From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx> This patch includes changes required for Rust kernel modules to utilize module parameters. Imported with minor changes from `rust` branch [1], see original code for attributions. [1] https://github.com/Rust-for-Linux/linux/tree/bc22545f38d74473cfef3e9fd65432733435b79f Cc: adamrk <ark.email@xxxxxxxxx> --- rust/kernel/lib.rs | 3 + rust/kernel/module_param.rs | 501 ++++++++++++++++++++++++++++++++++++ rust/macros/helpers.rs | 46 +++- rust/macros/module.rs | 402 +++++++++++++++++++++++++++-- 4 files changed, 920 insertions(+), 32 deletions(-) create mode 100644 rust/kernel/module_param.rs diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index cd798d12d97c..a0bd0b0e2aef 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -22,6 +22,7 @@ #![feature(pin_macro)] #![feature(receiver_trait)] #![feature(unsize)] +#![feature(const_mut_refs)] // Ensure conditional compilation based on the kernel configuration works; // otherwise we may silently break things like initcall handling. @@ -39,6 +40,8 @@ mod build_assert; pub mod error; pub mod init; pub mod ioctl; +#[doc(hidden)] +pub mod module_param; pub mod pages; pub mod prelude; pub mod print; diff --git a/rust/kernel/module_param.rs b/rust/kernel/module_param.rs new file mode 100644 index 000000000000..539decbdcd48 --- /dev/null +++ b/rust/kernel/module_param.rs @@ -0,0 +1,501 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Types for module parameters. +//! +//! C header: [`include/linux/moduleparam.h`](../../../include/linux/moduleparam.h) + +use crate::error::{code::*, from_result}; +use crate::str::{CStr, Formatter}; +use core::fmt::Write; + +/// Types that can be used for module parameters. +/// +/// Note that displaying the type in `sysfs` will fail if +/// [`alloc::string::ToString::to_string`] (as implemented through the +/// [`core::fmt::Display`] trait) writes more than [`PAGE_SIZE`] +/// bytes (including an additional null terminator). +/// +/// [`PAGE_SIZE`]: `crate::PAGE_SIZE` +pub trait ModuleParam: core::fmt::Display + core::marker::Sized { + /// The `ModuleParam` will be used by the kernel module through this type. + /// + /// This may differ from `Self` if, for example, `Self` needs to track + /// ownership without exposing it or allocate extra space for other possible + /// parameter values. See [`StringParam`] or [`ArrayParam`] for examples. + type Value: ?Sized; + + /// Whether the parameter is allowed to be set without an argument. + /// + /// Setting this to `true` allows the parameter to be passed without an + /// argument (e.g. just `module.param` instead of `module.param=foo`). + const NOARG_ALLOWED: bool; + + /// Convert a parameter argument into the parameter value. + /// + /// `None` should be returned when parsing of the argument fails. + /// `arg == None` indicates that the parameter was passed without an + /// argument. If `NOARG_ALLOWED` is set to `false` then `arg` is guaranteed + /// to always be `Some(_)`. + /// + /// Parameters passed at boot time will be set before [`kmalloc`] is + /// available (even if the module is loaded at a later time). However, in + /// this case, the argument buffer will be valid for the entire lifetime of + /// the kernel. So implementations of this method which need to allocate + /// should first check that the allocator is available (with + /// [`crate::bindings::slab_is_available`]) and when it is not available + /// provide an alternative implementation which doesn't allocate. In cases + /// where the allocator is not available it is safe to save references to + /// `arg` in `Self`, but in other cases a copy should be made. + /// + /// [`kmalloc`]: ../../../include/linux/slab.h + fn try_from_param_arg(arg: Option<&'static [u8]>) -> Option<Self>; + + /// Get the current value of the parameter for use in the kernel module. + /// + /// This function should not be used directly. Instead use the wrapper + /// `read` which will be generated by [`macros::module`]. + fn value(&self) -> &Self::Value; + + /// Set the module parameter from a string. + /// + /// Used to set the parameter value when loading the module or when set + /// through `sysfs`. + /// + /// # Safety + /// + /// If `val` is non-null then it must point to a valid null-terminated + /// string. The `arg` field of `param` must be an instance of `Self`. + unsafe extern "C" fn set_param( + val: *const core::ffi::c_char, + param: *const crate::bindings::kernel_param, + ) -> core::ffi::c_int { + let arg = if val.is_null() { + None + } else { + Some(unsafe { CStr::from_char_ptr(val).as_bytes() }) + }; + match Self::try_from_param_arg(arg) { + Some(new_value) => { + let old_value = unsafe { (*param).__bindgen_anon_1.arg as *mut Self }; + let _ = unsafe { core::ptr::replace(old_value, new_value) }; + 0 + } + None => EINVAL.to_errno(), + } + } + + /// Write a string representation of the current parameter value to `buf`. + /// + /// Used for displaying the current parameter value in `sysfs`. + /// + /// # Safety + /// + /// `buf` must be a buffer of length at least `kernel::PAGE_SIZE` that is + /// writeable. The `arg` field of `param` must be an instance of `Self`. + unsafe extern "C" fn get_param( + buf: *mut core::ffi::c_char, + param: *const crate::bindings::kernel_param, + ) -> core::ffi::c_int { + from_result(|| { + // SAFETY: The C contracts guarantees that the buffer is at least `PAGE_SIZE` bytes. + let mut f = unsafe { Formatter::from_buffer(buf.cast(), crate::PAGE_SIZE as usize) }; + unsafe { write!(f, "{}\0", *((*param).__bindgen_anon_1.arg as *mut Self)) }?; + Ok(f.bytes_written().try_into()?) + }) + } + + /// Drop the parameter. + /// + /// Called when unloading a module. + /// + /// # Safety + /// + /// The `arg` field of `param` must be an instance of `Self`. + unsafe extern "C" fn free(arg: *mut core::ffi::c_void) { + unsafe { core::ptr::drop_in_place(arg as *mut Self) }; + } +} + +/// Trait for parsing integers. +/// +/// Strings beginning with `0x`, `0o`, or `0b` are parsed as hex, octal, or +/// binary respectively. Strings beginning with `0` otherwise are parsed as +/// octal. Anything else is parsed as decimal. A leading `+` or `-` is also +/// permitted. Any string parsed by [`kstrtol()`] or [`kstrtoul()`] will be +/// successfully parsed. +/// +/// [`kstrtol()`]: https://www.kernel.org/doc/html/latest/core-api/kernel-api.html#c.kstrtol +/// [`kstrtoul()`]: https://www.kernel.org/doc/html/latest/core-api/kernel-api.html#c.kstrtoul +trait ParseInt: Sized { + fn from_str_radix(src: &str, radix: u32) -> Result<Self, core::num::ParseIntError>; + fn checked_neg(self) -> Option<Self>; + + fn from_str_unsigned(src: &str) -> Result<Self, core::num::ParseIntError> { + let (radix, digits) = if let Some(n) = src.strip_prefix("0x") { + (16, n) + } else if let Some(n) = src.strip_prefix("0X") { + (16, n) + } else if let Some(n) = src.strip_prefix("0o") { + (8, n) + } else if let Some(n) = src.strip_prefix("0O") { + (8, n) + } else if let Some(n) = src.strip_prefix("0b") { + (2, n) + } else if let Some(n) = src.strip_prefix("0B") { + (2, n) + } else if src.starts_with('0') { + (8, src) + } else { + (10, src) + }; + Self::from_str_radix(digits, radix) + } + + fn from_str(src: &str) -> Option<Self> { + match src.bytes().next() { + None => None, + Some(b'-') => Self::from_str_unsigned(&src[1..]).ok()?.checked_neg(), + Some(b'+') => Some(Self::from_str_unsigned(&src[1..]).ok()?), + Some(_) => Some(Self::from_str_unsigned(src).ok()?), + } + } +} + +macro_rules! impl_parse_int { + ($ty:ident) => { + impl ParseInt for $ty { + fn from_str_radix(src: &str, radix: u32) -> Result<Self, core::num::ParseIntError> { + $ty::from_str_radix(src, radix) + } + + fn checked_neg(self) -> Option<Self> { + self.checked_neg() + } + } + }; +} + +impl_parse_int!(i8); +impl_parse_int!(u8); +impl_parse_int!(i16); +impl_parse_int!(u16); +impl_parse_int!(i32); +impl_parse_int!(u32); +impl_parse_int!(i64); +impl_parse_int!(u64); +impl_parse_int!(isize); +impl_parse_int!(usize); + +macro_rules! impl_module_param { + ($ty:ident) => { + impl ModuleParam for $ty { + type Value = $ty; + + const NOARG_ALLOWED: bool = false; + + fn try_from_param_arg(arg: Option<&'static [u8]>) -> Option<Self> { + let bytes = arg?; + let utf8 = core::str::from_utf8(bytes).ok()?; + <$ty as crate::module_param::ParseInt>::from_str(utf8) + } + + #[inline(always)] + fn value(&self) -> &Self::Value { + self + } + } + }; +} + +#[doc(hidden)] +#[macro_export] +/// Generate a static [`kernel_param_ops`](../../../include/linux/moduleparam.h) struct. +/// +/// # Examples +/// +/// ```ignore +/// make_param_ops!( +/// /// Documentation for new param ops. +/// PARAM_OPS_MYTYPE, // Name for the static. +/// MyType // A type which implements [`ModuleParam`]. +/// ); +/// ``` +macro_rules! make_param_ops { + ($ops:ident, $ty:ty) => { + $crate::make_param_ops!( + #[doc=""] + $ops, + $ty + ); + }; + ($(#[$meta:meta])* $ops:ident, $ty:ty) => { + $(#[$meta])* + /// + /// Static [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// struct generated by [`make_param_ops`]. + pub static $ops: $crate::bindings::kernel_param_ops = $crate::bindings::kernel_param_ops { + flags: if <$ty as $crate::module_param::ModuleParam>::NOARG_ALLOWED { + $crate::bindings::KERNEL_PARAM_OPS_FL_NOARG + } else { + 0 + }, + set: Some(<$ty as $crate::module_param::ModuleParam>::set_param), + get: Some(<$ty as $crate::module_param::ModuleParam>::get_param), + free: Some(<$ty as $crate::module_param::ModuleParam>::free), + }; + }; +} + +impl_module_param!(i8); +impl_module_param!(u8); +impl_module_param!(i16); +impl_module_param!(u16); +impl_module_param!(i32); +impl_module_param!(u32); +impl_module_param!(i64); +impl_module_param!(u64); +impl_module_param!(isize); +impl_module_param!(usize); + +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`i8`]. + PARAM_OPS_I8, + i8 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`u8`]. + PARAM_OPS_U8, + u8 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`i16`]. + PARAM_OPS_I16, + i16 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`u16`]. + PARAM_OPS_U16, + u16 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`i32`]. + PARAM_OPS_I32, + i32 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`u32`]. + PARAM_OPS_U32, + u32 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`i64`]. + PARAM_OPS_I64, + i64 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`u64`]. + PARAM_OPS_U64, + u64 +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`isize`]. + PARAM_OPS_ISIZE, + isize +); +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`usize`]. + PARAM_OPS_USIZE, + usize +); + +impl ModuleParam for bool { + type Value = bool; + + const NOARG_ALLOWED: bool = true; + + fn try_from_param_arg(arg: Option<&'static [u8]>) -> Option<Self> { + match arg { + None => Some(true), + Some(b"y") | Some(b"Y") | Some(b"1") | Some(b"true") => Some(true), + Some(b"n") | Some(b"N") | Some(b"0") | Some(b"false") => Some(false), + _ => None, + } + } + + #[inline(always)] + fn value(&self) -> &Self::Value { + self + } +} + +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`bool`]. + PARAM_OPS_BOOL, + bool +); + +/// An array of at __most__ `N` values. +/// +/// # Invariant +/// +/// The first `self.used` elements of `self.values` are initialized. +pub struct ArrayParam<T, const N: usize> { + values: [core::mem::MaybeUninit<T>; N], + used: usize, +} + +impl<T, const N: usize> ArrayParam<T, { N }> { + fn values(&self) -> &[T] { + // SAFETY: The invariant maintained by `ArrayParam` allows us to cast + // the first `self.used` elements to `T`. + unsafe { + &*(&self.values[0..self.used] as *const [core::mem::MaybeUninit<T>] as *const [T]) + } + } +} + +impl<T: Copy, const N: usize> ArrayParam<T, { N }> { + const fn new() -> Self { + // INVARIANT: The first `self.used` elements of `self.values` are + // initialized. + ArrayParam { + values: [core::mem::MaybeUninit::uninit(); N], + used: 0, + } + } + + const fn push(&mut self, val: T) { + if self.used < N { + // INVARIANT: The first `self.used` elements of `self.values` are + // initialized. + self.values[self.used] = core::mem::MaybeUninit::new(val); + self.used += 1; + } + } + + /// Create an instance of `ArrayParam` initialized with `vals`. + /// + /// This function is only meant to be used in the [`module::module`] macro. + pub const fn create(vals: &[T]) -> Self { + let mut result = ArrayParam::new(); + let mut i = 0; + while i < vals.len() { + result.push(vals[i]); + i += 1; + } + result + } +} + +impl<T: core::fmt::Display, const N: usize> core::fmt::Display for ArrayParam<T, { N }> { + fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { + for val in self.values() { + write!(f, "{},", val)?; + } + Ok(()) + } +} + +impl<T: Copy + core::fmt::Display + ModuleParam, const N: usize> ModuleParam + for ArrayParam<T, { N }> +{ + type Value = [T]; + + const NOARG_ALLOWED: bool = false; + + fn try_from_param_arg(arg: Option<&'static [u8]>) -> Option<Self> { + arg.and_then(|args| { + let mut result = Self::new(); + for arg in args.split(|b| *b == b',') { + result.push(T::try_from_param_arg(Some(arg))?); + } + Some(result) + }) + } + + fn value(&self) -> &Self::Value { + self.values() + } +} + +/// A C-style string parameter. +/// +/// The Rust version of the [`charp`] parameter. This type is meant to be +/// used by the [`macros::module`] macro, not handled directly. Instead use the +/// `read` method generated by that macro. +/// +/// [`charp`]: ../../../include/linux/moduleparam.h +pub enum StringParam { + /// A borrowed parameter value. + /// + /// Either the default value (which is static in the module) or borrowed + /// from the original argument buffer used to set the value. + Ref(&'static [u8]), + + /// A value that was allocated when the parameter was set. + /// + /// The value needs to be freed when the parameter is reset or the module is + /// unloaded. + Owned(alloc::vec::Vec<u8>), +} + +impl StringParam { + fn bytes(&self) -> &[u8] { + match self { + StringParam::Ref(bytes) => *bytes, + StringParam::Owned(vec) => &vec[..], + } + } +} + +impl core::fmt::Display for StringParam { + fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { + let bytes = self.bytes(); + match core::str::from_utf8(bytes) { + Ok(utf8) => write!(f, "{}", utf8), + Err(_) => write!(f, "{:?}", bytes), + } + } +} + +impl ModuleParam for StringParam { + type Value = [u8]; + + const NOARG_ALLOWED: bool = false; + + fn try_from_param_arg(arg: Option<&'static [u8]>) -> Option<Self> { + // SAFETY: It is always safe to call [`slab_is_available`](../../../include/linux/slab.h). + let slab_available = unsafe { crate::bindings::slab_is_available() }; + arg.and_then(|arg| { + if slab_available { + let mut vec = alloc::vec::Vec::new(); + vec.try_extend_from_slice(arg).ok()?; + Some(StringParam::Owned(vec)) + } else { + Some(StringParam::Ref(arg)) + } + }) + } + + fn value(&self) -> &Self::Value { + self.bytes() + } +} + +make_param_ops!( + /// Rust implementation of [`kernel_param_ops`](../../../include/linux/moduleparam.h) + /// for [`StringParam`]. + PARAM_OPS_STR, + StringParam +); diff --git a/rust/macros/helpers.rs b/rust/macros/helpers.rs index b2bdd4d8c958..8b5f9bc414d7 100644 --- a/rust/macros/helpers.rs +++ b/rust/macros/helpers.rs @@ -18,6 +18,16 @@ pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> { } } +pub(crate) fn try_byte_string(it: &mut token_stream::IntoIter) -> Option<String> { + try_literal(it).and_then(|byte_string| { + if byte_string.starts_with("b\"") && byte_string.ends_with('\"') { + Some(byte_string[2..byte_string.len() - 1].to_string()) + } else { + None + } + }) +} + pub(crate) fn try_string(it: &mut token_stream::IntoIter) -> Option<String> { try_literal(it).and_then(|string| { if string.starts_with('\"') && string.ends_with('\"') { @@ -46,14 +56,8 @@ pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char { } } -pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String { - try_string(it).expect("Expected string") -} - -pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String { - let string = try_string(it).expect("Expected string"); - assert!(string.is_ascii(), "Expected ASCII string"); - string +pub(crate) fn expect_literal(it: &mut token_stream::IntoIter) -> String { + try_literal(it).expect("Expected Literal") } pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group { @@ -64,8 +68,34 @@ pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group { } } +pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String { + try_string(it).expect("Expected string") +} + +pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String { + let string = try_string(it).expect("Expected string"); + assert!(string.is_ascii(), "Expected ASCII string"); + string +} + pub(crate) fn expect_end(it: &mut token_stream::IntoIter) { if it.next().is_some() { panic!("Expected end"); } } + +pub(crate) fn get_literal(it: &mut token_stream::IntoIter, expected_name: &str) -> String { + assert_eq!(expect_ident(it), expected_name); + assert_eq!(expect_punct(it), ':'); + let literal = expect_literal(it); + assert_eq!(expect_punct(it), ','); + literal +} + +pub(crate) fn get_string(it: &mut token_stream::IntoIter, expected_name: &str) -> String { + assert_eq!(expect_ident(it), expected_name); + assert_eq!(expect_punct(it), ':'); + let string = expect_string(it); + assert_eq!(expect_punct(it), ','); + string +} diff --git a/rust/macros/module.rs b/rust/macros/module.rs index fb1244f8c2e6..172631e7fb05 100644 --- a/rust/macros/module.rs +++ b/rust/macros/module.rs @@ -1,25 +1,40 @@ // SPDX-License-Identifier: GPL-2.0 -use crate::helpers::*; -use proc_macro::{token_stream, Delimiter, Literal, TokenStream, TokenTree}; +use proc_macro::{token_stream, Delimiter, Group, Literal, TokenStream, TokenTree}; use std::fmt::Write; -fn expect_string_array(it: &mut token_stream::IntoIter) -> Vec<String> { - let group = expect_group(it); - assert_eq!(group.delimiter(), Delimiter::Bracket); - let mut values = Vec::new(); - let mut it = group.stream().into_iter(); - - while let Some(val) = try_string(&mut it) { - assert!(val.is_ascii(), "Expected ASCII string"); - values.push(val); - match it.next() { - Some(TokenTree::Punct(punct)) => assert_eq!(punct.as_char(), ','), - None => break, - _ => panic!("Expected ',' or end of array"), +use crate::helpers::*; + +#[derive(Clone, PartialEq)] +enum ParamType { + Ident(String), + Array { vals: String, max_length: usize }, +} + +fn expect_array_fields(it: &mut token_stream::IntoIter) -> ParamType { + assert_eq!(expect_punct(it), '<'); + let vals = expect_ident(it); + assert_eq!(expect_punct(it), ','); + let max_length_str = expect_literal(it); + let max_length = max_length_str + .parse::<usize>() + .expect("Expected usize length"); + assert_eq!(expect_punct(it), '>'); + ParamType::Array { vals, max_length } +} + +fn expect_type(it: &mut token_stream::IntoIter) -> ParamType { + if let TokenTree::Ident(ident) = it + .next() + .expect("Reached end of token stream for param type") + { + match ident.to_string().as_ref() { + "ArrayParam" => expect_array_fields(it), + _ => ParamType::Ident(ident.to_string()), } + } else { + panic!("Expected Param Type") } - values } struct ModInfoBuilder<'a> { @@ -87,6 +102,113 @@ impl<'a> ModInfoBuilder<'a> { self.emit_only_builtin(field, content); self.emit_only_loadable(field, content); } + + fn emit_param(&mut self, field: &str, param: &str, content: &str) { + let content = format!("{param}:{content}", param = param, content = content); + self.emit(field, &content); + } +} + +fn permissions_are_readonly(perms: &str) -> bool { + let (radix, digits) = if let Some(n) = perms.strip_prefix("0x") { + (16, n) + } else if let Some(n) = perms.strip_prefix("0o") { + (8, n) + } else if let Some(n) = perms.strip_prefix("0b") { + (2, n) + } else { + (10, perms) + }; + match u32::from_str_radix(digits, radix) { + Ok(perms) => perms & 0o222 == 0, + Err(_) => false, + } +} + +fn param_ops_path(param_type: &str) -> &'static str { + match param_type { + "bool" => "kernel::module_param::PARAM_OPS_BOOL", + "i8" => "kernel::module_param::PARAM_OPS_I8", + "u8" => "kernel::module_param::PARAM_OPS_U8", + "i16" => "kernel::module_param::PARAM_OPS_I16", + "u16" => "kernel::module_param::PARAM_OPS_U16", + "i32" => "kernel::module_param::PARAM_OPS_I32", + "u32" => "kernel::module_param::PARAM_OPS_U32", + "i64" => "kernel::module_param::PARAM_OPS_I64", + "u64" => "kernel::module_param::PARAM_OPS_U64", + "isize" => "kernel::module_param::PARAM_OPS_ISIZE", + "usize" => "kernel::module_param::PARAM_OPS_USIZE", + "str" => "kernel::module_param::PARAM_OPS_STR", + t => panic!("Unrecognized type {}", t), + } +} + +#[allow(clippy::type_complexity)] +fn try_simple_param_val( + param_type: &str, +) -> Box<dyn Fn(&mut token_stream::IntoIter) -> Option<String>> { + match param_type { + "bool" => Box::new(try_ident), + "str" => Box::new(|param_it| { + try_byte_string(param_it) + .map(|s| format!("kernel::module_param::StringParam::Ref(b\"{}\")", s)) + }), + _ => Box::new(try_literal), + } +} + +fn get_default(param_type: &ParamType, param_it: &mut token_stream::IntoIter) -> String { + let try_param_val = match param_type { + ParamType::Ident(ref param_type) + | ParamType::Array { + vals: ref param_type, + max_length: _, + } => try_simple_param_val(param_type), + }; + assert_eq!(expect_ident(param_it), "default"); + assert_eq!(expect_punct(param_it), ':'); + let default = match param_type { + ParamType::Ident(_) => try_param_val(param_it).expect("Expected default param value"), + ParamType::Array { + vals: _, + max_length: _, + } => { + let group = expect_group(param_it); + assert_eq!(group.delimiter(), Delimiter::Bracket); + let mut default_vals = Vec::new(); + let mut it = group.stream().into_iter(); + + while let Some(default_val) = try_param_val(&mut it) { + default_vals.push(default_val); + match it.next() { + Some(TokenTree::Punct(punct)) => assert_eq!(punct.as_char(), ','), + None => break, + _ => panic!("Expected ',' or end of array default values"), + } + } + + let mut default_array = "kernel::module_param::ArrayParam::create(&[".to_string(); + default_array.push_str( + &default_vals + .iter() + .map(|val| val.to_string()) + .collect::<Vec<String>>() + .join(","), + ); + default_array.push_str("])"); + default_array + } + }; + assert_eq!(expect_punct(param_it), ','); + default +} + +fn generated_array_ops_name(vals: &str, max_length: usize) -> String { + format!( + "__generated_array_ops_{vals}_{max_length}", + vals = vals, + max_length = max_length + ) } #[derive(Debug, Default)] @@ -96,15 +218,24 @@ struct ModuleInfo { name: String, author: Option<String>, description: Option<String>, - alias: Option<Vec<String>>, + alias: Option<String>, + params: Option<Group>, } impl ModuleInfo { fn parse(it: &mut token_stream::IntoIter) -> Self { let mut info = ModuleInfo::default(); - const EXPECTED_KEYS: &[&str] = - &["type", "name", "author", "description", "license", "alias"]; + const EXPECTED_KEYS: &[&str] = &[ + "type", + "name", + "author", + "description", + "license", + "alias", + "alias_rtnl_link", + "params", + ]; const REQUIRED_KEYS: &[&str] = &["type", "name", "license"]; let mut seen_keys = Vec::new(); @@ -130,7 +261,11 @@ impl ModuleInfo { "author" => info.author = Some(expect_string(it)), "description" => info.description = Some(expect_string(it)), "license" => info.license = expect_string_ascii(it), - "alias" => info.alias = Some(expect_string_array(it)), + "alias" => info.alias = Some(expect_string_ascii(it)), + "alias_rtnl_link" => { + info.alias = Some(format!("rtnl-link-{}", expect_string_ascii(it))) + } + "params" => info.params = Some(expect_group(it)), _ => panic!( "Unknown key \"{}\". Valid keys are: {:?}.", key, EXPECTED_KEYS @@ -181,10 +316,8 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { modinfo.emit("description", &description); } modinfo.emit("license", &info.license); - if let Some(aliases) = info.alias { - for alias in aliases { - modinfo.emit("alias", &alias); - } + if let Some(alias) = info.alias { + modinfo.emit("alias", &alias); } // Built-in modules also export the `file` modinfo string. @@ -192,6 +325,195 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { std::env::var("RUST_MODFILE").expect("Unable to fetch RUST_MODFILE environmental variable"); modinfo.emit_only_builtin("file", &file); + let mut array_types_to_generate = Vec::new(); + if let Some(params) = info.params { + assert_eq!(params.delimiter(), Delimiter::Brace); + + let mut it = params.stream().into_iter(); + + loop { + let param_name = match it.next() { + Some(TokenTree::Ident(ident)) => ident.to_string(), + Some(_) => panic!("Expected Ident or end"), + None => break, + }; + + assert_eq!(expect_punct(&mut it), ':'); + let param_type = expect_type(&mut it); + let group = expect_group(&mut it); + assert_eq!(expect_punct(&mut it), ','); + + assert_eq!(group.delimiter(), Delimiter::Brace); + + let mut param_it = group.stream().into_iter(); + let param_default = get_default(¶m_type, &mut param_it); + let param_permissions = get_literal(&mut param_it, "permissions"); + let param_description = get_string(&mut param_it, "description"); + expect_end(&mut param_it); + + // TODO: More primitive types. + // TODO: Other kinds: unsafes, etc. + let (param_kernel_type, ops): (String, _) = match param_type { + ParamType::Ident(ref param_type) => ( + param_type.to_string(), + param_ops_path(param_type).to_string(), + ), + ParamType::Array { + ref vals, + max_length, + } => { + array_types_to_generate.push((vals.clone(), max_length)); + ( + format!("__rust_array_param_{}_{}", vals, max_length), + generated_array_ops_name(vals, max_length), + ) + } + }; + + modinfo.emit_param("parmtype", ¶m_name, ¶m_kernel_type); + modinfo.emit_param("parm", ¶m_name, ¶m_description); + let param_type_internal = match param_type { + ParamType::Ident(ref param_type) => match param_type.as_ref() { + "str" => "kernel::module_param::StringParam".to_string(), + other => other.to_string(), + }, + ParamType::Array { + ref vals, + max_length, + } => format!( + "kernel::module_param::ArrayParam<{vals}, {max_length}>", + vals = vals, + max_length = max_length + ), + }; + let read_func = if permissions_are_readonly(¶m_permissions) { + format!( + " + fn read(&self) + -> &<{param_type_internal} as kernel::module_param::ModuleParam>::Value {{ + // SAFETY: Parameters do not need to be locked because they are + // read only or sysfs is not enabled. + unsafe {{ + <{param_type_internal} as kernel::module_param::ModuleParam>::value( + &__{name}_{param_name}_value + ) + }} + }} + ", + name = info.name, + param_name = param_name, + param_type_internal = param_type_internal, + ) + } else { + format!( + " + fn read<'lck>(&self, lock: &'lck kernel::KParamGuard) + -> &'lck <{param_type_internal} as kernel::module_param::ModuleParam>::Value {{ + // SAFETY: Parameters are locked by `KParamGuard`. + unsafe {{ + <{param_type_internal} as kernel::module_param::ModuleParam>::value( + &__{name}_{param_name}_value + ) + }} + }} + ", + name = info.name, + param_name = param_name, + param_type_internal = param_type_internal, + ) + }; + let kparam = format!( + " + kernel::bindings::kernel_param__bindgen_ty_1 {{ + arg: unsafe {{ &__{name}_{param_name}_value }} + as *const _ as *mut core::ffi::c_void, + }}, + ", + name = info.name, + param_name = param_name, + ); + write!( + modinfo.buffer, + " + static mut __{name}_{param_name}_value: {param_type_internal} = {param_default}; + + struct __{name}_{param_name}; + + impl __{name}_{param_name} {{ {read_func} }} + + const {param_name}: __{name}_{param_name} = __{name}_{param_name}; + + // Note: the C macro that generates the static structs for the `__param` section + // asks for them to be `aligned(sizeof(void *))`. However, that was put in place + // in 2003 in commit 38d5b085d2a0 (\"[PATCH] Fix over-alignment problem on x86-64\") + // to undo GCC over-alignment of static structs of >32 bytes. It seems that is + // not the case anymore, so we simplify to a transparent representation here + // in the expectation that it is not needed anymore. + // TODO: Revisit this to confirm the above comment and remove it if it happened. + #[repr(transparent)] + struct __{name}_{param_name}_RacyKernelParam(kernel::bindings::kernel_param); + + unsafe impl Sync for __{name}_{param_name}_RacyKernelParam {{ + }} + + #[cfg(not(MODULE))] + const __{name}_{param_name}_name: *const core::ffi::c_char = + b\"{name}.{param_name}\\0\" as *const _ as *const core::ffi::c_char; + + #[cfg(MODULE)] + const __{name}_{param_name}_name: *const core::ffi::c_char = + b\"{param_name}\\0\" as *const _ as *const core::ffi::c_char; + + #[link_section = \"__param\"] + #[used] + static __{name}_{param_name}_struct: __{name}_{param_name}_RacyKernelParam = + __{name}_{param_name}_RacyKernelParam(kernel::bindings::kernel_param {{ + name: __{name}_{param_name}_name, + // SAFETY: `__this_module` is constructed by the kernel at load time + // and will not be freed until the module is unloaded. + #[cfg(MODULE)] + mod_: unsafe {{ &kernel::bindings::__this_module as *const _ as *mut _ }}, + #[cfg(not(MODULE))] + mod_: core::ptr::null_mut(), + ops: unsafe {{ &{ops} }} as *const kernel::bindings::kernel_param_ops, + perm: {permissions}, + level: -1, + flags: 0, + __bindgen_anon_1: {kparam} + }}); + ", + name = info.name, + param_type_internal = param_type_internal, + read_func = read_func, + param_default = param_default, + param_name = param_name, + ops = ops, + permissions = param_permissions, + kparam = kparam, + ) + .unwrap(); + } + } + + let mut generated_array_types = String::new(); + + for (vals, max_length) in array_types_to_generate { + let ops_name = generated_array_ops_name(&vals, max_length); + write!( + generated_array_types, + " + kernel::make_param_ops!( + {ops_name}, + kernel::module_param::ArrayParam<{vals}, {{ {max_length} }}> + ); + ", + ops_name = ops_name, + vals = vals, + max_length = max_length, + ) + .unwrap(); + } + format!( " /// The module name. @@ -291,12 +613,44 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { }} {modinfo} + + {generated_array_types} ", type_ = info.type_, name = info.name, modinfo = modinfo.buffer, + generated_array_types = generated_array_types, initcall_section = ".initcall6.init" ) .parse() .expect("Error parsing formatted string into token stream.") } + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_permissions_are_readonly() { + assert!(permissions_are_readonly("0b000000000")); + assert!(permissions_are_readonly("0o000")); + assert!(permissions_are_readonly("000")); + assert!(permissions_are_readonly("0x000")); + + assert!(!permissions_are_readonly("0b111111111")); + assert!(!permissions_are_readonly("0o777")); + assert!(!permissions_are_readonly("511")); + assert!(!permissions_are_readonly("0x1ff")); + + assert!(permissions_are_readonly("0o014")); + assert!(permissions_are_readonly("0o015")); + + assert!(!permissions_are_readonly("0o214")); + assert!(!permissions_are_readonly("0o024")); + assert!(!permissions_are_readonly("0o012")); + + assert!(!permissions_are_readonly("0o315")); + assert!(!permissions_are_readonly("0o065")); + assert!(!permissions_are_readonly("0o017")); + } +} -- 2.40.0
