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rt: Add upcall_call_shim_on_rust_stack

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This commit is contained in:
Brian Anderson
2012-02-09 11:51:34 -08:00
parent 79b1563abb
commit 5d2442d89c
4 changed files with 67 additions and 3 deletions
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40
src/rt/rust_task.cpp
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@@ -90,7 +90,8 @@ rust_task::rust_task(rust_task_thread *thread, rust_task_list *state,
cc_counter(0),
total_stack_sz(0),
c_stack(NULL),
next_c_sp(0)
next_c_sp(0),
next_rust_sp(0)
{
LOGPTR(thread, "new task", (uintptr_t)this);
DLOG(thread, task, "sizeof(task) = %d (0x%x)", sizeof *this, sizeof *this);
@@ -658,6 +659,7 @@ rust_task::prev_stack() {
void
rust_task::record_stack_limit() {
I(thread, stk);
// The function prolog compares the amount of stack needed to the end of
// the stack. As an optimization, when the frame size is less than 256
// bytes, it will simply compare %esp to to the stack limit instead of
@@ -732,18 +734,40 @@ rust_task::config_notify(chan_handle chan) {
extern "C" void __morestack(void *args, void *fn_ptr, uintptr_t stack_ptr);
static uintptr_t
sanitize_next_sp(uintptr_t next_sp) {
// Since I'm not precisely sure where the next stack pointer sits in
// relation to where the context switch actually happened, nor in relation
// to the amount of stack needed for calling __morestack I've added some
// extra bytes here.
// FIXME: On the rust stack this potentially puts is quite far into the
// red zone. Might want to just allocate a new rust stack every time we
// switch back to rust.
const uintptr_t padding = 16;
return align_down(next_sp - padding);
}
void
rust_task::call_on_c_stack(void *args, void *fn_ptr) {
I(thread, on_rust_stack());
next_rust_sp = get_sp();
bool borrowed_a_c_stack = false;
uintptr_t sp;
if (c_stack == NULL) {
c_stack = thread->borrow_c_stack();
next_c_sp = align_down(c_stack->end);
sp = next_c_sp;
borrowed_a_c_stack = true;
} else {
sp = sanitize_next_sp(next_c_sp);
}
__morestack(args, fn_ptr, next_c_sp);
__morestack(args, fn_ptr, sp);
// Note that we may not actually get here if we threw an exception,
// in which case we will return the c stack when the exception is caught.
@@ -752,6 +776,18 @@ rust_task::call_on_c_stack(void *args, void *fn_ptr) {
}
}
void
rust_task::call_on_rust_stack(void *args, void *fn_ptr) {
I(thread, !on_rust_stack());
I(thread, next_rust_sp);
next_c_sp = get_sp();
uintptr_t sp = sanitize_next_sp(next_rust_sp);
__morestack(args, fn_ptr, sp);
}
void
rust_task::return_c_stack() {
I(thread, on_rust_stack());