ARM processors save the PC value in the Link Register when they handle
and exception, but they store it with an added offset (depending on the
exception type). In order to make crashes easier to read and correctly
support more complicated handlers in libpayload, this patch adjusts the
saved PC value on exception entry to correct for that offset.
(Note: The value that we now store is what ARM calls the "preferred
return address". For most exceptions this is the faulting instruction,
but for software interrupts (SWI) it is the instruction after that. This
is the way most programs like GDB expect the stored PC address to work,
so let's leave it at that.)
Numbers taken from the Architecture Reference Manual at the end of
section B1.8.3.
BRANCH=none
BUG=chrome-os-partner:18390
TEST=Provoked a data abort and an undefined instruction in both coreboot
and depthcharge, confirmed that the PC address was spot on.
Change-Id: Ia958a7edfcd4aa5e04c20148140a6148586935ba
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/199844
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
4a914d36bb