added eh_rust

src/libksupport/src/eh_rust.rs

@@ -0,0 +1,91 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// This is the Rust personality function, adapted for use in ARTIQ. We never actually panic
+// from Rust or recover from Rust exceptions (there's nothing to catch the panics), but we
+// need a personality function to step back through Rust frames in order to make a backtrace.
+//
+// By design, this personality function is only ever called in the search phase, although
+// to keep things simple and close to upstream, it is not modified
+use unwind as uw;
+use libc::{c_int, uintptr_t};
+
+use dwarf::{self, EHAction, EHContext};
+
+// Register ids were lifted from LLVM's TargetLowering::getExceptionPointerRegister()
+// and TargetLowering::getExceptionSelectorRegister() for each architecture,
+// then mapped to DWARF register numbers via register definition tables
+// (typically <arch>RegisterInfo.td, search for "DwarfRegNum").
+// See also http://llvm.org/docs/WritingAnLLVMBackend.html#defining-a-register.
+
+#[cfg(target_arch = "x86")]
+const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
+
+#[cfg(target_arch = "x86_64")]
+const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
+
+#[cfg(any(target_arch = "riscv32"))]
+const UNWIND_DATA_REG: (i32, i32) = (10, 11); // X10, X11
+
+// The following code is based on GCC's C and C++ personality routines.  For reference, see:
+// https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
+// https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c
+#[lang = "eh_personality"]
+#[no_mangle]
+#[allow(unused)]
+unsafe extern "C" fn rust_eh_personality(version: c_int,
+                                         actions: uw::_Unwind_Action,
+                                         exception_class: uw::_Unwind_Exception_Class,
+                                         exception_object: *mut uw::_Unwind_Exception,
+                                         context: *mut uw::_Unwind_Context)
+                                         -> uw::_Unwind_Reason_Code {
+    if version != 1 {
+        return uw::_URC_FATAL_PHASE1_ERROR;
+    }
+    let eh_action = match find_eh_action(context) {
+        Ok(action) => action,
+        Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
+    };
+    if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
+        match eh_action {
+            EHAction::None |
+            EHAction::Cleanup(_) => return uw::_URC_CONTINUE_UNWIND,
+            EHAction::Catch(_) => return uw::_URC_HANDLER_FOUND,
+            EHAction::Terminate => return uw::_URC_FATAL_PHASE1_ERROR,
+        }
+    } else {
+        match eh_action {
+            EHAction::None => return uw::_URC_CONTINUE_UNWIND,
+            EHAction::Cleanup(lpad) |
+            EHAction::Catch(lpad) => {
+                uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0, exception_object as uintptr_t);
+                uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
+                uw::_Unwind_SetIP(context, lpad);
+                return uw::_URC_INSTALL_CONTEXT;
+            }
+            EHAction::Terminate => return uw::_URC_FATAL_PHASE2_ERROR,
+        }
+    }
+}
+
+unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> Result<EHAction, ()> {
+    let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
+    let mut ip_before_instr: c_int = 0;
+    let ip = uw::_Unwind_GetIPInfo(context, &mut ip_before_instr);
+    let eh_context = EHContext {
+        // The return address points 1 byte past the call instruction,
+        // which could be in the next IP range in LSDA range table.
+        ip: if ip_before_instr != 0 { ip } else { ip - 1 },
+        func_start: uw::_Unwind_GetRegionStart(context),
+        get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
+        get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
+    };
+    dwarf::find_eh_action(lsda, &eh_context, 0)
+}

src/libksupport/src/lib.rs

@@ -21,6 +21,7 @@ pub use pl::csr::rtio_core;
 use void::Void;
 
 pub mod eh_artiq;
+pub mod eh_rust;
 pub mod i2c;
 pub mod irq;
 pub mod kernel;