pub const DW_EH_PE_indirect: u8 = 0x80;
#[derive(Copy, Clone)]
-pub struct EHContext {
+pub struct EHContext<'a> {
pub ip: usize, // Current instruction pointer
pub func_start: usize, // Address of the current function
- pub text_start: usize, // Address of the code section
- pub data_start: usize, // Address of the data section
+ pub get_text_start: &'a Fn() -> usize, // Get address of the code section
+ pub get_data_start: &'a Fn() -> usize, // Get address of the data section
}
-pub unsafe fn find_landing_pad(lsda: *const u8, context: &EHContext) -> Option<usize> {
+pub enum EHAction {
+ None,
+ Cleanup(usize),
+ Catch(usize),
+ Terminate,
+}
+
+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) -> EHAction {
if lsda.is_null() {
- return None;
+ return EHAction::None;
}
let func_start = context.func_start;
let call_site_encoding = reader.read::<u8>();
let call_site_table_length = reader.read_uleb128();
let action_table = reader.ptr.offset(call_site_table_length as isize);
- // Return addresses point 1 byte past the call instruction, which could
- // be in the next IP range.
- let ip = context.ip - 1;
-
- while reader.ptr < action_table {
- let cs_start = read_encoded_pointer(&mut reader, context, call_site_encoding);
- let cs_len = read_encoded_pointer(&mut reader, context, call_site_encoding);
- let cs_lpad = read_encoded_pointer(&mut reader, context, call_site_encoding);
- let cs_action = reader.read_uleb128();
- // Callsite table is sorted by cs_start, so if we've passed the ip, we
- // may stop searching.
- if ip < func_start + cs_start {
- break;
+ let ip = context.ip;
+
+ if !USING_SJLJ_EXCEPTIONS {
+ while reader.ptr < action_table {
+ let cs_start = read_encoded_pointer(&mut reader, context, call_site_encoding);
+ let cs_len = read_encoded_pointer(&mut reader, context, call_site_encoding);
+ let cs_lpad = read_encoded_pointer(&mut reader, context, call_site_encoding);
+ let cs_action = reader.read_uleb128();
+ // Callsite table is sorted by cs_start, so if we've passed the ip, we
+ // may stop searching.
+ if ip < func_start + cs_start {
+ break;
+ }
+ if ip < func_start + cs_start + cs_len {
+ if cs_lpad == 0 {
+ return EHAction::None;
+ } else {
+ let lpad = lpad_base + cs_lpad;
+ return interpret_cs_action(cs_action, lpad);
+ }
+ }
}
- if ip < func_start + cs_start + cs_len {
- if cs_lpad != 0 {
- return Some(lpad_base + cs_lpad);
- } else {
- return None;
+ // If ip is not present in the table, call terminate. This is for
+ // a destructor inside a cleanup, or a library routine the compiler
+ // was not expecting to throw
+ EHAction::Terminate
+ } else {
+ // SjLj version:
+ // 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 {
+ -1 => return EHAction::None,
+ 0 => return EHAction::Terminate,
+ _ => (),
+ }
+ let mut idx = ip;
+ loop {
+ let cs_lpad = reader.read_uleb128();
+ let cs_action = reader.read_uleb128();
+ idx -= 1;
+ if idx == 0 {
+ // Can never have null landing pad for sjlj -- that would have
+ // been indicated by a -1 call site index.
+ let lpad = (cs_lpad + 1) as usize;
+ return interpret_cs_action(cs_action, lpad);
}
}
}
- // IP range not found: gcc's C++ personality calls terminate() here,
- // however the rest of the languages treat this the same as cs_lpad == 0.
- // We follow this suit.
- None
+}
+
+fn interpret_cs_action(cs_action: u64, lpad: usize) -> EHAction {
+ if cs_action == 0 {
+ EHAction::Cleanup(lpad)
+ } else {
+ EHAction::Catch(lpad)
+ }
}
#[inline]
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_textrel => {
- assert!(context.text_start != 0);
- context.text_start
- }
- DW_EH_PE_datarel => {
- assert!(context.data_start != 0);
- context.data_start
- }
DW_EH_PE_funcrel => {
assert!(context.func_start != 0);
context.func_start
}
+ DW_EH_PE_textrel => {
+ (*context.get_text_start)()
+ }
+ DW_EH_PE_datarel => {
+ (*context.get_data_start)()
+ }
_ => panic!(),
};
0x4d4f5a_00_52555354
}
-// We could implement our personality routine in Rust, however exception
-// info decoding is tedious. More importantly, personality routines have to
-// handle various platform quirks, which are not fun to maintain. For this
-// reason, we attempt to reuse personality routine of the C language:
-// __gcc_personality_v0.
-//
-// Since C does not support exception catching, __gcc_personality_v0 simply
-// always returns _URC_CONTINUE_UNWIND in search phase, and always returns
-// _URC_INSTALL_CONTEXT (i.e. "invoke cleanup code") in cleanup phase.
-//
-// This is pretty close to Rust's exception handling approach, except that Rust
-// does have a single "catch-all" handler at the bottom of each thread's stack.
-// So we have two versions of the personality routine:
-// - rust_eh_personality, used by all cleanup landing pads, which never catches,
-// so the behavior of __gcc_personality_v0 is perfectly adequate there, and
-// - rust_eh_personality_catch, used only by rust_try(), which always catches.
-//
-// See also: rustc_trans::trans::intrinsic::trans_gnu_try
-
-#[cfg(all(not(target_arch = "arm"),
- not(all(windows, target_arch = "x86_64"))))]
+// All targets, except ARM which uses a slightly different ABI (however, iOS goes here as it uses
+// SjLj unwinding). Also, 64-bit Windows implementation lives in seh64_gnu.rs
+#[cfg(all(any(target_os = "ios", not(target_arch = "arm"))))]
pub mod eabi {
use unwind as uw;
- use libc::c_int;
+ use libc::{c_int, uintptr_t};
+ use dwarf::eh::{EHContext, EHAction, find_eh_action};
- extern "C" {
- fn __gcc_personality_v0(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- ue_header: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code;
- }
+ // 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.
- #[lang = "eh_personality"]
- #[no_mangle]
- extern "C" fn rust_eh_personality(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- ue_header: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- unsafe { __gcc_personality_v0(version, actions, exception_class, ue_header, context) }
- }
+ #[cfg(target_arch = "x86")]
+ const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
- #[lang = "eh_personality_catch"]
- #[no_mangle]
- pub extern "C" fn rust_eh_personality_catch(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- ue_header: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
+ #[cfg(target_arch = "x86_64")]
+ const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
- if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 {
- // search phase
- uw::_URC_HANDLER_FOUND // catch!
- } else {
- // cleanup phase
- unsafe { __gcc_personality_v0(version, actions, exception_class, ue_header, context) }
- }
- }
-}
-
-// iOS on armv7 is using SjLj exceptions and therefore requires to use
-// a specialized personality routine: __gcc_personality_sj0
+ #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
+ const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 / X0, X1
-#[cfg(all(target_os = "ios", target_arch = "arm"))]
-pub mod eabi {
- use unwind as uw;
- use libc::c_int;
+ #[cfg(any(target_arch = "mips", target_arch = "mipsel"))]
+ const UNWIND_DATA_REG: (i32, i32) = (4, 5); // A0, A1
- extern "C" {
- fn __gcc_personality_sj0(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- ue_header: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code;
- }
+ #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
+ const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 / X3, X4
+ // 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]
- pub extern "C" fn rust_eh_personality(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- ue_header: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- unsafe { __gcc_personality_sj0(version, actions, exception_class, ue_header, context) }
+ #[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 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),
+ };
+ let eh_action = find_eh_action(lsda, &eh_context);
+
+ 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,
+ }
+ }
}
+ #[cfg(stage0)]
#[lang = "eh_personality_catch"]
#[no_mangle]
- pub extern "C" fn rust_eh_personality_catch(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- ue_header: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 {
- // search phase
- uw::_URC_HANDLER_FOUND // catch!
- } else {
- // cleanup phase
- unsafe { __gcc_personality_sj0(version, actions, exception_class, ue_header, context) }
- }
+ pub unsafe extern "C" fn rust_eh_personality_catch(version: c_int,
+ actions: uw::_Unwind_Action,
+ exception_class: uw::_Unwind_Exception_Class,
+ ue_header: *mut uw::_Unwind_Exception,
+ context: *mut uw::_Unwind_Context)
+ -> uw::_Unwind_Reason_Code {
+ rust_eh_personality(version, actions, exception_class, ue_header, context)
}
}
-
// ARM EHABI uses a slightly different personality routine signature,
// but otherwise works the same.
#[cfg(all(target_arch = "arm", not(target_os = "ios")))]
projects / rust.git / commitdiff