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-rw-r--r--library/std/src/personality.rs46
-rw-r--r--library/std/src/personality/dwarf/eh.rs (renamed from library/panic_unwind/src/dwarf/eh.rs)9
-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.rs20
-rw-r--r--library/std/src/personality/gcc.rs279
6 files changed, 349 insertions, 5 deletions
diff --git a/library/std/src/personality.rs b/library/std/src/personality.rs
new file mode 100644
index 000000000..63f0ad4f1
--- /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 7394feab8..27b50c13b 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;
@@ -75,7 +75,7 @@ pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result
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);
+ let action_table = reader.ptr.add(call_site_table_length as usize);
let ip = context.ip;
if !USING_SJLJ_EXCEPTIONS {
@@ -98,9 +98,8 @@ pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result
}
}
}
- // Ip is not present in the table. This should not happen... but it does: issue #35011.
- // So rather than returning EHAction::Terminate, we do this.
- Ok(EHAction::None)
+ // Ip is not present in the table. This indicates a nounwind call.
+ Ok(EHAction::Terminate)
} else {
// SjLj version:
// The "IP" is an index into the call-site table, with two exceptions:
diff --git a/library/panic_unwind/src/dwarf/mod.rs b/library/std/src/personality/dwarf/mod.rs
index 652fbe95a..652fbe95a 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 1644f3708..1644f3708 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 000000000..f942bdf18
--- /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 000000000..7f0b0439c
--- /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)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-23 15:07:55 +0000