Add default sanitizers to TargetOptions

Some sanitizers are part of a system's ABI, like the shadow call stack
on Aarch64 and RISC-V Fuchsia. Typically ABI options have other
spellings, but LLVM has, for historical reasons, marked this as a
sanitizer instead of an alternate ABI option. As a result, Fuchsia
targets may not be compiled against the correct ABI unless this option
is set. This hasn't caused correctness problems, since the backend
reserves the SCS register, and thus preserves its value. But this is an
issue for unwinding, as the SCS will not be an array of PCs describing
the call complete call chain, and will have gaps from callers that don't
use the correct ABI.

In the long term, I'd like to see all the sanitizer configs that all
frontends copy from clang moved into llvm's libFrontend, and exposed so
that frontend consumers can use a small set of simple APIs to use
sanitizers in a consistent way across the LLVM ecosystem, but that work
is not yet ready today.

Author: ilovepi

compiler/rustc_codegen_llvm/src/abi.rs

@@ -96,7 +96,7 @@ fn get_attrs<'ll>(this: &ArgAttributes, cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'
                 }
             }
         }
-    } else if cx.tcx.sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::MEMORY) {
+    } else if cx.tcx.sess.sanitizers().contains(SanitizerSet::MEMORY) {
         // If we're not optimising, *but* memory sanitizer is on, emit noundef, since it affects
         // memory sanitizer's behavior.
 

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -101,7 +101,7 @@ pub(crate) fn sanitize_attrs<'ll, 'tcx>(
     no_sanitize: SanitizerSet,
 ) -> SmallVec<[&'ll Attribute; 4]> {
     let mut attrs = SmallVec::new();
-    let enabled = tcx.sess.opts.unstable_opts.sanitizer - no_sanitize;
+    let enabled = tcx.sess.sanitizers() - no_sanitize;
     if enabled.contains(SanitizerSet::ADDRESS) || enabled.contains(SanitizerSet::KERNELADDRESS) {
         attrs.push(llvm::AttributeKind::SanitizeAddress.create_attr(cx.llcx));
     }
@@ -240,13 +240,7 @@ fn probestack_attr<'ll, 'tcx>(cx: &SimpleCx<'ll>, tcx: TyCtxt<'tcx>) -> Option<&
     // Currently stack probes seem somewhat incompatible with the address
     // sanitizer and thread sanitizer. With asan we're already protected from
     // stack overflow anyway so we don't really need stack probes regardless.
-    if tcx
-        .sess
-        .opts
-        .unstable_opts
-        .sanitizer
-        .intersects(SanitizerSet::ADDRESS | SanitizerSet::THREAD)
-    {
+    if tcx.sess.sanitizers().intersects(SanitizerSet::ADDRESS | SanitizerSet::THREAD) {
         return None;
     }
 

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1226,7 +1226,7 @@ fn add_sanitizer_libraries(
         return;
     }
 
-    let sanitizer = sess.opts.unstable_opts.sanitizer;
+    let sanitizer = sess.sanitizers();
     if sanitizer.contains(SanitizerSet::ADDRESS) {
         link_sanitizer_runtime(sess, flavor, linker, "asan");
     }
@@ -2496,11 +2496,7 @@ fn add_order_independent_options(
         && crate_type == CrateType::Executable
         && !matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
     {
-        let prefix = if sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::ADDRESS) {
-            "asan/"
-        } else {
-            ""
-        };
+        let prefix = if sess.sanitizers().contains(SanitizerSet::ADDRESS) { "asan/" } else { "" };
         cmd.link_arg(format!("--dynamic-linker={prefix}ld.so.1"));
     }
 

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -176,7 +176,7 @@ impl ModuleConfig {
             debug_info_for_profiling: sess.opts.unstable_opts.debug_info_for_profiling,
             instrument_coverage: if_regular!(sess.instrument_coverage(), false),
 
-            sanitizer: if_regular!(sess.opts.unstable_opts.sanitizer, SanitizerSet::empty()),
+            sanitizer: if_regular!(sess.sanitizers(), SanitizerSet::empty()),
             sanitizer_dataflow_abilist: if_regular!(
                 sess.opts.unstable_opts.sanitizer_dataflow_abilist.clone(),
                 Vec::new()

compiler/rustc_metadata/src/creader.rs

@@ -412,7 +412,7 @@ impl CStore {
             match (&left_name_val, &right_name_val) {
                 (Some(l), Some(r)) => match l.1.opt.cmp(&r.1.opt) {
                     cmp::Ordering::Equal => {
-                        if !l.1.consistent(&tcx.sess.opts, Some(&r.1)) {
+                        if !l.1.consistent(&tcx.sess, Some(&r.1)) {
                             report_diff(
                                 &l.0.prefix,
                                 &l.0.name,
@@ -424,26 +424,26 @@ impl CStore {
                         right_name_val = None;
                     }
                     cmp::Ordering::Greater => {
-                        if !r.1.consistent(&tcx.sess.opts, None) {
+                        if !r.1.consistent(&tcx.sess, None) {
                             report_diff(&r.0.prefix, &r.0.name, None, Some(&r.1.value_name));
                         }
                         right_name_val = None;
                     }
                     cmp::Ordering::Less => {
-                        if !l.1.consistent(&tcx.sess.opts, None) {
+                        if !l.1.consistent(&tcx.sess, None) {
                             report_diff(&l.0.prefix, &l.0.name, Some(&l.1.value_name), None);
                         }
                         left_name_val = None;
                     }
                 },
                 (Some(l), None) => {
-                    if !l.1.consistent(&tcx.sess.opts, None) {
+                    if !l.1.consistent(&tcx.sess, None) {
                         report_diff(&l.0.prefix, &l.0.name, Some(&l.1.value_name), None);
                     }
                     left_name_val = None;
                 }
                 (None, Some(r)) => {
-                    if !r.1.consistent(&tcx.sess.opts, None) {
+                    if !r.1.consistent(&tcx.sess, None) {
                         report_diff(&r.0.prefix, &r.0.name, None, Some(&r.1.value_name));
                     }
                     right_name_val = None;

compiler/rustc_metadata/src/native_libs.rs

@@ -71,7 +71,7 @@ pub fn walk_native_lib_search_dirs<R>(
         || sess.target.os == "linux"
         || sess.target.os == "fuchsia"
         || sess.target.is_like_aix
-        || sess.target.is_like_darwin && !sess.opts.unstable_opts.sanitizer.is_empty()
+        || sess.target.is_like_darwin && !sess.sanitizers().is_empty()
     {
         f(&sess.target_tlib_path.dir, false)?;
     }

compiler/rustc_session/src/config/cfg.rs

@@ -224,7 +224,7 @@ pub(crate) fn default_configuration(sess: &Session) -> Cfg {
         ins_sym!(sym::relocation_model, sess.target.relocation_model.desc_symbol());
     }
 
-    for mut s in sess.opts.unstable_opts.sanitizer {
+    for mut s in sess.sanitizers() {
         // KASAN is still ASAN under the hood, so it uses the same attribute.
         if s == SanitizerSet::KERNELADDRESS {
             s = SanitizerSet::ADDRESS;

compiler/rustc_session/src/options.rs

@@ -22,7 +22,7 @@ use rustc_target::spec::{
 use crate::config::*;
 use crate::search_paths::SearchPath;
 use crate::utils::NativeLib;
-use crate::{EarlyDiagCtxt, lint};
+use crate::{EarlyDiagCtxt, Session, lint};
 
 macro_rules! insert {
     ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr) => {
@@ -111,12 +111,12 @@ mod target_modifier_consistency_check {
         lparsed & tmod_sanitizers == rparsed & tmod_sanitizers
     }
     pub(super) fn sanitizer_cfi_normalize_integers(
-        opts: &Options,
+        sess: &Session,
         l: &TargetModifier,
         r: Option<&TargetModifier>,
     ) -> bool {
         // For kCFI, the helper flag -Zsanitizer-cfi-normalize-integers should also be a target modifier
-        if opts.unstable_opts.sanitizer.contains(SanitizerSet::KCFI) {
+        if sess.sanitizers().contains(SanitizerSet::KCFI) {
             if let Some(r) = r {
                 return l.extend().tech_value == r.extend().tech_value;
             } else {
@@ -133,7 +133,7 @@ impl TargetModifier {
     }
     // Custom consistency check for target modifiers (or default `l.tech_value == r.tech_value`)
     // When other is None, consistency with default value is checked
-    pub fn consistent(&self, opts: &Options, other: Option<&TargetModifier>) -> bool {
+    pub fn consistent(&self, sess: &Session, other: Option<&TargetModifier>) -> bool {
         assert!(other.is_none() || self.opt == other.unwrap().opt);
         match self.opt {
             OptionsTargetModifiers::UnstableOptions(unstable) => match unstable {
@@ -142,7 +142,7 @@ impl TargetModifier {
                 }
                 UnstableOptionsTargetModifiers::sanitizer_cfi_normalize_integers => {
                     return target_modifier_consistency_check::sanitizer_cfi_normalize_integers(
-                        opts, self, other,
+                        sess, self, other,
                     );
                 }
                 _ => {}
@@ -2575,6 +2575,7 @@ written to standard error output)"),
     retpoline_external_thunk: bool = (false, parse_bool, [TRACKED TARGET_MODIFIER],
         "enables retpoline-external-thunk, retpoline-indirect-branches and retpoline-indirect-calls \
         target features (default: no)"),
+    #[rustc_lint_opt_deny_field_access("use `Session::sanitizers()` instead of this field")]
     sanitizer: SanitizerSet = (SanitizerSet::empty(), parse_sanitizers, [TRACKED TARGET_MODIFIER],
         "use a sanitizer"),
     sanitizer_cfi_canonical_jump_tables: Option<bool> = (Some(true), parse_opt_bool, [TRACKED],

compiler/rustc_session/src/session.rs

@@ -323,7 +323,7 @@ impl Session {
     }
 
     pub fn is_sanitizer_cfi_enabled(&self) -> bool {
-        self.opts.unstable_opts.sanitizer.contains(SanitizerSet::CFI)
+        self.sanitizers().contains(SanitizerSet::CFI)
     }
 
     pub fn is_sanitizer_cfi_canonical_jump_tables_disabled(&self) -> bool {
@@ -347,7 +347,7 @@ impl Session {
     }
 
     pub fn is_sanitizer_kcfi_enabled(&self) -> bool {
-        self.opts.unstable_opts.sanitizer.contains(SanitizerSet::KCFI)
+        self.sanitizers().contains(SanitizerSet::KCFI)
     }
 
     pub fn is_split_lto_unit_enabled(&self) -> bool {
@@ -527,7 +527,7 @@ impl Session {
         // AddressSanitizer and KernelAddressSanitizer uses lifetimes to detect use after scope bugs.
         // MemorySanitizer uses lifetimes to detect use of uninitialized stack variables.
         // HWAddressSanitizer will use lifetimes to detect use after scope bugs in the future.
-        || self.opts.unstable_opts.sanitizer.intersects(SanitizerSet::ADDRESS | SanitizerSet::KERNELADDRESS | SanitizerSet::MEMORY | SanitizerSet::HWADDRESS)
+        || self.sanitizers().intersects(SanitizerSet::ADDRESS | SanitizerSet::KERNELADDRESS | SanitizerSet::MEMORY | SanitizerSet::HWADDRESS)
     }
 
     pub fn diagnostic_width(&self) -> usize {
@@ -922,6 +922,10 @@ impl Session {
             min
         }
     }
+
+    pub fn sanitizers(&self) -> SanitizerSet {
+        return self.opts.unstable_opts.sanitizer | self.target.options.default_sanitizers;
+    }
 }
 
 // JUSTIFICATION: part of session construction

compiler/rustc_target/src/spec/json.rs

@@ -214,6 +214,11 @@ impl Target {
                 supported_sanitizers.into_iter().fold(SanitizerSet::empty(), |a, b| a | b);
         }
 
+        if let Some(default_sanitizers) = json.default_sanitizers {
+            base.default_sanitizers =
+                default_sanitizers.into_iter().fold(SanitizerSet::empty(), |a, b| a | b);
+        }
+
         forward!(generate_arange_section);
         forward!(supports_stack_protector);
         forward!(small_data_threshold_support);
@@ -392,6 +397,7 @@ impl ToJson for Target {
         target_option_val!(split_debuginfo);
         target_option_val!(supported_split_debuginfo);
         target_option_val!(supported_sanitizers);
+        target_option_val!(default_sanitizers);
         target_option_val!(c_enum_min_bits);
         target_option_val!(generate_arange_section);
         target_option_val!(supports_stack_protector);
@@ -612,6 +618,7 @@ struct TargetSpecJson {
     split_debuginfo: Option<SplitDebuginfo>,
     supported_split_debuginfo: Option<StaticCow<[SplitDebuginfo]>>,
     supported_sanitizers: Option<Vec<SanitizerSet>>,
+    default_sanitizers: Option<Vec<SanitizerSet>>,
     generate_arange_section: Option<bool>,
     supports_stack_protector: Option<bool>,
     small_data_threshold_support: Option<SmallDataThresholdSupport>,