copy on write image, we add several seals, to prevent
the image from being resized or modified. Set all the seals in a single
call, rather than doing one call per seal.
2022-07-01 16:00:18 -07:00
Alex Crichton
f0278c5db7 Implement canon lower of a canon lift function in the same component (#4347)
* Implement `canon lower` of a `canon lift` function in the same component

This commit implements the "degenerate" logic for implementing a
function within a component that is lifted and then immediately lowered
again. In this situation the lowered function will immediately generate
a trap and doesn't need to implement anything else.

The implementation in this commit is somewhat heavyweight but I think is
probably justified moreso in future additions to the component model
rather than what exactly is here right now. It's not expected that this
"always trap" functionality will really be used all that often since it
would generally mean a buggy component, but the functionality plumbed
through here is hopefully going to be useful for implementing
component-to-component adapter trampolines.

Specifically this commit implements a strategy where the `canon.lower`'d
function is generated by Cranelift and simply has a single trap
instruction when called, doing nothing else. The main complexity comes
from juggling around all the data associated with these functions,
primarily plumbing through the traps into the `ModuleRegistry` to
ensure that the global `is_wasm_trap_pc` function returns `true` and at
runtime when we lookup information about the trap it's all readily
available (e.g. translating the trapping pc to a `TrapCode`).

* Fix non-component build

* Fix some offset calculations

* Only create one "always trap" per signature

Use an internal map to deduplicate during compilation.
2022-06-29 16:35:37 +00:00
Alex Crichton
c1b3962f7b Implement lowered-then-lifted functions (#4327)
* Implement lowered-then-lifted functions

This commit is a few features bundled into one, culminating in the
implementation of lowered-then-lifted functions for the component model.
It's probably not going to be used all that often but this is possible
within a valid component so Wasmtime needs to do something relatively
reasonable. The main things implemented in this commit are:

* Component instances are now assigned a `RuntimeComponentInstanceIndex`
  to differentiate each one. This will be used in the future to detect
  fusion (one instance lowering a function from another instance). For
  now it's used to allocate separate `VMComponentFlags` for each
  internal component instance.

* The `CoreExport<FuncIndex>` of lowered functions was changed to a
  `CoreDef` since technically a lowered function can use another lowered
  function as the callee. This ended up being not too difficult to plumb
  through as everything else was already in place.

* A need arose to compile host-to-wasm trampolines which weren't already
  present. Currently wasm in a component is always entered through a
  host-to-wasm trampoline but core wasm modules are the source of all
  the trampolines. In the case of a lowered-then-lifted function there
  may not actually be any core wasm modules, so component objects now
  contain necessary trampolines not otherwise provided by the core wasm
  objects. This feature required splitting a new function into the
  `Compiler` trait for creating a host-to-wasm trampoline. After doing
  this core wasm compilation was also updated to leverage this which
  further enabled compiling trampolines in parallel as opposed to the
  previous synchronous compilation.

* Review comments
2022-06-28 18:50:08 +00:00
Alex Crichton
df1502531d Migrate from winapi to windows-sys (#4346)
* Migrate from `winapi` to `windows-sys`

I believe that Microsoft itself is supporting the development of
`windows-sys` and it's also used by `cap-std` now so this switches
Wasmtime's dependencies on Windows APIs from the `winapi` crate to the
`windows-sys` crate. We still have `winapi` in our dependency graph but
that may get phased out over time.

* Make windows-sys a target-specific dependency
2022-06-28 18:02:41 +00:00
Alex Crichton
82a31680d6 Use a StoreOpaque during backtraces for metadata (#4325)
Previous to this commit Wasmtime would use the `GlobalModuleRegistry`
when learning information about a trap such as its trap code, the
symbols for each frame, etc. This has a downside though of holding a
global read-write lock for the duration of this operation which hinders
registration of new modules in parallel. In addition there was a fair
amount of internal duplication between this "global module registry" and
the store-local module registry. Finally relying on global state for
information like this gets a bit more brittle over time as it seems best
to scope global queries to precisely what's necessary rather than
holding extra information.

With the refactoring in wasm backtraces done in #4183 it's now possible
to always have a `StoreOpaque` reference when a backtrace is collected
for symbolication and otherwise Trap-identification purposes. This
commit adds a `StoreOpaque` parameter to the `Trap::from_runtime`
constructor and then plumbs that everywhere. Note that while doing this
I changed the internal `traphandlers::lazy_per_thread_init` function to
no longer return a `Result` and instead just `panic!` on Unix if memory
couldn't be allocated for a stack. This removed quite a lot of
error-handling code for a case that's expected to quite rarely happen.
If necessary in the future we can add a fallible initialization point
but this feels like a better default balance for the code here.

With a `StoreOpaque` in use when a trap is being symbolicated that means
we have a `ModuleRegistry` which can be used for queries and such. This
meant that the `GlobalModuleRegistry` state could largely be dismantled
and moved to per-`Store` state (within the `ModuleRegistry`, mostly just
moving methods around).

The final state is that the global rwlock is not exclusively scoped
around insertions/deletions/`is_wasm_trap_pc` which is just a lookup and
atomic add. Otherwise symbolication for a backtrace exclusively uses
store-local state now (as intended).

The original motivation for this commit was that frame information
lookup and pieces were looking to get somewhat complicated with the
addition of components which are a new vector of traps coming out of
Cranelift-generated code. My hope is that by having a `Store` around for
more operations it's easier to plumb all this through.
2022-06-27 15:24:59 -05:00
Alex Crichton
77e06213b7 Refactor the internals of traps in wasmtime_runtime (#4326)
This commit is a small refactoring of `wasmtime_runtime::Trap` and
various internals. The `Trap` structure is now a reason plus backtrace,
and the old `Trap` enum is mostly in `TrapReason` now. Additionally all
`Trap`-returning methods of `wasmtime_runtime` are changed to returning
a `TrapCode` to indicate that they never capture a backtrace. Finally
the `UnwindReason` internally now no longer duplicates the trap reasons,
instead only having two variants of "panic" and "trap".

The motivation for this commit is mostly just cleaning up trap internals
and removing the need for methods like
`wasmtime_runtime::Trap::insert_backtrace` to leave it only happening at
the `wasmtime` layer.
2022-06-27 12:35:14 -05:00
Alex Crichton
3339dd1f01 Implement the post-return attribute (#4297)
This commit implements the `post-return` feature of the canonical ABI in
the component model. This attribute is an optionally-specified function
which is to be executed after the return value has been processed by the
caller to optionally clean-up the return value. This enables, for
example, returning an allocated string and the host then knows how to
clean it up to prevent memory leaks in the original module.

The API exposed in this PR changes the prior `TypedFunc::call` API in
behavior but not in its signature. Previously the `TypedFunc::call`
method would set the `may_enter` flag on the way out, but now that
operation is deferred until a new `TypedFunc::post_return` method is
called. This means that once a method on an instance is invoked then
nothing else can be done on the instance until the `post_return` method
is called. Note that the method must be called irrespective of whether
the `post-return` canonical ABI option was specified or not. Internally
wasm will be invoked if necessary.

This is a pretty wonky and unergonomic API to work with. For now I
couldn't think of a better alternative that improved on the ergonomics.
In the theory that the raw Wasmtime bindings for a component may not be
used all that heavily (instead `wit-bindgen` would largely be used) I'm
hoping that this isn't too much of an issue in the future.

cc #4185
2022-06-23 14:36:21 -05:00
Dan Gohman
fa36e86f2c Update WASI to cap-std 0.25 and windows-sys. (#4302)
This updates to rustix 0.35.6, and updates wasi-common to use cap-std 0.25 and
windows-sys (instead of winapi).

Changes include:

 - Better error code mappings on Windows.
 - Fixes undefined references to `utimensat` on Darwin.
 - Fixes undefined references to `preadv64` and `pwritev64` on Android.
 - Updates to io-lifetimes 0.7, which matches the io_safety API in Rust.
 - y2038 bug fixes for 32-bit platforms
2022-06-23 10:47:15 -07:00
Andrew Brown
b2e03ae873 shared memory: change some assertions to returned errors (#4292)
Previously, @alexcrichton had mentioned that some of these assertions
should be bubbled up as errors. This change re-factors two such
assertions, leaving others in this file as assertions since they
represent code paths that we should avoid internally (not by external
users).
2022-06-21 12:55:27 -07:00
Andrew Brown
2b52f47b83 Add shared memories (#4187)
* Add shared memories

This change adds the ability to use shared memories in Wasmtime when the
[threads proposal] is enabled. Shared memories are annotated as `shared`
in the WebAssembly syntax, e.g., `(memory 1 1 shared)`, and are
protected from concurrent access during `memory.size` and `memory.grow`.

[threads proposal]: https://github.com/WebAssembly/threads/blob/master/proposals/threads/Overview.md

In order to implement this in Wasmtime, there are two main cases to
cover:
    - a program may simply create a shared memory and possibly export it;
    this means that Wasmtime itself must be able to create shared
    memories
    - a user may create a shared memory externally and pass it in as an
    import during instantiation; this is the case when the program
    contains code like `(import "env" "memory" (memory 1 1
    shared))`--this case is handled by a new Wasmtime API
    type--`SharedMemory`

Because of the first case, this change allows any of the current
memory-creation mechanisms to work as-is. Wasmtime can still create
either static or dynamic memories in either on-demand or pooling modes,
and any of these memories can be considered shared. When shared, the
`Memory` runtime container will lock appropriately during `memory.size`
and `memory.grow` operations; since all memories use this container, it
is an ideal place for implementing the locking once and once only.

The second case is covered by the new `SharedMemory` structure. It uses
the same `Mmap` allocation under the hood as non-shared memories, but
allows the user to perform the allocation externally to Wasmtime and
share the memory across threads (via an `Arc`). The pointer address to
the actual memory is carefully wired through and owned by the
`SharedMemory` structure itself. This means that there are differing
views of where to access the pointer (i.e., `VMMemoryDefinition`): for
owned memories (the default), the `VMMemoryDefinition` is stored
directly by the `VMContext`; in the `SharedMemory` case, however, this
`VMContext` must point to this separate structure.

To ensure that the `VMContext` can always point to the correct
`VMMemoryDefinition`, this change alters the `VMContext` structure.
Since a `SharedMemory` owns its own `VMMemoryDefinition`, the
`defined_memories` table in the `VMContext` becomes a sequence of
pointers--in the shared memory case, they point to the
`VMMemoryDefinition` owned by the `SharedMemory` and in the owned memory
case (i.e., not shared) they point to `VMMemoryDefinition`s stored in a
new table, `owned_memories`.

This change adds an additional indirection (through the `*mut
VMMemoryDefinition` pointer) that could add overhead. Using an imported
memory as a proxy, we measured a 1-3% overhead of this approach on the
`pulldown-cmark` benchmark. To avoid this, Cranelift-generated code will
special-case the owned memory access (i.e., load a pointer directly to
the `owned_memories` entry) for `memory.size` so that only
shared memories (and imported memories, as before) incur the indirection
cost.

* review: remove thread feature check

* review: swap wasmtime-types dependency for existing wasmtime-environ use

* review: remove unused VMMemoryUnion

* review: reword cross-engine error message

* review: improve tests

* review: refactor to separate prevent Memory <-> SharedMemory conversion

* review: into_shared_memory -> as_shared_memory

* review: remove commented out code

* review: limit shared min/max to 32 bits

* review: skip imported memories

* review: imported memories are not owned

* review: remove TODO

* review: document unsafe send + sync

* review: add limiter assertion

* review: remove TODO

* review: improve tests

* review: fix doc test

* fix: fixes based on discussion with Alex

This changes several key parts:
 - adds memory indexes to imports and exports
 - makes `VMMemoryDefinition::current_length` an atomic usize

* review: add `Extern::SharedMemory`

* review: remove TODO

* review: atomically load from VMMemoryDescription in JIT-generated code

* review: add test probing the last available memory slot across threads

* fix: move assertion to new location due to rebase

* fix: doc link

* fix: add TODOs to c-api

* fix: broken doc link

* fix: modify pooling allocator messages in tests

* review: make owned_memory_index panic instead of returning an option

* review: clarify calculation of num_owned_memories

* review: move 'use' to top of file

* review: change '*const [u8]' to '*mut [u8]'

* review: remove TODO

* review: avoid hard-coding memory index

* review: remove 'preallocation' parameter from 'Memory::_new'

* fix: component model memory length

* review: check that shared memory plans are static

* review: ignore growth limits for shared memory

* review: improve atomic store comment

* review: add FIXME for memory growth failure

* review: add comment about absence of bounds-checked 'memory.size'

* review: make 'current_length()' doc comment more precise

* review: more comments related to memory.size non-determinism

* review: make 'vmmemory' unreachable for shared memory

* review: move code around

* review: thread plan through to 'wrap()'

* review: disallow shared memory allocation with the pooling allocator
2022-06-08 12:13:40 -05:00
wasmtime-publish
55946704cb Bump Wasmtime to 0.39.0 (#4225)
Co-authored-by: Wasmtime Publish <wasmtime-publish@users.noreply.github.com>
2022-06-06 09:12:47 -05:00
Alex Crichton
2af358dd9c Add a VMComponentContext type and create it on instantiation (#4215)
* Add a `VMComponentContext` type and create it on instantiation

This commit fills out the `wasmtime-runtime` crate's support for
`VMComponentContext` and creates it as part of the instantiation
process. This moves a few maps that were temporarily allocated in an
`InstanceData` into the `VMComponentContext` and additionally reads the
canonical options data from there instead.

This type still won't be used in its "full glory" until the lowering of
host functions is completely implemented, however, which will be coming
in a future commit.

* Remove `DerefMut` implementation

* Rebase conflicts
2022-06-03 13:34:50 -05:00
Alex Crichton
3ed6fae7b3 Add trampoline compilation support for lowered imports (#4206)
* Add trampoline compilation support for lowered imports

This commit adds support to the component model implementation for
compiling trampolines suitable for calling host imports. Currently this
is purely just the compilation side of things, modifying the
wasmtime-cranelift crate and additionally filling out a new
`VMComponentOffsets` type (similar to `VMOffsets`). The actual creation
of a `VMComponentContext` is still not performed and will be a
subsequent PR.

Internally though some tests are actually possible with this where we at
least assert that compilation of a component and creation of everything
in-memory doesn't panic or trip any assertions, so some tests are added
here for that as well.

* Fix some test errors
2022-06-03 10:01:42 -05:00
Alex Crichton
9f5f978baa Fix double-counting imports in VMOffsets calculations (#4209)
* Fix double-counting imports in `VMOffsets` calculations

This fixes an oversight in the initial creation of `VMOffsets` for a
module to avoid double-counting imported globals, tables, and memories
for calculating the size of the `VMContext`. Prior to this PR imported
items are accidentally also counted as defined items for sizing
calculations meaning that when a memory is imported but not defined, for
example, the `VMContext` will have a space for an inline
`VMMemoryDefinition` when it doesn't need to.

Auditing where all this relates to it appears that the only issue from
this mistake is that `VMContext` is a bit larger than it would otherwise
need to be. Extra slots are uninitialized memory but nothing in Wasmtime
ever actually accesses the memory either, so it should be harmless to
have extra space here. Nevertheless it seems better to shrink the size
as much as possible to avoid wasting space where we can.

* Fix tests
2022-06-02 13:39:38 -05:00
Alex Crichton
2a4851ad2b Change some VMContext pointers to () pointers (#4190)
* Change some `VMContext` pointers to `()` pointers

This commit is motivated by my work on the component model
implementation for imported functions. Currently all context pointers in
wasm are `*mut VMContext` but with the component model my plan is to
make some pointers instead along the lines of `*mut VMComponentContext`.
In doing this though one worry I have is breaking what has otherwise
been a core invariant of Wasmtime for quite some time, subtly
introducing bugs by accident.

To help assuage my worry I've opted here to erase knowledge of
`*mut VMContext` where possible. Instead where applicable a context
pointer is simply known as `*mut ()` and the embedder doesn't actually
know anything about this context beyond the value of the pointer. This
will help prevent Wasmtime from accidentally ever trying to interpret
this context pointer as an actual `VMContext` when it might instead be a
`VMComponentContext`.

Overall this was a pretty smooth transition. The main change here is
that the `VMTrampoline` (now sporting more docs) has its first argument
changed to `*mut ()`. The second argument, the caller context, is still
configured as `*mut VMContext` though because all functions are always
called from wasm still. Eventually for component-to-component calls I
think we'll probably "fake" the second argument as the same as the first
argument, losing track of the original caller, as an intentional way of
isolating components from each other.

Along the way there are a few host locations which do actually assume
that the first argument is indeed a `VMContext`. These are valid
assumptions that are upheld from a correct implementation, but I opted
to add a "magic" field to `VMContext` to assert this in debug mode. This
new "magic" field is inintialized during normal vmcontext initialization
and it's checked whenever a `VMContext` is reinterpreted as an
`Instance` (but only in debug mode). My hope here is to catch any future
accidental mistakes, if ever.

* Use a VMOpaqueContext wrapper

* Fix typos
2022-06-01 11:00:43 -05:00
Alex Crichton
7d3639522e Capture unresolved backtraces on traps (#4193)
I was running tests recently and was surprised that the `--test all`
test was taking more than a minute to run when I didn't recall it ever
taking more than a minute historically. A bisection pointed out #4183 as
the cause and after re-reviewing I realized I forgot that we capture
unresolved backtraces by default (and don't actually resolve them
anywhere yet but that's a problem for another day) rather than resolved
backtraces. This means that it's intended that we use
`Backtrace::new_unresolved` instead of `Backtrace::new` in the
traphandlers crate.

The reason that tests were running so slowly is that the tests which
deal with deep stacks (e.g. stack overflow) would take forever in
testing as the Rust-based decoding of DWARF information is egregiously
slow in unoptimized mode. I did discover independently that optimizing
these dependencies makes the tests ~6x faster, but that's irrelevant if
we're not symbolicating in the first place.
2022-05-31 09:56:56 -05:00
Pat Hickey
bffce37050 make backtrace collection a Config field rather than a cargo feature (#4183)
* sorta working in runtime

* wasmtime-runtime: get rid of wasm-backtrace feature

* wasmtime: factor to make backtraces recording optional. not configurable yet

* get rid of wasm-backtrace features

* trap tests: now a Trap optionally contains backtrace

* eliminate wasm-backtrace feature

* code review fixes

* ci: no more wasm-backtrace feature

* c_api: backtraces always enabled

* config: unwind required by backtraces and ref types

* plumbed

* test that disabling backtraces works

* code review comments

* fuzzing generator: wasm_backtrace is a runtime config now

* doc fix
2022-05-25 12:25:50 -07:00
Alex Crichton
a02a609528 Make ValRaw fields private (#4186)
* Make `ValRaw` fields private

Force accessing to go through constructors and accessors to localize the
knowledge about little-endian-ness. This is spawned since I made a
mistake in #4039 about endianness.

* Fix some tests

* Component model changes
2022-05-24 19:14:29 -05:00
wasmtime-publish
9a6854456d Bump Wasmtime to 0.38.0 (#4103)
Co-authored-by: Wasmtime Publish <wasmtime-publish@users.noreply.github.com>
2022-05-05 13:43:02 -05:00
Alex Crichton
7fdc616368 Remove the Paged memory initialization variant (#4046)
* Remove the `Paged` memory initialization variant

This commit simplifies the `MemoryInitialization` enum by removing the
`Paged` variant. The `Paged` variant was originally added for uffd, but
that support has now been removed in #4040. This is no longer necessary
but is still used as an intermediate step of becoming a `Static` variant
of initialized memory (which copy-on-write uses). As a result this
commit largely modifies the static initialization of memory steps and
folds the two methods together.

* Apply suggestions from code review

Co-authored-by: Peter Huene <peter@huene.dev>

Co-authored-by: Peter Huene <peter@huene.dev>
2022-05-05 09:44:48 -05:00
Andrew Brown
3dbdcfa220 runtime: refactor Memory to always use Box<dyn RuntimeLinearMemory> (#4086)
While working with the runtime `Memory` object, it became clear that
some refactoring was needed. In order to implement shared memory from
the threads proposal, we must be able to atomically change the memory
size. Previously, the split into variants, `Memory::Static` and
`Memory::Dynamic`, made any attempt to lock forced us to duplicate logic
in various places.

This change moves `enum Memory { Static..., Dynamic... }` to simply
`struct Memory(Box<dyn RuntimeLinearMemory>)`. A new type,
`ExternalMemory`, takes the place of `Memory::Static` and also
implements the `RuntimeLinearMemory` trait, allowing `Memory` to contain
the same two options as before: `MmapMemory` for `Memory::Dynamic` and
`ExternalMemory` for `Memory::Static`. To interface with the
`PoolingAllocator`, this change also required the ability to downcast to
the internal representation.
2022-04-29 08:12:38 -07:00
Dan Gohman
321124ad21 Update to rustix 0.33.7. (#4052)
This pulls in the fix for bytecodealliance/rustix#285, which fixes a
failure in the WASI `time` APIs on powerpc64.
2022-04-19 16:27:56 -07:00
Alex Crichton
90791a0e32 Reduce contention on the global module rwlock (#4041)
* Reduce contention on the global module rwlock

This commit intendes to close #4025 by reducing contention on the global
rwlock Wasmtime has for module information during instantiation and
dropping a store. Currently registration of a module into this global
map happens during instantiation, but this can be a hot path as
embeddings may want to, in parallel, instantiate modules.

Instead this switches to a strategy of inserting into the global module
map when a `Module` is created and then removing it from the map when
the `Module` is dropped. Registration in a `Store` now preserves the
entire `Module` within the store as opposed to trying to only save it
piecemeal. In reality the only piece that wasn't saved within a store
was the `TypeTables` which was pretty inconsequential for core wasm
modules anyway.

This means that instantiation should now clone a singluar `Arc` into a
`Store` per `Module` (previously it cloned two) with zero managemnt on
the global rwlock as that happened at `Module` creation time.
Additionally dropping a `Store` again involves zero rwlock management
and only a single `Arc` drop per-instantiated module (previously it was
two).

In the process of doing this I also went ahead and removed the
`Module::new_with_name` API. This has been difficult to support
historically with various variations on the internals of `ModuleInner`
because it involves mutating a `Module` after it's been created. My hope
is that this API is pretty rarely used and/or isn't super important, so
it's ok to remove.

Finally this change removes some internal `Arc` layerings that are no
longer necessary, attempting to use either `T` or `&T` where possible
without dealing with the overhead of an `Arc`.

Closes #4025

* Move back to a `BTreeMap` in `ModuleRegistry`
2022-04-19 15:13:47 -05:00
Alex Crichton
3f3afb455e Remove support for userfaultfd (#4040)
This commit removes support for the `userfaultfd` or "uffd" syscall on
Linux. This support was originally added for users migrating from Lucet
to Wasmtime, but the recent developments of kernel-supported
copy-on-write support for memory initialization wound up being more
appropriate for these use cases than usefaultfd. The main reason for
moving to copy-on-write initialization are:

* The `userfaultfd` feature was never necessarily intended for this
  style of use case with wasm and was susceptible to subtle and rare
  bugs that were extremely difficult to track down. We were never 100%
  certain that there were kernel bugs related to userfaultfd but the
  suspicion never went away.

* Handling faults with userfaultfd was always slow and single-threaded.
  Only one thread could handle faults and traveling to user-space to
  handle faults is inherently slower than handling them all in the
  kernel. The single-threaded aspect in particular presented a
  significant scaling bottleneck for embeddings that want to run many
  wasm instances in parallel.

* One of the major benefits of userfaultfd was lazy initialization of
  wasm linear memory which is also achieved with the copy-on-write
  initialization support we have right now.

* One of the suspected benefits of userfaultfd was less frobbing of the
  kernel vma structures when wasm modules are instantiated. Currently
  the copy-on-write support has a mitigation where we attempt to reuse
  the memory images where possible to avoid changing vma structures.
  When comparing this to userfaultfd's performance it was found that
  kernel modifications of vmas aren't a worrisome bottleneck so
  copy-on-write is suitable for this as well.

Overall there are no remaining benefits that userfaultfd gives that
copy-on-write doesn't, and copy-on-write solves a major downsides of
userfaultfd, the scaling issue with a single faulting thread.
Additionally copy-on-write support seems much more robust in terms of
kernel implementation since it's only using standard memory-management
syscalls which are heavily exercised. Finally copy-on-write support
provides a new bonus where read-only memory in WebAssembly can be mapped
directly to the same kernel cache page, even amongst many wasm instances
of the same module, which was never possible with userfaultfd.

In light of all this it's expected that all users of userfaultfd should
migrate to the copy-on-write initialization of Wasmtime (which is
enabled by default).
2022-04-18 12:42:26 -05:00
Alex Crichton
51d82aebfd Store the ValRaw type in little-endian format (#4035)
* Store the `ValRaw` type in little-endian format

This commit changes the internal representation of the `ValRaw` type to
an unconditionally little-endian format instead of its current
native-endian format. The documentation and various accessors here have
been updated as well as the associated trampolines that read `ValRaw`
to always work with little-endian values, converting to the host
endianness as necessary.

The motivation for this change originally comes from the implementation
of the component model that I'm working on. One aspect of the component
model's canonical ABI is how variants are passed to functions as
immediate arguments. For example for a component model function:

```
foo: function(x: expected<i32, f64>)
```

This translates to a core wasm function:

```wasm
(module
  (func (export "foo") (param i32 i64)
    ;; ...
  )
)
```

The first `i32` parameter to the core wasm function is the discriminant
of whether the result is an "ok" or an "err". The second `i64`, however,
is the "join" operation on the `i32` and `f64` payloads. Essentially
these two types are unioned into one type to get passed into the function.

Currently in the implementation of the component model my plan is to
construct a `*mut [ValRaw]` to pass through to WebAssembly, always
invoking component exports through host trampolines. This means that the
implementation for `Result<T, E>` needs to do the correct "join"
operation here when encoding a particular case into the corresponding
`ValRaw`.

I personally found this particularly tricky to do structurally. The
solution that I settled on with fitzgen was that if `ValRaw` was always
stored in a little endian format then we could employ a trick where when
encoding a variant we first set all the `ValRaw` slots to zero, then the
associated case we have is encoding. Afterwards the `ValRaw` values are
already encoded into the correct format as if they'd been "join"ed.

For example if we were to encode `Ok(1i32)` then this would produce
`ValRaw { i32: 1 }`, which memory-wise is equivalent to `ValRaw { i64: 1 }`
if the other bytes in the `ValRaw` are guaranteed to be zero. Similarly
storing `ValRaw { f64 }` is equivalent to the storage required for
`ValRaw { i64 }` here in the join operation.

Note, though, that this equivalence relies on everything being
little-endian. Otherwise the in-memory representations of `ValRaw { i32: 1 }`
and `ValRaw { i64: 1 }` are different.

That motivation is what leads to this change. It's expected that this is
a low-to-zero cost change in the sense that little-endian platforms will
see no change and big-endian platforms are already required to
efficiently byte-swap loads/stores as WebAssembly requires that.
Additionally the `ValRaw` type is an esoteric niche use case primarily
used for accelerating the C API right now, so it's expected that not
many users will have to update for this change.

* Track down some more endianness conversions
2022-04-14 13:09:32 -05:00
Yang Hau
bfae6384aa fix typo (#4030) 2022-04-14 09:35:53 -05:00
Dan Gohman
ade04c92c2 Update to rustix 0.33.6. (#4022)
Relevant to Wasmtime, this fixes undefined references to `utimensat` and
`futimens` on macOS 10.12 and earlier. See bytecodealliance/rustix#157
for details.

It also contains a fix for s390x which isn't currently needed by Wasmtime
itself, but which is needed to make rustix's own testsuite pass on s390x,
which helps people packaging rustix for use in Wasmtime. See
bytecodealliance/rustix#277 for details.
2022-04-13 11:51:57 -05:00
wasmtime-publish
78a595ac88 Bump Wasmtime to 0.37.0 (#3994)
Co-authored-by: Wasmtime Publish <wasmtime-publish@users.noreply.github.com>
2022-04-05 09:24:28 -05:00
Alex Crichton
7b5176baea Upgrade all crates to the Rust 2021 edition (#3991)
* Upgrade all crates to the Rust 2021 edition

I've personally started using the new format strings for things like
`panic!("some message {foo}")` or similar and have been upgrading crates
on a case-by-case basis, but I think it probably makes more sense to go
ahead and blanket upgrade everything so 2021 features are always
available.

* Fix compile of the C API

* Fix a warning

* Fix another warning
2022-04-04 12:27:12 -05:00
Alex Crichton
c89dc55108 Add a two-week delay to Wasmtime's release process (#3955)
* Bump to 0.36.0

* Add a two-week delay to Wasmtime's release process

This commit is a proposal to update Wasmtime's release process with a
two-week delay from branching a release until it's actually officially
released. We've had two issues lately that came up which led to this proposal:

* In #3915 it was realized that changes just before the 0.35.0 release
  weren't enough for an embedding use case, but the PR didn't meet the
  expectations for a full patch release.

* At Fastly we were about to start rolling out a new version of Wasmtime
  when over the weekend the fuzz bug #3951 was found. This led to the
  desire internally to have a "must have been fuzzed for this long"
  period of time for Wasmtime changes which we felt were better
  reflected in the release process itself rather than something about
  Fastly's own integration with Wasmtime.

This commit updates the automation for releases to unconditionally
create a `release-X.Y.Z` branch on the 5th of every month. The actual
release from this branch is then performed on the 20th of every month,
roughly two weeks later. This should provide a period of time to ensure
that all changes in a release are fuzzed for at least two weeks and
avoid any further surprises. This should also help with any last-minute
changes made just before a release if they need tweaking since
backporting to a not-yet-released branch is much easier.

Overall there are some new properties about Wasmtime with this proposal
as well:

* The `main` branch will always have a section in `RELEASES.md` which is
  listed as "Unreleased" for us to fill out.
* The `main` branch will always be a version ahead of the latest
  release. For example it will be bump pre-emptively as part of the
  release process on the 5th where if `release-2.0.0` was created then
  the `main` branch will have 3.0.0 Wasmtime.
* Dates for major versions are automatically updated in the
  `RELEASES.md` notes.

The associated documentation for our release process is updated and the
various scripts should all be updated now as well with this commit.

* Add notes on a security patch

* Clarify security fixes shouldn't be previewed early on CI
2022-04-01 13:11:10 -05:00