trampolines: __disable_execute_stack ?

[Richard Henderson]

On Tue, Jan 18, 2005 at 10:31:20AM -0800, Zack Weinberg wrote:
> I don't see why not.  The appropriate point to call it would be when
> the function that created the trampoline returns, and you could use
> the WITH_CLEANUP_EXPR/ CLEANUP_POINT_EXPR mechanism to guarantee that
> this would happen.  (Think of the trampoline object as a C++ object
> with a destructor.)

Because non-local goto doesn't respect that mechanism.

The only thing I've thought of before that would have a chance of
working is an external trampoline manager that garbage collects
based on the stack base/depth.  With the advantage that it would
be explicitly allocating anon mmap pages with the X bit set.

On the other hand, my feeling is that trampolines are either 
non-existant in the application, or common.  For the former, we
never enable the X bit; for the later it would be a waste of time
to turn it off afterward.  Thus I am more or less happy with the
PT_GNU_STACK solution we currently have.


r~