[WIP] 5 - Transmutes

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1843,6 +1843,17 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
     fn fptosi_sat(&mut self, val: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
         self.fptoint_sat(true, val, dest_ty)
     }
+
+    fn ptrauth_resign(
+        &mut self,
+        _value: Self::Value,
+        _old_key: u32,
+        _old_discriminator: u64,
+        _new_key: u32,
+        _new_discriminator: u64,
+    ) -> Self::Value {
+        bug!("Resigning of pointers not implemented");
+    }
 }
 
 impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {

compiler/rustc_codegen_gcc/src/common.rs

@@ -2,12 +2,12 @@ use gccjit::{LValue, RValue, ToRValue, Type};
 use rustc_abi::Primitive::Pointer;
 use rustc_abi::{self as abi, HasDataLayout};
 use rustc_codegen_ssa::traits::{
-    BaseTypeCodegenMethods, ConstCodegenMethods, MiscCodegenMethods, PacMetadata,
-    StaticCodegenMethods,
+    BaseTypeCodegenMethods, ConstCodegenMethods, MiscCodegenMethods, StaticCodegenMethods,
 };
 use rustc_middle::mir::Mutability;
 use rustc_middle::mir::interpret::{GlobalAlloc, PointerArithmetic, Scalar};
 use rustc_middle::ty::layout::LayoutOf;
+use rustc_session::PointerAuthSchema;
 
 use crate::consts::const_alloc_to_gcc;
 use crate::context::{CodegenCx, new_array_type};
@@ -247,7 +247,7 @@ impl<'gcc, 'tcx> ConstCodegenMethods for CodegenCx<'gcc, 'tcx> {
         cv: Scalar,
         layout: abi::Scalar,
         ty: Type<'gcc>,
-        _pac: Option<PacMetadata>,
+        _schema: Option<PointerAuthSchema>,
     ) -> RValue<'gcc> {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {

compiler/rustc_codegen_gcc/src/context.rs

@@ -5,9 +5,7 @@ use gccjit::{Block, CType, Context, Function, FunctionType, LValue, Location, RV
 use rustc_abi::{Align, HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
 use rustc_codegen_ssa::base::wants_msvc_seh;
 use rustc_codegen_ssa::errors as ssa_errors;
-use rustc_codegen_ssa::traits::{
-    BackendTypes, BaseTypeCodegenMethods, MiscCodegenMethods, PacMetadata,
-};
+use rustc_codegen_ssa::traits::{BackendTypes, BaseTypeCodegenMethods, MiscCodegenMethods};
 use rustc_data_structures::base_n::{ALPHANUMERIC_ONLY, ToBaseN};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_middle::mir::interpret::Allocation;
@@ -18,9 +16,9 @@ use rustc_middle::ty::layout::{
     LayoutOfHelpers,
 };
 use rustc_middle::ty::{self, ExistentialTraitRef, Instance, Ty, TyCtxt};
-use rustc_session::Session;
 #[cfg(feature = "master")]
 use rustc_session::config::DebugInfo;
+use rustc_session::{PointerAuthSchema, Session};
 use rustc_span::{DUMMY_SP, Span, Symbol, respan};
 use rustc_target::spec::{HasTargetSpec, HasX86AbiOpt, Target, TlsModel, X86Abi};
 
@@ -400,7 +398,11 @@ impl<'gcc, 'tcx> MiscCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         get_fn(self, instance)
     }
 
-    fn get_fn_addr(&self, instance: Instance<'tcx>, _pac: Option<PacMetadata>) -> RValue<'gcc> {
+    fn get_fn_addr(
+        &self,
+        instance: Instance<'tcx>,
+        _pointer_auth_schema: Option<PointerAuthSchema>,
+    ) -> RValue<'gcc> {
         let func_name = self.tcx.symbol_name(instance).name;
 
         let func = if let Some(variable) = self.get_declared_value(func_name) {

compiler/rustc_codegen_gcc/src/int.rs

@@ -375,6 +375,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
             fixed_count: 3,
             conv: CanonAbi::C,
             can_unwind: false,
+            ptrauth_type_discriminator: 0,
         };
         fn_abi.adjust_for_foreign_abi(self.cx, ExternAbi::C { unwind: false });
 

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -12,12 +12,9 @@ use rustc_session::config::{
 };
 use rustc_span::sym;
 use rustc_symbol_mangling::mangle_internal_symbol;
-use rustc_target::spec::{
-    Arch, FramePointer, LlvmAbi, SanitizerSet, StackProbeType, StackProtector,
-};
+use rustc_target::spec::{Arch, FramePointer, SanitizerSet, StackProbeType, StackProtector};
 use smallvec::SmallVec;
 
-use crate::common::pauth_fn_attrs;
 use crate::context::SimpleCx;
 use crate::errors::{PackedStackBackchainNeedsSoftfloat, SanitizerMemtagRequiresMte};
 use crate::llvm::AttributePlace::Function;
@@ -668,8 +665,9 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
         }
     }
 
-    if sess.target.llvm_abiname == LlvmAbi::Pauthtest {
-        for &ptrauth_attr in pauth_fn_attrs() {
+    if sess.pointer_authentication() {
+        let cfg = sess.pointer_auth_config.as_ref().unwrap();
+        for ptrauth_attr in cfg.fn_attrs() {
             to_add.push(llvm::CreateAttrString(cx.llcx, ptrauth_attr));
         }
     }

compiler/rustc_codegen_llvm/src/base.rs

@@ -25,13 +25,12 @@ use rustc_middle::mono::Visibility;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{DebugInfo, Offload};
 use rustc_span::Symbol;
-use rustc_target::spec::{LlvmAbi, SanitizerSet};
+use rustc_target::spec::SanitizerSet;
 
 use super::ModuleLlvm;
 use crate::attributes;
 use crate::builder::Builder;
 use crate::builder::gpu_offload::OffloadGlobals;
-use crate::common::pauth_fn_attrs;
 use crate::context::CodegenCx;
 use crate::llvm::{self, Value};
 
@@ -131,8 +130,9 @@ pub(crate) fn compile_codegen_unit(
                 // FIXME(jchlanda) If it ever becomes necessary to ensure that all compiler
                 // generated functions receive the ptrauth-* attributes, `declare_fn` or
                 // `declare_raw_fn` could be used to provide those.
-                if cx.sess().target.llvm_abiname == LlvmAbi::Pauthtest {
-                    for &ptrauth_attr in pauth_fn_attrs() {
+                if cx.sess().pointer_authentication() {
+                    let cfg = cx.sess().pointer_auth_config.as_ref().unwrap();
+                    for ptrauth_attr in cfg.fn_attrs() {
                         attrs.push(llvm::CreateAttrString(cx.llcx, ptrauth_attr));
                     }
                 }
@@ -152,28 +152,22 @@ pub(crate) fn compile_codegen_unit(
                 cx.add_objc_module_flags();
             }
 
-            if cx.sess().target.llvm_abiname == LlvmAbi::Pauthtest {
-                // FIXME(jchlanda): In LLVM/Clang, there are also `aarch64-elf-pauthabi-platform`
-                // and `aarch64-elf-pauthabi-version` module flags. These are emitted into the
-                // PAuth core info section of the resulting ELF, which the linker uses to enforce
-                // binary compatibility.
-                //
-                // We intentionally do not emit these flags now, since only a subset of features
-                // included in clang's pauthtest is currently supported. By default, the absence of
-                // this info is treated as compatible with any binary.
-                //
-                // Please note, that this would cause compatibility issues, specifically runtime
-                // crashes due to authentication failures (while compiling and linking
-                // successfully) when linking against binaries that support larger set of features
-                // (for example, signing of C++ member function pointers, virtual function
-                // pointers, virtual table pointers).
-                //
-                // Link to PAuth core info documentation:
-                // <https://github.com/ARM-software/abi-aa/blob/2025Q4/pauthabielf64/pauthabielf64.rst#core-information>
-                if cx.sess().opts.unstable_opts.ptrauth_elf_got {
+            if cx.sess().pointer_authentication() {
+                let cfg = cx.sess().pointer_auth_config.as_ref().unwrap();
+
+                let aarch64_elf_pauthabi_version =
+                    cfg.calculate_pauth_abi_version(&cx.sess().target);
+                if aarch64_elf_pauthabi_version != 0 {
+                    cx.add_ptrauth_pauthabi_version_and_platform_flags(
+                        aarch64_elf_pauthabi_version,
+                    );
+                }
+                if cfg.elf_got {
                     cx.add_ptrauth_elf_got_flag();
                 }
-                cx.add_ptrauth_sign_personality_flag();
+                if cx.sess().pointer_authentication_functions().is_some() {
+                    cx.add_ptrauth_sign_personality_flag();
+                }
             }
 
             // Finalize code coverage by injecting the coverage map. Note, the coverage map will

compiler/rustc_codegen_llvm/src/builder.rs

@@ -26,7 +26,7 @@ use rustc_sanitizers::{cfi, kcfi};
 use rustc_session::config::OptLevel;
 use rustc_span::Span;
 use rustc_target::callconv::{FnAbi, PassMode};
-use rustc_target::spec::{Arch, HasTargetSpec, LlvmAbi, SanitizerSet, Target};
+use rustc_target::spec::{Arch, HasTargetSpec, SanitizerSet, Target};
 use smallvec::SmallVec;
 use tracing::{debug, instrument};
 
@@ -1543,6 +1543,30 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         let cold_inline = llvm::AttributeKind::Cold.create_attr(self.llcx);
         attributes::apply_to_callsite(llret, llvm::AttributePlace::Function, &[cold_inline]);
     }
+
+    fn ptrauth_resign(
+        &mut self,
+        value: &'ll Value,
+        old_key: u32,
+        old_discriminator: u64,
+        new_key: u32,
+        new_discriminator: u64,
+    ) -> &'ll Value {
+        let ptr_as_int = self.ptrtoint(value, self.type_i64());
+        let resigned_int = self.call_intrinsic(
+            "llvm.ptrauth.resign",
+            &[],
+            &[
+                ptr_as_int,
+                self.const_i32(old_key as i32),
+                self.const_i64(old_discriminator as i64),
+                self.const_i32(new_key as i32),
+                self.const_i64(new_discriminator as i64),
+            ],
+        );
+
+        self.inttoptr(resigned_int, self.val_ty(value))
+    }
 }
 
 impl<'ll> StaticBuilderMethods for Builder<'_, 'll, '_> {
@@ -2040,7 +2064,7 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
         llfn: &'ll Value,
         fn_abi: Option<&FnAbi<'tcx, Ty<'tcx>>>,
     ) -> Option<llvm::OperandBundleBox<'ll>> {
-        if self.sess().target.llvm_abiname != LlvmAbi::Pauthtest {
+        if self.sess().pointer_authentication_functions().is_none() {
             return None;
         }
         // Pointer authentication support is currently limited to extern "C" calls; filter out other
@@ -2060,8 +2084,14 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
         // bundles.
         // Once this is resolved, we should analyze each call and skip direct calls. See the
         // discussion in the rust-lang issue: <https://github.com/rust-lang/rust/issues/152532>
-        let key: u32 = 0;
-        let discriminator: u64 = 0;
+
+        let key: u32 = self.sess().pointer_authentication_fn_ptr_key().unwrap() as u32;
+        let discriminator = if self.sess().pointer_authentication_fn_ptr_type_discrimination() {
+            fn_abi?.ptrauth_type_discriminator
+        } else {
+            0
+        };
+
         Some(llvm::OperandBundleBox::new(
             "ptrauth",
             &[self.const_u32(key), self.const_u64(discriminator)],

compiler/rustc_codegen_llvm/src/common.rs

@@ -16,7 +16,7 @@ use rustc_middle::bug;
 use rustc_middle::mir::interpret::{GlobalAlloc, PointerArithmetic, Scalar};
 use rustc_middle::ty::{Instance, TyCtxt};
 use rustc_session::cstore::DllImport;
-use rustc_target::spec::LlvmAbi;
+use rustc_session::{PointerAuthAddressDiscriminator, PointerAuthSchema};
 use tracing::debug;
 
 use crate::consts::{IsInitOrFini, IsStatic, const_alloc_to_llvm};
@@ -26,29 +26,13 @@ use crate::llvm::{
     self, BasicBlock, ConstantInt, FALSE, TRUE, ToLlvmBool, Type, Value, const_ptr_auth,
 };
 
-#[inline]
-pub(crate) fn pauth_fn_attrs() -> &'static [&'static str] {
-    // FIXME(jchlanda) This is not an exhaustive list of all `ptrauth`-related attributes, but only
-    // those currently supported. The list is expected to grow as additional functionality is
-    // implemented, particularly for C++ interoperability.
-    &[
-        "aarch64-jump-table-hardening",
-        "ptrauth-indirect-gotos",
-        "ptrauth-calls",
-        "ptrauth-returns",
-        "ptrauth-auth-traps",
-    ]
-}
-
 pub(crate) fn maybe_sign_fn_ptr<'ll, 'tcx>(
     cx: &CodegenCx<'ll, '_>,
     instance: Instance<'tcx>,
     llfn: &'ll llvm::Value,
-    pac: PacMetadata,
+    schema: PointerAuthSchema,
 ) -> &'ll llvm::Value {
-    if cx.sess().target.llvm_abiname != LlvmAbi::Pauthtest {
-        return llfn;
-    }
+    assert!(cx.tcx.sess.pointer_authentication_functions().is_some());
 
     // Only free functions or methods
     let def_id = instance.def_id();
@@ -68,16 +52,16 @@ pub(crate) fn maybe_sign_fn_ptr<'ll, 'tcx>(
         return llfn;
     }
 
-    let addr_diversity = match pac.addr_diversity {
-        AddressDiversity::None => None,
-        AddressDiversity::Real => Some(llfn),
-        AddressDiversity::Synthetic(val) => {
+    let addr_diversity = match schema.is_address_discriminated {
+        PointerAuthAddressDiscriminator::HardwareAddress(true) => Some(llfn),
+        PointerAuthAddressDiscriminator::HardwareAddress(false) => None,
+        PointerAuthAddressDiscriminator::Synthetic(val) => {
             let llval = cx.const_u64(val);
             let llty = cx.val_ty(llfn);
             Some(unsafe { llvm::LLVMConstIntToPtr(llval, llty) })
         }
     };
-    const_ptr_auth(llfn, pac.key, pac.disc, addr_diversity)
+    const_ptr_auth(llfn, schema.key as u32, schema.constant_discriminator as u64, addr_diversity)
 }
 
 /*
@@ -331,7 +315,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
         cv: Scalar,
         layout: abi::Scalar,
         llty: &'ll Type,
-        pac: Option<PacMetadata>,
+        schema: Option<PointerAuthSchema>,
     ) -> &'ll Value {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
@@ -366,6 +350,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
                                 alloc.inner(),
                                 IsStatic::No,
                                 IsInitOrFini::No,
+                                None,
                             );
                             let alloc = alloc.inner();
                             let value = match alloc.mutability {
@@ -387,7 +372,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
                             value
                         }
                     }
-                    GlobalAlloc::Function { instance, .. } => self.get_fn_addr(instance, pac),
+                    GlobalAlloc::Function { instance, .. } => self.get_fn_addr(instance, schema),
                     GlobalAlloc::VTable(ty, dyn_ty) => {
                         let alloc = self
                             .tcx
@@ -403,6 +388,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
                             alloc.inner(),
                             IsStatic::No,
                             IsInitOrFini::No,
+                            None,
                         );
                         self.static_addr_of_impl(init, alloc.inner().align, None)
                     }