From f98ca32b0a594b1ee59e22e1927198ed03eb0ce7 Mon Sep 17 00:00:00 2001 From: Mads Marquart Date: Sat, 7 Sep 2024 17:57:47 +0200 Subject: [PATCH] Fix linking error when compiling for 32-bit watchOS In https://github.com/rust-lang/rust/pull/124748, I mistakenly conflated "not SjLj" to mean "ARM EHABI", which isn't true, watchOS armv7k (specifically only that architecture) uses a third unwinding method called "DWARF CFI". --- library/std/src/sys/personality/dwarf/eh.rs | 6 +++--- library/std/src/sys/personality/gcc.rs | 13 +++++++------ library/unwind/src/libunwind.rs | 13 ++++++++----- 3 files changed, 18 insertions(+), 14 deletions(-) diff --git a/library/std/src/sys/personality/dwarf/eh.rs b/library/std/src/sys/personality/dwarf/eh.rs index c37c3e442ae..778d8686f02 100644 --- a/library/std/src/sys/personality/dwarf/eh.rs +++ b/library/std/src/sys/personality/dwarf/eh.rs @@ -54,10 +54,10 @@ pub enum EHAction { Terminate, } -/// 32-bit Apple ARM uses SjLj exceptions, except for watchOS. +/// 32-bit ARM Darwin platforms uses SjLj exceptions. /// -/// I.e. iOS and tvOS, as those are the only Apple OSes that used 32-bit ARM -/// devices. +/// The exception is watchOS armv7k (specifically that subarchitecture), which +/// instead uses DWARF Call Frame Information (CFI) unwinding. /// /// pub const USING_SJLJ_EXCEPTIONS: bool = diff --git a/library/std/src/sys/personality/gcc.rs b/library/std/src/sys/personality/gcc.rs index f6b1844e153..ad596ecff65 100644 --- a/library/std/src/sys/personality/gcc.rs +++ b/library/std/src/sys/personality/gcc.rs @@ -95,14 +95,15 @@ cfg_if::cfg_if! { if #[cfg(all( - target_arch = "arm", - not(all(target_vendor = "apple", not(target_os = "watchos"))), - not(target_os = "netbsd"), - ))] { + target_arch = "arm", + not(target_vendor = "apple"), + not(target_os = "netbsd"), + ))] { /// personality fn called by [ARM EHABI][armeabi-eh] /// - /// Apple 32-bit ARM (but not watchOS) uses the default routine instead - /// since it uses "setjmp-longjmp" unwinding. + /// 32-bit ARM on iOS/tvOS/watchOS does not use ARM EHABI, it uses + /// either "setjmp-longjmp" unwinding or DWARF CFI unwinding, which is + /// handled by the default routine. /// /// [armeabi-eh]: https://web.archive.org/web/20190728160938/https://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf #[lang = "eh_personality"] diff --git a/library/unwind/src/libunwind.rs b/library/unwind/src/libunwind.rs index e5e28f32e4d..1d856ce1879 100644 --- a/library/unwind/src/libunwind.rs +++ b/library/unwind/src/libunwind.rs @@ -33,10 +33,10 @@ pub enum _Unwind_Reason_Code { #[cfg(all(target_arch = "x86_64", target_os = "windows"))] pub const unwinder_private_data_size: usize = 6; -#[cfg(all(target_arch = "arm", not(all(target_vendor = "apple", not(target_os = "watchos")))))] +#[cfg(all(target_arch = "arm", not(target_vendor = "apple")))] pub const unwinder_private_data_size: usize = 20; -#[cfg(all(target_arch = "arm", all(target_vendor = "apple", not(target_os = "watchos"))))] +#[cfg(all(target_arch = "arm", target_vendor = "apple"))] pub const unwinder_private_data_size: usize = 5; #[cfg(all(target_arch = "aarch64", target_pointer_width = "64", not(target_os = "windows")))] @@ -123,8 +123,11 @@ pub enum _Unwind_Context {} } cfg_if::cfg_if! { -if #[cfg(any(all(target_vendor = "apple", not(target_os = "watchos")), target_os = "netbsd", not(target_arch = "arm")))] { +if #[cfg(any(target_vendor = "apple", target_os = "netbsd", not(target_arch = "arm")))] { // Not ARM EHABI + // + // 32-bit ARM on iOS/tvOS/watchOS use either DWARF/Compact unwinding or + // "setjmp-longjmp" / SjLj unwinding. #[repr(C)] #[derive(Copy, Clone, PartialEq)] pub enum _Unwind_Action { @@ -259,8 +262,8 @@ pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void { cfg_if::cfg_if! { if #[cfg(all(target_vendor = "apple", not(target_os = "watchos"), target_arch = "arm"))] { - // 32-bit ARM Apple (except for watchOS) uses SjLj and does not provide - // _Unwind_Backtrace() + // 32-bit ARM Apple (except for watchOS armv7k specifically) uses SjLj and + // does not provide _Unwind_Backtrace() extern "C-unwind" { pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code; }