Rollup merge of #68164 - tmiasko:no-sanitize, r=nikomatsakis

Selectively disable sanitizer instrumentation

Add `no_sanitize` attribute that allows to opt out from sanitizer
instrumentation in an annotated function.

Author: Dylan-DPC

src/doc/unstable-book/src/language-features/no-sanitize.md

@@ -0,0 +1,29 @@
+# `no_sanitize`
+
+The tracking issue for this feature is: [#39699]
+
+[#39699]: https://github.com/rust-lang/rust/issues/39699
+
+------------------------
+
+The `no_sanitize` attribute can be used to selectively disable sanitizer
+instrumentation in an annotated function. This might be useful to: avoid
+instrumentation overhead in a performance critical function, or avoid
+instrumenting code that contains constructs unsupported by given sanitizer.
+
+The precise effect of this annotation depends on particular sanitizer in use.
+For example, with `no_sanitize(thread)`, the thread sanitizer will no longer
+instrument non-atomic store / load operations, but it will instrument atomic
+operations to avoid reporting false positives and provide meaning full stack
+traces.
+
+## Examples
+
+``` rust
+#![feature(no_sanitize)]
+
+#[no_sanitize(address)]
+fn foo() {
+  // ...
+}
+```

src/librustc/middle/codegen_fn_attrs.rs

@@ -72,6 +72,14 @@ bitflags! {
         const FFI_RETURNS_TWICE         = 1 << 10;
         /// `#[track_caller]`: allow access to the caller location
         const TRACK_CALLER              = 1 << 11;
+        /// `#[no_sanitize(address)]`: disables address sanitizer instrumentation
+        const NO_SANITIZE_ADDRESS = 1 << 12;
+        /// `#[no_sanitize(memory)]`: disables memory sanitizer instrumentation
+        const NO_SANITIZE_MEMORY  = 1 << 13;
+        /// `#[no_sanitize(thread)]`: disables thread sanitizer instrumentation
+        const NO_SANITIZE_THREAD  = 1 << 14;
+        /// All `#[no_sanitize(...)]` attributes.
+        const NO_SANITIZE_ANY = Self::NO_SANITIZE_ADDRESS.bits | Self::NO_SANITIZE_MEMORY.bits | Self::NO_SANITIZE_THREAD.bits;
     }
 }
 

src/librustc_codegen_llvm/attributes.rs

@@ -46,6 +46,31 @@ fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr) {
     };
 }
 
+/// Apply LLVM sanitize attributes.
+#[inline]
+pub fn sanitize(cx: &CodegenCx<'ll, '_>, codegen_fn_flags: CodegenFnAttrFlags, llfn: &'ll Value) {
+    if let Some(ref sanitizer) = cx.tcx.sess.opts.debugging_opts.sanitizer {
+        match *sanitizer {
+            Sanitizer::Address => {
+                if !codegen_fn_flags.contains(CodegenFnAttrFlags::NO_SANITIZE_ADDRESS) {
+                    llvm::Attribute::SanitizeAddress.apply_llfn(Function, llfn);
+                }
+            }
+            Sanitizer::Memory => {
+                if !codegen_fn_flags.contains(CodegenFnAttrFlags::NO_SANITIZE_MEMORY) {
+                    llvm::Attribute::SanitizeMemory.apply_llfn(Function, llfn);
+                }
+            }
+            Sanitizer::Thread => {
+                if !codegen_fn_flags.contains(CodegenFnAttrFlags::NO_SANITIZE_THREAD) {
+                    llvm::Attribute::SanitizeThread.apply_llfn(Function, llfn);
+                }
+            }
+            Sanitizer::Leak => {}
+        }
+    }
+}
+
 /// Tell LLVM to emit or not emit the information necessary to unwind the stack for the function.
 #[inline]
 pub fn emit_uwtable(val: &'ll Value, emit: bool) {
@@ -288,6 +313,7 @@ pub fn from_fn_attrs(
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::ALLOCATOR) {
         Attribute::NoAlias.apply_llfn(llvm::AttributePlace::ReturnValue, llfn);
     }
+    sanitize(cx, codegen_fn_attrs.flags, llfn);
 
     unwind(
         llfn,

src/librustc_codegen_llvm/base.rs

@@ -15,6 +15,7 @@
 
 use super::ModuleLlvm;
 
+use crate::attributes;
 use crate::builder::Builder;
 use crate::common;
 use crate::context::CodegenCx;
@@ -23,7 +24,7 @@ use crate::metadata;
 use crate::value::Value;
 
 use rustc::dep_graph;
-use rustc::middle::codegen_fn_attrs::CodegenFnAttrs;
+use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc::middle::cstore::EncodedMetadata;
 use rustc::middle::exported_symbols;
 use rustc::mir::mono::{Linkage, Visibility};
@@ -131,7 +132,9 @@ pub fn compile_codegen_unit(
 
             // If this codegen unit contains the main function, also create the
             // wrapper here
-            maybe_create_entry_wrapper::<Builder<'_, '_, '_>>(&cx);
+            if let Some(entry) = maybe_create_entry_wrapper::<Builder<'_, '_, '_>>(&cx) {
+                attributes::sanitize(&cx, CodegenFnAttrFlags::empty(), entry);
+            }
 
             // Run replace-all-uses-with for statics that need it
             for &(old_g, new_g) in cx.statics_to_rauw().borrow().iter() {

src/librustc_codegen_llvm/declare.rs

@@ -19,7 +19,6 @@ use crate::llvm::AttributePlace::Function;
 use crate::type_::Type;
 use crate::value::Value;
 use log::debug;
-use rustc::session::config::Sanitizer;
 use rustc::ty::Ty;
 use rustc_codegen_ssa::traits::*;
 use rustc_data_structures::small_c_str::SmallCStr;
@@ -47,21 +46,6 @@ fn declare_raw_fn(
         llvm::Attribute::NoRedZone.apply_llfn(Function, llfn);
     }
 
-    if let Some(ref sanitizer) = cx.tcx.sess.opts.debugging_opts.sanitizer {
-        match *sanitizer {
-            Sanitizer::Address => {
-                llvm::Attribute::SanitizeAddress.apply_llfn(Function, llfn);
-            }
-            Sanitizer::Memory => {
-                llvm::Attribute::SanitizeMemory.apply_llfn(Function, llfn);
-            }
-            Sanitizer::Thread => {
-                llvm::Attribute::SanitizeThread.apply_llfn(Function, llfn);
-            }
-            _ => {}
-        }
-    }
-
     attributes::default_optimisation_attrs(cx.tcx.sess, llfn);
     attributes::non_lazy_bind(cx.sess(), llfn);
     llfn

src/librustc_codegen_ssa/base.rs

@@ -391,36 +391,36 @@ pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
 
 /// Creates the `main` function which will initialize the rust runtime and call
 /// users main function.
-pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(cx: &'a Bx::CodegenCx) {
+pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
+    cx: &'a Bx::CodegenCx,
+) -> Option<Bx::Function> {
     let (main_def_id, span) = match cx.tcx().entry_fn(LOCAL_CRATE) {
         Some((def_id, _)) => (def_id, cx.tcx().def_span(def_id)),
-        None => return,
+        None => return None,
     };
 
     let instance = Instance::mono(cx.tcx(), main_def_id);
 
     if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) {
         // We want to create the wrapper in the same codegen unit as Rust's main
         // function.
-        return;
+        return None;
     }
 
     let main_llfn = cx.get_fn_addr(instance);
 
-    let et = cx.tcx().entry_fn(LOCAL_CRATE).map(|e| e.1);
-    match et {
-        Some(EntryFnType::Main) => create_entry_fn::<Bx>(cx, span, main_llfn, main_def_id, true),
-        Some(EntryFnType::Start) => create_entry_fn::<Bx>(cx, span, main_llfn, main_def_id, false),
-        None => {} // Do nothing.
-    }
+    return cx.tcx().entry_fn(LOCAL_CRATE).map(|(_, et)| {
+        let use_start_lang_item = EntryFnType::Start != et;
+        create_entry_fn::<Bx>(cx, span, main_llfn, main_def_id, use_start_lang_item)
+    });
 
     fn create_entry_fn<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         cx: &'a Bx::CodegenCx,
         sp: Span,
         rust_main: Bx::Value,
         rust_main_def_id: DefId,
         use_start_lang_item: bool,
-    ) {
+    ) -> Bx::Function {
         // The entry function is either `int main(void)` or `int main(int argc, char **argv)`,
         // depending on whether the target needs `argc` and `argv` to be passed in.
         let llfty = if cx.sess().target.target.options.main_needs_argc_argv {
@@ -481,6 +481,8 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(cx: &'
         let result = bx.call(start_fn, &args, None);
         let cast = bx.intcast(result, cx.type_int(), true);
         bx.ret(cast);
+
+        llfn
     }
 }
 

src/librustc_feature/active.rs

@@ -541,6 +541,9 @@ declare_features! (
     /// Allows `T: ?const Trait` syntax in bounds.
     (active, const_trait_bound_opt_out, "1.42.0", Some(67794), None),
 
+    /// Allows the use of `no_sanitize` attribute.
+    (active, no_sanitize, "1.42.0", Some(39699), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------

src/librustc_feature/builtin_attrs.rs

@@ -261,6 +261,11 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ungated!(cold, Whitelisted, template!(Word)),
     ungated!(no_builtins, Whitelisted, template!(Word)),
     ungated!(target_feature, Whitelisted, template!(List: r#"enable = "name""#)),
+    gated!(
+        no_sanitize, Whitelisted,
+        template!(List: "address, memory, thread"),
+        experimental!(no_sanitize)
+    ),
 
     // FIXME: #14408 whitelist docs since rustdoc looks at them
     ungated!(doc, Whitelisted, template!(List: "hidden|inline|...", NameValueStr: "string")),

src/librustc_mir/transform/inline.rs

@@ -8,6 +8,7 @@ use rustc_index::vec::{Idx, IndexVec};
 use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc::mir::visit::*;
 use rustc::mir::*;
+use rustc::session::config::Sanitizer;
 use rustc::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt, TypeFoldable};
 
@@ -228,6 +229,28 @@ impl Inliner<'tcx> {
             return false;
         }
 
+        // Avoid inlining functions marked as no_sanitize if sanitizer is enabled,
+        // since instrumentation might be enabled and performed on the caller.
+        match self.tcx.sess.opts.debugging_opts.sanitizer {
+            Some(Sanitizer::Address) => {
+                if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_SANITIZE_ADDRESS) {
+                    return false;
+                }
+            }
+            Some(Sanitizer::Memory) => {
+                if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_SANITIZE_MEMORY) {
+                    return false;
+                }
+            }
+            Some(Sanitizer::Thread) => {
+                if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_SANITIZE_THREAD) {
+                    return false;
+                }
+            }
+            Some(Sanitizer::Leak) => {}
+            None => {}
+        }
+
         let hinted = match codegen_fn_attrs.inline {
             // Just treat inline(always) as a hint for now,
             // there are cases that prevent inlining that we

src/librustc_session/lint/builtin.rs

@@ -474,6 +474,12 @@ declare_lint! {
     };
 }
 
+declare_lint! {
+    pub INLINE_NO_SANITIZE,
+    Warn,
+    "detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`",
+}
+
 declare_lint_pass! {
     /// Does nothing as a lint pass, but registers some `Lint`s
     /// that are used by other parts of the compiler.
@@ -537,5 +543,6 @@ declare_lint_pass! {
         MUTABLE_BORROW_RESERVATION_CONFLICT,
         INDIRECT_STRUCTURAL_MATCH,
         SOFT_UNSTABLE,
+        INLINE_NO_SANITIZE,
     ]
 }