Browse Source

eh_artiq: handle catch clauses appropriately

exception
pca006132 11 months ago
parent
commit
acaf388dbb
  1. 2
      default.nix
  2. 70
      src/Cargo.lock
  3. 1
      src/libdwarf/Cargo.toml
  4. 150
      src/libdwarf/src/eh.rs
  5. 4
      src/libdwarf/src/lib.rs
  6. 17
      src/runtime/src/eh_artiq.rs

2
default.nix

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

70
src/Cargo.lock generated

@ -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"

1
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"

150
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 {
// Rust doesn't analyze exception types, so we don't care about the type table
reader.read_uleb128();
}
// we do care about the type table
let ttype_offset = if ttype_encoding != DW_EH_PE_omit {
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;
return Ok(interpret_cs_action(cs_action, lpad, foreign_exception));
let mut saw_cleanup = false;
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 {
DW_EH_PE_absptr => 0,
// relative to address of the encoded value, despite the name
DW_EH_PE_pcrel => reader.ptr as usize,
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(()),
result += if (encoding & 0x70) == DW_EH_PE_pcrel {
original_ptr as usize
} else {
base
};
if encoding & DW_EH_PE_indirect != 0 {

4
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

17
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

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