runtime: print (address-only) backtraces on core device panics.

artiq/firmware/Cargo.lock

@@ -13,6 +13,10 @@ dependencies = [
  "board 0.0.0",
 ]
 
+[[package]]
+name = "backtrace_artiq"
+version = "0.0.0"
+
 [[package]]
 name = "bitflags"
 version = "1.0.1"
@@ -150,6 +154,7 @@ version = "0.0.0"
 dependencies = [
  "alloc_list 0.0.0",
  "amp 0.0.0",
+ "backtrace_artiq 0.0.0",
  "board 0.0.0",
  "build_artiq 0.0.0",
  "byteorder 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",

artiq/firmware/ksupport/Makefile

@@ -23,7 +23,7 @@ $(RUSTOUT)/libksupport.a:
 
 ksupport.elf: $(RUSTOUT)/libksupport.a glue.o
 	$(LD) $(LDFLAGS) -T $(KSUPPORT_DIRECTORY)/ksupport.ld -o $@ $^ \
-		-lunwind -lcompiler-rt -lbase -lm
+		-lunwind-elf -lcompiler-rt -lbase -lm
 	@chmod -x $@
 
 %.o: $(KSUPPORT_DIRECTORY)/%.c

artiq/firmware/libbacktrace_artiq/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+authors = ["M-Labs"]
+name = "backtrace_artiq"
+version = "0.0.0"
+
+[lib]
+name = "backtrace_artiq"
+path = "lib.rs"

artiq/firmware/libbacktrace_artiq/lib.rs

@@ -0,0 +1,38 @@
+#![feature(libc, panic_unwind, never_type)]
+#![allow(non_upper_case_globals, non_camel_case_types)]
+#![no_std]
+
+extern crate unwind;
+extern crate libc;
+
+use unwind as uw;
+use libc::c_void;
+
+type _Unwind_Trace_Fn = extern "C" fn(*mut uw::_Unwind_Context, *mut c_void)
+                                     -> uw::_Unwind_Reason_Code;
+extern {
+    fn _Unwind_Backtrace(trace_fn: _Unwind_Trace_Fn, arg: *mut c_void)
+                        -> uw::_Unwind_Reason_Code;
+}
+
+pub fn backtrace<F>(mut f: F) -> Result<(), uw::_Unwind_Reason_Code>
+    where F: FnMut(usize) -> ()
+{
+    extern fn trace<F>(context: *mut uw::_Unwind_Context, arg: *mut c_void)
+                      -> uw::_Unwind_Reason_Code
+        where F: FnMut(usize) -> ()
+    {
+        unsafe {
+            let step_fn = &mut *(arg as *mut F);
+            step_fn(uw::_Unwind_GetIP(context));
+            uw::_URC_NO_REASON
+        }
+    }
+
+    unsafe {
+        match _Unwind_Backtrace(trace::<F>, &mut f as *mut _ as *mut c_void) {
+            uw::_URC_NO_REASON => Ok(()),
+            err => Err(err)
+        }
+    }
+}

artiq/firmware/runtime/Cargo.toml

@@ -19,6 +19,7 @@ log = { version = "0.3", default-features = false }
 alloc_list = { path = "../liballoc_list" }
 std_artiq = { path = "../libstd_artiq", features = ["alloc", "io_error_alloc"] }
 logger_artiq = { path = "../liblogger_artiq" }
+backtrace_artiq = { path = "../libbacktrace_artiq" }
 board = { path = "../libboard", features = ["uart_console"] }
 proto = { path = "../libproto", features = ["log"] }
 amp = { path = "../libamp" }

artiq/firmware/runtime/Makefile

@@ -1,7 +1,13 @@
 include ../include/generated/variables.mak
 include $(MISOC_DIRECTORY)/software/common.mak
 
-LDFLAGS += -L../libbase
+CFLAGS += \
+	-I$(LIBUNWIND_DIRECTORY) \
+	-I$(LIBUNWIND_DIRECTORY)/../unwinder/include \
+
+LDFLAGS += -L../libbase \
+	-L../libprintf \
+	-L../libunwind
 
 RUSTFLAGS += -Cpanic=abort
 
@@ -11,13 +17,17 @@ all: runtime.bin runtime.fbi
 $(RUSTOUT)/libruntime.a:
 	$(cargo) --manifest-path $(RUNTIME_DIRECTORY)/Cargo.toml
 
-runtime.elf: $(RUSTOUT)/libruntime.a ksupport_data.o
+runtime.elf: $(RUSTOUT)/libruntime.a ksupport_data.o glue.o
-	$(LD) $(LDFLAGS) -T $(RUNTIME_DIRECTORY)/runtime.ld -o $@ $^
+	$(LD) $(LDFLAGS) -T $(RUNTIME_DIRECTORY)/runtime.ld -o $@ $^ \
+		-lunwind-bare -lprintf-nofloat --eh-frame-hdr
 	@chmod -x $@
 
 ksupport_data.o: ../ksupport/ksupport.elf
 	$(LD) -r -b binary -o $@ $<
 
+%.o: $(RUNTIME_DIRECTORY)/%.c
+	$(compile)
+
 %.bin: %.elf
 	$(OBJCOPY) -O binary $< $@
 	@chmod -x $@

artiq/firmware/runtime/lib.rs

@@ -14,6 +14,7 @@ extern crate alloc_list;
 #[macro_use]
 extern crate std_artiq as std;
 extern crate logger_artiq;
+extern crate backtrace_artiq;
 #[macro_use]
 extern crate board;
 extern crate proto;
@@ -231,7 +232,9 @@ pub extern fn exception_handler(vect: u32, _regs: *const u32, pc: u32, ea: u32)
 
 #[no_mangle]
 pub extern fn abort() {
-    panic!("aborted")
+    println!("aborted");
+
+    loop {}
 }
 
 #[no_mangle]
@@ -239,6 +242,11 @@ pub extern fn abort() {
 pub extern fn panic_fmt(args: core::fmt::Arguments, file: &'static str, line: u32) -> ! {
     println!("panic at {}:{}: {}", file, line, args);
 
+    println!("backtrace:");
+    let _ = backtrace_artiq::backtrace(|ip| {
+        println!("{:#08x}", ip);
+    });
+
     if config::read_str("panic_reboot", |r| r == Ok("1")) {
         println!("rebooting...");
         unsafe { board::boot::reboot() }
@@ -248,11 +256,3 @@ pub extern fn panic_fmt(args: core::fmt::Arguments, file: &'static str, line: u3
         loop {}
     }
 }
-
-// Allow linking with crates that are built as -Cpanic=unwind even if we use -Cpanic=abort.
-// This is never called.
-#[allow(non_snake_case)]
-#[no_mangle]
-pub extern fn _Unwind_Resume() -> ! {
-    loop {}
-}

artiq/firmware/runtime/runtime.ld

@@ -20,6 +20,21 @@ SECTIONS
         _etext = .;
     } > runtime
 
+    .eh_frame :
+    {
+        __eh_frame_start = .;
+        KEEP(*(.eh_frame))
+        __eh_frame_end = .;
+    } > runtime
+
+    .eh_frame_hdr :
+    {
+        KEEP(*(.eh_frame_hdr))
+    } > runtime
+
+    __eh_frame_hdr_start = SIZEOF(.eh_frame_hdr) > 0 ? ADDR(.eh_frame_hdr) : 0;
+    __eh_frame_hdr_end = SIZEOF(.eh_frame_hdr) > 0 ? . : 0;
+
     /* https://sourceware.org/bugzilla/show_bug.cgi?id=20475 */
     .got :
     {
@@ -79,10 +94,4 @@ SECTIONS
         . = ORIGIN(runtime) + LENGTH(runtime);
         _eheap = .;
     } > runtime
-
-    /DISCARD/ :
-    {
-        *(.eh_frame)
-        *(.gcc_except_table)
-    }
 }

conda/artiq-dev/meta.yaml

@@ -15,7 +15,7 @@ requirements:
     - python >=3.5.3,<3.6
     - setuptools 33.1.1
     - migen 0.6.dev py35_50+git82b06ee
-    - misoc 0.8.dev py35_15+git5c201712
+    - misoc 0.8.dev py35_30+gitd95f4edb
     - jesd204b 0.4
     - binutils-or1k-linux >=2.27
     - llvm-or1k