From 22098763a10d9c1340827fcf6edab66f153b27f0 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 13 Sep 2026 12:27:00 -0700 Subject: Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Don't destroy user event fields when removal fails User event fields are destroyed before the event is removed from visibility. But that can fail leaving the still visible event with no fields. Move the destroying of the fields to after the event is successfully removed from visibility. - Initialize function graph state is fork before calling copy_exec_state() For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state. If that allocation fails, ftrace_graph_exit_task() will free the tasks ret_stack pointer. Since that pointer is still using the parent's ret_stack, it mistakenly frees the parent's pointer too. Call ftrace_graph_init() on the task first which will NULL out the new tasks's ret_stack and if the copy fails, it will not free anything. - Remove FGRAPH_MAX_INDEX The macro FGRAPH_MAX_INDEX was added but never used. Remove it. - Save ent_size in function graph printing of nested functions The function graph tracer needs to look at the next event to see if the next event is the return of the current function entry. If it is, it prints a single line: ktime_get(); Otherwise it prints it like a nested function: tick_nohz_irq_exit() { ktime_get(); kcpustat_irq_exit(); } In order to look at the next event, it must save the current event so that it has the information to print from it. It saves the event in the iterator descriptor called "ent". What it doesn't save is the ent_size of the event which is now used to know if the function graph arguments are to be printed. The peek doesn't save the size so the size used happens to be that of the size of the last event that was seen. Save the entry event size in the iterator descriptor so that the correct size is used. - Fix several errors with freeing data in the histogram code The histogram code had a lot of leaked or or incorrect accounting when failures happen. Correct them. - Fix histogram regression of .percent and .graph modifiers Up until 6.3 histogram values could have "percent" or "graph" modifiers that changed how they were printed. But a change that added restricting histograms values from being strings, stack traces and other modifiers inadvertently prevented them from using the percent and graph modifiers, which were legal use cases for values. Put back the percent and graph modifiers. - Fix various typos in the comments - Set the trace_clock before initializing a histogram with clock argument The histogram API allows the user to specific which trace clock to use via a "clock=" string. The histogram is set up first before the clock is checked. If the passed in clock is not valid, it exits without fully fixing up the histogram leaving it on the list and a use-after-free can trigger. Update the clock argument first and if it fails then exit gracefully before the histogram trigger is placed on any lists. - Restore :mod: trailer after parsing in ftrace_set_clr_event The function ftrace_set_clr_event() modifies the parse string and needs to put it back to what was passed in. It searches for ":mod:" via a strsep() but fails to put back the first ':' in the string. Add back the ':' in the passed in string. - Take trace_array reference when opening a tracer options file The options files are dynamically created and some tracers add their own options. When a tracer adds their own list of options, the trace_array holding them has an array to hold the list of options for each tracer. This array increases in size via a krealloc(), and the new entry gets a newly allocated array to hold the options of the new tracer being added. The element in each entry of the tracer's option array holds a pointer back to the trace_array, a pointer to the tracer it is associated to, a pointer to the flags of the option. The issue is that these arrays are freed when the trace_array is freed when its instance it represents is removed from the instances directory. There's a race that an open of one of these options files can happen when the instance is being removed. Add a new helper function to be called by the open function of the options file to iterate all existing trace_arrays under a lock and find the one that has the given option element in one of it's tracer arrays. If found, then update the associated trace_array's reference counter to keep it from being freed. If not found, have the open call return -ENODEV. - Disable interrupts when acquiring the lock in rb_wake_up_waiters() The function rb_wake_up_waiters() assumes it will be called in interrupt context and does not disable irqs when taking cpu_buffer->reader_lock, which can be called in hard interrupt context. The issue is in PREEMPT_RT, this function is called in thread context leaving this lock open to a deadlock. Take the lock with interrupts disabled. - Use rcu_assign_pointer() for tmp_ops filter hash The tmp_ops used in update_ftrace_direct_mod() assigns its filter_hash field directly, but that field is annotated as __rcu and sparse complains. Assign it with rcu_assign_pointer() - Fix use-after-free in enable_trigger_private_data_free() The trace_event_call is accessed through the event_trigger_data's trace_event_file pointer to put the trace_event_call on freeing. The issue is that the trace_event_file data may have been freed already causing a use-after-free. Add a field to the event_trigger_data that points directly to the trace_event_call so that it can decrement its reference directly without needing to go through the trace_event_file. - Fix accounting of buffer data remote headers trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount the number of pages is needed for the asked for size as it doesn't take into account the meta data on each page. Add a helper function to do the calculation properly and use that in these functions. - Catch nr_page_va overflow in ring_buffer_desc sizing The number of pages per remote ring buffer is capped by ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to overflow that field would silently allocate a descriptor smaller than what was asked for. - Do not resize the subbuf order if any per_cpu buffer is disabled The mmapping of ring buffers disables resizing the subbuffers, but it is done per-cpu whereas the subbuf size change is done for all the per_cpu buffers under the buffer->mutex. It could change the size of some while the mapping is happening on others. Have the resize of the subbuf order check all the per_cpu buffers under the lock to see if any of them is disabled before starting and causing an inconsistency between buffers that are being mapped. * tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits) ring-buffer: Check resize_disabled before publishing the new subbuf order tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing tracing/remotes: Account for ring buffer page header in size calculation tracing: Don't dereference trace_event_file in deferred trigger free ftrace: Use rcu_assign_pointer() for tmp_ops filter hash ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters() tracing: Take trace_array reference when opening a tracer options file tracing: Fix ring_buffer_read_page_size() kernel-doc tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event() tracing: Fix memory corruption from a "STACKTRACE" histogram key tracing: Fix memory corruption from the histogram stacktrace modifier tracing: Undo the registration when enabling the histogram trigger fails tracing: Take the reference before publishing the named histogram trigger tracing: Set the trace clock before registering the histogram trigger tracing: Fix typo "preceeded" in comment tracing: Fix typo "availabe" in comment tracing: Let histogram values keep the percent and graph modifiers tracing: Keep the entry count when the histogram stats allocation fails tracing: Free histogram the field rejected for a bad modifier tracing: Free histogram the var ref when its initialization fails ... --- rust/pin-init/internal/src/diagnostics.rs | 44 +++ rust/pin-init/internal/src/init.rs | 482 +++++++++++++++++++++++++++ rust/pin-init/internal/src/lib.rs | 59 ++++ rust/pin-init/internal/src/pin_data.rs | 537 ++++++++++++++++++++++++++++++ rust/pin-init/internal/src/pinned_drop.rs | 61 ++++ rust/pin-init/internal/src/zeroable.rs | 78 +++++ 6 files changed, 1261 insertions(+) create mode 100644 rust/pin-init/internal/src/diagnostics.rs create mode 100644 rust/pin-init/internal/src/init.rs create mode 100644 rust/pin-init/internal/src/lib.rs create mode 100644 rust/pin-init/internal/src/pin_data.rs create mode 100644 rust/pin-init/internal/src/pinned_drop.rs create mode 100644 rust/pin-init/internal/src/zeroable.rs (limited to 'rust/pin-init/internal/src') diff --git a/rust/pin-init/internal/src/diagnostics.rs b/rust/pin-init/internal/src/diagnostics.rs new file mode 100644 index 000000000..c7d9b3e62 --- /dev/null +++ b/rust/pin-init/internal/src/diagnostics.rs @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use std::fmt::Display; + +use proc_macro2::TokenStream; +use quote::quote_spanned; +use syn::{spanned::Spanned, Error}; + +pub(crate) struct DiagCtxt(TokenStream); +pub(crate) struct ErrorGuaranteed(()); + +impl DiagCtxt { + pub(crate) fn error(&mut self, span: impl Spanned, msg: impl Display) -> ErrorGuaranteed { + let error = Error::new(span.span(), msg); + self.0.extend(error.into_compile_error()); + ErrorGuaranteed(()) + } + + pub(crate) fn warn(&mut self, span: impl Spanned, msg: impl Display) { + // Have the message start on a new line for visual clarity. + let msg = format!("\n{}", msg); + self.0.extend(quote_spanned!(span.span() => + // Approximate using deprecated warning while `proc_macro_diagnostic` is unstable. + const _: () = { + #[deprecated = #msg] + const fn warn() {} + warn(); + }; + )); + } + + pub(crate) fn with( + fun: impl FnOnce(&mut DiagCtxt) -> Result, + ) -> TokenStream { + let mut dcx = Self(TokenStream::new()); + match fun(&mut dcx) { + Ok(mut stream) => { + stream.extend(dcx.0); + stream + } + Err(ErrorGuaranteed(())) => dcx.0, + } + } +} diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs new file mode 100644 index 000000000..fd0b5ea4a --- /dev/null +++ b/rust/pin-init/internal/src/init.rs @@ -0,0 +1,482 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro2::{Span, TokenStream}; +use quote::{format_ident, quote}; +use syn::{ + braced, + parse::{End, Parse}, + parse_quote, + punctuated::Punctuated, + spanned::Spanned, + token, Attribute, Block, Expr, ExprCall, ExprPath, Ident, Path, Token, Type, +}; + +use crate::diagnostics::{DiagCtxt, ErrorGuaranteed}; + +pub(crate) struct Initializer { + attrs: Vec, + this: Option, + path: Path, + brace_token: token::Brace, + fields: Punctuated, + rest: Option<(Token![..], Expr)>, + error: Option<(Token![?], Type)>, +} + +struct This { + _and_token: Token![&], + ident: Ident, + _in_token: Token![in], +} + +struct InitializerField { + attrs: Vec, + kind: InitializerKind, +} + +enum InitializerKind { + Value { + ident: Ident, + value: Option<(Token![:], Expr)>, + }, + Init { + ident: Ident, + _left_arrow_token: Token![<-], + value: Expr, + }, + Code { + _underscore_token: Token![_], + _colon_token: Token![:], + block: Block, + }, +} + +impl InitializerKind { + fn ident(&self) -> Option<&Ident> { + match self { + Self::Value { ident, .. } | Self::Init { ident, .. } => Some(ident), + Self::Code { .. } => None, + } + } +} + +enum InitializerAttribute { + DefaultError(DefaultErrorAttribute), +} + +struct DefaultErrorAttribute { + ty: Box, +} + +pub(crate) fn expand( + Initializer { + attrs, + this, + path, + brace_token, + fields, + rest, + error, + }: Initializer, + default_error: Option<&'static str>, + pinned: bool, + dcx: &mut DiagCtxt, +) -> Result { + let error = error.map_or_else( + || { + if let Some(default_error) = attrs.iter().fold(None, |acc, attr| { + #[expect(irrefutable_let_patterns)] + if let InitializerAttribute::DefaultError(DefaultErrorAttribute { ty }) = attr { + Some(ty.clone()) + } else { + acc + } + }) { + default_error + } else if let Some(default_error) = default_error { + syn::parse_str(default_error).unwrap() + } else { + dcx.error(brace_token.span.close(), "expected `? ` after `}`"); + parse_quote!(::core::convert::Infallible) + } + }, + |(_, err)| Box::new(err), + ); + let slot = format_ident!("slot"); + let (has_data_trait, get_data, init_from_closure) = if pinned { + ( + format_ident!("HasPinData"), + format_ident!("__pin_data"), + format_ident!("pin_init_from_closure"), + ) + } else { + ( + format_ident!("HasInitData"), + format_ident!("__init_data"), + format_ident!("init_from_closure"), + ) + }; + let init_kind = get_init_kind(rest, dcx); + let zeroable_check = match init_kind { + InitKind::Normal => quote!(), + InitKind::Zeroing => quote! { + // The user specified `..Zeroable::zeroed()` at the end of the list of fields. + // Therefore we check if the struct implements `Zeroable` and then zero the memory. + // This allows us to also remove the check that all fields are present (since we + // already set the memory to zero and that is a valid bit pattern). + fn assert_zeroable(_: *mut T) + where T: ::pin_init::Zeroable + {} + // Ensure that the struct is indeed `Zeroable`. + assert_zeroable(#slot); + // SAFETY: The type implements `Zeroable` by the check above. + unsafe { ::core::ptr::write_bytes(#slot, 0, 1) }; + }, + }; + let this = match this { + None => quote!(), + Some(This { ident, .. }) => quote! { + // Create the `this` so it can be referenced by the user inside of the + // expressions creating the individual fields. + let #ident = unsafe { ::core::ptr::NonNull::new_unchecked(slot) }; + }, + }; + // `mixed_site` ensures that the data is not accessible to the user-controlled code. + let data = Ident::new("__data", Span::mixed_site()); + let init_fields = init_fields(&fields, pinned, &data, &slot); + let field_check = make_field_check(&fields, init_kind, &path); + Ok(quote! {{ + // Get the data about fields from the supplied type. + // SAFETY: TODO + let #data = unsafe { + use ::pin_init::__internal::#has_data_trait; + // Can't use `<#path as #has_data_trait>::#get_data`, since the user is able to omit + // generics (which need to be present with that syntax). + #path::#get_data() + }; + // Ensure that `#data` really is of type `#data` and help with type inference: + let init = #data.__make_closure::<_, #error>( + move |slot| { + #zeroable_check + #this + #init_fields + #field_check + // SAFETY: we are the `init!` macro that is allowed to call this. + Ok(unsafe { ::pin_init::__internal::InitOk::new() }) + } + ); + let init = move |slot| -> ::core::result::Result<(), #error> { + init(slot).map(|__InitOk| ()) + }; + // SAFETY: TODO + unsafe { ::pin_init::#init_from_closure::<_, #error>(init) } + }}) +} + +enum InitKind { + Normal, + Zeroing, +} + +fn get_init_kind(rest: Option<(Token![..], Expr)>, dcx: &mut DiagCtxt) -> InitKind { + let Some((dotdot, expr)) = rest else { + return InitKind::Normal; + }; + match &expr { + Expr::Call(ExprCall { func, args, .. }) if args.is_empty() => match &**func { + Expr::Path(ExprPath { + attrs, + qself: None, + path: + Path { + leading_colon: None, + segments, + }, + }) if attrs.is_empty() + && segments.len() == 2 + && segments[0].ident == "Zeroable" + && segments[0].arguments.is_none() + && segments[1].ident == "init_zeroed" + && segments[1].arguments.is_none() => + { + return InitKind::Zeroing; + } + _ => {} + }, + _ => {} + } + dcx.error( + dotdot.span().join(expr.span()).unwrap_or(expr.span()), + "expected nothing or `..Zeroable::init_zeroed()`.", + ); + InitKind::Normal +} + +/// Generate the code that initializes the fields of the struct using the initializers in `field`. +fn init_fields( + fields: &Punctuated, + pinned: bool, + data: &Ident, + slot: &Ident, +) -> TokenStream { + let mut guards = vec![]; + let mut guard_attrs = vec![]; + let mut res = TokenStream::new(); + for InitializerField { attrs, kind } in fields { + let cfgs = { + let mut cfgs = attrs.clone(); + cfgs.retain(|attr| attr.path().is_ident("cfg")); + cfgs + }; + + let ident = match kind { + InitializerKind::Value { ident, .. } => ident, + InitializerKind::Init { ident, .. } => ident, + InitializerKind::Code { block, .. } => { + let stmt = &block.stmts; + res.extend(quote! { + #(#attrs)* + { + #(#stmt)* + } + }); + continue; + } + }; + + let slot = if pinned { + quote! { + // SAFETY: + // - `slot` is valid and properly aligned. + // - `make_field_check` checks that `&raw mut (*slot).#ident` is properly aligned. + // - `make_field_check` prevents `#ident` from being used twice, therefore + // `(*slot).#ident` is exclusively accessed and has not been initialized. + (unsafe { #data.#ident(#slot) }) + } + } else { + quote! { + // For `init!()` macro, everything is unpinned. + // SAFETY: + // - `&raw mut (*slot).#ident` is valid. + // - `make_field_check` checks that `&raw mut (*slot).#ident` is properly aligned. + // - `make_field_check` prevents `#ident` from being used twice, therefore + // `(*slot).#ident` is exclusively accessed and has not been initialized. + (unsafe { + ::pin_init::__internal::Slot::<::pin_init::__internal::Unpinned, _>::new( + &raw mut (*#slot).#ident + ) + }) + } + }; + + // `mixed_site` ensures that the guard is not accessible to the user-controlled code. + let guard = format_ident!("__{ident}_guard", span = Span::mixed_site()); + + let init = match kind { + InitializerKind::Value { ident, value } => { + let value = value + .as_ref() + .map(|(_, value)| quote!(#value)) + .unwrap_or_else(|| quote!(#ident)); + + quote! { + #(#attrs)* + let mut #guard = #slot.write(#value); + + } + } + InitializerKind::Init { value, .. } => { + quote! { + #(#attrs)* + let mut #guard = #slot.init(#value)?; + } + } + InitializerKind::Code { .. } => unreachable!(), + }; + + res.extend(quote! { + #init + + #(#cfgs)* + // Allow `non_snake_case` since the same warning is going to be reported for the struct + // field. + #[allow(unused_variables, non_snake_case)] + let #ident = #guard.let_binding(); + }); + + guards.push(guard); + guard_attrs.push(cfgs); + } + quote! { + #res + // If execution reaches this point, all fields have been initialized. Therefore we can now + // dismiss the guards by forgetting them. + #( + #(#guard_attrs)* + ::core::mem::forget(#guards); + )* + } +} + +/// Generate the check for ensuring that every field has been initialized and aligned. +fn make_field_check( + fields: &Punctuated, + init_kind: InitKind, + path: &Path, +) -> TokenStream { + let field_attrs: Vec<_> = fields + .iter() + .filter_map(|f| f.kind.ident().map(|_| &f.attrs)) + .collect(); + let field_name: Vec<_> = fields.iter().filter_map(|f| f.kind.ident()).collect(); + let zeroing_trailer = match init_kind { + InitKind::Normal => None, + InitKind::Zeroing => Some(quote! { + ..::core::mem::zeroed() + }), + }; + quote! { + #[allow(unreachable_code)] + // We use unreachable code to perform field checks. They're still checked by the compiler. + // SAFETY: this code is never executed. + let _ = || unsafe { + // Create references to ensure that the initialized field is properly aligned. + // Unaligned fields will cause the compiler to emit E0793. We do not support + // unaligned fields since `Init::__init` requires an aligned pointer; the call to + // `ptr::write` for value-initialization case has the same requirement. + #( + #(#field_attrs)* + let _ = &(*slot).#field_name; + )* + + // If the zeroing trailer is not present, this checks that all fields have been + // mentioned exactly once. If the zeroing trailer is present, all missing fields will be + // zeroed, so this checks that all fields have been mentioned at most once. The use of + // struct initializer will still generate very natural error messages for any misuse. + ::core::ptr::write(slot, #path { + #( + #(#field_attrs)* + #field_name: loop {}, + )* + #zeroing_trailer + }) + }; + } +} + +impl Parse for Initializer { + fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result { + let attrs = input.call(Attribute::parse_outer)?; + let this = input.peek(Token![&]).then(|| input.parse()).transpose()?; + let path = input.parse()?; + let content; + let brace_token = braced!(content in input); + let mut fields = Punctuated::new(); + loop { + let lh = content.lookahead1(); + if lh.peek(End) || lh.peek(Token![..]) { + break; + } else if lh.peek(Ident) || lh.peek(Token![_]) || lh.peek(Token![#]) { + fields.push_value(content.parse()?); + let lh = content.lookahead1(); + if lh.peek(End) { + break; + } else if lh.peek(Token![,]) { + fields.push_punct(content.parse()?); + } else { + return Err(lh.error()); + } + } else { + return Err(lh.error()); + } + } + let rest = content + .peek(Token![..]) + .then(|| Ok::<_, syn::Error>((content.parse()?, content.parse()?))) + .transpose()?; + let error = input + .peek(Token![?]) + .then(|| Ok::<_, syn::Error>((input.parse()?, input.parse()?))) + .transpose()?; + let attrs = attrs + .into_iter() + .map(|a| { + if a.path().is_ident("default_error") { + a.parse_args::() + .map(InitializerAttribute::DefaultError) + } else { + Err(syn::Error::new_spanned(a, "unknown initializer attribute")) + } + }) + .collect::, _>>()?; + Ok(Self { + attrs, + this, + path, + brace_token, + fields, + rest, + error, + }) + } +} + +impl Parse for DefaultErrorAttribute { + fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result { + Ok(Self { ty: input.parse()? }) + } +} + +impl Parse for This { + fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result { + Ok(Self { + _and_token: input.parse()?, + ident: input.parse()?, + _in_token: input.parse()?, + }) + } +} + +impl Parse for InitializerField { + fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result { + let attrs = input.call(Attribute::parse_outer)?; + Ok(Self { + attrs, + kind: input.parse()?, + }) + } +} + +impl Parse for InitializerKind { + fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result { + let lh = input.lookahead1(); + if lh.peek(Token![_]) { + Ok(Self::Code { + _underscore_token: input.parse()?, + _colon_token: input.parse()?, + block: input.parse()?, + }) + } else if lh.peek(Ident) { + let ident = input.parse()?; + let lh = input.lookahead1(); + if lh.peek(Token![<-]) { + Ok(Self::Init { + ident, + _left_arrow_token: input.parse()?, + value: input.parse()?, + }) + } else if lh.peek(Token![:]) { + Ok(Self::Value { + ident, + value: Some((input.parse()?, input.parse()?)), + }) + } else if lh.peek(Token![,]) || lh.peek(End) { + Ok(Self::Value { ident, value: None }) + } else { + Err(lh.error()) + } + } else { + Err(lh.error()) + } + } +} diff --git a/rust/pin-init/internal/src/lib.rs b/rust/pin-init/internal/src/lib.rs new file mode 100644 index 000000000..60d5093f3 --- /dev/null +++ b/rust/pin-init/internal/src/lib.rs @@ -0,0 +1,59 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +// When fixdep scans this, it will find this string `CONFIG_RUSTC_VERSION_TEXT` +// and thus add a dependency on `include/config/RUSTC_VERSION_TEXT`, which is +// touched by Kconfig when the version string from the compiler changes. + +//! `pin-init` proc macros. + +// Documentation is done in the pin-init crate instead. +#![allow(missing_docs)] + +use proc_macro::TokenStream; +use syn::parse_macro_input; + +use crate::diagnostics::DiagCtxt; + +mod diagnostics; +mod init; +mod pin_data; +mod pinned_drop; +mod zeroable; + +#[proc_macro_attribute] +pub fn pin_data(args: TokenStream, input: TokenStream) -> TokenStream { + let args = parse_macro_input!(args); + let input = parse_macro_input!(input); + DiagCtxt::with(|dcx| pin_data::pin_data(args, input, dcx)).into() +} + +#[proc_macro_attribute] +pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { + let args = parse_macro_input!(args); + let input = parse_macro_input!(input); + DiagCtxt::with(|dcx| pinned_drop::pinned_drop(args, input, dcx)).into() +} + +#[proc_macro_derive(Zeroable)] +pub fn derive_zeroable(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input); + DiagCtxt::with(|dcx| zeroable::derive(input, dcx)).into() +} + +#[proc_macro_derive(MaybeZeroable)] +pub fn maybe_derive_zeroable(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input); + DiagCtxt::with(|dcx| zeroable::maybe_derive(input, dcx)).into() +} +#[proc_macro] +pub fn init(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input); + DiagCtxt::with(|dcx| init::expand(input, Some("::core::convert::Infallible"), false, dcx)) + .into() +} + +#[proc_macro] +pub fn pin_init(input: TokenStream) -> TokenStream { + let input = parse_macro_input!(input); + DiagCtxt::with(|dcx| init::expand(input, Some("::core::convert::Infallible"), true, dcx)).into() +} diff --git a/rust/pin-init/internal/src/pin_data.rs b/rust/pin-init/internal/src/pin_data.rs new file mode 100644 index 000000000..ff194d275 --- /dev/null +++ b/rust/pin-init/internal/src/pin_data.rs @@ -0,0 +1,537 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro2::TokenStream; +use quote::{format_ident, quote, ToTokens}; +use syn::{ + parse::{End, Nothing, Parse}, + parse_quote, parse_quote_spanned, + spanned::Spanned, + visit_mut::VisitMut, + Field, Fields, Generics, Ident, Item, PathSegment, Type, TypePath, Visibility, WhereClause, +}; + +use crate::diagnostics::{DiagCtxt, ErrorGuaranteed}; + +pub(crate) mod kw { + syn::custom_keyword!(PinnedDrop); +} + +pub(crate) enum Args { + Nothing(Nothing), + #[allow(dead_code)] + PinnedDrop(kw::PinnedDrop), +} + +impl Parse for Args { + fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result { + let lh = input.lookahead1(); + if lh.peek(End) { + input.parse().map(Self::Nothing) + } else if lh.peek(kw::PinnedDrop) { + input.parse().map(Self::PinnedDrop) + } else { + Err(lh.error()) + } + } +} + +impl ToTokens for Args { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + Self::Nothing(_) => (), + Self::PinnedDrop(kw) => kw.to_tokens(tokens), + } + } +} + +struct FieldInfo<'a> { + field: &'a Field, + pinned: bool, +} + +pub(crate) fn pin_data( + args: Args, + input: Item, + dcx: &mut DiagCtxt, +) -> Result { + let mut struct_ = match input { + Item::Struct(struct_) => struct_, + Item::Enum(enum_) => { + return Err(dcx.error( + enum_.enum_token, + "`#[pin_data]` only supports structs for now", + )); + } + Item::Union(union) => { + return Err(dcx.error( + union.union_token, + "`#[pin_data]` only supports structs for now", + )); + } + rest => { + return Err(dcx.error( + rest, + "`#[pin_data]` can only be applied to struct, enum and union definitions", + )); + } + }; + + // Handling cfg can gets very complicated, especially for tuple structs. Therefore, resolve all + // field cfgs first before continuing. + // + // We need to perform this after parsing so we can reliably detect field cfgs. + for (field_idx, field) in struct_.fields.iter_mut().enumerate() { + let cfg: Vec<_> = field + .attrs + .iter() + .filter(|a| a.path().is_ident("cfg")) + .map(|a| { + a.parse_args::() + .expect("parse as token stream cannot fail") + }) + .collect(); + + if cfg.is_empty() { + continue; + } + + field.attrs.retain(|a| !a.path().is_ident("cfg")); + let cfg_true_struct = quote!(#struct_); + + let punctuated = match &mut struct_.fields { + Fields::Named(fields) => &mut fields.named, + Fields::Unnamed(fields) => &mut fields.unnamed, + Fields::Unit => unreachable!(), + }; + *punctuated = std::mem::take(punctuated) + .into_pairs() + .enumerate() + .filter(|&(i, _)| i != field_idx) + .map(|(_, p)| p) + .collect(); + let cfg_false_struct = quote!(#struct_); + + // Resolve one field at a time until we've got no more field cfgs. + // + // This is linear time because macro invocations with false cfg will not be expanded. + return Ok(quote!( + #[cfg(all(#(#cfg,)*))] + #[::pin_init::pin_data(#args)] + #cfg_true_struct + + #[cfg(not(all(#(#cfg,)*)))] + #[::pin_init::pin_data(#args)] + #cfg_false_struct + )); + } + + // The generics might contain the `Self` type. Since this macro will define a new type with the + // same generics and bounds, this poses a problem: `Self` will refer to the new type as opposed + // to this struct definition. Therefore we have to replace `Self` with the concrete name. + let mut replacer = { + let name = &struct_.ident; + let (_, ty_generics, _) = struct_.generics.split_for_impl(); + SelfReplacer(parse_quote!(#name #ty_generics)) + }; + replacer.visit_generics_mut(&mut struct_.generics); + replacer.visit_fields_mut(&mut struct_.fields); + + let fields: Vec> = struct_ + .fields + .iter_mut() + .map(|field| { + let len = field.attrs.len(); + field.attrs.retain(|a| !a.path().is_ident("pin")); + let pinned_count = len - field.attrs.len(); + if pinned_count > 1 { + dcx.error(&field, "#[pin] attribute specified more than once"); + } + + assert!( + !field.attrs.iter().any(|a| a.path().is_ident("cfg")), + "cfgs should be all resolved at this point" + ); + + FieldInfo { + field: &*field, + pinned: pinned_count != 0, + } + }) + .collect(); + + for field in &fields { + let ident = field.field.ident.as_ref().unwrap(); + + if !field.pinned && is_phantom_pinned(&field.field.ty) { + dcx.warn( + field.field, + format!( + "The field `{ident}` of type `PhantomPinned` only has an effect \ + if it has the `#[pin]` attribute", + ), + ); + } + } + + let unpin_impl = generate_unpin_impl(&struct_.ident, &struct_.generics, &fields); + let drop_impl = generate_drop_impl(&struct_.ident, &struct_.generics, args); + let projections = + generate_projections(&struct_.vis, &struct_.ident, &struct_.generics, &fields); + let the_pin_data = + generate_the_pin_data(&struct_.vis, &struct_.ident, &struct_.generics, &fields); + + Ok(quote! { + #struct_ + #projections + // We put the rest into this const item, because it then will not be accessible to anything + // outside. + const _: () = { + #the_pin_data + #unpin_impl + #drop_impl + }; + }) +} + +fn is_phantom_pinned(ty: &Type) -> bool { + match ty { + Type::Path(TypePath { qself: None, path }) => { + // Cannot possibly refer to `PhantomPinned` (except alias, but that's on the user). + if path.segments.len() > 3 { + return false; + } + // If there is a `::`, then the path needs to be `::core::marker::PhantomPinned` or + // `::std::marker::PhantomPinned`. + if path.leading_colon.is_some() && path.segments.len() != 3 { + return false; + } + let expected: Vec<&[&str]> = vec![&["PhantomPinned"], &["marker"], &["core", "std"]]; + for (actual, expected) in path.segments.iter().rev().zip(expected) { + if !actual.arguments.is_empty() || expected.iter().all(|e| actual.ident != e) { + return false; + } + } + true + } + _ => false, + } +} + +fn generate_unpin_impl( + ident: &Ident, + generics: &Generics, + fields: &[FieldInfo<'_>], +) -> TokenStream { + let (_, ty_generics, _) = generics.split_for_impl(); + let mut generics_with_pin_lt = generics.clone(); + generics_with_pin_lt.params.insert(0, parse_quote!('__pin)); + generics_with_pin_lt.make_where_clause(); + let ( + impl_generics_with_pin_lt, + ty_generics_with_pin_lt, + Some(WhereClause { + where_token, + predicates, + }), + ) = generics_with_pin_lt.split_for_impl() + else { + unreachable!() + }; + let pinned_fields = fields.iter().filter(|f| f.pinned).map(|f| { + let ident = f.field.ident.as_ref().unwrap(); + let ty = &f.field.ty; + quote!( + #ident: #ty + ) + }); + quote! { + // This struct will be used for the unpin analysis. It is needed, because only structurally + // pinned fields are relevant whether the struct should implement `Unpin`. + #[allow( + dead_code, // The fields below are never used. + non_snake_case // The warning will be emitted on the struct definition. + )] + struct __Unpin #generics_with_pin_lt + #where_token + #predicates + { + __phantom_pin: ::pin_init::__internal::PhantomInvariantLifetime<'__pin>, + __phantom: ::pin_init::__internal::PhantomInvariant<#ident #ty_generics>, + #(#pinned_fields),* + } + + #[doc(hidden)] + impl #impl_generics_with_pin_lt ::core::marker::Unpin for #ident #ty_generics + #where_token + __Unpin #ty_generics_with_pin_lt: ::core::marker::Unpin, + #predicates + {} + } +} + +fn generate_drop_impl(ident: &Ident, generics: &Generics, args: Args) -> TokenStream { + let (impl_generics, ty_generics, whr) = generics.split_for_impl(); + let has_pinned_drop = matches!(args, Args::PinnedDrop(_)); + // We need to disallow normal `Drop` implementation, the exact behavior depends on whether + // `PinnedDrop` was specified in `args`. + if has_pinned_drop { + // When `PinnedDrop` was specified we just implement `Drop` and delegate. + quote! { + impl #impl_generics ::core::ops::Drop for #ident #ty_generics + #whr + { + fn drop(&mut self) { + // SAFETY: Since this is a destructor, `self` will not move after this function + // terminates, since it is inaccessible. + let pinned = unsafe { ::core::pin::Pin::new_unchecked(self) }; + // SAFETY: Since this is a drop function, we can create this token to call the + // pinned destructor of this type. + let token = unsafe { ::pin_init::__internal::OnlyCallFromDrop::new() }; + ::pin_init::PinnedDrop::drop(pinned, token); + } + } + } + } else { + // When no `PinnedDrop` was specified, then we have to prevent implementing drop. + quote! { + // We prevent this by creating a trait that will be implemented for all types implementing + // `Drop`. Additionally we will implement this trait for the struct leading to a conflict, + // if it also implements `Drop` + trait MustNotImplDrop {} + impl MustNotImplDrop for T {} + impl #impl_generics MustNotImplDrop for #ident #ty_generics + #whr + {} + // We also take care to prevent users from writing a useless `PinnedDrop` implementation. + // They might implement `PinnedDrop` correctly for the struct, but forget to give + // `PinnedDrop` as the parameter to `#[pin_data]`. + trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {} + impl + UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for T {} + impl #impl_generics + UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for #ident #ty_generics + #whr + {} + } + } +} + +fn generate_projections( + vis: &Visibility, + ident: &Ident, + generics: &Generics, + fields: &[FieldInfo<'_>], +) -> TokenStream { + let (impl_generics, ty_generics, _) = generics.split_for_impl(); + let mut generics_with_pin_lt = generics.clone(); + generics_with_pin_lt.params.insert(0, parse_quote!('__pin)); + let (_, ty_generics_with_pin_lt, whr) = generics_with_pin_lt.split_for_impl(); + let projection = format_ident!("{ident}Projection"); + let this = format_ident!("this"); + + let (fields_decl, fields_proj): (Vec<_>, Vec<_>) = fields + .iter() + .map(|field| { + let Field { vis, ident, ty, .. } = &field.field; + + let ident = ident + .as_ref() + .expect("only structs with named fields are supported"); + if field.pinned { + ( + quote!( + #vis #ident: ::core::pin::Pin<&'__pin mut #ty>, + ), + quote!( + // SAFETY: this field is structurally pinned. + #ident: unsafe { ::core::pin::Pin::new_unchecked(&mut #this.#ident) }, + ), + ) + } else { + ( + quote!( + #vis #ident: &'__pin mut #ty, + ), + quote!( + #ident: &mut #this.#ident, + ), + ) + } + }) + .collect(); + let structurally_pinned_fields_docs = fields + .iter() + .filter(|f| f.pinned) + .map(|f| format!(" - `{}`", f.field.ident.as_ref().unwrap())); + let not_structurally_pinned_fields_docs = fields + .iter() + .filter(|f| !f.pinned) + .map(|f| format!(" - `{}`", f.field.ident.as_ref().unwrap())); + let docs = format!(" Pin-projections of [`{ident}`]"); + quote! { + #[doc = #docs] + // Allow `non_snake_case` since the same warning will be emitted on + // the struct definition. + #[allow(dead_code, non_snake_case)] + #[doc(hidden)] + #vis struct #projection #generics_with_pin_lt + #whr + { + #(#fields_decl)* + ___pin_phantom_data: ::core::marker::PhantomData<&'__pin mut ()>, + } + + impl #impl_generics #ident #ty_generics + #whr + { + /// Pin-projects all fields of `Self`. + /// + /// These fields are structurally pinned: + #(#[doc = #structurally_pinned_fields_docs])* + /// + /// These fields are **not** structurally pinned: + #(#[doc = #not_structurally_pinned_fields_docs])* + #[inline] + #vis fn project<'__pin>( + self: ::core::pin::Pin<&'__pin mut Self>, + ) -> #projection #ty_generics_with_pin_lt { + // SAFETY: we only give access to `&mut` for fields not structurally pinned. + let #this = unsafe { ::core::pin::Pin::get_unchecked_mut(self) }; + #projection { + #(#fields_proj)* + ___pin_phantom_data: ::core::marker::PhantomData, + } + } + } + } +} + +fn generate_the_pin_data( + vis: &Visibility, + struct_name: &Ident, + generics: &Generics, + fields: &[FieldInfo<'_>], +) -> TokenStream { + let (impl_generics, ty_generics, whr) = generics.split_for_impl(); + + // For every field, we create an initializing projection function according to its projection + // type. If a field is structurally pinned, we create a `Slot` with `Pinned` which must be + // initialized via `PinInit`; if it is not structurally pinned, then we create a `Slot` with + // `Unpinned` which allows initialization via `Init`. + let field_accessors = fields + .iter() + .map(|f| { + let Field { vis, ident, ty, .. } = f.field; + + let field_name = ident + .as_ref() + .expect("only structs with named fields are supported"); + let pin_marker = if f.pinned { + quote!(Pinned) + } else { + quote!(Unpinned) + }; + quote! { + /// # Safety + /// + /// - `slot` is valid and properly aligned. + /// - `(*slot).#field_name` is properly aligned. + /// - `(*slot).#field_name` points to uninitialized and exclusively accessed + /// memory. + // Allow `non_snake_case` since the same warning will be emitted on + // the struct definition. + #[allow(non_snake_case)] + #[inline(always)] + #vis unsafe fn #field_name( + self, + slot: *mut #struct_name #ty_generics, + ) -> ::pin_init::__internal::Slot<::pin_init::__internal::#pin_marker, #ty> { + // SAFETY: + // - If `#pin_marker` is `Pinned`, the corresponding field is structurally + // pinned. + // - Other safety requirements follows the safety requirement. + unsafe { ::pin_init::__internal::Slot::new(&raw mut (*slot).#field_name) } + } + } + }) + .collect::(); + quote! { + // We declare this struct which will host all of the projection function for our type. It + // will be invariant over all generic parameters which are inherited from the struct. + #[doc(hidden)] + #vis struct __ThePinData #generics + #whr + { + __phantom: ::pin_init::__internal::PhantomInvariant<#struct_name #ty_generics>, + } + + impl #impl_generics ::core::clone::Clone for __ThePinData #ty_generics + #whr + { + #[inline] + fn clone(&self) -> Self { *self } + } + + impl #impl_generics ::core::marker::Copy for __ThePinData #ty_generics + #whr + {} + + #[allow(dead_code)] // Some functions might never be used and private. + impl #impl_generics __ThePinData #ty_generics + #whr + { + /// Type inference helper function. + #[inline(always)] + #vis fn __make_closure<__F, __E>(self, f: __F) -> __F + where + __F: FnOnce(*mut #struct_name #ty_generics) -> + ::core::result::Result<::pin_init::__internal::InitOk, __E>, + { + f + } + + #field_accessors + } + + // SAFETY: We have added the correct projection functions above to `__ThePinData` and + // we also use the least restrictive generics possible. + unsafe impl #impl_generics ::pin_init::__internal::HasPinData for #struct_name #ty_generics + #whr + { + type PinData = __ThePinData #ty_generics; + + #[inline] + unsafe fn __pin_data() -> Self::PinData { + __ThePinData { __phantom: ::pin_init::__internal::PhantomInvariant::new() } + } + } + } +} + +struct SelfReplacer(PathSegment); + +impl VisitMut for SelfReplacer { + fn visit_path_mut(&mut self, i: &mut syn::Path) { + if i.is_ident("Self") { + let span = i.span(); + let seg = &self.0; + *i = parse_quote_spanned!(span=> #seg); + } else { + syn::visit_mut::visit_path_mut(self, i); + } + } + + fn visit_path_segment_mut(&mut self, seg: &mut PathSegment) { + if seg.ident == "Self" { + let span = seg.span(); + let this = &self.0; + *seg = parse_quote_spanned!(span=> #this); + } else { + syn::visit_mut::visit_path_segment_mut(self, seg); + } + } + + fn visit_item_mut(&mut self, _: &mut Item) { + // Do not descend into items, since items reset/change what `Self` refers to. + } +} diff --git a/rust/pin-init/internal/src/pinned_drop.rs b/rust/pin-init/internal/src/pinned_drop.rs new file mode 100644 index 000000000..a20ac314c --- /dev/null +++ b/rust/pin-init/internal/src/pinned_drop.rs @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro2::TokenStream; +use quote::quote; +use syn::{parse::Nothing, parse_quote, spanned::Spanned, ImplItem, ItemImpl, Token}; + +use crate::diagnostics::{DiagCtxt, ErrorGuaranteed}; + +pub(crate) fn pinned_drop( + _args: Nothing, + mut input: ItemImpl, + dcx: &mut DiagCtxt, +) -> Result { + if let Some(unsafety) = input.unsafety { + dcx.error(unsafety, "implementing `PinnedDrop` is safe"); + } + input.unsafety = Some(Token![unsafe](input.impl_token.span)); + match &mut input.trait_ { + Some((not, path, _for)) => { + if let Some(not) = not { + dcx.error(not, "cannot implement `!PinnedDrop`"); + } + for (seg, expected) in path + .segments + .iter() + .rev() + .zip(["PinnedDrop", "pin_init", ""]) + { + if expected.is_empty() || seg.ident != expected { + dcx.error(seg, "bad import path for `PinnedDrop`"); + } + if !seg.arguments.is_none() { + dcx.error(&seg.arguments, "unexpected arguments for `PinnedDrop` path"); + } + } + *path = parse_quote!(::pin_init::PinnedDrop); + } + None => { + let span = input + .impl_token + .span + .join(input.self_ty.span()) + .unwrap_or(input.impl_token.span); + dcx.error( + span, + "expected `impl ... PinnedDrop for ...`, got inherent impl", + ); + } + } + for item in &mut input.items { + if let ImplItem::Fn(fn_item) = item { + if fn_item.sig.ident == "drop" { + fn_item + .sig + .inputs + .push(parse_quote!(_: ::pin_init::__internal::OnlyCallFromDrop)); + } + } + } + Ok(quote!(#input)) +} diff --git a/rust/pin-init/internal/src/zeroable.rs b/rust/pin-init/internal/src/zeroable.rs new file mode 100644 index 000000000..b11feaeb1 --- /dev/null +++ b/rust/pin-init/internal/src/zeroable.rs @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro2::TokenStream; +use quote::quote; +use syn::{parse_quote, Data, DeriveInput, Field, Fields}; + +use crate::{diagnostics::ErrorGuaranteed, DiagCtxt}; + +pub(crate) fn derive( + input: DeriveInput, + dcx: &mut DiagCtxt, +) -> Result { + let fields = match input.data { + Data::Struct(data_struct) => data_struct.fields, + Data::Union(data_union) => Fields::Named(data_union.fields), + Data::Enum(data_enum) => { + return Err(dcx.error(data_enum.enum_token, "cannot derive `Zeroable` for an enum")); + } + }; + let name = input.ident; + let mut generics = input.generics; + for param in generics.type_params_mut() { + param.bounds.insert(0, parse_quote!(::pin_init::Zeroable)); + } + let (impl_gen, ty_gen, whr) = generics.split_for_impl(); + let field_type = fields.iter().map(|field| &field.ty); + Ok(quote! { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl #impl_gen ::pin_init::Zeroable for #name #ty_gen + #whr + {} + const _: () = { + fn assert_zeroable() {} + fn ensure_zeroable #impl_gen () + #whr + { + #( + assert_zeroable::<#field_type>(); + )* + } + }; + }) +} + +pub(crate) fn maybe_derive( + input: DeriveInput, + dcx: &mut DiagCtxt, +) -> Result { + let fields = match input.data { + Data::Struct(data_struct) => data_struct.fields, + Data::Union(data_union) => Fields::Named(data_union.fields), + Data::Enum(data_enum) => { + return Err(dcx.error(data_enum.enum_token, "cannot derive `Zeroable` for an enum")); + } + }; + let name = input.ident; + let mut generics = input.generics; + for param in generics.type_params_mut() { + param.bounds.insert(0, parse_quote!(::pin_init::Zeroable)); + } + for Field { ty, .. } in fields { + generics + .make_where_clause() + .predicates + // the `for<'__dummy>` HRTB makes this not error without the `trivial_bounds` + // feature . + .push(parse_quote!(#ty: for<'__dummy> ::pin_init::Zeroable)); + } + let (impl_gen, ty_gen, whr) = generics.split_for_impl(); + Ok(quote! { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl #impl_gen ::pin_init::Zeroable for #name #ty_gen + #whr + {} + }) +} -- cgit v1.3.1