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firmware: fixed personality function

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This commit is contained in:
pca006132 2022-01-10 19:48:57 +08:00 committed by Sebastien Bourdeauducq
parent 61349f9685
commit 12ee326fb4
4 changed files with 145 additions and 24 deletions
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4
artiq/firmware/ksupport/eh_artiq.rs
View File

@ -88,7 +88,9 @@ pub extern fn personality(version: c_int,
let exception_info = &mut *(uw_exception as *mut ExceptionInfo);
let exception = &exception_info.exception.unwrap();
let eh_action = match dwarf::find_eh_action(lsda, &eh_context) {
let name_ptr = exception.name.as_ptr();
let len = exception.name.len();
let eh_action = match dwarf::find_eh_action(lsda, &eh_context, name_ptr, len) {
Ok(action) => action,
Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
};

159
artiq/firmware/libeh/dwarf.rs
View File

@ -12,6 +12,7 @@
#![allow(unused)]
use core::mem;
use cslice::CSlice;
pub const DW_EH_PE_omit: u8 = 0xFF;
pub const DW_EH_PE_absptr: u8 = 0x00;
@ -63,6 +64,10 @@ impl DwarfReader {
result
}
pub unsafe fn offset(&mut self, offset: isize) {
self.ptr = self.ptr.offset(offset);
}
// ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable
// Length Data".
pub unsafe fn read_uleb128(&mut self) -> u64 {
@ -104,11 +109,20 @@ 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;
@ -128,19 +142,10 @@ 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 {
@ -150,6 +155,7 @@ unsafe fn read_encoded_pointer(
Ok(result)
}
#[derive(Debug)]
pub enum EHAction {
None,
Cleanup(usize),
@ -159,7 +165,46 @@ pub enum EHAction {
pub const USING_SJLJ_EXCEPTIONS: bool = cfg!(all(target_os = "ios", target_arch = "arm"));
pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result<EHAction, ()> {
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,
ttype_base,
)
.map(|v| v as *const u8)
}
pub unsafe fn find_eh_action(
lsda: *const u8,
context: &EHContext<'_>,
name: *const u8,
len: usize,
) -> Result<EHAction, ()> {
if lsda.is_null() {
return Ok(EHAction::None);
}
@ -176,10 +221,14 @@ pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result
};
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
};
let ttype_base = get_base(ttype_encoding, context).unwrap_or(0);
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();
@ -198,11 +247,62 @@ pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result
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 {
let lpad = lpad_base + cs_lpad;
return Ok(interpret_cs_action(cs_action, lpad));
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,
)?;
if (catch_type as *const CSlice<u8>).is_null() {
return Ok(EHAction::Catch(lpad));
}
// this seems to be target dependent
let clause_ptr = *(catch_type as *const CSlice<u8>);
let clause_name_ptr = (clause_ptr).as_ptr();
let clause_name_len = (clause_ptr).len();
if clause_name_len == 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);
}
}
}
}
@ -210,7 +310,7 @@ pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result
// 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 {
@ -246,5 +346,20 @@ fn interpret_cs_action(cs_action: u64, lpad: usize) -> EHAction {
#[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(()),
}
}

2
artiq/firmware/libeh/eh_rust.rs
View File

@ -87,5 +87,5 @@ unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> Result<EHAction,
get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
};
dwarf::find_eh_action(lsda, &eh_context)
dwarf::find_eh_action(lsda, &eh_context, core::ptr::null(), 0)
}

4
artiq/test/libartiq_support/lib.rs
View File

@ -25,6 +25,10 @@ mod cslice {
pub fn len(&self) -> usize {
self.len as usize
}
pub fn as_ptr(&self) -> *const T {
self.base
}
}
impl<'a, T> AsRef<[T]> for CSlice<'a, T> {