From<bool> turns true into 1. A signed Bounded with N = 1 can hold
only -1 and 0. The current implementation can therefore create a value
that breaks Bounded's invariant. Deref relies on that invariant and
calls unreachable_unchecked() when it is broken, so safe Rust can reach
undefined behavior.
The other primitive conversions require the source and destination to
have the same signedness. Treat bool as an unsigned one-bit value and
allow conversions between bool and Bounded only when the backing integer
type is unsigned.
Fixes: 01e345e82ec3 ("rust: num: add Bounded integer wrapping type")
Closes: https://lore.kernel.org/rust-for-linux/OzuVxu0--J-9@younes.io/
Cc: stable@vger.kernel.org
Suggested-by: Alexandre Courbot <acourbot@nvidia.com>
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Younes Akhouayri <git@younes.io>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260822-fix-rust-bounded-from-bool-submit-v4-1-aa780bfe7f30@younes.io
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The core library's `From` implementations do not cover conversions that are not portable or future-proof. For instance, even though it is safe today, `From<usize>` is not implemented for `u64` because of the possibility of supporting larger-than-64bit architectures in the future. However, the kernel supports a narrower set of architectures, with a considerable amount of code that is architecture-specific. This makes it helpful and desirable to provide more infallible conversions, lest we rely on the `as` keyword and carry the risk of silently losing data. Thus, introduce a new module `num::casts` that provides safe const functions performing more conversions allowed by the build target, as well as `FromSafeCast` and `IntoSafeCast` traits that are just extensions of `From` and `Into` to conversions that are known to be lossless. Some conversions are architecture-specific: for instance, converting a `u64` to a `usize` is only lossless on 64-bit platforms. These conversions are made available via a dedicated `arch` sub-module. Suggested-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/rust-for-linux/DDK4KADWJHMG.1FUPL3SDR26XF@kernel.org/ Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Danilo Krummrich <dakr@kernel.org> Link: https://patch.msgid.link/20260806-as_casts-v2-1-cb76a4d3a6ef@nvidia.com [ Added a few more intra-doc links. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add `shr_exact` in the vein of `try_shrink` which shifts a bounded right only if it loses no set bits. This is useful for getting a shifted down integer while simultaneously checking that it's aligned. Signed-off-by: Eliot Courtney <ecourtney@nvidia.com> Acked-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Danilo Krummrich <dakr@kernel.org> Link: https://patch.msgid.link/20260810-pramin-split-v2-3-65a00b3c7309@nvidia.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Make `shr` reject shifts of at least the type's bit width at build
time, instead of panicking or masking the shift amount at runtime.
[ This implies we can break the type invariant, which in turn means
we can trigger UB via `Deref`, e.g.:
rust_kernel: panicked at rust/kernel/num/bounded.rs:528:22:
unsafe precondition(s) violated: hint::unreachable_unchecked must never be reached
- Miguel ]
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Cc: stable@vger.kernel.org
Fixes: c59a2d14cd24 ("rust: num: add `shr` and `shl` methods to `Bounded`")
Link: https://patch.msgid.link/20260810-pramin-split-v2-2-65a00b3c7309@nvidia.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Convert the const-block asserts in bounded.rs to const_assert!, matching the rest of the file. Signed-off-by: Eliot Courtney <ecourtney@nvidia.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Danilo Krummrich <dakr@kernel.org> Suggested-by: Gary Guo <gary@garyguo.net> Link: https://lore.kernel.org/rust-for-linux/DKIY9YGIPUUE.SZD2DUQM9NGK@garyguo.net/ Link: https://patch.msgid.link/20260810-pramin-split-v2-1-65a00b3c7309@nvidia.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Given the macro scoping rules, all macros are rendered twice, in the
module and in the top-level of kernel crate.
Add `#[doc(hidden)]` to the macro definition and `#[doc(inline)]` to the
re-export inside `build_assert` module so the top-level items are hidden.
[ Sadly, because the definition is hidden, `rustdoc` decides to not list
them as re-exports in the `prelude` page anymore, even if we refer to
the not-actually-hidden item.
- Miguel ]
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Acked-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260609142637.373347-1-gary@kernel.org
[ Kept a single declaration in the prelude, and reworded since they
already had `no_inline`. Removed other imports from `predefine` since
we now use the prelude. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Pull driver core updates from Danilo Krummrich:
"debugfs:
- Fix NULL pointer dereference in debugfs_create_str()
- Fix misplaced EXPORT_SYMBOL_GPL for debugfs_create_str()
- Fix soundwire debugfs NULL pointer dereference from uninitialized
firmware_file
device property:
- Make fwnode flags modifications thread safe; widen the field to
unsigned long and use set_bit() / clear_bit() based accessors
- Document how to check for the property presence
devres:
- Separate struct devres_node from its "subclasses" (struct devres,
struct devres_group); give struct devres_node its own release and
free callbacks for per-type dispatch
- Introduce struct devres_action for devres actions, avoiding the
ARCH_DMA_MINALIGN alignment overhead of struct devres
- Export struct devres_node and its init/add/remove/dbginfo
primitives for use by Rust Devres<T>
- Fix missing node debug info in devm_krealloc()
- Use guard(spinlock_irqsave) where applicable; consolidate unlock
paths in devres_release_group()
driver_override:
- Convert PCI, WMI, vdpa, s390/cio, s390/ap, and fsl-mc to the
generic driver_override infrastructure, replacing per-bus
driver_override strings, sysfs attributes, and match logic; fixes a
potential UAF from unsynchronized access to driver_override in bus
match() callbacks
- Simplify __device_set_driver_override() logic
kernfs:
- Send IN_DELETE_SELF and IN_IGNORED inotify events on kernfs file
and directory removal
- Add corresponding selftests for memcg
platform:
- Allow attaching software nodes when creating platform devices via a
new 'swnode' field in struct platform_device_info
- Add kerneldoc for struct platform_device_info
software node:
- Move software node initialization from postcore_initcall() to
driver_init(), making it available early in the boot process
- Move kernel_kobj initialization (ksysfs_init) earlier to support
the above
- Remove software_node_exit(); dead code in a built-in unit
SoC:
- Introduce of_machine_read_compatible() and of_machine_read_model()
OF helpers and export soc_attr_read_machine() to replace direct
accesses to of_root from SoC drivers; also enables
CONFIG_COMPILE_TEST coverage for these drivers
sysfs:
- Constify attribute group array pointers to
'const struct attribute_group *const *' in sysfs functions,
device_add_groups() / device_remove_groups(), and struct class
Rust:
- Devres:
- Embed struct devres_node directly in Devres<T> instead of going
through devm_add_action(), avoiding the extra allocation and the
unnecessary ARCH_DMA_MINALIGN alignment
- I/O:
- Turn IoCapable from a marker trait into a functional trait
carrying the raw I/O accessor implementation (io_read /
io_write), providing working defaults for the per-type Io
methods
- Add RelaxedMmio wrapper type, making relaxed accessors usable in
code generic over the Io trait
- Remove overloaded per-type Io methods and per-backend macros
from Mmio and PCI ConfigSpace
- I/O (Register):
- Add IoLoc trait and generic read/write/update methods to the Io
trait, making I/O operations parameterizable by typed locations
- Add register! macro for defining hardware register types with
typed bitfield accessors backed by Bounded values; supports
direct, relative, and array register addressing
- Add write_reg() / try_write_reg() and LocatedRegister trait
- Update PCI sample driver to demonstrate the register! macro
Example:
```
register! {
/// UART control register.
CTRL(u32) @ 0x18 {
/// Receiver enable.
19:19 rx_enable => bool;
/// Parity configuration.
14:13 parity ?=> Parity;
}
/// FIFO watermark and counter register.
WATER(u32) @ 0x2c {
/// Number of datawords in the receive FIFO.
26:24 rx_count;
/// RX interrupt threshold.
17:16 rx_water;
}
}
impl WATER {
fn rx_above_watermark(&self) -> bool {
self.rx_count() > self.rx_water()
}
}
fn init(bar: &pci::Bar<BAR0_SIZE>) {
let water = WATER::zeroed()
.with_const_rx_water::<1>(); // > 3 would not compile
bar.write_reg(water);
let ctrl = CTRL::zeroed()
.with_parity(Parity::Even)
.with_rx_enable(true);
bar.write_reg(ctrl);
}
fn handle_rx(bar: &pci::Bar<BAR0_SIZE>) {
if bar.read(WATER).rx_above_watermark() {
// drain the FIFO
}
}
fn set_parity(bar: &pci::Bar<BAR0_SIZE>, parity: Parity) {
bar.update(CTRL, |r| r.with_parity(parity));
}
```
- IRQ:
- Move 'static bounds from where clauses to trait declarations for
IRQ handler traits
- Misc:
- Enable the generic_arg_infer Rust feature
- Extend Bounded with shift operations, single-bit bool
conversion, and const get()
Misc:
- Make deferred_probe_timeout default a Kconfig option
- Drop auxiliary_dev_pm_ops; the PM core falls back to driver PM
callbacks when no bus type PM ops are set
- Add conditional guard support for device_lock()
- Add ksysfs.c to the DRIVER CORE MAINTAINERS entry
- Fix kernel-doc warnings in base.h
- Fix stale reference to memory_block_add_nid() in documentation"
* tag 'driver-core-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: (67 commits)
bus: fsl-mc: use generic driver_override infrastructure
s390/ap: use generic driver_override infrastructure
s390/cio: use generic driver_override infrastructure
vdpa: use generic driver_override infrastructure
platform/wmi: use generic driver_override infrastructure
PCI: use generic driver_override infrastructure
driver core: make software nodes available earlier
software node: remove software_node_exit()
kernel: ksysfs: initialize kernel_kobj earlier
MAINTAINERS: add ksysfs.c to the DRIVER CORE entry
drivers/base/memory: fix stale reference to memory_block_add_nid()
device property: Document how to check for the property presence
soundwire: debugfs: initialize firmware_file to empty string
debugfs: fix placement of EXPORT_SYMBOL_GPL for debugfs_create_str()
debugfs: check for NULL pointer in debugfs_create_str()
driver core: Make deferred_probe_timeout default a Kconfig option
driver core: simplify __device_set_driver_override() clearing logic
driver core: auxiliary bus: Drop auxiliary_dev_pm_ops
device property: Make modifications of fwnode "flags" thread safe
rust: devres: embed struct devres_node directly
...
The macro is a more powerful version of `static_assert!` for use inside
function contexts. This is powered by inline consts, so enable the feature
for old compiler versions that does not have it stably.
While it is possible already to write `const { assert!(...) }`, this
provides a short hand that is more uniform with other assertions. It also
formats nicer with rustfmt where it will not be formatted into multiple
lines.
Two users that would route via the Rust tree are converted.
Reviewed-by: Yury Norov <ynorov@nvidia.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260319121653.2975748-3-gary@kernel.org
[ Rebased. Fixed period typo. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
There is a need to access the inner value of a `Bounded` in const context, notably for bitfields and registers. Remove the invariant check of `Bounded::get`, which allows us to make it const. Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Link: https://patch.msgid.link/20260314-register-v9-4-86805b2f7e9d@nvidia.com Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Single-bit numbers are typically treated as booleans. There is an `Into<bool>` implementation for those, but invoking it from contexts that lack type expectations is not always convenient. Add an `into_bool` method as a simpler shortcut. Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com> Reviewed-by: Yury Norov <yury.norov@gmail.com> Tested-by: Dirk Behme <dirk.behme@de.bosch.com> Acked-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Link: https://patch.msgid.link/20260314-register-v9-3-86805b2f7e9d@nvidia.com Signed-off-by: Danilo Krummrich <dakr@kernel.org>