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std: unsafe-wrap gcc::rust_eh_personality and impl
This commit is contained in:
Jubilee Young
parent
2ccafed862
commit
2c7ae388b3
@ -35,6 +35,7 @@
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//!
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//! Once stack has been unwound down to the handler frame level, unwinding stops
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//! and the last personality routine transfers control to the catch block.
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#![forbid(unsafe_op_in_unsafe_fn)]
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use super::dwarf::eh::{self, EHAction, EHContext};
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use crate::ffi::c_int;
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@ -92,7 +93,11 @@ const UNWIND_DATA_REG: (i32, i32) = (4, 5); // a0, a1
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// https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c
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cfg_if::cfg_if! {
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if #[cfg(all(not(all(target_vendor = "apple", not(target_os = "watchos"))), target_arch = "arm", not(target_os = "netbsd")))] {
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if #[cfg(all(
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target_arch = "arm",
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not(all(target_vendor = "apple", not(target_os = "watchos"))),
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not(target_os = "netbsd"),
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))] {
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// ARM EHABI personality routine.
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// https://web.archive.org/web/20190728160938/https://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf
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//
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@ -104,90 +109,94 @@ cfg_if::cfg_if! {
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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) -> uw::_Unwind_Reason_Code {
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let state = state as c_int;
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let action = state & uw::_US_ACTION_MASK as c_int;
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let search_phase = if action == uw::_US_VIRTUAL_UNWIND_FRAME as c_int {
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// Backtraces on ARM will call the personality routine with
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// state == _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND. In those cases
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// we want to continue unwinding the stack, otherwise all our backtraces
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// would end at __rust_try
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if state & uw::_US_FORCE_UNWIND as c_int != 0 {
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return continue_unwind(exception_object, context);
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}
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true
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} else if action == uw::_US_UNWIND_FRAME_STARTING as c_int {
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false
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} else if action == uw::_US_UNWIND_FRAME_RESUME as c_int {
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return continue_unwind(exception_object, context);
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} else {
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return uw::_URC_FAILURE;
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};
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// The DWARF unwinder assumes that _Unwind_Context holds things like the function
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// and LSDA pointers, however ARM EHABI places them into the exception object.
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// To preserve signatures of functions like _Unwind_GetLanguageSpecificData(), which
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// take only the context pointer, GCC personality routines stash a pointer to
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// exception_object in the context, using location reserved for ARM's
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// "scratch register" (r12).
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uw::_Unwind_SetGR(context, uw::UNWIND_POINTER_REG, exception_object as uw::_Unwind_Ptr);
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// ...A more principled approach would be to provide the full definition of ARM's
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// _Unwind_Context in our libunwind bindings and fetch the required data from there
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// directly, bypassing DWARF compatibility functions.
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let eh_action = match find_eh_action(context) {
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Ok(action) => action,
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Err(_) => return uw::_URC_FAILURE,
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};
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if search_phase {
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match eh_action {
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EHAction::None | EHAction::Cleanup(_) => {
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unsafe {
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let state = state as c_int;
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let action = state & uw::_US_ACTION_MASK as c_int;
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let search_phase = if action == uw::_US_VIRTUAL_UNWIND_FRAME as c_int {
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// Backtraces on ARM will call the personality routine with
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// state == _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND. In those cases
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// we want to continue unwinding the stack, otherwise all our backtraces
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// would end at __rust_try
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if state & uw::_US_FORCE_UNWIND as c_int != 0 {
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return continue_unwind(exception_object, context);
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}
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EHAction::Catch(_) | EHAction::Filter(_) => {
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// EHABI requires the personality routine to update the
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// SP value in the barrier cache of the exception object.
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(*exception_object).private[5] =
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uw::_Unwind_GetGR(context, uw::UNWIND_SP_REG);
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return uw::_URC_HANDLER_FOUND;
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}
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EHAction::Terminate => return uw::_URC_FAILURE,
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}
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} else {
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match eh_action {
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EHAction::None => return continue_unwind(exception_object, context),
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EHAction::Filter(_) if state & uw::_US_FORCE_UNWIND as c_int != 0 => return continue_unwind(exception_object, context),
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EHAction::Cleanup(lpad) | EHAction::Catch(lpad) | EHAction::Filter(lpad) => {
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uw::_Unwind_SetGR(
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context,
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UNWIND_DATA_REG.0,
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exception_object as uw::_Unwind_Ptr,
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);
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, core::ptr::null());
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uw::_Unwind_SetIP(context, lpad);
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return uw::_URC_INSTALL_CONTEXT;
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}
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EHAction::Terminate => return uw::_URC_FAILURE,
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}
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}
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// On ARM EHABI the personality routine is responsible for actually
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// unwinding a single stack frame before returning (ARM EHABI Sec. 6.1).
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unsafe fn continue_unwind(
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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) -> uw::_Unwind_Reason_Code {
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if __gnu_unwind_frame(exception_object, context) == uw::_URC_NO_REASON {
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uw::_URC_CONTINUE_UNWIND
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true
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} else if action == uw::_US_UNWIND_FRAME_STARTING as c_int {
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false
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} else if action == uw::_US_UNWIND_FRAME_RESUME as c_int {
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return continue_unwind(exception_object, context);
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} else {
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uw::_URC_FAILURE
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return uw::_URC_FAILURE;
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};
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// The DWARF unwinder assumes that _Unwind_Context holds things like the function
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// and LSDA pointers, however ARM EHABI places them into the exception object.
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// To preserve signatures of functions like _Unwind_GetLanguageSpecificData(), which
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// take only the context pointer, GCC personality routines stash a pointer to
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// exception_object in the context, using location reserved for ARM's
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// "scratch register" (r12).
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uw::_Unwind_SetGR(context, uw::UNWIND_POINTER_REG, exception_object as uw::_Unwind_Ptr);
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// ...A more principled approach would be to provide the full definition of ARM's
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// _Unwind_Context in our libunwind bindings and fetch the required data from there
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// directly, bypassing DWARF compatibility functions.
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let eh_action = match find_eh_action(context) {
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Ok(action) => action,
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Err(_) => return uw::_URC_FAILURE,
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};
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if search_phase {
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match eh_action {
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EHAction::None | EHAction::Cleanup(_) => {
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return continue_unwind(exception_object, context);
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}
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EHAction::Catch(_) | EHAction::Filter(_) => {
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// EHABI requires the personality routine to update the
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// SP value in the barrier cache of the exception object.
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(*exception_object).private[5] =
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uw::_Unwind_GetGR(context, uw::UNWIND_SP_REG);
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return uw::_URC_HANDLER_FOUND;
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}
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EHAction::Terminate => return uw::_URC_FAILURE,
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}
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} else {
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match eh_action {
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EHAction::None => return continue_unwind(exception_object, context),
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EHAction::Filter(_) if state & uw::_US_FORCE_UNWIND as c_int != 0 => return continue_unwind(exception_object, context),
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EHAction::Cleanup(lpad) | EHAction::Catch(lpad) | EHAction::Filter(lpad) => {
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uw::_Unwind_SetGR(
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context,
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UNWIND_DATA_REG.0,
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exception_object as uw::_Unwind_Ptr,
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);
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, core::ptr::null());
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uw::_Unwind_SetIP(context, lpad);
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return uw::_URC_INSTALL_CONTEXT;
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}
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EHAction::Terminate => return uw::_URC_FAILURE,
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}
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}
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}
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// defined in libgcc
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extern "C" {
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fn __gnu_unwind_frame(
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// On ARM EHABI the personality routine is responsible for actually
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// unwinding a single stack frame before returning (ARM EHABI Sec. 6.1).
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unsafe fn continue_unwind(
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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) -> uw::_Unwind_Reason_Code;
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) -> uw::_Unwind_Reason_Code {
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unsafe {
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if __gnu_unwind_frame(exception_object, context) == uw::_URC_NO_REASON {
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uw::_URC_CONTINUE_UNWIND
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} else {
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uw::_URC_FAILURE
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}
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}
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}
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// defined in libgcc
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extern "C" {
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fn __gnu_unwind_frame(
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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) -> uw::_Unwind_Reason_Code;
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}
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}
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}
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} else {
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@ -200,35 +209,37 @@ cfg_if::cfg_if! {
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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) -> uw::_Unwind_Reason_Code {
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if version != 1 {
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return uw::_URC_FATAL_PHASE1_ERROR;
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}
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let eh_action = match find_eh_action(context) {
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Ok(action) => action,
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Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
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};
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if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
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match eh_action {
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EHAction::None | EHAction::Cleanup(_) => uw::_URC_CONTINUE_UNWIND,
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EHAction::Catch(_) | EHAction::Filter(_) => uw::_URC_HANDLER_FOUND,
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EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR,
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unsafe {
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if version != 1 {
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return uw::_URC_FATAL_PHASE1_ERROR;
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}
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} else {
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match eh_action {
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EHAction::None => uw::_URC_CONTINUE_UNWIND,
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// Forced unwinding hits a terminate action.
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EHAction::Filter(_) if actions as i32 & uw::_UA_FORCE_UNWIND as i32 != 0 => uw::_URC_CONTINUE_UNWIND,
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EHAction::Cleanup(lpad) | EHAction::Catch(lpad) | EHAction::Filter(lpad) => {
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uw::_Unwind_SetGR(
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context,
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UNWIND_DATA_REG.0,
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exception_object.cast(),
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);
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, core::ptr::null());
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uw::_Unwind_SetIP(context, lpad);
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uw::_URC_INSTALL_CONTEXT
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let eh_action = match find_eh_action(context) {
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Ok(action) => action,
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Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
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};
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if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
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match eh_action {
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EHAction::None | EHAction::Cleanup(_) => uw::_URC_CONTINUE_UNWIND,
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EHAction::Catch(_) | EHAction::Filter(_) => uw::_URC_HANDLER_FOUND,
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EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR,
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}
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} else {
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match eh_action {
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EHAction::None => uw::_URC_CONTINUE_UNWIND,
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// Forced unwinding hits a terminate action.
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EHAction::Filter(_) if actions as i32 & uw::_UA_FORCE_UNWIND as i32 != 0 => uw::_URC_CONTINUE_UNWIND,
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EHAction::Cleanup(lpad) | EHAction::Catch(lpad) | EHAction::Filter(lpad) => {
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uw::_Unwind_SetGR(
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context,
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UNWIND_DATA_REG.0,
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exception_object.cast(),
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);
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, core::ptr::null());
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uw::_Unwind_SetIP(context, lpad);
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uw::_URC_INSTALL_CONTEXT
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}
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EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR,
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}
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EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR,
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}
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}
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}
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@ -245,13 +256,15 @@ cfg_if::cfg_if! {
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contextRecord: *mut uw::CONTEXT,
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dispatcherContext: *mut uw::DISPATCHER_CONTEXT,
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) -> uw::EXCEPTION_DISPOSITION {
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uw::_GCC_specific_handler(
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exceptionRecord,
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establisherFrame,
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contextRecord,
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dispatcherContext,
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rust_eh_personality_impl,
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)
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unsafe {
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uw::_GCC_specific_handler(
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exceptionRecord,
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establisherFrame,
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contextRecord,
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dispatcherContext,
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rust_eh_personality_impl,
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)
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}
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}
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} else {
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// The personality routine for most of our targets.
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@ -263,13 +276,15 @@ cfg_if::cfg_if! {
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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) -> uw::_Unwind_Reason_Code {
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rust_eh_personality_impl(
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version,
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actions,
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exception_class,
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exception_object,
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context,
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)
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unsafe {
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rust_eh_personality_impl(
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version,
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actions,
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exception_class,
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exception_object,
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context,
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)
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}
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}
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}
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}
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@ -277,18 +292,20 @@ cfg_if::cfg_if! {
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}
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unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> Result<EHAction, ()> {
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let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
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let mut ip_before_instr: c_int = 0;
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let ip = uw::_Unwind_GetIPInfo(context, &mut ip_before_instr);
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let eh_context = EHContext {
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// The return address points 1 byte past the call instruction,
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// which could be in the next IP range in LSDA range table.
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//
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// `ip = -1` has special meaning, so use wrapping sub to allow for that
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ip: if ip_before_instr != 0 { ip } else { ip.wrapping_sub(1) },
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func_start: uw::_Unwind_GetRegionStart(context),
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get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
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get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
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};
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eh::find_eh_action(lsda, &eh_context)
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unsafe {
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let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
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let mut ip_before_instr: c_int = 0;
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let ip = uw::_Unwind_GetIPInfo(context, &mut ip_before_instr);
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let eh_context = EHContext {
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// The return address points 1 byte past the call instruction,
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// which could be in the next IP range in LSDA range table.
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//
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// `ip = -1` has special meaning, so use wrapping sub to allow for that
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ip: if ip_before_instr != 0 { ip } else { ip.wrapping_sub(1) },
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func_start: uw::_Unwind_GetRegionStart(context),
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get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
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get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
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};
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eh::find_eh_action(lsda, &eh_context)
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}
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}
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