smm: Push a null stack base pointer

When generating a backtrace we need an indicator when we have hit the
beginning of the stack. The i386 ABI states that %ebp points to the next
stack frame. NULL can be used to indicate the end of the stack.

We could add a NULL return pointer at %ebp+4, but I decided to omit it
since a NULL stack pointer can be used as an indicator that there is no
return pointer.

TEST=built and tested on grunt

Change-Id: I8a48114d31a5c716335d264fa4fe4da41dc5bf11
Signed-off-by: Raul E Rangel <>
Reviewed-by: Martin Roth <>
Tested-by: build bot (Jenkins) <>
1 file changed