Rollup merge of rust-lang#127766 - folkertdev:c-cmse-nonsecure-entry,…

… r=jackh726

add `extern "C-cmse-nonsecure-entry" fn`

tracking issue rust-lang#75835

in rust-lang#75835 (comment) it was decided that using an abi, rather than an attribute, was the right way to go for this feature.

This PR adds that ABI and removes the `#[cmse_nonsecure_entry]` attribute. All relevant tests have been updated, some are now obsolete and have been removed.

Error 0775 is no longer generated. It contains the list of targets that support the CMSE feature, and maybe we want to still use this? right now a generic "this abi is not supported on this platform" error is returned when this abi is used on an unsupported platform. On the other hand, users of this abi are likely to be experienced rust users, so maybe the generic error is good enough.

compiler/rustc_codegen_cranelift/src/abi/mod.rs

@@ -61,6 +61,9 @@ pub(crate) fn conv_to_call_conv(sess: &Session, c: Conv, default_call_conv: Call
         Conv::CCmseNonSecureCall => {
             sess.dcx().fatal("C-cmse-nonsecure-call call conv is not yet implemented");
         }
+        Conv::CCmseNonSecureEntry => {
+            sess.dcx().fatal("C-cmse-nonsecure-entry call conv is not yet implemented");
+        }
 
         Conv::Msp430Intr | Conv::PtxKernel | Conv::AvrInterrupt | Conv::AvrNonBlockingInterrupt => {
             unreachable!("tried to use {c:?} call conv which only exists on an unsupported target");

compiler/rustc_codegen_llvm/src/abi.rs

@@ -422,6 +422,9 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
         if let Conv::RiscvInterrupt { kind } = self.conv {
             func_attrs.push(llvm::CreateAttrStringValue(cx.llcx, "interrupt", kind.as_str()));
         }
+        if let Conv::CCmseNonSecureEntry = self.conv {
+            func_attrs.push(llvm::CreateAttrString(cx.llcx, "cmse_nonsecure_entry"))
+        }
         attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &{ func_attrs });
 
         let mut i = 0;
@@ -659,9 +662,11 @@ impl<'tcx> AbiBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
 impl From<Conv> for llvm::CallConv {
     fn from(conv: Conv) -> Self {
         match conv {
-            Conv::C | Conv::Rust | Conv::CCmseNonSecureCall | Conv::RiscvInterrupt { .. } => {
-                llvm::CCallConv
-            }
+            Conv::C
+            | Conv::Rust
+            | Conv::CCmseNonSecureCall
+            | Conv::CCmseNonSecureEntry
+            | Conv::RiscvInterrupt { .. } => llvm::CCallConv,
             Conv::Cold => llvm::ColdCallConv,
             Conv::PreserveMost => llvm::PreserveMost,
             Conv::PreserveAll => llvm::PreserveAll,

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -483,9 +483,6 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
         let allocated_pointer = AttributeKind::AllocatedPointer.create_attr(cx.llcx);
         attributes::apply_to_llfn(llfn, AttributePlace::Argument(0), &[allocated_pointer]);
     }
-    if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY) {
-        to_add.push(llvm::CreateAttrString(cx.llcx, "cmse_nonsecure_entry"));
-    }
     if let Some(align) = codegen_fn_attrs.alignment {
         llvm::set_alignment(llfn, align);
     }

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -195,24 +195,6 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                     }
                 }
             }
-            sym::cmse_nonsecure_entry => {
-                if let Some(fn_sig) = fn_sig()
-                    && !matches!(fn_sig.skip_binder().abi(), abi::Abi::C { .. })
-                {
-                    struct_span_code_err!(
-                        tcx.dcx(),
-                        attr.span,
-                        E0776,
-                        "`#[cmse_nonsecure_entry]` requires C ABI"
-                    )
-                    .emit();
-                }
-                if !tcx.sess.target.llvm_target.contains("thumbv8m") {
-                    struct_span_code_err!(tcx.dcx(), attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
-                    .emit();
-                }
-                codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY
-            }
             sym::thread_local => codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL,
             sym::track_caller => {
                 let is_closure = tcx.is_closure_like(did.to_def_id());

compiler/rustc_error_codes/src/error_codes/E0775.md

@@ -1,13 +1,14 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 `#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M
 extension.
 
 Erroneous code example:
 
-```compile_fail,E0775
+```ignore (no longer emitted)
 #![feature(cmse_nonsecure_entry)]
 
-#[cmse_nonsecure_entry]
-pub extern "C" fn entry_function() {}
+pub extern "C-cmse-nonsecure-entry" fn entry_function() {}
 ```
 
 To fix this error, compile your code for a Rust target that supports the

compiler/rustc_error_codes/src/error_codes/E0776.md

@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 `#[cmse_nonsecure_entry]` functions require a C ABI
 
 Erroneous code example:
 
-```compile_fail,E0776
+```ignore (no longer emitted)
 #![feature(cmse_nonsecure_entry)]
 
 #[no_mangle]

compiler/rustc_error_codes/src/lib.rs

@@ -681,4 +681,5 @@ E0800: 0800,
 //  E0723, // unstable feature in `const` context
 //  E0738, // Removed; errored on `#[track_caller] fn`s in `extern "Rust" { ... }`.
 //  E0744, // merged into E0728
+//  E0776, // Removed; cmse_nonsecure_entry is now `C-cmse-nonsecure-entry`
 //  E0796, // unused error code. We use `static_mut_refs` lint instead.

compiler/rustc_feature/src/builtin_attrs.rs

@@ -551,10 +551,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         EncodeCrossCrate::No, experimental!(register_tool),
     ),
 
-    gated!(
-        cmse_nonsecure_entry, Normal, template!(Word), WarnFollowing,
-        EncodeCrossCrate::No, experimental!(cmse_nonsecure_entry)
-    ),
     // RFC 2632
     gated!(
         const_trait, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No, const_trait_impl,

compiler/rustc_feature/src/unstable.rs

@@ -395,7 +395,7 @@ declare_features! (
     (unstable, closure_lifetime_binder, "1.64.0", Some(97362)),
     /// Allows `#[track_caller]` on closures and coroutines.
     (unstable, closure_track_caller, "1.57.0", Some(87417)),
-    /// Allows to use the `#[cmse_nonsecure_entry]` attribute.
+    /// Allows `extern "C-cmse-nonsecure-entry" fn()`.
     (unstable, cmse_nonsecure_entry, "1.48.0", Some(75835)),
     /// Allows `async {}` expressions in const contexts.
     (unstable, const_async_blocks, "1.53.0", Some(85368)),

compiler/rustc_middle/src/middle/codegen_fn_attrs.rs

@@ -120,9 +120,7 @@ bitflags::bitflags! {
         /// #[ffi_const]: applies clang's `const` attribute to a foreign function
         /// declaration.
         const FFI_CONST                 = 1 << 12;
-        /// #[cmse_nonsecure_entry]: with a TrustZone-M extension, declare a
-        /// function as an entry function from Non-Secure code.
-        const CMSE_NONSECURE_ENTRY      = 1 << 13;
+        // (Bit 13 was used for `#[cmse_nonsecure_entry]`, but is now unused.)
         // (Bit 14 was used for `#[coverage(off)]`, but is now unused.)
         /// `#[used(linker)]`:
         /// indicates that neither LLVM nor the linker will eliminate this function.

compiler/rustc_middle/src/ty/layout.rs

@@ -1191,6 +1191,7 @@ pub fn fn_can_unwind(tcx: TyCtxt<'_>, fn_def_id: Option<DefId>, abi: SpecAbi) ->
         | RiscvInterruptM
         | RiscvInterruptS
         | CCmseNonSecureCall
+        | CCmseNonSecureEntry
         | Unadjusted => false,
         Rust | RustCall | RustCold | RustIntrinsic => {
             tcx.sess.panic_strategy() == PanicStrategy::Unwind

compiler/rustc_passes/src/check_attr.rs

@@ -188,9 +188,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 | [sym::rustc_must_implement_one_of, ..]
                 | [sym::rustc_deny_explicit_impl, ..]
                 | [sym::const_trait, ..] => self.check_must_be_applied_to_trait(attr, span, target),
-                [sym::cmse_nonsecure_entry, ..] => {
-                    self.check_cmse_nonsecure_entry(hir_id, attr, span, target)
-                }
                 [sym::collapse_debuginfo, ..] => self.check_collapse_debuginfo(attr, span, target),
                 [sym::must_not_suspend, ..] => self.check_must_not_suspend(attr, span, target),
                 [sym::must_use, ..] => self.check_must_use(hir_id, attr, target),
@@ -563,27 +560,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
-    fn check_cmse_nonsecure_entry(
-        &self,
-        hir_id: HirId,
-        attr: &Attribute,
-        span: Span,
-        target: Target,
-    ) {
-        match target {
-            Target::Fn
-            | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => {}
-            _ => {
-                self.dcx().emit_err(errors::AttrShouldBeAppliedToFn {
-                    attr_span: attr.span,
-                    defn_span: span,
-                    on_crate: hir_id == CRATE_HIR_ID,
-                });
-            }
-        }
-    }
-
     /// Debugging aid for `object_lifetime_default` query.
     fn check_object_lifetime_default(&self, hir_id: HirId) {
         let tcx = self.tcx;

compiler/rustc_smir/src/rustc_internal/internal.rs

@@ -470,6 +470,7 @@ impl RustcInternal for Abi {
             Abi::AvrInterrupt => rustc_target::spec::abi::Abi::AvrInterrupt,
             Abi::AvrNonBlockingInterrupt => rustc_target::spec::abi::Abi::AvrNonBlockingInterrupt,
             Abi::CCmseNonSecureCall => rustc_target::spec::abi::Abi::CCmseNonSecureCall,
+            Abi::CCmseNonSecureEntry => rustc_target::spec::abi::Abi::CCmseNonSecureEntry,
             Abi::System { unwind } => rustc_target::spec::abi::Abi::System { unwind },
             Abi::RustIntrinsic => rustc_target::spec::abi::Abi::RustIntrinsic,
             Abi::RustCall => rustc_target::spec::abi::Abi::RustCall,

compiler/rustc_smir/src/rustc_smir/convert/abi.rs

@@ -105,6 +105,7 @@ impl<'tcx> Stable<'tcx> for rustc_target::abi::call::Conv {
             Conv::PreserveAll => CallConvention::PreserveAll,
             Conv::ArmAapcs => CallConvention::ArmAapcs,
             Conv::CCmseNonSecureCall => CallConvention::CCmseNonSecureCall,
+            Conv::CCmseNonSecureEntry => CallConvention::CCmseNonSecureEntry,
             Conv::Msp430Intr => CallConvention::Msp430Intr,
             Conv::PtxKernel => CallConvention::PtxKernel,
             Conv::X86Fastcall => CallConvention::X86Fastcall,

compiler/rustc_smir/src/rustc_smir/convert/ty.rs

@@ -910,6 +910,7 @@ impl<'tcx> Stable<'tcx> for rustc_target::spec::abi::Abi {
             abi::Abi::AvrInterrupt => Abi::AvrInterrupt,
             abi::Abi::AvrNonBlockingInterrupt => Abi::AvrNonBlockingInterrupt,
             abi::Abi::CCmseNonSecureCall => Abi::CCmseNonSecureCall,
+            abi::Abi::CCmseNonSecureEntry => Abi::CCmseNonSecureEntry,
             abi::Abi::System { unwind } => Abi::System { unwind },
             abi::Abi::RustIntrinsic => Abi::RustIntrinsic,
             abi::Abi::RustCall => Abi::RustCall,

compiler/rustc_target/src/abi/call/mod.rs

@@ -779,6 +779,7 @@ pub enum Conv {
     // Target-specific calling conventions.
     ArmAapcs,
     CCmseNonSecureCall,
+    CCmseNonSecureEntry,
 
     Msp430Intr,
 
@@ -972,6 +973,7 @@ impl FromStr for Conv {
             "RustCold" => Ok(Conv::Rust),
             "ArmAapcs" => Ok(Conv::ArmAapcs),
             "CCmseNonSecureCall" => Ok(Conv::CCmseNonSecureCall),
+            "CCmseNonSecureEntry" => Ok(Conv::CCmseNonSecureEntry),
             "Msp430Intr" => Ok(Conv::Msp430Intr),
             "PtxKernel" => Ok(Conv::PtxKernel),
             "X86Fastcall" => Ok(Conv::X86Fastcall),

compiler/rustc_target/src/json.rs

@@ -103,6 +103,7 @@ impl ToJson for crate::abi::call::Conv {
             Self::PreserveAll => "PreserveAll",
             Self::ArmAapcs => "ArmAapcs",
             Self::CCmseNonSecureCall => "CCmseNonSecureCall",
+            Self::CCmseNonSecureEntry => "CCmseNonSecureEntry",
             Self::Msp430Intr => "Msp430Intr",
             Self::PtxKernel => "PtxKernel",
             Self::X86Fastcall => "X86Fastcall",

compiler/rustc_target/src/spec/abi/mod.rs

@@ -48,6 +48,7 @@ pub enum Abi {
     AvrInterrupt,
     AvrNonBlockingInterrupt,
     CCmseNonSecureCall,
+    CCmseNonSecureEntry,
     System {
         unwind: bool,
     },
@@ -124,6 +125,7 @@ const AbiDatas: &[AbiData] = &[
     AbiData { abi: Abi::AvrInterrupt, name: "avr-interrupt" },
     AbiData { abi: Abi::AvrNonBlockingInterrupt, name: "avr-non-blocking-interrupt" },
     AbiData { abi: Abi::CCmseNonSecureCall, name: "C-cmse-nonsecure-call" },
+    AbiData { abi: Abi::CCmseNonSecureEntry, name: "C-cmse-nonsecure-entry" },
     AbiData { abi: Abi::System { unwind: false }, name: "system" },
     AbiData { abi: Abi::System { unwind: true }, name: "system-unwind" },
     AbiData { abi: Abi::RustIntrinsic, name: "rust-intrinsic" },
@@ -244,6 +246,10 @@ pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
             feature: sym::abi_c_cmse_nonsecure_call,
             explain: "C-cmse-nonsecure-call ABI is experimental and subject to change",
         }),
+        "C-cmse-nonsecure-entry" => Err(AbiDisabled::Unstable {
+            feature: sym::cmse_nonsecure_entry,
+            explain: "C-cmse-nonsecure-entry ABI is experimental and subject to change",
+        }),
         _ => Err(AbiDisabled::Unrecognized),
     }
 }
@@ -286,15 +292,16 @@ impl Abi {
             AvrInterrupt => 23,
             AvrNonBlockingInterrupt => 24,
             CCmseNonSecureCall => 25,
+            CCmseNonSecureEntry => 26,
             // Cross-platform ABIs
-            System { unwind: false } => 26,
-            System { unwind: true } => 27,
-            RustIntrinsic => 28,
-            RustCall => 29,
-            Unadjusted => 30,
-            RustCold => 31,
-            RiscvInterruptM => 32,
-            RiscvInterruptS => 33,
+            System { unwind: false } => 27,
+            System { unwind: true } => 28,
+            RustIntrinsic => 29,
+            RustCall => 30,
+            Unadjusted => 31,
+            RustCold => 32,
+            RiscvInterruptM => 33,
+            RiscvInterruptS => 34,
         };
         debug_assert!(
             AbiDatas

compiler/rustc_target/src/spec/mod.rs

@@ -2724,7 +2724,10 @@ impl Target {
             }
             X86Interrupt => ["x86", "x86_64"].contains(&&self.arch[..]),
             Aapcs { .. } => "arm" == self.arch,
-            CCmseNonSecureCall => ["arm", "aarch64"].contains(&&self.arch[..]),
+            CCmseNonSecureCall | CCmseNonSecureEntry => {
+                ["thumbv8m.main-none-eabi", "thumbv8m.main-none-eabihf", "thumbv8m.base-none-eabi"]
+                    .contains(&&self.llvm_target[..])
+            }
             Win64 { .. } | SysV64 { .. } => self.arch == "x86_64",
             PtxKernel => self.arch == "nvptx64",
             Msp430Interrupt => self.arch == "msp430",

compiler/rustc_ty_utils/src/abi.rs

@@ -312,6 +312,7 @@ fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi, c_variadic: bool) -> Conv {
         SysV64 { .. } => Conv::X86_64SysV,
         Aapcs { .. } => Conv::ArmAapcs,
         CCmseNonSecureCall => Conv::CCmseNonSecureCall,
+        CCmseNonSecureEntry => Conv::CCmseNonSecureEntry,
         PtxKernel => Conv::PtxKernel,
         Msp430Interrupt => Conv::Msp430Intr,
         X86Interrupt => Conv::X86Intr,

compiler/stable_mir/src/abi.rs

@@ -433,6 +433,7 @@ pub enum CallConvention {
     // Target-specific calling conventions.
     ArmAapcs,
     CCmseNonSecureCall,
+    CCmseNonSecureEntry,
 
     Msp430Intr,
 

compiler/stable_mir/src/ty.rs

@@ -1062,6 +1062,7 @@ pub enum Abi {
     AvrInterrupt,
     AvrNonBlockingInterrupt,
     CCmseNonSecureCall,
+    CCmseNonSecureEntry,
     System { unwind: bool },
     RustIntrinsic,
     RustCall,

src/doc/unstable-book/src/language-features/cmse-nonsecure-entry.md

@@ -15,10 +15,10 @@ LLVM, the Rust compiler and the linker are providing
 TrustZone-M feature.
 
 One of the things provided, with this unstable feature, is the
-`cmse_nonsecure_entry` attribute.  This attribute marks a Secure function as an
+`C-cmse-nonsecure-entry` ABI. This ABI marks a Secure function as an
 entry function (see [section
 5.4](https://developer.arm.com/documentation/ecm0359818/latest/) for details).
-With this attribute, the compiler will do the following:
+With this ABI, the compiler will do the following:
 * add a special symbol on the function which is the `__acle_se_` prefix and the
   standard function name
 * constrain the number of parameters to avoid using the Non-Secure stack
@@ -38,11 +38,11 @@ gateway veneer.
 <!-- NOTE(ignore) this example is specific to thumbv8m targets -->
 
 ``` rust,ignore
+#![no_std]
 #![feature(cmse_nonsecure_entry)]
 
 #[no_mangle]
-#[cmse_nonsecure_entry]
-pub extern "C" fn entry_function(input: u32) -> u32 {
+pub extern "C-cmse-nonsecure-entry" fn entry_function(input: u32) -> u32 {
     input + 6
 }
 ```

src/tools/rust-analyzer/crates/hir-ty/src/lib.rs

@@ -377,6 +377,7 @@ pub enum FnAbi {
     AvrNonBlockingInterrupt,
     C,
     CCmseNonsecureCall,
+    CCmseNonsecureEntry,
     CDecl,
     CDeclUnwind,
     CUnwind,
@@ -434,6 +435,7 @@ impl FnAbi {
             s if *s == sym::avr_dash_interrupt => FnAbi::AvrInterrupt,
             s if *s == sym::avr_dash_non_dash_blocking_dash_interrupt => FnAbi::AvrNonBlockingInterrupt,
             s if *s == sym::C_dash_cmse_dash_nonsecure_dash_call => FnAbi::CCmseNonsecureCall,
+            s if *s == sym::C_dash_cmse_dash_nonsecure_dash_entry => FnAbi::CCmseNonsecureEntry,
             s if *s == sym::C_dash_unwind => FnAbi::CUnwind,
             s if *s == sym::C => FnAbi::C,
             s if *s == sym::cdecl_dash_unwind => FnAbi::CDeclUnwind,
@@ -477,6 +479,7 @@ impl FnAbi {
             FnAbi::AvrNonBlockingInterrupt => "avr-non-blocking-interrupt",
             FnAbi::C => "C",
             FnAbi::CCmseNonsecureCall => "C-cmse-nonsecure-call",
+            FnAbi::CCmseNonsecureEntry => "C-cmse-nonsecure-entry",
             FnAbi::CDecl => "C-decl",
             FnAbi::CDeclUnwind => "cdecl-unwind",
             FnAbi::CUnwind => "C-unwind",

src/tools/rust-analyzer/crates/ide-completion/src/completions/extern_abi.rs

@@ -32,6 +32,7 @@ const SUPPORTED_CALLING_CONVENTIONS: &[&str] = &[
     "riscv-interrupt-m",
     "riscv-interrupt-s",
     "C-cmse-nonsecure-call",
+    "C-cmse-nonsecure-entry",
     "wasm",
     "system",
     "system-unwind",

src/tools/rust-analyzer/crates/intern/src/symbol/symbols.rs

@@ -94,6 +94,7 @@ define_symbols! {
     avr_dash_interrupt = "avr-interrupt",
     avr_dash_non_dash_blocking_dash_interrupt = "avr-non-blocking-interrupt",
     C_dash_cmse_dash_nonsecure_dash_call = "C-cmse-nonsecure-call",
+    C_dash_cmse_dash_nonsecure_dash_entry = "C-cmse-nonsecure-entry",
     C_dash_unwind = "C-unwind",
     cdecl_dash_unwind = "cdecl-unwind",
     fastcall_dash_unwind = "fastcall-unwind",

src/tools/tidy/src/issues.txt

@@ -467,7 +467,6 @@ ui/closures/issue-87814-2.rs
 ui/closures/issue-90871.rs
 ui/closures/issue-97607.rs
 ui/closures/issue-99565.rs
-ui/cmse-nonsecure/cmse-nonsecure-entry/issue-83475.rs
 ui/codegen/auxiliary/issue-97708-aux.rs
 ui/codegen/issue-101585-128bit-repeat.rs
 ui/codegen/issue-16602-1.rs