On Thu, Nov 19, 2009 at 03:17:16PM -0500, Steven Rostedt wrote: > On Thu, 2009-11-19 at 15:05 -0500, Steven Rostedt wrote: > > > Well, other archs use a register to store the return address. But it > > would also be easy to do (pseudo arch assembly): > > > > <function>: > > mov lr, (%sp) > > add 8, %sp > > blr __fentry__ > > Should be bl __fentry__ for "branch and link". > > > sub 8, %sp > > mov (%sp), lr > > > > > > That way the lr would have the current function, and the parent would > > still be at 8(%sp) > > Actually, if we add a new profiler and can make our own specification, I > would say that the add and sub lines be the responsibility of > __fentry__. Then we would have: > > <function>: > mov lr, (%sp) > bl __fentry__ > mov (%sp), lr > > If sp points to the current content, then replace (%sp) above with > -8(%sp). Then the implementation of a nop __fentry__ would simply be: > > __fentry__: > blr
Good point! > For anything more elaborate, __fentry__ would be responsible for all > adjustments. Yep. The more we control it from __fentry__, the less we fall down into unexpected surprises.
