Change in coreboot[master]: smm: Add canary to end of stack and die() if a stack overflow occurs

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Change subject: smm: Add canary to end of stack and die() if a stack overflow occurs
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Patch Set 2: Verified+1

Build Successful

https://qa.coreboot.org/job/coreboot-checkpatch/29369/ : SUCCESS

https://qa.coreboot.org/job/coreboot-gerrit/75317/ : SUCCESS