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rt: Various tweaks to make __morestack unwinding work on linux

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When unwinding through __morestack the stack limit in the TLS is invalidated
and must be reset. Instead of actually landing at __morestack we're
just going to make all our Rust landing pads call upcall_reset_stack_limit,
which will find the stack segment that corresponds to the current stack
pointer and put the limit in the TLS.

Also massively expand the stack segment red zone to make more room for the
dynamic linker. Will fix in the future.
This commit is contained in:
Brian Anderson
2011-12-06 16:26:47 -08:00
parent a1b215aea1
commit 9a738fd61d
10 changed files with 65 additions and 6 deletions
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27
src/rt/rust_task.cpp
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@@ -18,11 +18,11 @@
// to the rt, compiler and dynamic linker for running small functions
// FIXME: We want this to be 128 but need to slim the red zone calls down
#ifdef __i386__
#define RED_ZONE_SIZE 2048
#define RED_ZONE_SIZE 65536
#endif
#ifdef __x86_64__
#define RED_ZONE_SIZE 2048
#define RED_ZONE_SIZE 65536
#endif
// Stack size
@@ -613,6 +613,29 @@ rust_task::record_stack_limit() {
"Stack size must be greater than LIMIT_OFFSET");
record_sp(stk->data + LIMIT_OFFSET + RED_ZONE_SIZE);
}
extern "C" uintptr_t get_sp();
/*
Called by landing pads during unwinding to figure out which
stack segment we are currently running on, delete the others,
and record the stack limit (which was not restored when unwinding
through __morestack).
*/
void
rust_task::reset_stack_limit() {
uintptr_t sp = get_sp();
// Not positive these bounds for sp are correct.
// I think that the first possible value for esp on a new
// stack is stk->limit, which points one word in front of
// the first work to be pushed onto a new stack.
while (sp <= (uintptr_t)stk->data || stk->limit < sp) {
del_stk(this, stk);
A(sched, stk != NULL, "Failed to find the current stack");
}
record_stack_limit();
}
//
// Local Variables:
// mode: C++