exercising current aarch64 kprobe support with systemtap

[William Cohen]

I dummied up the hw_addr_*.stp tests to not run.  The test made it further, but then got stuck spewing out:

[ 1648.037580] Unexpected kernel single-step exception at EL1
[ 1648.043060] Unexpected kernel single-step exception at EL1
[ 1648.048540] Unexpected kernel single-step exception at EL1


This happens during the "systemtap.onthefly/kprobes_onthefly.exp" tests  and can be reliably triggered running that portion of the systemtap tests with:

make installcheck RUNTESTFLAGS="--debug systemtap.onthefly/kprobes_onthefly.exp"


Seems like the tests get past the following and then start spewing the error message:

Executing: kill -KILL 22311
kill: kill: sending signal to 22311 failed: No such process
PASS: kprobes_onthefly - otf_stress_hard_iter_2000 (survived)

However the testsuite doesn't seem to make it through to print out the next test:

PASS: hrtimer_onthefly - otf_stress_max_iter_5000 (survived)

Note that this kernel (clone of https://github.com/pratyushanand/linux on test_upstream_arm64_devel branch) does have the patch to avoid having the atomic region search go before the start of a function by look for the "stp x29, x30, [sp, -#xx]!"

-Will