/**
The exception handling personality function. It figures
out what to do with each landing pad. Just a stack-switching
wrapper around the C++ personality function.
*/
extern "C" _Unwind_Reason_Code
upcall_rust_personality(int version,
_Unwind_Action actions,
uint64_t exception_class,
_Unwind_Exception *ue_header,
_Unwind_Context *context) {
s_rust_personality_args args = {(_Unwind_Reason_Code)0,
version, actions, exception_class,
ue_header, context};
rust_task *task = rust_try_get_current_task();
if (task == NULL) {
// Assuming we're running with the new scheduler
upcall_s_rust_personality(&args);
return args.retval;
}
// The personality function is run on the stack of the
// last function that threw or landed, which is going
// to sometimes be the C stack. If we're on the Rust stack
// then switch to the C stack.
if (task->on_rust_stack()) {
UPCALL_SWITCH_STACK(task, &args, upcall_s_rust_personality);
} else {
upcall_s_rust_personality(&args);
}
return args.retval;
}
// Landing pads need to call this to insert the
// correct limit into TLS.
// NB: This must run on the Rust stack because it
// needs to acquire the value of the stack pointer
extern "C" CDECL void
upcall_reset_stack_limit() {
rust_task *task = rust_try_get_current_task();
if (task != NULL) {
task->reset_stack_limit();
} else {
// We must be in a newsched task
}
}
extern "C" CDECL void
upcall_fail(char const *expr,
char const *file,
size_t line) {
rust_task *task = rust_try_get_current_task();
if (task == NULL) {
// FIXME #5161: Need to think about what to do here
printf("failure outside of a task");
abort();
}
s_fail_args args = {task,expr,file,line};
UPCALL_SWITCH_STACK(task, &args, upcall_s_fail);
}
/**********************************************************************
* Switches to the C-stack and invokes |fn_ptr|, passing |args| as argument.
* This is used by the C compiler to call foreign functions and by other
* upcalls to switch to the C stack. The return value is passed through a
* field in the args parameter. This upcall is specifically for switching
* to the shim functions generated by rustc.
*/
extern "C" CDECL void
upcall_call_shim_on_c_stack(void *args, void *fn_ptr) {
rust_task *task = rust_try_get_current_task();
if (task) {
// We're running in task context, do a stack switch
try {
task->call_on_c_stack(args, fn_ptr);
} catch (...) {
// Logging here is not reliable
assert(false && "Foreign code threw an exception");
}
} else {
// There's no task. Call the function and hope for the best
stack_switch_shim f = (stack_switch_shim)fn_ptr;
f(args);
}
}
/*
* The opposite of above. Starts on a C stack and switches to the Rust
* stack. This is the only upcall that runs from the C stack.
*/
extern "C" CDECL void
upcall_call_shim_on_rust_stack(void *args, void *fn_ptr) {
rust_task *task = rust_try_get_current_task();
if (task) {
try {
task->call_on_rust_stack(args, fn_ptr);
} catch (...) {
// We can't count on being able to unwind through arbitrary
// code. Our best option is to just fail hard.
// Logging here is not reliable
assert(false
&& "Rust task failed after reentering the Rust stack");
}
} else {
// There's no task. Call the function and hope for the best
stack_switch_shim f = (stack_switch_shim)fn_ptr;
f(args);
}
}
extern "C" rust_task *
rust_try_get_task() {
return rust_try_get_current_task();
}
