Change in coreboot[master]: arch/x86: Add support for catching null deferences through debug regs

[Robert Zieba (Code Review)]

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Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/63657

to look at the new patch set (#5).

Change subject: arch/x86: Add support for catching null deferences through debug regs
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arch/x86: Add support for catching null deferences through debug regs

This commit adds support for catching null deferences and execution
through x86's debug registers. This is particularly useful when running
32-bit coreboot as paging is not enabled to catch these through page
faults. To support this feature three new configs have been added:
DEBUG_HW_BREAKPOINTS, DEBUG_NULL_DEREF_BREAKPOINTS and
DEBUG_NULL_DEREF_HALT.

BUG=b:223902046
TEST=Ran on nipperkin device, verifying that HW breakpoints work as
expected

Change-Id: I113590689046a13c2a552741bbfe7668a834354a
Signed-off-by: Robert Zieba 
---
M src/arch/x86/Kconfig
M src/arch/x86/Makefile.inc
A src/arch/x86/breakpoint.c
M src/arch/x86/exception.c
A src/arch/x86/include/arch/breakpoint.h
A src/arch/x86/include/arch/null_breakpoint.h
A src/arch/x86/null_breakpoint.c
7 files changed, 422 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/57/63657/5