diff options
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/symbol_export.rs | 18 | ||||
| -rw-r--r-- | library/panic_abort/src/lib.rs | 33 | ||||
| -rw-r--r-- | library/panic_unwind/src/emcc.rs | 16 | ||||
| -rw-r--r-- | library/panic_unwind/src/gcc.rs | 262 | ||||
| -rw-r--r-- | library/panic_unwind/src/lib.rs | 5 | ||||
| -rw-r--r-- | library/panic_unwind/src/seh.rs | 10 | ||||
| -rw-r--r-- | library/rtstartup/rsbegin.rs | 19 | ||||
| -rw-r--r-- | library/std/src/lib.rs | 1 | ||||
| -rw-r--r-- | library/std/src/personality.rs | 46 | ||||
| -rw-r--r-- | library/std/src/personality/dwarf/eh.rs (renamed from library/panic_unwind/src/dwarf/eh.rs) | 2 | ||||
| -rw-r--r-- | library/std/src/personality/dwarf/mod.rs (renamed from library/panic_unwind/src/dwarf/mod.rs) | 0 | ||||
| -rw-r--r-- | library/std/src/personality/dwarf/tests.rs (renamed from library/panic_unwind/src/dwarf/tests.rs) | 0 | ||||
| -rw-r--r-- | library/std/src/personality/emcc.rs | 20 | ||||
| -rw-r--r-- | library/std/src/personality/gcc.rs | 279 | ||||
| -rw-r--r-- | src/test/run-make-fulldeps/issue-69368/a.rs | 5 | ||||
| -rw-r--r-- | src/tools/tidy/src/pal.rs | 2 |
16 files changed, 379 insertions, 339 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs index e6b6055759d..32b340832ce 100644 --- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs +++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs @@ -103,18 +103,14 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< } }) .map(|def_id| { - let (export_level, used) = if special_runtime_crate { - let name = tcx.symbol_name(Instance::mono(tcx, def_id.to_def_id())).name; - // We won't link right if these symbols are stripped during LTO. - let used = match name { - "rust_eh_personality" - | "rust_eh_register_frames" - | "rust_eh_unregister_frames" => true, - _ => false, - }; - (SymbolExportLevel::Rust, used) + // We won't link right if this symbol is stripped during LTO. + let name = tcx.symbol_name(Instance::mono(tcx, def_id.to_def_id())).name; + let used = name == "rust_eh_personality"; + + let export_level = if special_runtime_crate { + SymbolExportLevel::Rust } else { - (symbol_export_level(tcx, def_id.to_def_id()), false) + symbol_export_level(tcx, def_id.to_def_id()) }; let codegen_attrs = tcx.codegen_fn_attrs(def_id.to_def_id()); debug!( diff --git a/library/panic_abort/src/lib.rs b/library/panic_abort/src/lib.rs index 8801c670bc9..cba8ef25db6 100644 --- a/library/panic_abort/src/lib.rs +++ b/library/panic_abort/src/lib.rs @@ -113,27 +113,11 @@ pub unsafe fn __rust_start_panic(_payload: *mut &mut dyn BoxMeUp) -> u32 { // binaries, but it should never be called as we don't link in an unwinding // runtime at all. pub mod personalities { - #[rustc_std_internal_symbol] - #[cfg(not(any( - all(target_family = "wasm", not(target_os = "emscripten")), - all(target_os = "windows", target_env = "gnu", target_arch = "x86_64",), - )))] - pub extern "C" fn rust_eh_personality() {} - - // On x86_64-pc-windows-gnu we use our own personality function that needs - // to return `ExceptionContinueSearch` as we're passing on all our frames. - #[rustc_std_internal_symbol] - #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86_64"))] - pub extern "C" fn rust_eh_personality( - _record: usize, - _frame: usize, - _context: usize, - _dispatcher: usize, - ) -> u32 { - 1 // `ExceptionContinueSearch` - } + // In the past this module used to contain stubs for the personality + // functions of various platforms, but these where removed when personality + // functions were moved to std. - // Similar to above, this corresponds to the `eh_catch_typeinfo` lang item + // This corresponds to the `eh_catch_typeinfo` lang item // that's only used on Emscripten currently. // // Since panics don't generate exceptions and foreign exceptions are @@ -143,13 +127,4 @@ pub mod personalities { #[allow(non_upper_case_globals)] #[cfg(target_os = "emscripten")] static rust_eh_catch_typeinfo: [usize; 2] = [0; 2]; - - // These two are called by our startup objects on i686-pc-windows-gnu, but - // they don't need to do anything so the bodies are nops. - #[rustc_std_internal_symbol] - #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))] - pub extern "C" fn rust_eh_register_frames() {} - #[rustc_std_internal_symbol] - #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))] - pub extern "C" fn rust_eh_unregister_frames() {} } diff --git a/library/panic_unwind/src/emcc.rs b/library/panic_unwind/src/emcc.rs index 1ee69ff9cb2..7c233c7c3a1 100644 --- a/library/panic_unwind/src/emcc.rs +++ b/library/panic_unwind/src/emcc.rs @@ -12,7 +12,6 @@ use core::intrinsics; use core::mem; use core::ptr; use core::sync::atomic::{AtomicBool, Ordering}; -use libc::{self, c_int}; use unwind as uw; // This matches the layout of std::type_info in C++ @@ -105,21 +104,6 @@ extern "C" fn exception_cleanup(ptr: *mut libc::c_void) -> *mut libc::c_void { } } -// This is required by the compiler to exist (e.g., it's a lang item), but it's -// never actually called by the compiler. Emscripten EH doesn't use a -// personality function at all, it instead uses __cxa_find_matching_catch. -// Wasm error handling would use __gxx_personality_wasm0. -#[lang = "eh_personality"] -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 { - core::intrinsics::abort() -} - extern "C" { fn __cxa_allocate_exception(thrown_size: libc::size_t) -> *mut libc::c_void; fn __cxa_begin_catch(thrown_exception: *mut libc::c_void) -> *mut libc::c_void; diff --git a/library/panic_unwind/src/gcc.rs b/library/panic_unwind/src/gcc.rs index a596592311a..261404e8795 100644 --- a/library/panic_unwind/src/gcc.rs +++ b/library/panic_unwind/src/gcc.rs @@ -39,8 +39,6 @@ use alloc::boxed::Box; use core::any::Any; -use crate::dwarf::eh::{self, EHAction, EHContext}; -use libc::{c_int, uintptr_t}; use unwind as uw; #[repr(C)] @@ -89,263 +87,3 @@ fn rust_exception_class() -> uw::_Unwind_Exception_Class { // M O Z \0 R U S T -- vendor, language 0x4d4f5a_00_52555354 } - -// 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 https://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 = "arm", target_arch = "aarch64"))] -const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 / X0, X1 - -#[cfg(target_arch = "m68k")] -const UNWIND_DATA_REG: (i32, i32) = (0, 1); // D0, D1 - -#[cfg(any(target_arch = "mips", target_arch = "mips64"))] -const UNWIND_DATA_REG: (i32, i32) = (4, 5); // A0, A1 - -#[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))] -const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 / X3, X4 - -#[cfg(target_arch = "s390x")] -const UNWIND_DATA_REG: (i32, i32) = (6, 7); // R6, R7 - -#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))] -const UNWIND_DATA_REG: (i32, i32) = (24, 25); // I0, I1 - -#[cfg(target_arch = "hexagon")] -const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 - -#[cfg(any(target_arch = "riscv64", 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 - -cfg_if::cfg_if! { - if #[cfg(all(target_arch = "arm", not(target_os = "ios"), not(target_os = "watchos"), not(target_os = "netbsd")))] { - // ARM EHABI personality routine. - // https://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf - // - // iOS uses the default routine instead since it uses SjLj unwinding. - #[lang = "eh_personality"] - unsafe extern "C" fn rust_eh_personality(state: uw::_Unwind_State, - exception_object: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context) - -> uw::_Unwind_Reason_Code { - let state = state as c_int; - let action = state & uw::_US_ACTION_MASK as c_int; - let search_phase = if action == uw::_US_VIRTUAL_UNWIND_FRAME as c_int { - // Backtraces on ARM will call the personality routine with - // state == _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND. In those cases - // we want to continue unwinding the stack, otherwise all our backtraces - // would end at __rust_try - if state & uw::_US_FORCE_UNWIND as c_int != 0 { - return continue_unwind(exception_object, context); - } - true - } else if action == uw::_US_UNWIND_FRAME_STARTING as c_int { - false - } else if action == uw::_US_UNWIND_FRAME_RESUME as c_int { - return continue_unwind(exception_object, context); - } else { - return uw::_URC_FAILURE; - }; - - // The DWARF unwinder assumes that _Unwind_Context holds things like the function - // and LSDA pointers, however ARM EHABI places them into the exception object. - // To preserve signatures of functions like _Unwind_GetLanguageSpecificData(), which - // take only the context pointer, GCC personality routines stash a pointer to - // exception_object in the context, using location reserved for ARM's - // "scratch register" (r12). - uw::_Unwind_SetGR(context, - uw::UNWIND_POINTER_REG, - exception_object as uw::_Unwind_Ptr); - // ...A more principled approach would be to provide the full definition of ARM's - // _Unwind_Context in our libunwind bindings and fetch the required data from there - // directly, bypassing DWARF compatibility functions. - - let eh_action = match find_eh_action(context) { - Ok(action) => action, - Err(_) => return uw::_URC_FAILURE, - }; - if search_phase { - match eh_action { - EHAction::None | - EHAction::Cleanup(_) => return continue_unwind(exception_object, context), - EHAction::Catch(_) => { - // EHABI requires the personality routine to update the - // SP value in the barrier cache of the exception object. - (*exception_object).private[5] = - uw::_Unwind_GetGR(context, uw::UNWIND_SP_REG); - return uw::_URC_HANDLER_FOUND; - } - EHAction::Terminate => return uw::_URC_FAILURE, - } - } else { - match eh_action { - EHAction::None => return continue_unwind(exception_object, context), - 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_FAILURE, - } - } - - // On ARM EHABI the personality routine is responsible for actually - // unwinding a single stack frame before returning (ARM EHABI Sec. 6.1). - unsafe fn continue_unwind(exception_object: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context) - -> uw::_Unwind_Reason_Code { - if __gnu_unwind_frame(exception_object, context) == uw::_URC_NO_REASON { - uw::_URC_CONTINUE_UNWIND - } else { - uw::_URC_FAILURE - } - } - // defined in libgcc - extern "C" { - fn __gnu_unwind_frame(exception_object: *mut uw::_Unwind_Exception, - context: *mut uw::_Unwind_Context) - -> uw::_Unwind_Reason_Code; - } - } - } else { - // Default personality routine, which is used directly on most targets - // and indirectly on Windows x86_64 via SEH. - unsafe extern "C" fn rust_eh_personality_impl(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(_) => uw::_URC_CONTINUE_UNWIND, - EHAction::Catch(_) => uw::_URC_HANDLER_FOUND, - EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR, - } - } else { - match eh_action { - EHAction::None => 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); - uw::_URC_INSTALL_CONTEXT - } - EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR, - } - } - } - - cfg_if::cfg_if! { - if #[cfg(all(windows, target_arch = "x86_64", target_env = "gnu"))] { - // On x86_64 MinGW targets, the unwinding mechanism is SEH however the unwind - // handler data (aka LSDA) uses GCC-compatible encoding. - #[lang = "eh_personality"] - #[allow(nonstandard_style)] - unsafe extern "C" fn rust_eh_personality(exceptionRecord: *mut uw::EXCEPTION_RECORD, - establisherFrame: uw::LPVOID, - contextRecord: *mut uw::CONTEXT, - dispatcherContext: *mut uw::DISPATCHER_CONTEXT) - -> uw::EXCEPTION_DISPOSITION { - uw::_GCC_specific_handler(exceptionRecord, - establisherFrame, - contextRecord, - dispatcherContext, - rust_eh_personality_impl) - } - } else { - // The personality routine for most of our targets. - #[lang = "eh_personality"] - 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 { - rust_eh_personality_impl(version, - actions, - exception_class, - exception_object, - context) - } - } - } - } -} - -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 = -1` has special meaning, so use wrapping sub to allow for that - ip: if ip_before_instr != 0 { ip } else { ip.wrapping_sub(1) }, - func_start: uw::_Unwind_GetRegionStart(context), - get_text_start: &|| uw::_Unwind_GetTextRelBase(context), - get_data_start: &|| uw::_Unwind_GetDataRelBase(context), - }; - eh::find_eh_action(lsda, &eh_context) -} - -// Frame unwind info registration -// -// Each module's image contains a frame unwind info section (usually -// ".eh_frame"). When a module is loaded/unloaded into the process, the -// unwinder must be informed about the location of this section in memory. The -// methods of achieving that vary by the platform. On some (e.g., Linux), the -// unwinder can discover unwind info sections on its own (by dynamically -// enumerating currently loaded modules via the dl_iterate_phdr() API and -// finding their ".eh_frame" sections); Others, like Windows, require modules -// to actively register their unwind info sections via unwinder API. -// -// This module defines two symbols which are referenced and called from -// rsbegin.rs to register our information with the GCC runtime. The -// implementation of stack unwinding is (for now) deferred to libgcc_eh, however -// Rust crates use these Rust-specific entry points to avoid potential clashes -// with any GCC runtime. -#[cfg(all(target_os = "windows", target_arch = "x86", target_env = "gnu"))] -pub mod eh_frame_registry { - extern "C" { - fn __register_frame_info(eh_frame_begin: *const u8, object: *mut u8); - fn __deregister_frame_info(eh_frame_begin: *const u8, object: *mut u8); - } - - #[rustc_std_internal_symbol] - pub unsafe extern "C" fn rust_eh_register_frames(eh_frame_begin: *const u8, object: *mut u8) { - __register_frame_info(eh_frame_begin, object); - } - - #[rustc_std_internal_symbol] - pub unsafe extern "C" fn rust_eh_unregister_frames(eh_frame_begin: *const u8, object: *mut u8) { - __deregister_frame_info(eh_frame_begin, object); - } -} diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs index f9acb42c46b..1eb4f378904 100644 --- a/library/panic_unwind/src/lib.rs +++ b/library/panic_unwind/src/lib.rs @@ -52,9 +52,6 @@ cfg_if::cfg_if! { all(target_family = "unix", not(target_os = "espidf")), all(target_vendor = "fortanix", target_env = "sgx"), ))] { - // Rust runtime's startup objects depend on these symbols, so make them public. - #[cfg(all(target_os="windows", target_arch = "x86", target_env="gnu"))] - pub use real_imp::eh_frame_registry::*; #[path = "gcc.rs"] mod real_imp; } else { @@ -92,8 +89,6 @@ extern "C" { fn __rust_foreign_exception() -> !; } -mod dwarf; - #[rustc_std_internal_symbol] #[allow(improper_ctypes_definitions)] pub unsafe extern "C" fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any + Send + 'static) { diff --git a/library/panic_unwind/src/seh.rs b/library/panic_unwind/src/seh.rs index b243333c48e..6b8d0656861 100644 --- a/library/panic_unwind/src/seh.rs +++ b/library/panic_unwind/src/seh.rs @@ -326,13 +326,3 @@ pub unsafe fn cleanup(payload: *mut u8) -> Box<dyn Any + Send> { exception.data.take().unwrap() } } - -// This is required by the compiler to exist (e.g., it's a lang item), but -// it's never actually called by the compiler because __C_specific_handler -// or _except_handler3 is the personality function that is always used. -// Hence this is just an aborting stub. -#[lang = "eh_personality"] -#[cfg(not(test))] -fn rust_eh_personality() { - core::intrinsics::abort() -} diff --git a/library/rtstartup/rsbegin.rs b/library/rtstartup/rsbegin.rs index c6a4548ec0c..1df0c897053 100644 --- a/library/rtstartup/rsbegin.rs +++ b/library/rtstartup/rsbegin.rs @@ -35,6 +35,16 @@ pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) { drop_in_place(to_drop); } +// Frame unwind info registration +// +// Each module's image contains a frame unwind info section (usually +// ".eh_frame"). When a module is loaded/unloaded into the process, the +// unwinder must be informed about the location of this section in memory. The +// methods of achieving that vary by the platform. On some (e.g., Linux), the +// unwinder can discover unwind info sections on its own (by dynamically +// enumerating currently loaded modules via the dl_iterate_phdr() API and +// finding their ".eh_frame" sections); Others, like Windows, require modules +// to actively register their unwind info sections via unwinder API. #[cfg(all(target_os = "windows", target_arch = "x86", target_env = "gnu"))] pub mod eh_frames { #[no_mangle] @@ -62,20 +72,19 @@ pub mod eh_frames { } // Unwind info registration/deregistration routines. - // See the docs of libpanic_unwind. extern "C" { - fn rust_eh_register_frames(eh_frame_begin: *const u8, object: *mut u8); - fn rust_eh_unregister_frames(eh_frame_begin: *const u8, object: *mut u8); + fn __register_frame_info(eh_frame_begin: *const u8, object: *mut u8); + fn __deregister_frame_info(eh_frame_begin: *const u8, object: *mut u8); } unsafe extern "C" fn init() { // register unwind info on module startup - rust_eh_register_frames(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8); + __register_frame_info(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8); } unsafe extern "C" fn uninit() { // unregister on shutdown - rust_eh_unregister_frames(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8); + __deregister_frame_info(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8); } // MinGW-specific init/uninit routine registration diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs index 50e3acc9400..c918c9ba818 100644 --- a/library/std/src/lib.rs +++ b/library/std/src/lib.rs @@ -594,6 +594,7 @@ pub mod alloc; // Private support modules mod panicking; +mod personality; #[path = "../../backtrace/src/lib.rs"] #[allow(dead_code, unused_attributes)] diff --git a/library/std/src/personality.rs b/library/std/src/personality.rs new file mode 100644 index 00000000000..63f0ad4f16e --- /dev/null +++ b/library/std/src/personality.rs @@ -0,0 +1,46 @@ +//! This module contains the implementation of the `eh_personality` lang item. +//! +//! The actual implementation is heavily dependent on the target since Rust +//! tries to use the native stack unwinding mechanism whenever possible. +//! +//! This personality function is still required with `-C panic=abort` because +//! it is used to catch foreign exceptions from `extern "C-unwind"` and turn +//! them into aborts. +//! +//! Additionally, ARM EHABI uses the personality function when generating +//! backtraces. + +mod dwarf; + +#[cfg(not(test))] +cfg_if::cfg_if! { + if #[cfg(target_os = "emscripten")] { + mod emcc; + } else if #[cfg(target_env = "msvc")] { + // This is required by the compiler to exist (e.g., it's a lang item), + // but it's never actually called by the compiler because + // _CxxFrameHandler3 is the personality function that is always used. + // Hence this is just an aborting stub. + #[lang = "eh_personality"] + fn rust_eh_personality() { + core::intrinsics::abort() + } + } else if #[cfg(any( + all(target_family = "windows", target_env = "gnu"), + target_os = "psp", + target_os = "solid_asp3", + all(target_family = "unix", not(target_os = "espidf")), + all(target_vendor = "fortanix", target_env = "sgx"), + ))] { + mod gcc; + } else { + // Targets that don't support unwinding. + // - family=wasm + // - os=none ("bare metal" targets) + // - os=uefi + // - os=espidf + // - os=hermit + // - nvptx64-nvidia-cuda + // - arch=avr + } +} diff --git a/library/panic_unwind/src/dwarf/eh.rs b/library/std/src/personality/dwarf/eh.rs index 9aa966b5063..8799137b78f 100644 --- a/library/panic_unwind/src/dwarf/eh.rs +++ b/library/std/src/personality/dwarf/eh.rs @@ -11,7 +11,7 @@ #![allow(non_upper_case_globals)] #![allow(unused)] -use crate::dwarf::DwarfReader; +use super::DwarfReader; use core::mem; pub const DW_EH_PE_omit: u8 = 0xFF; diff --git a/library/panic_unwind/src/dwarf/mod.rs b/library/std/src/personality/dwarf/mod.rs index 652fbe95a14..652fbe95a14 100644 --- a/library/panic_unwind/src/dwarf/mod.rs +++ b/library/std/src/personality/dwarf/mod.rs diff --git a/library/panic_unwind/src/dwarf/tests.rs b/library/std/src/personality/dwarf/tests.rs index 1644f37083a..1644f37083a 100644 --- a/library/panic_unwind/src/dwarf/tests.rs +++ b/library/std/src/personality/dwarf/tests.rs diff --git a/library/std/src/personality/emcc.rs b/library/std/src/personality/emcc.rs new file mode 100644 index 00000000000..f942bdf18c1 --- /dev/null +++ b/library/std/src/personality/emcc.rs @@ -0,0 +1,20 @@ +//! On Emscripten Rust panics are wrapped in C++ exceptions, so we just forward +//! to `__gxx_personality_v0` which is provided by Emscripten. + +use libc::c_int; +use unwind as uw; + +// This is required by the compiler to exist (e.g., it's a lang item), but it's +// never actually called by the compiler. Emscripten EH doesn't use a +// personality function at all, it instead uses __cxa_find_matching_catch. +// Wasm error handling would use __gxx_personality_wasm0. +#[lang = "eh_personality"] +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 { + core::intrinsics::abort() +} diff --git a/library/std/src/personality/gcc.rs b/library/std/src/personality/gcc.rs new file mode 100644 index 00000000000..7f0b0439cf0 --- /dev/null +++ b/library/std/src/personality/gcc.rs @@ -0,0 +1,279 @@ +//! Implementation of panics backed by libgcc/libunwind (in some form). +//! +//! For background on exception handling and stack unwinding please see +//! "Exception Handling in LLVM" (llvm.org/docs/ExceptionHandling.html) and +//! documents linked from it. +//! These are also good reads: +//! * <https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html> +//! * <https://monoinfinito.wordpress.com/series/exception-handling-in-c/> +//! * <https://www.airs.com/blog/index.php?s=exception+frames> +//! +//! ## A brief summary +//! +//! Exception handling happens in two phases: a search phase and a cleanup +//! phase. +//! +//! In both phases the unwinder walks stack frames from top to bottom using +//! information from the stack frame unwind sections of the current process's +//! modules ("module" here refers to an OS module, i.e., an executable or a +//! dynamic library). +//! +//! For each stack frame, it invokes the associated "personality routine", whose +//! address is also stored in the unwind info section. +//! +//! In the search phase, the job of a personality routine is to examine +//! exception object being thrown, and to decide whether it should be caught at +//! that stack frame. Once the handler frame has been identified, cleanup phase +//! begins. +//! +//! In the cleanup phase, the unwinder invokes each personality routine again. +//! This time it decides which (if any) cleanup code needs to be run for +//! the current stack frame. If so, the control is transferred to a special +//! branch in the function body, the "landing pad", which invokes destructors, +//! frees memory, etc. At the end of the landing pad, control is transferred +//! back to the unwinder and unwinding resumes. +//! +//! Once stack has been unwound down to the handler frame level, unwinding stops +//! and the last personality routine transfers control to the catch block. + +use super::dwarf::eh::{self, EHAction, EHContext}; +use libc::{c_int, uintptr_t}; +use unwind as uw; + +// 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 https://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 = "arm", target_arch = "aarch64"))] +const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 / X0, X1 + +#[cfg(target_arch = "m68k")] +const UNWIND_DATA_REG: (i32, i32) = (0, 1); // D0, D1 + +#[cfg(any(target_arch = "mips", target_arch = "mips64"))] +const UNWIND_DATA_REG: (i32, i32) = (4, 5); // A0, A1 + +#[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))] +const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 / X3, X4 + +#[cfg(target_arch = "s390x")] +const UNWIND_DATA_REG: (i32, i32) = (6, 7); // R6, R7 + +#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))] +const UNWIND_DATA_REG: (i32, i32) = (24, 25); // I0, I1 + +#[cfg(target_arch = "hexagon")] +const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 + +#[cfg(any(target_arch = "riscv64", 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 + +cfg_if::cfg_if! { + if #[cfg(all(target_arch = "arm", not(target_os = "ios"), not(target_os = "watchos"), not(target_os = "netbsd")))] { + // ARM EHABI personality routine. + // https://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf + // + // iOS uses the default routine instead since it uses SjLj unwinding. + #[lang = "eh_personality"] + unsafe extern "C" fn rust_eh_personality( + state: uw::_Unwind_State, + exception_object: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context, + ) -> uw::_Unwind_Reason_Code { + let state = state as c_int; + let action = state & uw::_US_ACTION_MASK as c_int; + let search_phase = if action == uw::_US_VIRTUAL_UNWIND_FRAME as c_int { + // Backtraces on ARM will call the personality routine with + // state == _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND. In those cases + // we want to continue unwinding the stack, otherwise all our backtraces + // would end at __rust_try + if state & uw::_US_FORCE_UNWIND as c_int != 0 { + return continue_unwind(exception_object, context); + } + true + } else if action == uw::_US_UNWIND_FRAME_STARTING as c_int { + false + } else if action == uw::_US_UNWIND_FRAME_RESUME as c_int { + return continue_unwind(exception_object, context); + } else { + return uw::_URC_FAILURE; + }; + + // The DWARF unwinder assumes that _Unwind_Context holds things like the function + // and LSDA pointers, however ARM EHABI places them into the exception object. + // To preserve signatures of functions like _Unwind_GetLanguageSpecificData(), which + // take only the context pointer, GCC personality routines stash a pointer to + // exception_object in the context, using location reserved for ARM's + // "scratch register" (r12). + uw::_Unwind_SetGR(context, uw::UNWIND_POINTER_REG, exception_object as uw::_Unwind_Ptr); + // ...A more principled approach would be to provide the full definition of ARM's + // _Unwind_Context in our libunwind bindings and fetch the required data from there + // directly, bypassing DWARF compatibility functions. + + let eh_action = match find_eh_action(context) { + Ok(action) => action, + Err(_) => return uw::_URC_FAILURE, + }; + if search_phase { + match eh_action { + EHAction::None | EHAction::Cleanup(_) => { + return continue_unwind(exception_object, context); + } + EHAction::Catch(_) => { + // EHABI requires the personality routine to update the + // SP value in the barrier cache of the exception object. + (*exception_object).private[5] = + uw::_Unwind_GetGR(context, uw::UNWIND_SP_REG); + return uw::_URC_HANDLER_FOUND; + } + EHAction::Terminate => return uw::_URC_FAILURE, + } + } else { + match eh_action { + EHAction::None => return continue_unwind(exception_object, context), + 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_FAILURE, + } + } + + // On ARM EHABI the personality routine is responsible for actually + // unwinding a single stack frame before returning (ARM EHABI Sec. 6.1). + unsafe fn continue_unwind( + exception_object: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context, + ) -> uw::_Unwind_Reason_Code { + if __gnu_unwind_frame(exception_object, context) == uw::_URC_NO_REASON { + uw::_URC_CONTINUE_UNWIND + } else { + uw::_URC_FAILURE + } + } + // defined in libgcc + extern "C" { + fn __gnu_unwind_frame( + exception_object: *mut uw::_Unwind_Exception, + context: *mut uw::_Unwind_Context, + ) -> uw::_Unwind_Reason_Code; + } + } + } else { + // Default personality routine, which is used directly on most targets + // and indirectly on Windows x86_64 via SEH. + unsafe extern "C" fn rust_eh_personality_impl( + 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(_) => uw::_URC_CONTINUE_UNWIND, + EHAction::Catch(_) => uw::_URC_HANDLER_FOUND, + EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR, + } + } else { + match eh_action { + EHAction::None => 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); + uw::_URC_INSTALL_CONTEXT + } + EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR, + } + } + } + + cfg_if::cfg_if! { + if #[cfg(all(windows, target_arch = "x86_64", target_env = "gnu"))] { + // On x86_64 MinGW targets, the unwinding mechanism is SEH however the unwind + // handler data (aka LSDA) uses GCC-compatible encoding. + #[lang = "eh_personality"] + #[allow(nonstandard_style)] + unsafe extern "C" fn rust_eh_personality( + exceptionRecord: *mut uw::EXCEPTION_RECORD, + establisherFrame: uw::LPVOID, + contextRecord: *mut uw::CONTEXT, + dispatcherContext: *mut uw::DISPATCHER_CONTEXT, + ) -> uw::EXCEPTION_DISPOSITION { + uw::_GCC_specific_handler( + exceptionRecord, + establisherFrame, + contextRecord, + dispatcherContext, + rust_eh_personality_impl, + ) + } + } else { + // The personality routine for most of our targets. + #[lang = "eh_personality"] + 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 { + rust_eh_personality_impl( + version, + actions, + exception_class, + exception_object, + context, + ) + } + } + } + } +} + +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 = -1` has special meaning, so use wrapping sub to allow for that + ip: if ip_before_instr != 0 { ip } else { ip.wrapping_sub(1) }, + func_start: uw::_Unwind_GetRegionStart(context), + get_text_start: &|| uw::_Unwind_GetTextRelBase(context), + get_data_start: &|| uw::_Unwind_GetDataRelBase(context), + }; + eh::find_eh_action(lsda, &eh_context) +} diff --git a/src/test/run-make-fulldeps/issue-69368/a.rs b/src/test/run-make-fulldeps/issue-69368/a.rs index 7d339c5a5da..a54f429550e 100644 --- a/src/test/run-make-fulldeps/issue-69368/a.rs +++ b/src/test/run-make-fulldeps/issue-69368/a.rs @@ -19,3 +19,8 @@ extern "C" fn __rust_drop_panic() -> ! { extern "C" fn __rust_foreign_exception() -> ! { loop {} } + +#[lang = "eh_personality"] +fn eh_personality() { + loop {} +} diff --git a/src/tools/tidy/src/pal.rs b/src/tools/tidy/src/pal.rs index c5414233f09..4d86fe8be4e 100644 --- a/src/tools/tidy/src/pal.rs +++ b/src/tools/tidy/src/pal.rs @@ -59,6 +59,8 @@ const EXCEPTION_PATHS: &[&str] = &[ "library/std/src/sys_common", // Should only contain abstractions over platforms "library/std/src/net/test.rs", // Utility helpers for tests "library/std/src/panic.rs", // fuchsia-specific panic backtrace handling + "library/std/src/personality.rs", + "library/std/src/personality/", ]; pub fn check(path: &Path, bad: &mut bool) { |