89 lines
2.8 KiB
Rust
89 lines
2.8 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_then;
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use rustc_ast::InlineAsmOptions;
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use rustc_hir::{Expr, ExprKind, InlineAsm, InlineAsmOperand};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::declare_lint_pass;
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use rustc_span::Span;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks if any pointer is being passed to an asm! block with `nomem` option.
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///
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/// ### Why is this bad?
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/// `nomem` forbids any reads or writes to memory and passing a pointer suggests
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/// that either of those will happen.
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///
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/// ### Example
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/// ```no_run
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/// fn f(p: *mut u32) {
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/// unsafe { core::arch::asm!("mov [{p}], 42", p = in(reg) p, options(nomem, nostack)); }
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/// }
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/// ```
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/// Use instead:
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/// ```no_run
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/// fn f(p: *mut u32) {
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/// unsafe { core::arch::asm!("mov [{p}], 42", p = in(reg) p, options(nostack)); }
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/// }
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/// ```
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#[clippy::version = "1.81.0"]
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pub POINTERS_IN_NOMEM_ASM_BLOCK,
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suspicious,
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"pointers in nomem asm block"
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}
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declare_lint_pass!(PointersInNomemAsmBlock => [POINTERS_IN_NOMEM_ASM_BLOCK]);
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impl<'tcx> LateLintPass<'tcx> for PointersInNomemAsmBlock {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if let ExprKind::InlineAsm(asm) = &expr.kind {
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check_asm(cx, asm);
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}
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}
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}
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fn check_asm(cx: &LateContext<'_>, asm: &InlineAsm<'_>) {
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if !asm.options.contains(InlineAsmOptions::NOMEM) {
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return;
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}
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let spans = asm
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.operands
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.iter()
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.filter(|(op, _span)| has_in_operand_pointer(cx, op))
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.map(|(_op, span)| *span)
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.collect::<Vec<Span>>();
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if spans.is_empty() {
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return;
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}
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span_lint_and_then(
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cx,
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POINTERS_IN_NOMEM_ASM_BLOCK,
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spans,
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"passing pointers to nomem asm block",
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additional_notes,
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);
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}
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fn has_in_operand_pointer(cx: &LateContext<'_>, asm_op: &InlineAsmOperand<'_>) -> bool {
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let asm_in_expr = match asm_op {
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InlineAsmOperand::SymStatic { .. }
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| InlineAsmOperand::Out { .. }
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| InlineAsmOperand::Const { .. }
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| InlineAsmOperand::SymFn { .. }
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| InlineAsmOperand::Label { .. } => return false,
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InlineAsmOperand::SplitInOut { in_expr, .. } => in_expr,
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InlineAsmOperand::In { expr, .. } | InlineAsmOperand::InOut { expr, .. } => expr,
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};
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// This checks for raw ptrs, refs and function pointers - the last one
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// also technically counts as reading memory.
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cx.typeck_results().expr_ty(asm_in_expr).is_any_ptr()
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}
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fn additional_notes(diag: &mut rustc_errors::Diag<'_, ()>) {
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diag.note("`nomem` means that no memory write or read happens inside the asm! block");
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diag.note("if this is intentional and no pointers are read or written to, consider allowing the lint");
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}
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