selftests: Skip TM tests on synthetic TM implementations

Transactional Memory was removed from the architecture in ISA v3.1. For
threads running in P8/P9 compatibility mode on P10 a synthetic TM
implementation is provided. In this implementation, tbegin. always sets
cr0 eq meaning the abort handler is always called. This is not an issue
as users of TM are expected to have a fallback non transactional way to
make forward progress in the abort handler. The TEXASR indicates if a
transaction failure is due to a synthetic implementation.

Some of the TM self tests need a non-degenerate TM implementation for
their testing to be meaningful so check for a synthetic implementation
and skip the test if so.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210729041317.366612-2-jniethe5@gmail.com

selftests/powerpc: Skip tm-signal-sigreturn-nt if TM not available

On systems where TM (Transactional Memory) is disabled the
tm-signal-sigreturn-nt test causes a SIGILL:

test: tm_signal_sigreturn_nt
tags: git_version:7c202575ef63
!! child died by signal 4
failure: tm_signal_sigreturn_nt

We should skip the test if TM is not available.

Fixes: 34642d70ac7e ("selftests/powerpc: Add checks for transactional sigreturn")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191104233524.24348-1-mpe@ellerman.id.au

selftests/powerpc: Add checks for transactional sigreturn

This is a new test case that creates a signal and starts a suspended
transaction inside the signal handler.

It returns from the signal handler with the CPU at suspended state, but
without setting user context MSR Transaction State (TS) field.

The kernel signal handler code should be able to handle this discrepancy
instead of crashing.

This code could be compiled and used to test 32 and 64-bits signal
handlers.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Gustavo Romero <gromero@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>