eh_artiq: handle catch clauses appropriately

default.nix

@@ -28,7 +28,7 @@ let
       name = "firmware";
 
       src = ./src;
-      cargoSha256 = "sha256-uiwESZNwPdVnDkA1n0v1DQHp3rTazDkgIYscVTpgNq0=";
+      cargoSha256 = "sha256-uCqCeqXbTjTDEoZERPDb3kX+CTfzSJ/jGlrFxuKO8HQ=";
 
       nativeBuildInputs = [
         pkgs.gnumake

src/Cargo.lock

@@ -29,6 +29,16 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
+[[package]]
+name = "build_const"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4ae4235e6dac0694637c763029ecea1a2ec9e4e06ec2729bd21ba4d9c863eb7"
+
+[[package]]
+name = "build_zynq"
+version = "0.0.0"
+
 [[package]]
 name = "byteorder"
 version = "1.4.3"
@@ -68,6 +78,15 @@ dependencies = [
  "rustc_version",
 ]
 
+[[package]]
+name = "crc"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d663548de7f5cca343f1e0a48d14dcfb0e9eb4e079ec58883b7251539fa10aeb"
+dependencies = [
+ "build_const",
+]
+
 [[package]]
 name = "cslice"
 version = "0.3.0"
@@ -80,6 +99,7 @@ version = "0.0.0"
 dependencies = [
  "cfg-if 0.1.10",
  "compiler_builtins",
+ "cslice",
  "libc",
  "unwind",
 ]
@@ -192,6 +212,15 @@ dependencies = [
  "proc-macro-nested",
 ]
 
+[[package]]
+name = "io"
+version = "0.0.0"
+dependencies = [
+ "byteorder",
+ "core_io",
+ "libsupport_zynq",
+]
+
 [[package]]
 name = "libasync"
 version = "0.0.0"
@@ -204,6 +233,26 @@ dependencies = [
  "smoltcp",
 ]
 
+[[package]]
+name = "libboard_artiq"
+version = "0.0.0"
+dependencies = [
+ "build_zynq",
+ "core_io",
+ "crc",
+ "embedded-hal",
+ "io",
+ "libasync",
+ "libboard_zynq",
+ "libconfig",
+ "libcortex_a9",
+ "libregister",
+ "log",
+ "log_buffer",
+ "nb 1.0.0",
+ "void",
+]
+
 [[package]]
 name = "libboard_zynq"
 version = "0.0.0"
@@ -395,6 +444,7 @@ name = "runtime"
 version = "0.1.0"
 dependencies = [
  "async-recursion",
+ "build_zynq",
  "byteorder",
  "core_io",
  "cslice",
@@ -402,7 +452,9 @@ dependencies = [
  "dyld",
  "embedded-hal",
  "futures",
+ "io",
  "libasync",
+ "libboard_artiq",
  "libboard_zynq",
  "libc",
  "libconfig",
@@ -429,6 +481,24 @@ dependencies = [
  "semver",
 ]
 
+[[package]]
+name = "satman"
+version = "0.0.0"
+dependencies = [
+ "build_zynq",
+ "embedded-hal",
+ "libasync",
+ "libboard_artiq",
+ "libboard_zynq",
+ "libc",
+ "libconfig",
+ "libcortex_a9",
+ "libregister",
+ "libsupport_zynq",
+ "log",
+ "unwind",
+]
+
 [[package]]
 name = "semver"
 version = "0.1.20"

src/libdwarf/Cargo.toml

@@ -15,3 +15,4 @@ libc = { path = "../libc" }
 unwind = { path = "../libunwind" }
 compiler_builtins = "0.1.0"
 cfg-if = "0.1.8"
+cslice = "0.3"

src/libdwarf/src/eh.rs

@@ -13,6 +13,7 @@
 
 use crate::DwarfReader;
 use core::mem;
+use cslice::CSlice;
 
 pub const DW_EH_PE_omit: u8 = 0xFF;
 pub const DW_EH_PE_absptr: u8 = 0x00;
@@ -51,10 +52,46 @@ pub enum EHAction {
 
 pub const USING_SJLJ_EXCEPTIONS: bool = cfg!(all(target_os = "ios", target_arch = "arm"));
 
+fn size_of_encoded_value(encoding: u8) -> usize {
+    if encoding == DW_EH_PE_omit {
+        0
+    } else {
+        let encoding = encoding & 0x07;
+        match encoding {
+            DW_EH_PE_absptr => core::mem::size_of::<*const ()>(),
+            DW_EH_PE_udata2 => 2,
+            DW_EH_PE_udata4 => 4,
+            DW_EH_PE_udata8 => 8,
+            _ => unreachable!(),
+        }
+    }
+}
+
+unsafe fn get_ttype_entry(
+    offset: usize,
+    encoding: u8,
+    ttype_base: usize,
+    ttype: *const u8,
+) -> Result<*const u8, ()> {
+    let i = (offset * size_of_encoded_value(encoding)) as isize;
+    read_encoded_pointer_with_base(
+        &mut DwarfReader::new(ttype.offset(-i)),
+        // the DW_EH_PE_pcrel is a hack.
+        // It seems that the default encoding is absolute, but we have to take reallocation into
+        // account. Unsure if we can fix this in the compiler setting or if this would be affected
+        // by updating the compiler
+        encoding | DW_EH_PE_pcrel,
+        ttype_base,
+    )
+    .map(|v| v as *const u8)
+}
+
 pub unsafe fn find_eh_action(
     lsda: *const u8,
     context: &EHContext<'_>,
     foreign_exception: bool,
+    name: *const u8,
+    len: usize,
 ) -> Result<EHAction, ()> {
     if lsda.is_null() {
         return Ok(EHAction::None);
@@ -72,10 +109,17 @@ pub unsafe fn find_eh_action(
     };
 
     let ttype_encoding = reader.read::<u8>();
-    if ttype_encoding != DW_EH_PE_omit {
+    // we do care about the type table
-        // Rust doesn't analyze exception types, so we don't care about the type table
+    let ttype_offset = if ttype_encoding != DW_EH_PE_omit {
-        reader.read_uleb128();
+        reader.read_uleb128()
-    }
+    } else {
+        0
+    };
+    // for rust functions, it seems that there is no type table, so I just put whatever value here.
+    // we should not return an error, otherwise we would abort unwinding and cannot unwind through
+    // rust functions
+    let ttype_base = get_base(ttype_encoding, context).unwrap_or(1);
+    let ttype_table = reader.ptr.offset(ttype_offset as isize);
 
     let call_site_encoding = reader.read::<u8>();
     let call_site_table_length = reader.read_uleb128();
@@ -94,11 +138,61 @@ pub unsafe fn find_eh_action(
                 break;
             }
             if ip < func_start + cs_start + cs_len {
+                // https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/libsupc%2B%2B/eh_personality.cc#L528
+                let lpad = lpad_base + cs_lpad;
                 if cs_lpad == 0 {
+                    // no cleanups/handler
+                    return Ok(EHAction::None);
+                } else if cs_action == 0 {
+                    return Ok(EHAction::Cleanup(lpad));
+                } else if foreign_exception {
                     return Ok(EHAction::None);
                 } else {
-                    let lpad = lpad_base + cs_lpad;
+                    let mut saw_cleanup = false;
-                    return Ok(interpret_cs_action(cs_action, lpad, foreign_exception));
+                    let mut action_record = action_table.offset(cs_action as isize - 1);
+                    loop {
+                        let mut reader = DwarfReader::new(action_record);
+                        let ar_filter = reader.read_sleb128();
+                        action_record = reader.ptr;
+                        let ar_disp = reader.read_sleb128();
+                        if ar_filter == 0 {
+                            saw_cleanup = true;
+                        } else if ar_filter > 0 {
+                            let catch_type = get_ttype_entry(
+                                ar_filter as usize,
+                                ttype_encoding,
+                                ttype_base,
+                                ttype_table,
+                            )?;
+                            let clause_ptr = *(catch_type as *const *const CSlice<u8>);
+                            if clause_ptr.is_null() {
+                                return Ok(EHAction::Catch(lpad));
+                            }
+                            let clause_name_ptr = (*clause_ptr).as_ptr();
+                            let clause_name_len = (*clause_ptr).len();
+                            if (clause_name_ptr == core::ptr::null() ||
+                                clause_name_ptr == name ||
+                                // somehow their name pointers might differ, but the content is the
+                                // same
+                                core::slice::from_raw_parts(clause_name_ptr, clause_name_len) ==
+                                core::slice::from_raw_parts(name, len))
+                            {
+                                return Ok(EHAction::Catch(lpad));
+                            }
+                        } else if ar_filter < 0 {
+                            // FIXME: how to handle this?
+                            break;
+                        }
+                        if ar_disp == 0 {
+                            break;
+                        }
+                        action_record = action_record.offset((ar_disp as usize) as isize);
+                    }
+                    if saw_cleanup {
+                        return Ok(EHAction::Cleanup(lpad));
+                    } else {
+                        return Ok(EHAction::None);
+                    }
                 }
             }
         }
@@ -106,7 +200,7 @@ pub unsafe fn find_eh_action(
         // So rather than returning EHAction::Terminate, we do this.
         Ok(EHAction::None)
     } else {
-        // SjLj version:
+        // SjLj version: (not yet modified)
         // The "IP" is an index into the call-site table, with two exceptions:
         // -1 means 'no-action', and 0 means 'terminate'.
         match ip as isize {
@@ -146,18 +240,41 @@ fn interpret_cs_action(cs_action: u64, lpad: usize, foreign_exception: bool) ->
 
 #[inline]
 fn round_up(unrounded: usize, align: usize) -> Result<usize, ()> {
-    if align.is_power_of_two() { Ok((unrounded + align - 1) & !(align - 1)) } else { Err(()) }
+    if align.is_power_of_two() {
+        Ok((unrounded + align - 1) & !(align - 1))
+    } else {
+        Err(())
+    }
+}
+
+fn get_base(encoding: u8, context: &EHContext<'_>) -> Result<usize, ()> {
+    match encoding & 0x70 {
+        DW_EH_PE_absptr | DW_EH_PE_pcrel | DW_EH_PE_aligned => Ok(0),
+        DW_EH_PE_textrel => Ok((*context.get_text_start)()),
+        DW_EH_PE_datarel => Ok((*context.get_data_start)()),
+        DW_EH_PE_funcrel if context.func_start != 0 => Ok(context.func_start),
+        _ => return Err(()),
+    }
 }
 
 unsafe fn read_encoded_pointer(
     reader: &mut DwarfReader,
     context: &EHContext<'_>,
     encoding: u8,
+) -> Result<usize, ()> {
+    read_encoded_pointer_with_base(reader, encoding, get_base(encoding, context)?)
+}
+
+unsafe fn read_encoded_pointer_with_base(
+    reader: &mut DwarfReader,
+    encoding: u8,
+    base: usize,
 ) -> Result<usize, ()> {
     if encoding == DW_EH_PE_omit {
         return Err(());
     }
 
+    let original_ptr = reader.ptr;
     // DW_EH_PE_aligned implies it's an absolute pointer value
     if encoding == DW_EH_PE_aligned {
         reader.ptr = round_up(reader.ptr as usize, mem::size_of::<usize>())? as *const u8;
@@ -177,19 +294,10 @@ unsafe fn read_encoded_pointer(
         _ => return Err(()),
     };
 
-    result += match encoding & 0x70 {
+    result += if (encoding & 0x70) == DW_EH_PE_pcrel {
-        DW_EH_PE_absptr => 0,
+        original_ptr as usize
-        // relative to address of the encoded value, despite the name
+    } else {
-        DW_EH_PE_pcrel => reader.ptr as usize,
+        base
-        DW_EH_PE_funcrel => {
-            if context.func_start == 0 {
-                return Err(());
-            }
-            context.func_start
-        }
-        DW_EH_PE_textrel => (*context.get_text_start)(),
-        DW_EH_PE_datarel => (*context.get_data_start)(),
-        _ => return Err(()),
     };
 
     if encoding & DW_EH_PE_indirect != 0 {

src/libdwarf/src/lib.rs

@@ -26,6 +26,10 @@ impl DwarfReader {
         DwarfReader { ptr }
     }
 
+    pub unsafe fn offset(&mut self, offset: isize) {
+        self.ptr = self.ptr.offset(offset);
+    }
+
     // DWARF streams are packed, so e.g., a u32 would not necessarily be aligned
     // on a 4-byte boundary. This may cause problems on platforms with strict
     // alignment requirements. By wrapping data in a "packed" struct, we are

src/runtime/src/eh_artiq.rs

@@ -67,6 +67,8 @@ struct ExceptionInfo {
 unsafe fn find_eh_action(
     context: *mut uw::_Unwind_Context,
     foreign_exception: bool,
+    name: *const u8,
+    len: usize,
 ) -> Result<EHAction, ()> {
     let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
     let mut ip_before_instr: c_int = 0;
@@ -79,7 +81,7 @@ unsafe fn find_eh_action(
         get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
         get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
     };
-    eh::find_eh_action(lsda, &eh_context, foreign_exception)
+    eh::find_eh_action(lsda, &eh_context, foreign_exception, name, len)
 }
 
 pub unsafe fn artiq_personality(state: uw::_Unwind_State,
@@ -120,11 +122,18 @@ pub unsafe fn artiq_personality(state: uw::_Unwind_State,
 
     let exception_class = (*exception_object).exception_class;
     let foreign_exception = exception_class != EXCEPTION_CLASS;
-    let eh_action = match find_eh_action(context, foreign_exception) {
+    let exception_info = &mut *(exception_object as *mut ExceptionInfo);
+
+    let (name_ptr, len) = if foreign_exception || exception_info.exception.is_none() {
+        (core::ptr::null(), 0)
+    } else {
+        let name = (exception_info.exception.unwrap()).name;
+        (name.as_ptr(), name.len())
+    };
+    let eh_action = match find_eh_action(context, foreign_exception, name_ptr, len) {
         Ok(action) => action,
         Err(_) => return uw::_URC_FAILURE,
     };
-    let exception_info = &mut *(exception_object as *mut ExceptionInfo);
     let exception = &exception_info.exception.unwrap();
     if search_phase {
         match eh_action {
@@ -209,7 +218,7 @@ pub unsafe extern fn raise(exception: *const Exception) -> ! {
     INFLIGHT.handled   = false;
 
     let result = uw::_Unwind_RaiseException(&mut INFLIGHT.uw_exception);
-    assert!(result == uw::_URC_END_OF_STACK);
+    assert!(result == uw::_URC_FAILURE || result == uw::_URC_END_OF_STACK);
 
     INFLIGHT.backtrace_size = 0;
     // read backtrace