library/panic_abort/src/lib.rs

   1 //! Implementation of Rust panics via process aborts
   2 //!
   3 //! When compared to the implementation via unwinding, this crate is *much*
   4 //! simpler! That being said, it's not quite as versatile, but here goes!
   5
   6 #![no_std]
   7 #![unstable(feature = "panic_abort", issue = "32837")]
   8 #![doc(issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/")]
   9 #![panic_runtime]
  10 #![allow(unused_features)]
  11 #![feature(core_intrinsics)]
  12 #![feature(panic_runtime)]
  13 #![feature(std_internals)]
  14 #![feature(staged_api)]
  15 #![feature(rustc_attrs)]
  16 #![feature(c_unwind)]
  17
  18 #[cfg(target_os = "android")]
  19 mod android;
  20
  21 use core::any::Any;
  22 use core::panic::BoxMeUp;
  23
  24 #[rustc_std_internal_symbol]
  25 #[allow(improper_ctypes_definitions)]
  26 pub unsafe extern "C" fn __rust_panic_cleanup(_: *mut u8) -> *mut (dyn Any + Send + 'static) {
  27     unreachable!()
  28 }
  29
  30 // "Leak" the payload and shim to the relevant abort on the platform in question.
  31 #[rustc_std_internal_symbol]
  32 pub unsafe fn __rust_start_panic(_payload: *mut &mut dyn BoxMeUp) -> u32 {
  33     // Android has the ability to attach a message as part of the abort.
  34     #[cfg(target_os = "android")]
  35     android::android_set_abort_message(_payload);
  36
  37     abort();
  38
  39     cfg_if::cfg_if! {
  40         if #[cfg(unix)] {
  41             unsafe fn abort() -> ! {
  42                 libc::abort();
  43             }
  44         } else if #[cfg(any(target_os = "hermit",
  45                             target_os = "solid_asp3",
  46                             all(target_vendor = "fortanix", target_env = "sgx")
  47         ))] {
  48             unsafe fn abort() -> ! {
  49                 // call std::sys::abort_internal
  50                 extern "C" {
  51                     pub fn __rust_abort() -> !;
  52                 }
  53                 __rust_abort();
  54             }
  55         } else if #[cfg(all(windows, not(miri)))] {
  56             // On Windows, use the processor-specific __fastfail mechanism. In Windows 8
  57             // and later, this will terminate the process immediately without running any
  58             // in-process exception handlers. In earlier versions of Windows, this
  59             // sequence of instructions will be treated as an access violation,
  60             // terminating the process but without necessarily bypassing all exception
  61             // handlers.
  62             //
  63             // https://docs.microsoft.com/en-us/cpp/intrinsics/fastfail
  64             //
  65             // Note: this is the same implementation as in libstd's `abort_internal`
  66             unsafe fn abort() -> ! {
  67                 #[allow(unused)]
  68                 const FAST_FAIL_FATAL_APP_EXIT: usize = 7;
  69                 cfg_if::cfg_if! {
  70                     if #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {
  71                         core::arch::asm!("int $$0x29", in("ecx") FAST_FAIL_FATAL_APP_EXIT);
  72                     } else if #[cfg(all(target_arch = "arm", target_feature = "thumb-mode"))] {
  73                         core::arch::asm!(".inst 0xDEFB", in("r0") FAST_FAIL_FATAL_APP_EXIT);
  74                     } else if #[cfg(target_arch = "aarch64")] {
  75                         core::arch::asm!("brk 0xF003", in("x0") FAST_FAIL_FATAL_APP_EXIT);
  76                     } else {
  77                         core::intrinsics::abort();
  78                     }
  79                 }
  80                 core::intrinsics::unreachable();
  81             }
  82         } else {
  83             unsafe fn abort() -> ! {
  84                 core::intrinsics::abort();
  85             }
  86         }
  87     }
  88 }
  89
  90 // This... is a bit of an oddity. The tl;dr; is that this is required to link
  91 // correctly, the longer explanation is below.
  92 //
  93 // Right now the binaries of libcore/libstd that we ship are all compiled with
  94 // `-C panic=unwind`. This is done to ensure that the binaries are maximally
  95 // compatible with as many situations as possible. The compiler, however,
  96 // requires a "personality function" for all functions compiled with `-C
  97 // panic=unwind`. This personality function is hardcoded to the symbol
  98 // `rust_eh_personality` and is defined by the `eh_personality` lang item.
  99 //
 100 // So... why not just define that lang item here? Good question! The way that
 101 // panic runtimes are linked in is actually a little subtle in that they're
 102 // "sort of" in the compiler's crate store, but only actually linked if another
 103 // isn't actually linked. This ends up meaning that both this crate and the
 104 // panic_unwind crate can appear in the compiler's crate store, and if both
 105 // define the `eh_personality` lang item then that'll hit an error.
 106 //
 107 // To handle this the compiler only requires the `eh_personality` is defined if
 108 // the panic runtime being linked in is the unwinding runtime, and otherwise
 109 // it's not required to be defined (rightfully so). In this case, however, this
 110 // library just defines this symbol so there's at least some personality
 111 // somewhere.
 112 //
 113 // Essentially this symbol is just defined to get wired up to libcore/libstd
 114 // binaries, but it should never be called as we don't link in an unwinding
 115 // runtime at all.
 116 pub mod personalities {
 117     #[rustc_std_internal_symbol]
 118     #[cfg(not(any(
 119         all(target_family = "wasm", not(target_os = "emscripten")),
 120         all(target_os = "windows", target_env = "gnu", target_arch = "x86_64",),
 121     )))]
 122     pub extern "C" fn rust_eh_personality() {}
 123
 124     // On x86_64-pc-windows-gnu we use our own personality function that needs
 125     // to return `ExceptionContinueSearch` as we're passing on all our frames.
 126     #[rustc_std_internal_symbol]
 127     #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86_64"))]
 128     pub extern "C" fn rust_eh_personality(
 129         _record: usize,
 130         _frame: usize,
 131         _context: usize,
 132         _dispatcher: usize,
 133     ) -> u32 {
 134         1 // `ExceptionContinueSearch`
 135     }
 136
 137     // Similar to above, this corresponds to the `eh_catch_typeinfo` lang item
 138     // that's only used on Emscripten currently.
 139     //
 140     // Since panics don't generate exceptions and foreign exceptions are
 141     // currently UB with -C panic=abort (although this may be subject to
 142     // change), any catch_unwind calls will never use this typeinfo.
 143     #[rustc_std_internal_symbol]
 144     #[allow(non_upper_case_globals)]
 145     #[cfg(target_os = "emscripten")]
 146     static rust_eh_catch_typeinfo: [usize; 2] = [0; 2];
 147
 148     // These two are called by our startup objects on i686-pc-windows-gnu, but
 149     // they don't need to do anything so the bodies are nops.
 150     #[rustc_std_internal_symbol]
 151     #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))]
 152     pub extern "C" fn rust_eh_register_frames() {}
 153     #[rustc_std_internal_symbol]
 154     #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))]
 155     pub extern "C" fn rust_eh_unregister_frames() {}
 156 }