Rollup merge of rust-lang#53996 - sekineh:thumb-run, r=japaric

[CI] Run a `thumbv7m-none-eabi` binary using `qemu-system-arm` [IRR-2018-embedded]

## What's included?

- Run a `thumbv7m-none-eabi` binary using `qemu-system-arm`
- We are using `cortex-m-rt = "=0.5.4"` which does not use `proc_macro`.
(reason: stage2 build of rustc does not work well with `proc_macro` in `run-make` phase.)
- We are using GNU LD for now.

## Blocker

All resolved.
- ~[Waiting] `#[panic_handler]` is not available in stable.~
  - [Merged] rust-lang#53619
- ~[Waiting] https://github.com/japaric/lm3s6965evb: does not compile on stable.~
  - [OK] dependent crate ~`panic-abort`~ `panic-halt`: already moved to use `#[panic_handler]`.

## Update

`#[panic_handler]` will be stabilized in Rust 1.30.

CC @kennytm @jamesmunns @nerdyvaishali

Author: kennytm

src/ci/docker/dist-various-1/Dockerfile

@@ -22,7 +22,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   libssl-dev \
   pkg-config \
   gcc-arm-none-eabi \
-  libnewlib-arm-none-eabi
+  libnewlib-arm-none-eabi \
+  qemu-system-arm
 
 WORKDIR /build
 

src/test/run-make/thumb-none-qemu/Makefile

@@ -0,0 +1,30 @@
+-include ../../run-make-fulldeps/tools.mk
+
+# How to run this
+# $ ./x.py clean
+# $ ./x.py test --target thumbv7m-none-eabi src/test/run-make
+
+ifneq (,$(filter $(TARGET),thumbv6m-none-eabi thumbv7m-none-eabi))
+
+# For cargo setting
+export RUSTC := $(RUSTC_ORIGINAL)
+export LD_LIBRARY_PATH := $(HOST_RPATH_DIR)
+# We need to be outside of 'src' dir in order to run cargo
+export WORK_DIR := $(TMPDIR)
+export HERE := $(shell pwd)
+
+## clean up unused env variables which might cause harm.
+unexport RUSTC_LINKER
+unexport RUSTC_BOOTSTRAP
+unexport RUST_BUILD_STAGE
+unexport RUST_TEST_THREADS
+unexport RUST_TEST_TMPDIR
+unexport AR
+unexport CC
+unexport CXX
+
+all:
+	bash script.sh
+else
+all:
+endif

src/test/run-make/thumb-none-qemu/example/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "example"
+version = "0.1.0"
+authors = ["Hideki Sekine <sekineh@me.com>"]
+# edition = "2018"
+
+[dependencies]
+cortex-m = "0.5.4"
+cortex-m-rt = "=0.5.4"
+panic-halt = "0.2.0"
+cortex-m-semihosting = "0.3.1"

src/test/run-make/thumb-none-qemu/example/memory.x

@@ -0,0 +1,23 @@
+/* Device specific memory layout */
+
+/* This file is used to build the cortex-m-rt examples,
+   but not other applications using cortex-m-rt. */
+
+MEMORY
+{
+  /* FLASH and RAM are mandatory memory regions */
+  /* Update examples/data_overflow.rs if you change these sizes. */
+  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 64K
+
+  /* More memory regions can declared: for example this is a second RAM region */
+  /* CCRAM : ORIGIN = 0x10000000, LENGTH = 8K */
+}
+
+/* The location of the stack can be overridden using the `_stack_start` symbol.
+   By default it will be placed at the end of the RAM region */
+/* _stack_start = ORIGIN(CCRAM) + LENGTH(CCRAM); */
+
+/* The location of the .text section can be overridden using the `_stext` symbol.
+   By default it will place after .vector_table */
+/* _stext = ORIGIN(FLASH) + 0x40c; */

src/test/run-make/thumb-none-qemu/example/src/main.rs

@@ -0,0 +1,30 @@
+// #![feature(stdsimd)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m;
+
+extern crate cortex_m_rt as rt;
+extern crate cortex_m_semihosting as semihosting;
+extern crate panic_halt;
+
+use core::fmt::Write;
+use cortex_m::asm;
+use rt::entry;
+
+entry!(main);
+
+fn main() -> ! {
+    let x = 42;
+
+    loop {
+        asm::nop();
+
+        // write something through semihosting interface
+        let mut hstdout = semihosting::hio::hstdout().unwrap();
+        write!(hstdout, "x = {}\n", x);
+
+        // exit from qemu
+        semihosting::debug::exit(semihosting::debug::EXIT_SUCCESS);
+    }
+}

src/test/run-make/thumb-none-qemu/script.sh

@@ -0,0 +1,16 @@
+set -exuo pipefail
+
+CRATE=example
+
+env | sort
+mkdir -p $WORK_DIR
+pushd $WORK_DIR
+    rm -rf $CRATE || echo OK
+    cp -a $HERE/example .
+    pushd $CRATE
+        env RUSTFLAGS="-C linker=arm-none-eabi-ld -C link-arg=-Tlink.x" \
+            $CARGO run --target $TARGET           | grep "x = 42"
+        env RUSTFLAGS="-C linker=arm-none-eabi-ld -C link-arg=-Tlink.x" \
+            $CARGO run --target $TARGET --release | grep "x = 42"
+    popd
+popd