Merge #189

189: Initial Rust CMSE support r=thejpster a=hug-dev

Armv8-M and Armv8.1-M architecture profiles have an optional Security Extension which provides a set of Security features.
This patch adds initial support of the Cortex-M Security Extensions but providing support for the TT intrinsics and helper functions on top of it in the newly added `cmse` module of this crate.
The code is a Rust idiomatic implementation of the C requirements described in this document: https://developer.arm.com/docs/ecm0359818/latest

Executed `assemble.sh` to generate the new static libraries containing the `TT*` instructions. Tested `check_blobs.sh` locally and it passed.
Tested on QEMU using the `mps2-an505` machine.

Co-authored-by: Hugues de Valon <[email protected]>

Author: bors[bot]

Cargo.toml

@@ -18,6 +18,7 @@ links = "cortex-m"  # prevent multiple versions of this crate to be linked toget
 [dependencies]
 bare-metal = { version = "0.2.0", features = ["const-fn"] }
 volatile-register = "0.2.0"
+bitfield = "0.13.2"
 
 [features]
 cm7-r0p1 = []

asm-v8.s

@@ -0,0 +1,27 @@
+  .section .text.__tt
+  .global __tt
+  .thumb_func
+__tt:
+  tt r0, r0
+  bx lr
+
+  .section .text.__ttt
+  .global __ttt
+  .thumb_func
+__ttt:
+  ttt r0, r0
+  bx lr
+
+  .section .text.__tta
+  .global __tta
+  .thumb_func
+__tta:
+  tta r0, r0
+  bx lr
+
+  .section .text.__ttat
+  .global __ttat
+  .thumb_func
+__ttat:
+  ttat r0, r0
+  bx lr

assemble.sh

@@ -23,15 +23,18 @@ ar crs bin/thumbv7em-none-eabi.a bin/$crate.o bin/$crate-v7.o bin/$crate-cm7-r0p
 ar crs bin/thumbv7em-none-eabihf.a bin/$crate.o bin/$crate-v7.o bin/$crate-cm7-r0p1.o
 
 arm-none-eabi-as -march=armv8-m.base asm.s -o bin/$crate.o
-ar crs bin/thumbv8m.base-none-eabi.a bin/$crate.o
+arm-none-eabi-as -march=armv8-m.base asm-v8.s -o bin/$crate-v8.o
+ar crs bin/thumbv8m.base-none-eabi.a bin/$crate.o bin/$crate-v8.o
 
 arm-none-eabi-as -march=armv8-m.main asm.s -o bin/$crate.o
 arm-none-eabi-as -march=armv8-m.main asm-v7.s -o bin/$crate-v7.o
+arm-none-eabi-as -march=armv8-m.main asm-v8.s -o bin/$crate-v8.o
 arm-none-eabi-as -march=armv8-m.main asm-v8-main.s -o bin/$crate-v8-main.o
-ar crs bin/thumbv8m.main-none-eabi.a bin/$crate.o bin/$crate-v7.o bin/$crate-v8-main.o
-ar crs bin/thumbv8m.main-none-eabihf.a bin/$crate.o bin/$crate-v7.o bin/$crate-v8-main.o
+ar crs bin/thumbv8m.main-none-eabi.a bin/$crate.o bin/$crate-v7.o bin/$crate-v8.o bin/$crate-v8-main.o
+ar crs bin/thumbv8m.main-none-eabihf.a bin/$crate.o bin/$crate-v7.o bin/$crate-v8.o bin/$crate-v8-main.o
 
 rm bin/$crate.o
 rm bin/$crate-v7.o
 rm bin/$crate-cm7-r0p1.o
+rm bin/$crate-v8.o
 rm bin/$crate-v8-main.o

bin/thumbv8m.base-none-eabi.a

@@ -222,3 +222,144 @@ pub fn dmb() {
         () => unimplemented!(),
     }
 }
+
+/// Test Target
+///
+/// Queries the Security state and access permissions of a memory location.
+/// Returns a Test Target Response Payload (cf section D1.2.215 of
+/// Armv8-M Architecture Reference Manual).
+#[inline]
+#[cfg(armv8m)]
+// The __tt function does not dereference the pointer received.
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+pub fn tt(addr: *mut u32) -> u32 {
+    match () {
+        #[cfg(all(cortex_m, feature = "inline-asm"))]
+        () => {
+            let tt_resp: u32;
+            unsafe {
+                asm!("tt $0, $1" : "=r"(tt_resp) : "r"(addr) :: "volatile");
+            }
+            tt_resp
+        }
+
+        #[cfg(all(cortex_m, not(feature = "inline-asm")))]
+        () => unsafe {
+            extern "C" {
+                fn __tt(_: *mut u32) -> u32;
+            }
+
+            __tt(addr)
+        },
+
+        #[cfg(not(cortex_m))]
+        () => unimplemented!(),
+    }
+}
+
+/// Test Target Unprivileged
+///
+/// Queries the Security state and access permissions of a memory location for an unprivileged
+/// access to that location.
+/// Returns a Test Target Response Payload (cf section D1.2.215 of
+/// Armv8-M Architecture Reference Manual).
+#[inline]
+#[cfg(armv8m)]
+// The __ttt function does not dereference the pointer received.
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+pub fn ttt(addr: *mut u32) -> u32 {
+    match () {
+        #[cfg(all(cortex_m, feature = "inline-asm"))]
+        () => {
+            let tt_resp: u32;
+            unsafe {
+                asm!("ttt $0, $1" : "=r"(tt_resp) : "r"(addr) :: "volatile");
+            }
+            tt_resp
+        }
+
+        #[cfg(all(cortex_m, not(feature = "inline-asm")))]
+        () => unsafe {
+            extern "C" {
+                fn __ttt(_: *mut u32) -> u32;
+            }
+
+            __ttt(addr)
+        },
+
+        #[cfg(not(cortex_m))]
+        () => unimplemented!(),
+    }
+}
+
+/// Test Target Alternate Domain
+///
+/// Queries the Security state and access permissions of a memory location for a Non-Secure access
+/// to that location. This instruction is only valid when executing in Secure state and is
+/// undefined if used from Non-Secure state.
+/// Returns a Test Target Response Payload (cf section D1.2.215 of
+/// Armv8-M Architecture Reference Manual).
+#[inline]
+#[cfg(armv8m)]
+// The __tta function does not dereference the pointer received.
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+pub fn tta(addr: *mut u32) -> u32 {
+    match () {
+        #[cfg(all(cortex_m, feature = "inline-asm"))]
+        () => {
+            let tt_resp: u32;
+            unsafe {
+                asm!("tta $0, $1" : "=r"(tt_resp) : "r"(addr) :: "volatile");
+            }
+            tt_resp
+        }
+
+        #[cfg(all(cortex_m, not(feature = "inline-asm")))]
+        () => unsafe {
+            extern "C" {
+                fn __tta(_: *mut u32) -> u32;
+            }
+
+            __tta(addr)
+        },
+
+        #[cfg(not(cortex_m))]
+        () => unimplemented!(),
+    }
+}
+
+/// Test Target Alternate Domain Unprivileged
+///
+/// Queries the Security state and access permissions of a memory location for a Non-Secure and
+/// unprivileged access to that location. This instruction is only valid when executing in Secure
+/// state and is undefined if used from Non-Secure state.
+/// Returns a Test Target Response Payload (cf section D1.2.215 of
+/// Armv8-M Architecture Reference Manual).
+#[inline]
+#[cfg(armv8m)]
+// The __ttat function does not dereference the pointer received.
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+pub fn ttat(addr: *mut u32) -> u32 {
+    match () {
+        #[cfg(all(cortex_m, feature = "inline-asm"))]
+        () => {
+            let tt_resp: u32;
+            unsafe {
+                asm!("ttat $0, $1" : "=r"(tt_resp) : "r"(addr) :: "volatile");
+            }
+            tt_resp
+        }
+
+        #[cfg(all(cortex_m, not(feature = "inline-asm")))]
+        () => unsafe {
+            extern "C" {
+                fn __ttat(_: *mut u32) -> u32;
+            }
+
+            __ttat(addr)
+        },
+
+        #[cfg(not(cortex_m))]
+        () => unimplemented!(),
+    }
+}