assembly on stable

japaric · japaric · commit 81eb4609c642 · 2018-09-23T21:06:16.000+02:00
diff --git a/.gitignore b/.gitignore
@@ -1,3 +1,4 @@
+*.o
 .stderr
 .stdout
 Cargo.lock
diff --git a/ci/asm/app/.cargo b/ci/asm/app/.cargo
@@ -0,0 +1 @@
+../../memory-layout/.cargo
diff --git a/ci/asm/app/Cargo.toml b/ci/asm/app/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+authors = ["Jorge Aparicio <jorge@japaric.io>"]
+edition = "2018"
+name = "app"
+version = "0.1.0"
+
+[dependencies]
+rt = { path = "../rt" }
diff --git a/ci/asm/app/release.objdump b/ci/asm/app/release.objdump
@@ -0,0 +1,23 @@
+
+app:	file format ELF32-arm-little
+
+Disassembly of section .text:
+HardFault:
+      40:	b	#-0x4 <HardFault>
+
+main:
+      42:	trap
+
+Reset:
+      44:	bl	#-0x6
+      48:	trap
+
+DefaultExceptionHandler:
+      4a:	b	#-0x4 <DefaultExceptionHandler>
+
+UsageFault:
+      4b: <unknown>
+
+HardFaultTrampoline:
+      4c:	mrs	r0, msp
+      50:	b	#-0x14 <HardFault>
diff --git a/ci/asm/app/release.vector_table b/ci/asm/app/release.vector_table
@@ -0,0 +1,8 @@
+
+app:	file format ELF32-arm-little
+
+Contents of section .vector_table:
+ 0000 00000120 45000000 4b000000 4d000000  ... E...K...M...
+ 0010 4b000000 4b000000 4b000000 00000000  K...K...K.......
+ 0020 00000000 00000000 00000000 4b000000  ............K...
+ 0030 00000000 00000000 4b000000 4b000000  ........K...K...
diff --git a/ci/asm/app/src/main.rs b/ci/asm/app/src/main.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+use rt::entry;
+
+entry!(main);
+
+fn main() -> ! {
+    loop {}
+}
+
+#[allow(non_snake_case)]
+#[no_mangle]
+pub fn HardFault(_ef: *const u32) -> ! {
+    loop {}
+}
diff --git a/ci/asm/app2/.cargo b/ci/asm/app2/.cargo
@@ -0,0 +1 @@
+../../memory-layout/.cargo
diff --git a/ci/asm/app2/Cargo.toml b/ci/asm/app2/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+authors = ["Jorge Aparicio <jorge@japaric.io>"]
+edition = "2018"
+name = "app"
+version = "0.1.0"
+
+[dependencies]
+rt = { path = "../rt2" }
diff --git a/ci/asm/app2/release.objdump b/ci/asm/app2/release.objdump
@@ -0,0 +1 @@
+../app/release.objdump
diff --git a/ci/asm/app2/release.vector_table b/ci/asm/app2/release.vector_table
@@ -0,0 +1 @@
+../app/release.vector_table
diff --git a/ci/asm/app2/src b/ci/asm/app2/src
@@ -0,0 +1 @@
+../app/src
diff --git a/ci/asm/rt/Cargo.toml b/ci/asm/rt/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+edition = "2018"
+name = "rt"
+version = "0.1.0"
+authors = ["Jorge Aparicio <jorge@japaric.io>"]
+
+[build-dependencies]
+cc = "1.0.25"
diff --git a/ci/asm/rt/asm.s b/ci/asm/rt/asm.s
@@ -0,0 +1,6 @@
+  .section .text.HardFaultTrampoline
+  .global HardFaultTrampoline
+  .thumb_func
+HardFaultTrampoline:
+  mrs r0, MSP
+  b HardFault
diff --git a/ci/asm/rt/build.rs b/ci/asm/rt/build.rs
@@ -0,0 +1,19 @@
+use std::{env, error::Error, fs::File, io::Write, path::PathBuf};
+
+use cc::Build;
+
+fn main() -> Result<(), Box<Error>> {
+    // build directory for this crate
+    let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+
+    // extend the library search path
+    println!("cargo:rustc-link-search={}", out_dir.display());
+
+    // put `link.x` in the build directory
+    File::create(out_dir.join("link.x"))?.write_all(include_bytes!("link.x"))?;
+
+    // assemble the `asm.s` file
+    Build::new().file("asm.s").compile("asm"); // <- NEW!
+
+    Ok(())
+}
diff --git a/ci/asm/rt/link.x b/ci/asm/rt/link.x
@@ -0,0 +1,69 @@
+/* Memory layout of the LM3S6965 microcontroller */
+/* 1K = 1 KiBi = 1024 bytes */
+MEMORY
+{
+  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 64K
+}
+
+/* The entry point is the reset handler */
+ENTRY(Reset);
+
+EXTERN(RESET_VECTOR);
+EXTERN(EXCEPTIONS);
+
+SECTIONS
+{
+  .vector_table ORIGIN(FLASH) :
+  {
+    /* First entry: initial Stack Pointer value */
+    LONG(ORIGIN(RAM) + LENGTH(RAM));
+
+    /* Second entry: reset vector */
+    KEEP(*(.vector_table.reset_vector));
+
+    /* The next 14 entries are exception vectors */
+    KEEP(*(.vector_table.exceptions)); /* <- NEW */
+  } > FLASH
+
+  .text :
+  {
+    *(.text .text.*);
+  } > FLASH
+
+  /* CHANGED! */
+  .rodata :
+  {
+    *(.rodata .rodata.*);
+  } > FLASH
+
+  .bss :
+  {
+    _sbss = .;
+    *(.bss .bss.*);
+    _ebss = .;
+  } > RAM
+
+  .data : AT(ADDR(.rodata) + SIZEOF(.rodata))
+  {
+    _sdata = .;
+    *(.data .data.*);
+    _edata = .;
+  } > RAM
+
+  _sidata = LOADADDR(.data);
+
+  /DISCARD/ :
+  {
+    *(.ARM.exidx.*);
+  }
+}
+
+PROVIDE(NMI = DefaultExceptionHandler);
+PROVIDE(HardFault = DefaultExceptionHandler);
+PROVIDE(MemManage = DefaultExceptionHandler);
+PROVIDE(BusFault = DefaultExceptionHandler);
+PROVIDE(UsageFault = DefaultExceptionHandler);
+PROVIDE(SVCall = DefaultExceptionHandler);
+PROVIDE(PendSV = DefaultExceptionHandler);
+PROVIDE(SysTick = DefaultExceptionHandler);
diff --git a/ci/asm/rt/src/lib.rs b/ci/asm/rt/src/lib.rs
@@ -0,0 +1,96 @@
+#![no_std]
+
+use core::panic::PanicInfo;
+// use core::ptr;
+
+#[no_mangle]
+pub unsafe extern "C" fn Reset() -> ! {
+    // Omitted to simplify the `objdump` output
+    // Initialize RAM
+    extern "C" {
+        // static mut _sbss: u8;
+        // static mut _ebss: u8;
+
+        // static mut _sdata: u8;
+        // static mut _edata: u8;
+        // static _sidata: u8;
+    }
+
+    // let count = &_ebss as *const u8 as usize - &_sbss as *const u8 as usize;
+    // ptr::write_bytes(&mut _sbss as *mut u8, 0, count);
+
+    // let count = &_edata as *const u8 as usize - &_sdata as *const u8 as usize;
+    // ptr::copy_nonoverlapping(&_sidata as *const u8, &mut _sdata as *mut u8, count);
+
+    // Call user entry point
+    extern "Rust" {
+        fn main() -> !;
+    }
+
+    main()
+}
+
+// The reset vector, a pointer into the reset handler
+#[link_section = ".vector_table.reset_vector"]
+#[no_mangle]
+pub static RESET_VECTOR: unsafe extern "C" fn() -> ! = Reset;
+
+#[panic_handler]
+fn panic(_panic: &PanicInfo<'_>) -> ! {
+    loop {}
+}
+
+#[macro_export]
+macro_rules! entry {
+    ($path:path) => {
+        #[export_name = "main"]
+        pub unsafe fn __main() -> ! {
+            // type check the given path
+            let f: fn() -> ! = $path;
+
+            f()
+        }
+    }
+}
+
+pub union Vector {
+    reserved: u32,
+    handler: unsafe extern "C" fn(),
+}
+
+extern "C" {
+    fn NMI();
+    fn HardFaultTrampoline(); // <- CHANGED!
+    fn MemManage();
+    fn BusFault();
+    fn UsageFault();
+    fn SVCall();
+    fn PendSV();
+    fn SysTick();
+}
+
+#[link_section = ".vector_table.exceptions"]
+#[no_mangle]
+pub static EXCEPTIONS: [Vector; 14] = [
+    Vector { handler: NMI },
+    Vector { handler: HardFaultTrampoline }, // <- CHANGED!
+    Vector { handler: MemManage },
+    Vector { handler: BusFault },
+    Vector {
+        handler: UsageFault,
+    },
+    Vector { reserved: 0 },
+    Vector { reserved: 0 },
+    Vector { reserved: 0 },
+    Vector { reserved: 0 },
+    Vector { handler: SVCall },
+    Vector { reserved: 0 },
+    Vector { reserved: 0 },
+    Vector { handler: PendSV },
+    Vector { handler: SysTick },
+];
+
+#[no_mangle]
+pub extern "C" fn DefaultExceptionHandler() {
+    loop {}
+}
diff --git a/ci/asm/rt2/Cargo.toml b/ci/asm/rt2/Cargo.toml
@@ -0,0 +1,5 @@
+[package]
+edition = "2018"
+name = "rt"
+version = "0.1.0"
+authors = ["Jorge Aparicio <jorge@japaric.io>"]
diff --git a/ci/asm/rt2/asm.s b/ci/asm/rt2/asm.s
@@ -0,0 +1 @@
+../rt/asm.s
diff --git a/ci/asm/rt2/build.rs b/ci/asm/rt2/build.rs
@@ -0,0 +1,24 @@
+use std::{
+    env,
+    error::Error,
+    fs::{self, File},
+    io::Write,
+    path::PathBuf,
+};
+
+fn main() -> Result<(), Box<Error>> {
+    // build directory for this crate
+    let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+
+    // extend the library search path
+    println!("cargo:rustc-link-search={}", out_dir.display());
+
+    // put `link.x` in the build directory
+    File::create(out_dir.join("link.x"))?.write_all(include_bytes!("link.x"))?;
+
+    // link to `librt.a`
+    fs::copy("librt.a", out_dir.join("librt.a"))?; // <- NEW!
+    println!("cargo:rustc-link-lib=static=rt"); // <- NEW!
+
+    Ok(())
+}
diff --git a/ci/asm/rt2/librt.a b/ci/asm/rt2/librt.a
diff --git a/ci/asm/rt2/librt.objdump b/ci/asm/rt2/librt.objdump
@@ -0,0 +1,10 @@
+In archive librt.a:
+
+asm.o:     file format elf32-littlearm
+
+
+Disassembly of section .text.HardFaultTrampoline:
+
+00000000 <HardFaultTrampoline>:
+   0:	f3ef 8008 	mrs	r0, MSP
+   4:	e7fe      	b.n	0 <HardFault>
diff --git a/ci/asm/rt2/link.x b/ci/asm/rt2/link.x
@@ -0,0 +1 @@
+../rt/link.x
diff --git a/ci/asm/rt2/src b/ci/asm/rt2/src
@@ -0,0 +1 @@
+../rt/src
diff --git a/ci/script.sh b/ci/script.sh
@@ -99,6 +99,37 @@ main() {
 
         popd
     fi
+
+    # # Assembly on stable
+    pushd asm
+
+    # check that the disassembly matches
+    pushd app
+    diff release.objdump \
+         <(cargo objdump --bin app --release -- -d -no-show-raw-insn -print-imm-hex)
+    diff release.vector_table \
+         <(cargo objdump --bin app --release -- -s -j .vector_table)
+    edition_check
+    popd
+
+    # check that the binary blob is up to date
+    pushd rt2
+    arm-none-eabi-as -march=armv7-m asm.s -o asm.o
+    ar crs librt.a asm.o
+    diff librt.objdump \
+         <(arm-none-eabi-objdump -Cd librt.a)
+    popd
+
+    # check that the disassembly matches
+    pushd app2
+    diff release.objdump \
+         <(cargo objdump --bin app --release -- -d -no-show-raw-insn -print-imm-hex)
+    diff release.vector_table \
+         <(cargo objdump --bin app --release -- -s -j .vector_table)
+    edition_check
+    popd
+
+    popd
 }
 
 # checks that 2018 idioms are being used
diff --git a/src/SUMMARY.md b/src/SUMMARY.md
@@ -5,5 +5,6 @@
 - [Memory layout](./memory-layout.md)
 - [A `main` interface](./main.md)
 - [Exception handling](./exceptions.md)
+- [Assembly on stable](./asm.md)
 ---
 [A note on compiler support](./compiler-support.md)
diff --git a/src/asm.md b/src/asm.md

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,4 @@`
	`1`	`+*.o`
`1`	`2`	`.stderr`
`2`	`3`	`.stdout`
`3`	`4`	`Cargo.lock`