`capptr_domesticate<Backend>(Backend::LocalState*, CapPtr<T, B>)` is the
intended affordance for conversion to covert from a `CapPtr<T, B>` with
`B::wildness` `Wild` to a `CapPtr<>` with `B::with_wildness<Tame>` and thence
plumbed into the rest of the machinery.
David added the SFINAE wrapper so that `Backend`-s now don't need to implement a
domestication callback; instead, if the `Backend` does not provide a
`capptr_domesticate` function, a default, which just does an explicit type cast,
will be used instead.
This is not yet hooked into the rest of the tree.
Co-authored-by: David Chisnall <David.Chisnall@microsoft.com>
The memcpy implementation is not completely stupid but is almost
certainly not as good as a carefully tuned and optimised one.
Building snmalloc with FreeBSD's libc memcpy + jemalloc and with this,
each 10 times, does not show a statistically significant performance
difference at 95% confidence. The snmalloc version has very slightly
lower median and worst-case times. This is in no way a sensible
benchmark, but it serves as a smoke test for significant performance
regressions.
The CI self-host job now uses the checked memcpy.
This also fixes an off-by-one error in the external bounds. This is
triggered by ninja, so we will see breakage in CI if it is reintroduced.
In debug builds, we provide a verbose error containing the address of
the allocation, the base and bounds of the allocation, and a backtrace.
The backtrace was broken by the CI cleanup moving the BACKTRACE_HEADER
macro into the SNMALLOC_ namespace. This is also fixed.
The test involves hijacking `abort`, which doesn't work everywhere. It
also requires `backtrace` to work in configurations where stack traces
are enabled. This is disabled in QEMU because `backtrace` appears to
crash reliably in QEMU user mode.
For now, in the -checks build configurations, we are hitting a slow path
in the pagemap on accesses so that the pages that are `PROT_NONE` don't
cause crashes. These need to be made read-only, but this requires a PAL
change.
This is the set of changes required for snmalloc2 to be usable by the
process sandboxing code and incorporates some API changes that reduce
the amount of code required to embed snmalloc. Highlights:
- Merge the config and back-end classes.
- Everything in config is now global (all methods are static)
- The GlobalState class is gone (all global state is managed by global
methods on the config class)
- LocalState is now a member of the config class, all methods are
instance methods.
- Not every configuration needs to use the lazy initialisation hooks.
They now need to be provided only if they are used. If the
configuration does not provide an `ensure_init` method, it is not
called. If it does not provide an `is_initialised` method then the
global initialisation state is not checked.
- There is now an `snmalloc::Options` class that default initialises
itself to the default behaviour. Every configuration must provide a
`constexpr` instance of this class. Each flag can be separately
overridden and new flags can be added without breaking any existing
API consumers.
The config classes are moved into the backend directory.
