selftests/powerpc: Detect taint change in mitigation patching test

Currently the mitigation patching test errors out if the kernel is
tainted prior to the test running.

That causes the test to fail

selftests/powerpc: Detect taint change in mitigation patching test

Currently the mitigation patching test errors out if the kernel is
tainted prior to the test running.

That causes the test to fail unnecessarily if some other test has caused
the kernel to be tainted, or if a proprietary or force module is loaded
for example.

Instead just warn if the kernel is tainted to begin with, and only
report a change in the taint state as an error in the test.

Signed-off-by: Michael Ellerman <[email protected]>
Link: https://patch.msgid.link/[email protected]

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selftests/powerpc: skip tests for unavailable mitigations.

Mitigation patching test iterates over a set of mitigations irrespective
of whether a certain mitigation is supported/available in the kern

selftests/powerpc: skip tests for unavailable mitigations.

Mitigation patching test iterates over a set of mitigations irrespective
of whether a certain mitigation is supported/available in the kernel.
This causes following messages on a kernel where some mitigations
are unavailable:

Spawned threads enabling/disabling mitigations ...
cat: entry_flush: No such file or directory
cat: uaccess_flush: No such file or directory
Waiting for timeout ...
OK

This patch adds a check for available mitigations in the kernel.

Reported-by: Nageswara R Sastry <[email protected]>
Signed-off-by: Sachin Sant <[email protected]>
Tested-by: Nageswara R Sastry <[email protected]>
Reviewed-by: Russell Currey <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/163941374362.36967.18016981579099073379.sendpatchset@1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa

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selftests/powerpc: Use date instead of EPOCHSECONDS in mitigation-patching.sh

The EPOCHSECONDS environment variable was added in bash 5.0 (released
2019). Some distributions of the "stable" and "lo

selftests/powerpc: Use date instead of EPOCHSECONDS in mitigation-patching.sh

The EPOCHSECONDS environment variable was added in bash 5.0 (released
2019). Some distributions of the "stable" and "long-term" variety ship
older versions of bash than this, so swap to using the date command
instead.

"%s" was added to coreutils `date` in 1993 so we should be good, but who
knows, it is a GNU extension and not part of the POSIX spec for `date`.

Signed-off-by: Russell Currey <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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selftests/powerpc: Add test of mitigation patching

We recently discovered some of our mitigation patching was not safe
against other CPUs running concurrently.

Add a test which enable/disables all

selftests/powerpc: Add test of mitigation patching

We recently discovered some of our mitigation patching was not safe
against other CPUs running concurrently.

Add a test which enable/disables all mitigations in a tight loop while
also running some stress load. On an unpatched system this almost always
leads to an oops and panic/reboot, but we also check if the kernel
becomes tainted in case we have a non-fatal oops.

Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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