Merge #262

262: Merge asm implementations r=therealprof a=jonas-schievink

This replaces the implementation of `inline-asm` with the file I wrote in #259 (and some fixes).

All functions that call assembly now do so via a `call_asm!` macro that either dispatches to a call to an `#[inline(always)]` function containing the inline `asm!`, or to the FFI shim. This makes all functions that call into asm significantly shorter.

The FFI shim is now also macro-generated, which makes it very small.

Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>

1 files changed, 0 insertions, 346 deletions

diff --git a/asm.rs b/asm.rs
deleted file mode 100644
index f5b0179..0000000
--- a/asm.rs
+++ /dev/null
@@ -1,346 +0,0 @@
-//! Assembly stubs for the `cortex-m` crate.
-//!
-//! We use this file to precompile some assembly stubs into the static libraries you can find in
-//! `bin`. Apps using the `cortex-m` crate then link against those static libraries and don't need
-//! to build this file themselves.
-//!
-//! Nowadays the assembly stubs are no longer actual assembly files, but actually just this Rust
-//! file `asm.rs` that uses unstable inline assembly, coupled with the `xtask` tool to invoke rustc
-//! and build the files.
-//!
-//! Precompiling this to a static lib allows users to call assembly routines from stable Rust, but
-//! also perform [linker plugin LTO] with the precompiled artifacts to completely inline the
-//! assembly routines into their code, which brings the "outline assembly" on par with "real" inline
-//! assembly.
-//!
-//! For developers and contributors to `cortex-m`, this setup means that they don't have to install
-//! any binutils, assembler, or C compiler to hack on the crate. All they need is to run `cargo
-//! xtask assemble` to rebuild the archives from this file.
-//!
-//! Cool, right?
-//!
-//! # Rust version management
-//!
-//! Since inline assembly is still unstable, and we want to ensure that the created blobs are
-//! up-to-date in CI, we have to pin the nightly version we use for this. The nightly toolchain is
-//! stored in `asm-toolchain`.
-//!
-//! The `cargo xtask` automation will automatically install the `asm-toolchain` as well as all
-//! Cortex-M targets needed to generate the blobs.
-//!
-//! [linker plugin LTO]: https://doc.rust-lang.org/stable/rustc/linker-plugin-lto.html
-
-#![feature(asm)]
-#![no_std]
-#![crate_type = "staticlib"]
-#![deny(warnings)]
-
-#[no_mangle]
-pub unsafe extern "C" fn __bkpt() {
-    asm!("bkpt");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __control_r() -> u32 {
-    let r;
-    asm!("mrs {}, CONTROL", out(reg) r);
-    r
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __control_w(w: u32) {
-    asm!("msr CONTROL, {}", in(reg) w);
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __cpsid() {
-    asm!("cpsid i");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __cpsie() {
-    asm!("cpsie i");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __delay(cyc: u32) {
-    asm!("
-    1:
-        nop
-        subs {}, #1
-        bne 1b
-        // Branch to 1 instead of __delay does not generate R_ARM_THM_JUMP8 relocation, which breaks
-        // linking on the thumbv6m-none-eabi target
-    ", in(reg) cyc);
-}
-
-// FIXME do we need compiler fences here or should we expect them in the caller?
-#[no_mangle]
-pub unsafe extern "C" fn __dmb() {
-    asm!("dmb 0xF");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __dsb() {
-    asm!("dsb 0xF");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __isb() {
-    asm!("isb 0xF");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __msp_r() -> u32 {
-    let r;
-    asm!("mrs {}, MSP", out(reg) r);
-    r
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __msp_w(val: u32) {
-    asm!("msr MSP, {}", in(reg) val);
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __nop() {
-    // NOTE: This is a `pure` asm block, but applying that option allows the compiler to eliminate
-    // the nop entirely (or to collapse multiple subsequent ones). Since the user probably wants N
-    // nops when they call `nop` N times, let's not add that option.
-    asm!("nop");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __primask() -> u32 {
-    // FIXME: rename to __primask_r
-    let r;
-    asm!("mrs {}, PRIMASK", out(reg) r);
-    r
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __psp_r() -> u32 {
-    let r;
-    asm!("mrs {}, PSP", out(reg) r);
-    r
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __psp_w(val: u32) {
-    asm!("msr PSP, {}", in(reg) val);
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __sev() {
-    asm!("sev");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __udf() {
-    asm!("udf #0");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __wfe() {
-    asm!("wfe");
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn __wfi() {
-    asm!("wfi");
-}
-
-#[cfg(armv7m)]
-pub mod v7m {
-    #[no_mangle]
-    pub unsafe extern "C" fn __basepri_max(val: u8) {
-        asm!("msr BASEPRI_MAX, {}", in(reg) val);
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __basepri_r() -> u8 {
-        let r;
-        asm!("mrs {}, BASEPRI", out(reg) r);
-        r
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __basepri_w(val: u8) {
-        asm!("msr BASEPRI, {}", in(reg) val);
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __faultmask() -> u32 {
-        let r;
-        asm!("mrs {}, FAULTMASK", out(reg) r);
-        r
-    }
-
-    // FIXME: compiler_fences necessary?
-    #[no_mangle]
-    pub unsafe extern "C" fn __enable_icache() {
-        asm!(
-            "
-            ldr r0, =0xE000ED14       @ CCR
-            mrs r2, PRIMASK           @ save critical nesting info
-            cpsid i                   @ mask interrupts
-            ldr r1, [r0]              @ read CCR
-            orr.w r1, r1, #(1 << 17)  @ Set bit 17, IC
-            str r1, [r0]              @ write it back
-            dsb                       @ ensure store completes
-            isb                       @ synchronize pipeline
-            msr PRIMASK, r2           @ unnest critical section
-            ",
-            out("r0") _,
-            out("r1") _,
-            out("r2") _,
-        );
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __enable_dcache() {
-        asm!(
-            "
-            ldr r0, =0xE000ED14       @ CCR
-            mrs r2, PRIMASK           @ save critical nesting info
-            cpsid i                   @ mask interrupts
-            ldr r1, [r0]              @ read CCR
-            orr.w r1, r1, #(1 << 16)  @ Set bit 16, DC
-            str r1, [r0]              @ write it back
-            dsb                       @ ensure store completes
-            isb                       @ synchronize pipeline
-            msr PRIMASK, r2           @ unnest critical section
-            ",
-            out("r0") _,
-            out("r1") _,
-            out("r2") _,
-        );
-    }
-}
-
-#[cfg(armv7em)]
-mod v7em {
-    #[no_mangle]
-    pub unsafe extern "C" fn __basepri_max_cm7_r0p1(val: u8) {
-        asm!(
-            "
-            mrs r1, PRIMASK
-            cpsid i
-            tst.w r1, #1
-            msr BASEPRI_MAX, {}
-            it ne
-            bxne lr
-            cpsie i
-            ",
-            in(reg) val,
-            out("r1") _,
-        );
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __basepri_w_cm7_r0p1(val: u8) {
-        asm!(
-            "
-            mrs r1, PRIMASK
-            cpsid i
-            tst.w r1, #1
-            msr BASEPRI, {}
-            it ne
-            bxne lr
-            cpsie i
-            ",
-            in(reg) val,
-            out("r1") _,
-        );
-    }
-}
-
-/// Baseline and Mainline.
-#[cfg(armv8m)]
-pub mod v8m {
-    #[no_mangle]
-    pub unsafe extern "C" fn __tt(mut target: u32) -> u32 {
-        asm!("tt {target}, {target}", target = inout(reg) target);
-        target
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __ttt(mut target: u32) -> u32 {
-        asm!("ttt {target}, {target}", target = inout(reg) target);
-        target
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __tta(mut target: u32) -> u32 {
-        asm!("tta {target}, {target}", target = inout(reg) target);
-        target
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __ttat(mut target: u32) -> u32 {
-        asm!("ttat {target}, {target}", target = inout(reg) target);
-        target
-    }
-}
-
-/// Mainline only.
-#[cfg(armv8m_main)]
-pub mod v8m_main {
-    #[no_mangle]
-    pub unsafe extern "C" fn __msplim_r() -> u32 {
-        let r;
-        asm!("mrs {}, MSPLIM", out(reg) r);
-        r
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __msplim_w(val: u32) {
-        asm!("msr MSPLIM, {}", in(reg) val);
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __psplim_r() -> u32 {
-        let r;
-        asm!("mrs {}, PSPLIM", out(reg) r);
-        r
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __psplim_w(val: u32) {
-        asm!("msr PSPLIM, {}", in(reg) val);
-    }
-}
-
-/// All targets with FPU.
-#[cfg(has_fpu)]
-pub mod fpu {
-    #[no_mangle]
-    pub unsafe extern "C" fn __get_FPSCR() -> u32 {
-        let r;
-        asm!("vmrs {}, fpscr", out(reg) r);
-        r
-    }
-
-    #[no_mangle]
-    pub unsafe extern "C" fn __set_FPSCR(val: u32) {
-        asm!("vmsr fpscr, {}", in(reg) val);
-    }
-}
-
-/// We *must* define a panic handler here, even though nothing here should ever be able to panic.
-///
-/// We prove that nothing will ever panic by calling a function that doesn't exist. If the panic
-/// handler gets linked in, this causes a linker error. We always build this file with optimizations
-/// enabled, but even without them the panic handler should never be linked in.
-#[panic_handler]
-fn panic(_: &core::panic::PanicInfo) -> ! {
-    extern "C" {
-        #[link_name = "cortex-m internal error: panic handler not optimized out, please file an \
-        issue at https://github.com/rust-embedded/cortex-m"]
-        fn __cortex_m_should_not_panic() -> !;
-    }
-
-    unsafe {
-        __cortex_m_should_not_panic();
-    }
-}