Merge #84

84: refactor the linker script r=therealprof a=japaric

to make it more compatible with LLD. This commit contains no functional changes.

fixes #70

Overview of changes:

- Alignment checks are enabled now that rust-lld (LLD 7.0) supports the modulo
operator.

- Removed some private symbols (e.g. __foo) in favor of ADDR and SIZEOF.

- Turned .got into a NOLOAD section now that rust-lld supports it.

- Replaced `ABSOLUTE(.)` with `.` as an old LLD overlap bug seems to be gone and
ABSOLUTE seems to cause problems, like #70, on bigger programs.

- Made the linker assertion messages more uniform.

- Extended test suite to check that linking works with both rust-lld and GNU
LD.

r? therealprof (chosen at random)

Co-authored-by: Jorge Aparicio <[email protected]>

Author: bors[bot]

.travis.yml

@@ -7,10 +7,6 @@ matrix:
 
     - env: TARGET=thumbv6m-none-eabi
       rust: stable
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv6m-none-eabi CC=clang
@@ -19,10 +15,6 @@ matrix:
 
     - env: TARGET=thumbv7m-none-eabi
       rust: stable
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7m-none-eabi CC=clang
@@ -31,10 +23,6 @@ matrix:
 
     - env: TARGET=thumbv7em-none-eabi
       rust: stable
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7em-none-eabi CC=clang
@@ -43,10 +31,6 @@ matrix:
 
     - env: TARGET=thumbv7em-none-eabihf
       rust: stable
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7em-none-eabihf CC=clang
@@ -55,40 +39,25 @@ matrix:
 
     - env: TARGET=thumbv6m-none-eabi
       rust: nightly
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7m-none-eabi
       rust: nightly
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7em-none-eabi
       rust: nightly
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7em-none-eabihf
       rust: nightly
-      addons:
-        apt:
-          packages:
-            - gcc-arm-none-eabi
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
 before_install: set -e
 
 install:
   - bash ci/install.sh
+  - export PATH="$PATH:$PWD/gcc/bin"
 
 script:
   - bash ci/script.sh

Cargo.toml

@@ -17,6 +17,7 @@ r0 = "0.2.1"
 
 [dev-dependencies]
 panic-semihosting = "0.3.0"
+panic-abort = "0.2.0"
 
 [features]
 device = []

build.rs

@@ -42,12 +42,12 @@ INCLUDE device.x"#
     writeln!(
         f,
         r#"
-ASSERT(__einterrupts - __eexceptions <= 0x{:x}, "
-There can't be more than {} interrupt handlers. This may be a bug in
-your device crate, or you may have registered more than 240 interrupt
+ASSERT(SIZEOF(.vector_table) <= 0x{:x}, "
+There can't be more than {1} interrupt handlers. This may be a bug in
+your device crate, or you may have registered more than {1} interrupt
 handlers.");
 "#,
-        max_int_handlers * 4,
+        max_int_handlers * 4 + 0x40,
         max_int_handlers
     ).unwrap();
 

ci/install.sh

@@ -3,6 +3,12 @@ set -euxo pipefail
 main() {
     if [ $TARGET != x86_64-unknown-linux-gnu ]; then
         rustup target add $TARGET
+
+        if [ ${CC:-gcc} = gcc ]; then
+            mkdir gcc
+
+            curl -L https://developer.arm.com/-/media/Files/downloads/gnu-rm/7-2018q2/gcc-arm-none-eabi-7-2018-q2-update-linux.tar.bz2?revision=bc2c96c0-14b5-4bb4-9f18-bceb4050fee7?product=GNU%20Arm%20Embedded%20Toolchain,64-bit,,Linux,7-2018-q2-update | tar --strip-components=1 -C gcc -xj
+        fi
     fi
 }
 

ci/script.sh

@@ -6,11 +6,13 @@ main() {
     cargo check --target $TARGET --features device
 
     local examples=(
+        alignment
         minimal
         main
         state
     )
     if [ $TRAVIS_RUST_VERSION = nightly ]; then
+        # linking with GNU LD
         for ex in "${examples[@]}"; do
             cargo rustc --target $TARGET --example $ex -- \
                   -C link-arg=-nostartfiles \
@@ -28,6 +30,29 @@ main() {
         cargo rustc --target $TARGET --example device --features device --release -- \
               -C link-arg=-nostartfiles \
               -C link-arg=-Wl,-Tlink.x
+
+        # linking with rustc's LLD
+        for ex in "${examples[@]}"; do
+            cargo rustc --target $TARGET --example $ex -- \
+                  -C linker=rust-lld \
+                  -Z linker-flavor=ld.lld \
+                  -C link-arg=-Tlink.x
+
+            cargo rustc --target $TARGET --example $ex --release -- \
+                  -C linker=rust-lld \
+                  -Z linker-flavor=ld.lld \
+                  -C link-arg=-Tlink.x
+        done
+
+        cargo rustc --target $TARGET --example device --features device -- \
+              -C linker=rust-lld \
+              -Z linker-flavor=ld.lld \
+              -C link-arg=-Tlink.x
+
+        cargo rustc --target $TARGET --example device --features device --release -- \
+              -C linker=rust-lld \
+              -Z linker-flavor=ld.lld \
+              -C link-arg=-Tlink.x
     fi
 }
 

examples/alignment.rs

@@ -0,0 +1,45 @@
+//! This is not an example; this is a link-pass test
+
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+#[macro_use(entry, exception)]
+extern crate cortex_m_rt as rt;
+extern crate panic_abort;
+
+use core::ptr;
+
+use rt::ExceptionFrame;
+
+entry!(main);
+
+static mut BSS1: u16 = 0;
+static mut BSS2: u8 = 0;
+static mut DATA1: u8 = 1;
+static mut DATA2: u16 = 1;
+static RODATA1: &[u8; 3] = b"012";
+static RODATA2: &[u8; 2] = b"34";
+
+fn main() -> ! {
+    unsafe {
+        let _bss1 = ptr::read_volatile(&BSS1);
+        let _bss2 = ptr::read_volatile(&BSS2);
+        let _data1 = ptr::read_volatile(&DATA1);
+        let _data2 = ptr::read_volatile(&DATA2);
+        let _rodata1 = ptr::read_volatile(&RODATA1);
+        let _rodata2 = ptr::read_volatile(&RODATA2);
+    }
+
+    loop {}
+}
+
+exception!(HardFault, hard_fault);
+
+fn hard_fault(_ef: &ExceptionFrame) -> ! {
+    loop {}
+}
+
+exception!(*, default_handler);
+
+fn default_handler(_irqn: i16) {}