Merge pull request #64 from japaric/v4

v0.4.0: with LLD support

Author: japaric

cortex-m-rt/CHANGELOG.md

@@ -7,6 +7,37 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## [v0.4.0] - 2018-04-09
+
+### Added
+
+- LLD support. The linker script provided by this crate has been tweaked to support both LLD and GNU
+  LD. To use LLD as a linker change `.cargo/config` to look like this:
+
+``` diff
+ [target.thumbv7m-none-eabi]
+ rustflags = [
+   "-C", "link-arg=-Tlink.x",
+-  "-C", "linker=arm-none-eabi-ld",
+-  "-Z", "linker-flavor=ld",
++  "-C", "linker=lld",
++  "-Z", "linker-flavor=ld.lld",
+ ]
+```
+
+### Removed
+
+- [breaking-change] Stack overflow protection has been removed. Unfortunately, supporting this
+  feature produces totally wrong `arm-none-eabi-size` reports when LLD is used to link the
+  program. If you need the stack overflow protection feature you can continue to use version
+  v0.3.13+.
+
+- [breaking-change] The "abort-on-panic" Cargo feature, which provided a `panic_fmt` implementation,
+  has been removed. If you were using this feature you can instead use a [panic implementation
+  crate][panic-impl].
+
+[panic-impl]: https://crates.io/keywords/panic-impl
+
 ## [v0.3.15] - 2018-04-08
 
 ### Fixed

cortex-m-rt/Cargo.toml

@@ -7,16 +7,8 @@ keywords = ["arm", "cortex-m", "runtime", "startup"]
 license = "MIT OR Apache-2.0"
 name = "cortex-m-rt"
 repository = "https://github.com/japaric/cortex-m-rt"
-version = "0.3.15"
+version = "0.4.0"
 
 [dependencies]
 cortex-m = "0.3.0"
-r0 = "0.2.1"
-
-[features]
-# provides a panic_fmt implementation that calls the abort instruction (`udf 0xfe`)
-abort-on-panic = []
-
-[build-dependencies]
-rustc_version = "0.2.1"
-chrono = "0.4.0"
+r0 = "0.2.1"

cortex-m-rt/build.rs

@@ -1,28 +1,9 @@
-extern crate chrono;
-extern crate rustc_version;
-
 use std::env;
 use std::fs::File;
 use std::io::Write;
 use std::path::PathBuf;
 
-use chrono::NaiveDate;
-
 fn main() {
-    let meta = rustc_version::version_meta().unwrap();
-    let commit_date = meta.commit_date.unwrap().parse::<NaiveDate>().unwrap();
-    if meta.channel == rustc_version::Channel::Dev
-        || commit_date > NaiveDate::from_ymd(2017, 12, 26)
-    {
-        println!("cargo:rustc-cfg=has_termination_lang")
-    }
-
-    // newest nightlies don't need 'extern crate compiler_builtins'
-    if commit_date < NaiveDate::from_ymd(2018, 04, 07)
-    {
-        println!("cargo:rustc-cfg=needs_cb")
-    }
-
     let target = env::var("TARGET").unwrap();
 
     has_fpu(&target);

cortex-m-rt/link.x

@@ -48,27 +48,16 @@ SECTIONS
     . = ALIGN(4);
   } > FLASH
 
-  /* limits of the .stack region */
-  _estack = _stack_start;
-  /* HACK the `true` case indicates that two RAM regions are being used and
-  /* that the stack was placed in the second region. In that case we don't know
-  /* the size of the second RAM region, or its start address, so we just assume
-  /* its zero sized */
-  _sstack = _stack_start < ORIGIN(RAM)? _stack_start : ORIGIN(RAM);
-
-  /* fictitious region that represents the memory available for the stack */
-  .stack _sstack (INFO) : ALIGN(4)
-  {
-    . += (_estack - _sstack);
-  }
-
   PROVIDE(_sbss = ORIGIN(RAM));
   .bss _sbss : ALIGN(4)
   {
     *(.bss .bss.*);
     . = ALIGN(4);
     _ebss = .;
-  } > RAM
+  } > RAM AT > FLASH
+  /* NOTE(AT > FLASH) without this LLD v6 produces a binary that crashes OpenOCD whereas LLD v7
+     emits a ".rodata and .bss sections overlap" error ... This hacky workaround doesn't increase
+     the binary size AFAICT */
 
   .data : ALIGN(4)
   {
@@ -79,16 +68,8 @@ SECTIONS
     _edata = .;
   } > RAM AT > FLASH
 
-  PROVIDE(_heap_size = 0);
-
+  /* The heap starts right after the .bss + .data section ends */
   _sheap = _edata;
-  _eheap = _sheap + _heap_size;
-
-  /* fictitious region that represents the memory available for the heap */
-  .heap _sheap (INFO) : ALIGN(4)
-  {
-    . += _heap_size;
-  }
 
   /* fake output .got section */
   /* Dynamic relocations are unsupported. This section is only used to detect
@@ -101,26 +82,9 @@ SECTIONS
     _egot = .;
   } > RAM AT > FLASH
 
-  /* The heap starts right after the .bss + .data section ends */
-  _sheap = _edata;
-
-  /* Due to an unfortunate combination of legacy concerns,
-     toolchain drawbacks, and insufficient attention to detail,
-     rustc has no choice but to mark .debug_gdb_scripts as allocatable.
-     We really do not want to upload it to our target, so we
-     remove the allocatable bit. Unfortunately, it appears
-     that the only way to do this in a linker script is
-     the extremely obscure "INFO" output section type specifier. */
-  /* a rustc hack will force the program to read the first byte of this section,
-     so we'll set the (fake) start address of this section to something we're
-     sure can be read at runtime: the start of the .text section */
-  .debug_gdb_scripts _stext (INFO) : {
-    KEEP(*(.debug_gdb_scripts))
-  }
-
   /DISCARD/ :
   {
-    *(.ARM.exidx.*)
+    *(.ARM.exidx.*);
   }
 }
 

cortex-m-rt/src/lang_items.rs

@@ -1,10 +1,3 @@
-/// Default panic handler
-#[cfg(feature = "abort-on-panic")]
-#[lang = "panic_fmt"]
-unsafe extern "C" fn panic_fmt(_: ::core::fmt::Arguments, _: &'static str, _: u32, _: u32) -> ! {
-    ::core::intrinsics::abort()
-}
-
 // Lang item required to make the normal `main` work in applications
 //
 // This is how the `start` lang item works:
@@ -24,7 +17,6 @@ unsafe extern "C" fn panic_fmt(_: ::core::fmt::Arguments, _: &'static str, _: u3
 // The final piece is that the entry point of our program, the reset handler,
 // has to call `rustc_main`. That's covered by the `reset_handler` function in
 // root of this crate.
-#[cfg(has_termination_lang)]
 #[lang = "start"]
 extern "C" fn start<T>(main: fn() -> T, _argc: isize, _argv: *const *const u8) -> isize
 where
@@ -35,21 +27,11 @@ where
     0
 }
 
-#[cfg(not(has_termination_lang))]
-#[lang = "start"]
-extern "C" fn start(main: fn(), _argc: isize, _argv: *const *const u8) -> isize {
-    main();
-
-    0
-}
-
 #[lang = "termination"]
-#[cfg(has_termination_lang)]
 pub trait Termination {
     fn report(self) -> i32;
 }
 
-#[cfg(has_termination_lang)]
 impl Termination for () {
     fn report(self) -> i32 {
         0